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EFFECTS OF DEPRESSION, STRESS AND OTHER FACTORS ON CRADLING BIAS IN SAUDI MALES AND FEMALES

ABDULRAHMAN DERBASH M. ALZAHRANI

Doctorate in clinical psychology The University of Edinburgh 2012 Declaration

I composed this thesis, the work is my own. No part of this thesis has been submitted for any other degree or qualification.

Name……………………………….. Date………………………………………

ii ACKNOWLEDGEMENTS

I am extremely thankful to His Excellency, The Minister of Higher Education Dr. Khalid Al Anqari, who granted me a scholarship to the University of Edinburgh, one of the leading academic institutions in the UK in which to carry out doctoral research in clinical psychology.

I would also like to thank my supervisor, Prof. Mick Power, for all the help that he provided during this research.

Many thanks go to all the Saudi families in the United Kingdom and in Saudi Arabia, for giving me a chance to carry out this work in spite of the many difficulties we faced; there was light at the end.

I would also like to express my thanks to the Saudi Embassy staff for all their facilities and encouragement.

Special thanks are due to my beloved parents, wife and sons for their patience and support all this time. It would not have been possible to do this research without their support and incomparable patience.

iii

This piece of work is dedicated to those who offered me all of their love and encouragement, which made me feel confident enough to carry out this work,

To my loving parents

&

To my Beloved Wife and Sons.

iv TABLE OF CONTENTS

Tables

Figures

Abstract

CHAPTER 1: BRAIN LATERALISATION AND CRADLING BIAS

Overview 1

Introduction 3

The incidence of cradling bias 4

Culture 9

Imagination 10

Left-side cradling in males 11

Investigation methods 14

Previous explanation 16

Handedness 16

Handedness in Islamic societies 22

Mother’s Heartbeat 23

Depression and Stress 25

Section summary 29

Hemispheric specialisation 30

Experience in parenting 34

Summary and conclusion 36

CHAPTER 2: LATERALISATION OF LANGUAGE AND EMOTION

Introduction 37

Laterality of the human brain 38

Handedness 43

Lateralisation of language 44

v Lateralisation of emotion (processing positive & negative emotions) 48

Section Summary 56

Lateralisation of emotion; auditory field studies 57

Section Summary 59

Lateralisation of emotion; visual field studies 60

Section Summary 61

Lateralisation of emotion and holding side 62

Summary and Conclusions 66

CHAPTER 3: BRAIN STRUCTURE

Introduction 68

The emergence of affective neuroscience 69

Brain structure 73

Amygdala 73

Posterior Cingulate Cortex 79

Inferior Frontal Gyrus 81

Dorsolateral Prefrontal Cortex 82

Insula 84

Orbitofrontal cortex 86

Basal ganglia 87

Section summary 89

Brain injury 91

Section Summary 98

Gender differences in the brain 99

Conclusion 104

vi CHAPTER 4: METHODOLOGY

Overview 106

The hypotheses for the study 108

Ethical Considerations 109

Methodology 110

The cultural comparison 112

Stimuli types 112

Design 114

Participants 115

Instruments 117

Beck Depression Inventory (BDI-II) 118

Perceived Stress Scale (PSS) 120

Waterloo Footedness Questionnaire-Revised 121

Edinburgh Handedness Inventory (EHI) 122

Dichotic Listening Task (DLT) 123

The equivalence of the Arabic and English versions 125

Videotaping 127

Procedure 128

Statistical analysis 129

Terminology 130

Limitations 131

CHAPTER 5 : PILOT STUDY

Dichotic listening Task 134

Reasons for carrying out a dichotic Listening Task 134

Introduction 134

vii Gender differences in Dichotic Listening 140

Summary 144

Pilot study 145

Methodology 146

Design 146

Ethic 146

The sample 147

Apparatus 147

Results 149

Discussion 154

CHAPTER 6

Overview 159

The questionnaire results 161

Was there a bias in the side of cradling real infants? 164

Was there a bias in cradling an infant-like doll? 167

Discussion 169

Summary and conclusion 175

CHAPTER 7: STATISTICAL ANALYSIS OF QUESTIONNAIRE RESULTS

Introduction 176

Analysis of preferred cradling side for a real infant 176

Analysis of preferred cradling side for a doll 182

Excluding doll cradling in the prediction of infant cradling and vice versa 185

Discussion 187

Summary and Conclusions 191

viii

CHAPTER 8: RESULTS AND ANALYSIS OF SPONTANEOUS

CRADLING EXPERIMENTS

Introduction 193

Methodology 194

Design 194

Ethics 194

Participants 195

Procedure 196

Results 196

Analysis of results for spontaneous infant cradling 197

From inter to stepwise 199

Analysis of results for spontaneous doll cradling 201

Discussion 206

Conclusion 208

CHAPTER 9:GENERAL CONCLUSION

Discussion of experiment and findings 209

Further research and implications 214

Limitations 216

Summary and conclusion 219

References 221

ix TABLES

DESCRIPTION Page

Ear Preference Right / left 149

Pearson Chi-Square for sex/Handedness and ear preference 150

Means and SD for the paired samples 152

Comparing mean scores of the emotion types 153

Total number and percentage of preferred cradling-side(stimulus: real baby) 161

Total number and percentage of preferred cradling-side(stimulus: doll) 162

Frequencies of stress, depression, handedness and footedness 163

Pearson Chi-Square of real baby cradling and the examined factors 166

Contingency Coefficient of real baby cradling preference and other examined factors 166

Pearson Chi-Square of doll cradling and the examined factors 168

Contingency Coefficient of doll cradling preference and other examined factors 168

Classification table 179

Classification table 181

The suggested predictors 184

Predictors after excluding “doll cradling” as a predictor from the equation 186

Predictors after excluding “infant cradling” as a predictor from the equation 186

Sample frequencies 195

Mean duration of cradling time 196

Mean and SD for the sample 197

Collinearity Statistics 199 descriptive statistics 202

The relationship between the two types of cradling 205

x FIGURES Description Page Broca’s and Wernicke’s areas 45 Amygdala 74 Posterior Cingulate Cortex 80 Inferior Frontal Gyrus 82 Dorsolateral Prefrontal Cortex 83 Insula 85 Orbitofrontal cortex 86 Basal ganglia 88 Infant-like doll 114 Participants’ group 117 Handedness and earedness 151 Ear preference and gender of participants 151 Baby cradling preference 161 Doll cradling preference 162

xi ABSTRACT Several studies have reported a strong bias in both human and non-human species for cradling their infants to the left side of the body. Most studies suggest that the main reason this phenomenon is the predominance of the right hemisphere of the brain for the processing of emotions and its transference, through brain laterality, to the left side of the body. Many other variables, including handedness, footedness, stress and depression have also been found to have some effect on cradling side.

However, no study has been published for an Arab population. Given the strong religious and cultural belief of most Arabs that only the right hand should be used for most daily tasks, this study investigated the affect on cradling side of this habit, in addition to the factors named above.

369 Saudi citizens took part in this study. 234 lived in Saudi Arabia and 135 had lived in the UK for five or more years. 267 were women and 102 were men. Each answered a questionnaire which asked about their ‘preferred’ cradling side and then the 102 men were videotaped spontaneously cradling a real infant and an infant-like doll. Unfortunately, only the male sample could be videotaped due to restrictions on filming females in Saudi Arabia.

The results confirmed those of previous studies by showing a very strong bias to left- side cradling. No difference was found between males and females in cradling a doll, or between the Saudi-based sample and the UK-based sample but the bias was significantly reduced in men. Apart from the influence of gender, the factors that reduced the cradling bias for a real infant were found to be lack of experience of parenthood, depression, stress and greater age of the infant. In cradling a doll, the most influential variables were handedness, footedness and depression.

Further work is required on Arab samples, especially in examining spontaneous cradling by women and its relation to depression and stress. A mother’s mental state is known to affect the health of the infant and cradling side could be a useful filter for neo- natal women who might require psychiatric treatment. Further research could also shed light on gender differences in the processing of emotion.

xii Chapter 1

Brain Lateralisation and Cradling Bias

1.1 Overview

The strong tendency of people, especially mothers, to cradle their infant children to the left side of their body is a behaviour that shows how the human brain is lateralised and can be affected by various factors. Although this cradling bias was first studied over fifty years ago by Lee Salk (1960), an American psychologist, more recently it has been investigated in different cultures and with males and females of different ages. There have been suggestions that cradling bias in males is absent or weak. However, there has been no single study carried out in the Middle East. One of the potentially interesting factors in the current study is the effect on cradling bias of the religious and cultural habit of Muslims in carrying out most daily tasks using the right hand, except for personal activities; this is true even for naturally left-handed

Muslims.

Nevertheless, left cradling bias is still observed in the Muslim culture. This leads us to conclude that factors other than handedness or footedness are involved in cradling behaviour, as will be detailed in the relevant chapters. Thus, it is interesting to investigate cradling bias in an Islamic country and to seek more explanations of this phenomenon.

The review of the psychological literature relevant to the present study focuses on recent studies that report cradling bias in human and non-human species, the effects

1 of depression and stress on that behaviour, and gender differences that may lead to different behaviour.

The keywords searched were “cradling bias”, “holding behaviour”, “effect of depression”, “effect of stress on behaviour”, “handedness”, “footedness”,

“laterality”, “lateralisation of emotion”, “regulation of emotion” and “sex differences” in all the available e-sources available at the University of Edinburgh

Library, such as Athens and e-journals services. Subsequently, some essential papers were ordered from the British Library via the Inter-Library Loan service. The most important search was on “Lateralisation of emotion” since this was key to investigating the effects of depression and stress on emotion and how affected emotion affects human behaviour.

In addition, all the available resources at King Abdulaziz University, Jeddah, Saudi

Arabia were used to search for literature on Muslims’ behaviours and beliefs, especially on how Muslims behave personally and socially in their daily lives and, in particular, on how toddlers are held. Other behaviours and studies with female- holders were excluded. Moreover, Even though Saudi males and females over 16 years of age were included in the current study, women were excluded from videotaping method but included in questionnaire data. Infant was excluded if he/she was over 15 months of age or was upset during videotaping method.

It moves from specific work on cradling bias to studies about brain activity and the specialisation of various parts of the brain. It is divided into three chapters. The first examines studies that have been conducted on cradling bias in human and non- human species. Chapter 2 reviews studies on lateralisation of language and emotion

2 because they facilitate holder-infant communication. Finally, chapter 3 looks at studies on the brain regions commonly reported to be involved in emotion and language.

The aim is to build a solid base for the present study.

1.2 Introduction

The term ‘lateralisation’ means that the human brain is made up of two hemispheres, which may have different functions, as discussed in Chapter 2. Differences in the brain’s structure and functions that result in differences in behaviour have been observed and reported. These differences are thought provoking for researchers and they have led to further investigations in an effort to discover the operation of the human brain.

Although each hemisphere of the brain has its own functional specialisations, some functions, such as language, are processed in both hemispheres; however, each hemisphere processes some features of that function. Studies have shown that grammar is processed by the left hemisphere, while tones and prosody are processed by the right hemisphere (e.g. Morais and Ladavas, 1987). The two hemispheres can communicate with each other through the corpus callosum, which is known as interhemispheric communication. Evidence for interhemispheric communication was first provided by Sperry, Hubel and Wiesel, who were awarded the Nobel Prize in

1981. Their findings were a good starting point for more recent investigations. The first marker of brain lateralisation was handedness, until the introduction of Wada’s

Sodium Amytal Test in the 1960s. Additionally, split-brain patients who have

3 undergone corpus callosotomies have provided rich information in terms of how the two hemispheres work independently and communicate with each other. This chapter will review previous studies that have reported cradling to the left-side of the body in humans as an aspect of brain lateralisation.

1.3 The incidence of cradling bias

This section will review previous reports of the incidence of cradling to the left side of the body in both human and non-human species. Cradling bias has been examined and investigated in many studies with different methods but, to the best of our knowledge, no studies have been carried out in Arabic countries either on this topic or on any other laterality issues in relation to the human brain. It would, therefore, be very interesting to try to test the results of previous research on cradling bias through an investigation of cradling behaviour in a culture that has not been studied.

Cognitive psychology is a new area of study in the Arabic region, and conducting such research could act as a trigger for more investigations, and a greater understanding of the patterns of human behaviour.

The mother-infant relationship has been described as a complex and unique human bond containing several different characteristics, such as cradling (Suter,

Huggenberger and Richter, 2009). In other words, cradling is a strong manifestation of the relationship between mother and infant in human and non-human beings. For this reason, it needs to be studied in more depth, taking into account the results of the previous research, and considering the effects of a range of possible factors. This study will examine those factors that might influence cradling bias amongst men and women from two different cultures, including handedness, footedness, mood state

4 (stress and depression), lateralisation of emotion, infant care experience, cradler gender, infant gender and culture. Because it will compare participants in Saudi

Arabia with participants from Britain, it will be a cross-cultural comparison study.

Several human and non-human studies (Hopkin, 2004; Manning and Chamberlain,

1990) have reported participants cradling infants to the left side of their body. In adult women, previous studies have shown rates of left side cradling of between 65% and 86% (e.g. Salk, 1973; Bundy, 1979; Bogren, 1984; De Chateau, 1991; Todd and

Butterworth, 1998; Bourne and Todd, 2004; Vauclair and Donnot, 2005; Reissland et al., 2009; Suter et.al., 2009; Huggenbuerger et al., 2009). This tendency seems to be independent of handedness (Saling and Tyson, 1981; De Chateau, 1978) and culture

(Finger, 1975; Saling and Cooke, 1984). Similarly, women showed left-sided preference in holding dogs whereas men did show the same preference (Abel, 2010).

Some psychologists have argued that this tendency might be unique to the cradling of infants because a bias has not been found in holding other objects such as books

(Scheman, Lochard and Mehler, 1978), packages (Weiland, 1964), vases or shoe boxes (Almerigi, Carbary and Harris, 2002).

Following previous research (Reissland, 2009; Vauclair and Donnot, 2005; Bogren,

1984; De Chateau, Maki, and Nyberg, 1982), cradling is defined as “holding the infant’ and cradling side as “the side of the mother’s body on which the infant’s head was positioned” (Reissland, 2007, p.3). Another definition holds that cradling preferences “are more directly linked to the emergent caregiver-infant social interaction system” (Dagenbach, Harris and Fitzgerald, 1988; p.220). According to

Finger (1975) and Grusser (1983), the left cradling bias which is apparent in works of art was originally reported some time ago. To our knowledge, the first study that

5 investigated the way that people cradle their infants was conducted by Dennis and

Dennis (1940) with Pueblo Indians, but the first that reported a left-side bias was carried out by Gaffron (1950). In this latter study, which examined paintings of mother and child, it was noticed that most cradlers tended to cradle to the left. Since then, the American psychologist Lee Salk has reported the incidence of this phenomenon in Western art, animals and human mothers (Salk, 1960, 1973).

Moreover, Finger (1975) carried out a more detailed analysis of patterns of infant holding in the works of 34 European and American artists and found that mothers showed a left-sided bias in holding a child. Interestingly for the current study, he found no significant preference for either side in pictures in which infants were held by males.

To assess the incidence of left-side cradling in art and photography that had been reported by Salk, Richards and Finger (1975) analysed a total of 268 photographs from Western, Eastern, and American Indian cultures. Their observations showed that women but not men showed a significant tendency to hold infants to the left side of the body in all the cultures they studied, suggesting that this preference is not restricted to geographical areas or even to a particular culture. Alvarez (1990) also observed this tendency in works of art through studying 71 pieces of pre-Columbian ceramics depicting infants and created between approximately 300 B.C. and 600 A.D

(37 were Mesoamerican and 34 were Andean). In these he found that 83% of the

Mesoamerican pieces and 54% of the Andean objects showed a left side cradling preference. However, it must be pointed out that whereas analysing photographs shows the preference of the holders, studying works of art may reflects the preference of the artist.

6 Lockard, Daley and Gunderson (1979) observed 1,916 adult-child groupings in public places in Seattle. They found that young infants were equally often carried by adult males and females, though very young infants were carried more often by adult females than by adult males did. In contrast, older infants were more often carried by adult males than by adult females. The gender and age of the held infant could thus affect the preferred side of cradling for both fathers and mothers. In this study, adult males carried older infants predominantly to the right side, in contrast to female adults, who carried them mostly to the left side. Although adult males did not show a predominant left-side bias in carrying young infants, they showed a slight tendency to cradle female infants to the left-side of the body, but this result was not statistically significant.

The recent studies that have been carried out on leftward cradling have stemmed from the observations of Lee Salk from 1960 onwards. In 1960, he published his first work as a result of his observations at the Central Park Zoo in New York. He examined the association between maternal behaviour and laterality of the developing infant in rhesus monkeys. Salk’s observations revealed that rhesus monkey mothers held their newborns to the left side during 40 of the 42 observations he made. Subsequently, Salk (1962) conducted a study examining the effect of the sound of the heartbeat on an infant. Two groups were used: control and experimental groups. Without any change in food intake, Salk found that the experimental group showed a significant increase in body weight and a decrease in the levels of stress and injuries compared to the control group.

In 1973, Salk undertook a similar study to investigate the way that human mothers cradled their newborn infants. The total number of mothers who participated was

7 287, 255 of whom were right-handed and 32 of whom were left-handed, and he observed them during the first 4 days after they had given birth to healthy infants.

83% of the right-handed mothers and 78% of the left-handed mothers showed a leftward cradling bias after their infant was presented directly at the midline of their body.

When they were asked why they cradled the way they did, right-handed mothers justified their preference by saying that it helped them to free their right hand for other tasks, whereas left-handed mothers explained their holding preference by saying that it was better to hold the baby in their left arm because they were left- handed (Salk, 1973).

Subsequently, Finger (1975), Bruser (1981), Bogren (1984), Harris and Fitzgerald

(1985), De Château (1987), Manning and Denman (1994), Harris, Almerigi and

Kirsch (2000) Almerigi, Carbary and Harris (2002), Victoria and Todd (2004),

Donnot and Vauclair (2005) and Donnot (2007) have reported a left-side cradling preference amongst both men and women.

In the arrivals lounge of an international airport, Turnbull, Stein and Lucas (1995) observed people greeting each other without them being aware that they were being observed. They found that women preferred to embrace to the left side, as is the case in cradling, but the tendency for men was to embrace to the right side, which is contrary to the hemispheric asymmetry theory, as detailed in Chapter 2.

In summary, and based on reviewing the literature, it has been found that about 60%

– 90% of women cradle their infants to the left side of the body.

8 1.4 Culture

The occurrence of cradling bias has been found in different cultures and races.

Several studies have reported strong evidence for the tendency of human beings to cradle their infants to the left side (e.g., Saling and Cooke, 1984). Studies carried out in Europe (for example, Bogren, 1974; De Château, Holmberg and Winberg, 1978), the United States (for example, Dagenbach et al., 1988; Salk, 1960), South Africa

(Saling, 1987; Saling and Cooke, 1984), and America Indian cultures (Finger, 1975) have all reported a tendency towards left-side cradling.

Left-sided cradling has also been reported when mothers were observed in a variety of locations and situations throughout the day, as in Saling and Cooke’s (1984) work in South Africa and Bruser’s (1981) Sri Lankan research with both Sinhalese and

Tamil women.

However, it has been found that leftward cradling is not universal. In Nakamichi's

(1996) study, the author found that, in Madagascar, 64% of women and 73% of men held their infants to the right side of the body. Thus, the observed sample had a significant right side bias. One methodological problem with this study is that infant size was not controlled for, and other infants may have been included in the study.

Thus, the effect of the infant’s size on child-holding patterns could explain this result, as had been discussed previously by Lockard, Daley and Gunderson (1979) and it could be also related to carrying children over long distances. However, the cultural effect explanation cannot be ruled out in this context because it is very clear that, in Madagascan society, there is a belief that the left side means bad whereas the right side means good (Nakamichi, 1996). Moreover, holders were carrying rather

9 than cradling, which means that to hold and carry an infant to the right side could help with better visual-field perception.

1.5 Imagination

Interesting results about cradling infants have been found by asking participants to put themselves in imaginary situations. In a study conducted by Almerigi, Carbary and Harris (2002), 300 university undergraduates were asked to imagine cradling/holding in their arms, first, an object (either an “expensive vase” or “an old shoebox”), and then an infant. They found cradling side biases to be significantly different from chance and from each other. Of the 300 subjects, the right arm was used by 64% for the imagined shoebox, by 81% for the imagined vase and by only

34% for the imagined infant. These results suggested that the left-side bias might be unique to infants, although the gender and handedness of the holder as well as the qualities of the imagined object were also found to contribute to the side and strength of the bias in this study.

In addition to these variables, experience of parenthood may be a factor that could play a critical role in cradling bias. This factor should be taken into account and careful attention paid to it because those who are not experienced in parenting may not be able to hold or cradle an infant as well as those who are experienced. Thus, the left-side cradling of infants may well be an innate behaviour in human and animals but the contribution of the experience of parenthood may also be important. Bearing this in mind, the current study was designed to test this factor along with other

10 factors, such as handedness and culture. Full detailed analyses and results of its experiments are presented in later chapters of this thesis (chapter 6, 7 and 8).

1.6 Left-side cradling in males

Despite the findings of different studies that have been carried out to examine the incidence of cradling bias in both human and nonhuman species, the contrast between the cradling behaviours of men and women is controversial because studies on men have produced very varied results. For example, Harris and Fitzgerald (1985) reported that both fathers and mothers showed almost the same left-side preference in a survey of photographs from developmental psychology textbooks. In other studies, few differences were found in left-side preference among mothers and fathers of newborn infants (De Chateau, 1983; Dagenbach et al., 1988). These photographic surveys were criticised for their under-representation of males, and the unknown infant age. As explained above, it is very important to take into account the age of the held infant in such investigations, because this affects the left-side tendency (Lockard et al. 1979; Manning, 1991).

To overcome these problems, Manning (1991) conducted a survey using a family album. These collections consisted of photographs of 1,119 women and 577 men.

Out of the total, 61% of the women showed a left-holding preference whereas only

47% of men did so. This bias was greatest when the men or women were holding a child who was aged three-months or less. Additionally, the women showed a consistent left-side holding bias for all infant age groups, but this was not true for the men. In this Manning (1991) survey, unlike previous surveys, each photograph was classified by the child’s age, gender, and his or her relationship to the adult, the

11 gender of the adult, and finally, the side of the cradling. The child’s age was estimated by the owner of the album.

In sum, observations of samples in natural situations are much better than those conducted in experimental laboratories and they are likely to provide good and accurate results. However, the normality of cradling or holding can be affected by the taking of photographs, leading to misleading results. Video-taping cradler behaviour is even better than using photographs, as it can allow for more spontaneity and more accuracy.

The first study that investigated the incidence of left-side cradling in males was carried out by De Chateau (1983), closely followed by Bogren (1984). The latter investigation began by observing fathers during their visits to maternity wards.

Surprisingly, 83% of fathers cradled their own newborn infants to the left side and only 17% cradled to the right. In addition to this, the study by De Château (1983) showed that 84% of fathers held their newborn infants against the left side of the body and a strong left-side cradling bias was found when fathers of older children held unfamiliar newborn infants (De Chateau, 1983).

However, the evidence for a left-side cradling preference in men is more problematical. Data from the USA (Abel, 2010) indicate that adult males exhibit no left-side bias, whereas the data for men in the Wolof tribe in Africa suggest that infants are held on the left side (Lockard et al, 1979). The latter is backed up by a study in Sweden by Bogren (1984), which found left-side cradling in up to 83% of fathers with their own infants. However, Bogren identified a correspondence between holding preference and the holder’s attachment to their own fathers or

12 mothers. That is, if the holder was more attached to the parent of his/her own sex, they were likely to be left-holders while, if their primary attachment was to the opposite sex parent, they were likely to be right-holders.

On the other hand, although a left cradling bias in males has been confirmed, this bias could be considered to be weaker compared with its incidence in females, especially in mothers. Furthermore, there is evidence that cradling bias is much weaker or absent when the cradler is a non-father, that is, has no parenting experience. 62% of 21 male students and 60% of 41 non-fathers held unfamiliar newborn infants to the left side (De Chateau, Holmberg and Winberg, 1978)

The absence or weakness of a left-side bias in males can be explained by the fact that cradling is a mostly feminine behaviour, especially in some societies like Saudi

Arabia. In other words, the mother is the primary provider of all the infant’s needs, such as breastfeeding, cleaning and being close to another person, while the male cannot meet some of those needs and is unable or unwilling to meet others. Since, for physiological, psychological and cultural reasons, cradling a baby is usually seen as a task that normally needs to be carried out by the mother, it can be seen as only an occasional task for males.

One of the studies that has considered genetics in this context is that of Davies and

Wilkinson (2006) who argued that, as the X chromosome contains more genes than the Y chromosome, sex chromosome genes can affect phenotype because male- specific genes are present only on the Y chromosome. These findings confirm the results of previous studies that reported the involvement of hormones in gender differentiation of the brain that contribute to gender differences in behaviour.

13 Previously, it had been widely reported in the psychological literature that females score more highly than males on verbal motor skills tasks of perception, and the retrieval of phonological and semantic information (Davies and Wilkinson, 2006).

Another possibility is a direct contribution of the X and Y chromosome genes to gender differences through imprinting. Females receive imprinted X chromosomes from both their mother and their father, while males receive only a single maternally imprinted X chromosome (Lenroot and Giedd, 2010).

Because only a small amount of research has been conducted on the cradling habits of men, this area requires further investigation.

1.7 Investigation methods

The methods that have been used for investigating the incidence of left-side cradling vary from one study to another due to the nature of the sample, the environment and the available facilities. For example, techniques used include surveys and self-report questionnaires and, recently, video-taping. Because videotaping is considered to be an accurate technique, it was used in the current study along with questionnaires.

Researchers have tried to explain the incidence of cradling to the left by means of factors such as handedness, lateralisation of emotions, the importance of the heartbeat, monitoring of the infant and socio-psychological factors. These explanations will be discussed in detail later in this chapter.

Because several studies (e.g. Nicollas et al., 1999; Dimberg and Patterson, 2000;

Vauclair, 2005) have confirmed that the right hemisphere of the brain is responsible for processing emotion (both its perception and expression), we can hypothesise that

14 it is possible that depression may reduce left-side bias because the right hemisphere controls the left side of the body. An interesting finding worth mentioning here is the study of Manning et al. (1991) which confirmed this lateralisation by covering the participants’ left eyes and discovering that this removed or reduced the tendency for left-side cradling. Thus, logical inference, based on previous findings, supports the hypothesis of the current study that depression affects/reduces left side cradling.

In order to examine the contribution of these factors (depression, stress, culture, handedness, footedness, sex and age of the holder, infant, and participant’s status), in this study, two stimuli were presented to the subjects, and the responses of the cradlers were observed and coded. The first stimulus was a real infant aged between one month and fifteen months. This age range was intended to test if left cradling bias declines as infants grow older, as suggested by Dagenbach et al. (1988). In agreement with Dagenbach et al.'s study, Todd (2007) found a significant left holding bias with infants aged up to 9 weeks but no holding bias after 12 weeks.

The second stimulus was a doll of the same size and weight as the real infant. This was because we wanted to find clear cradling behaviour, to control the examined variables and to investigate the differences between behaviour with a doll and behaviour with a real infant. We replicated previous studies by using a doll in the current research because we believed this would be helpful for investigating other factors, such as the influence of a real infant and a baby-like doll on the lateralisation of emotion and the role of culture. In other words, we wanted to investigate if there a difference between cradling a real infant and a doll.

15 1.8 Previous explanations

Some explanations for the predominance of cradling to the left-side have been suggested, such as the importance of the mother’s heartbeat, handedness, lateralisation of emotions, monitoring of the infant and socio-psychological factors.

The remainder of the chapter reviews the explanations that previous studies have suggested.

1.8.1 Handedness

For several decades, the large number of methods that have been used to measure and quantify handedness have led to some difficulties with its definition. Although some researchers argue that handedness can be defined as the writing hand in the literate population, more accurate definitions of handedness consider motor tasks in which the performance of each hand can be compared (Tapley and Bryden, 1985;

Triggs et al., 2000). For instance, self-reports, inventories and questionnaires, identification of writing, examining other actions such as throwing, holding or using scissors, have all been used to assess and define handedness in human beings

(Papadatou-Pastou, Martin, Munafo and Jones, 2008).

In the current study, handedness will be taken to mean an individual’s preference for using either the right or the left hand for different daily tasks. Despite culture, gender and other factors, right-handers constitute the majority of the world’s human population. It has been estimated that about 90% of people are right-handed (Annett,

2004) with a slight gender difference; 92% of females and 88% of males are right- handed (Hellige, 1993). Peters, Reimers and Manning (2006) reported that the

16 incidence of left-handedness is approximately 11% in females and 13% in males.

The factors that might determine handedness are debatable, and can be traced back to

Greek philosophers. However, discussing this is not within the remit of the current study. Generally, there is wide agreement that a number of genetic and environmental factors are responsible for determining handedness, although these factors are not well understood.

Several factors have been reported in various studies to play important roles in handedness formation in humans. For instance, gender (Gilbert and Wysocki, 1992), age (Ellis et al., 1998), maternal handedness and family history of sinistrality

(Annett, 1999), testosterone level (Tan, 1991), and history of early brain injury

(Rasmussen, 1977) have all been implicated.

Studies have shown that handedness and eye preference are significantly associated, and that the incidence of left-handedness is higher in males than females, whereas the incidence of left-eyedness is higher in females than males (Bourassa, McMaus and Bryden, 1996). More studies on gender differences for handedness have been carried out; Annett's (1999) study suggested that the displacement of a chance distribution of asymmetry more to the right in females than males by about 20% is the reason for the sex differences for handedness.

An interesting study was carried out by Ittyerah (2000) on the hand ability and hand preferences of 100 congenitally blind and 100 blindfolded sighted children. The sample age was between 6 and 15 years. The author found no differences between the rates of left-handedness of the blind and the sighted children. It was also found that the sighted children were faster than the blind children on some of the hand

17 ability tasks, and that lateralisation increased with age in both the blind and the sighted children (Ittyerah, 2000).

However, some recent findings are inconsistent with those of Ittyerah. Caliskan and

Dane (2009) investigated the association between handedness and eyedness among

1,387 sighted and blind children, of whom 823 (59.34%) were boys and 564

2 (40.66%) were girls. The gender frequency difference was significant (χ = 48.36, p<.001). In the total sample, they found that the incidence of left-handedness amongst boys and girls was significantly higher in blind than in sighted children

2 2 2 (both boys and girls: χ = 28.14, p <.001; boys: χ = 11.84, p<.001; girls: χ =

7.14, p<.001) (Caliskan and Dane, 2009).

A question addressed in some previous studies may be relevant and it is worth asking again. Does the season of birth affect the likelihood that a person will be right or left–handed? Studies of seasonal influence on the incidence of left-handedness are contradictory. One of these studies was conducted only on females (Leviton and

Kilty, 1979) and one was conducted only on males (Dellatolas et al., 1991). The latter found that handedness is not related to the season of birth. However, the authors found that the frequency of left-handedness was greater in those males born in the Summer and Spring than in those born in the Autumn and Winter, but this result was not significant. In the population, the incidence of left-handedness is lower in females than in males (Corballis, 1997) but the study of Dellatolas et.al. (1991) was conducted only on males and all the participants were in the French Army.

In 1999 Martin and Jones conducted a similar study on university students but they included the role of gender. Interestingly, this study confirmed the findings of

18 Dellatolas et al. (1991) that people born from March to July were more likely to be left-handed than those born during the other months. They also found that the proportion of left-handed students who were born during the period March to July

(43.9%) was significantly higher than the proportion of right-handed students

(33.4%) born during those months and the pattern of seasonal influence upon handedness did not vary significantly between males and females. Martin and Jones

(1999) argued that there are some factors that could play a role in hand preference among humans. They found a reliable association between handedness and reading difficulties in childhood, such as widespread dyslexia among children who were born during May to July.

Recent studies have not confirmed the seasonal influence upon handedness. Karev

(2008) reported that there is no association between month of birth and handedness.

By including sex as a factor, the distributions showed no association between month of birth and handedness either in females or in males. The results also showed no association between maternal or paternal age and handedness (Karev, 2008).

Milenković et al. (2008) also failed to confirm the influence of birth month upon handedness. They concluded that neither their right-handed groups nor their left- handed groups showed a birth asymmetry, compared with the normal population birth distribution. Comparing the right-handed with the non-right-handed groups, no between-groups difference was found in the seasonal distribution of birth

(Milenković et al., 2008).

In terms of the pathology related to handedness, Ramadhani (2006) reported that left- handedness is related to an increased risk of breast cancer, and these kind of

19 associations can be considered as a marker of physical diseases and psychological problems such as depression.

Klar (1999) argued that most psychologists tend to accept non-genetic models, such as rate of maturation of the cerebral hemispheres that is caused by excessive levels of foetal testosterone, and which can result in brain damage due to birth stress. In contrast, nurture models propose that prenatal and postnatal environmental events modulate the phenotypic expression of asymmetries (Fagard, 2006). These models challenge those of evolutionists, who believe that all individuals contain the same genotype and it is cultural influences usually produce left-handedness (Leland et al.,

1995). Furthermore, previous studies reported that about 18% of monozygotic twins are discordant for handedness (cited in Klar, 1999). A recent study was carried out by Medland et al. (2003) on a large number of twins and their siblings. They found no difference in left-handedness between twins and siblings.

Meer and Husby (2006) suggested that all motor skills are influenced by one’s handedness, and that it is a major determinant of functional cradling bias. Their study examined the relationship between handedness and cradling preference. The results, for 765 participants, roughly half of whom were women and half of whom were men, showed a clear tendency for participants to cradle a doll that was the same size as a baby in their non-dominant arm (p < .001). In addition, this tendency increased with the apparent age of the child and was present in both males and females, even though it was markedly stronger in women than in men. One possible explanation for this tendency might be that use of the non-dominant arm leaves the dominant arm free for other tasks when cradling.

20 Intuitively, this explanation seems sensible. However, Salk’s (1973) observations, as reported earlier, cast doubt on this, since the right-handed mothers explained their left-sided cradling preference using this explanation, but the left-handed mothers reported that they preferred to hold their baby in their 'better' arm (resulting in the same left-side cradling). The handedness explanation for cradling suggests that left- handed parents should show a cradling bias to the right of the body’s midline, but

Salk's study did not show this to be the case. Meanwhile, other explanations suggest that there are more factors at play here, including the increasing effect of handedness with increasing size of the infant (Bundy, 1979).

There are two different methods used to assess handedness. The first is by recording hand preference for everyday tasks, such as through questionnaires or interviewing participants, and the second method is based on measuring hand performance for a specific manual task, such as moving pegs. In adult studies, preference measures have been used much more frequently than performance measures (Mandal, Bulman-

Fleming and Tiwari, 2000).

Additionally, it should be recognised that using writing behaviour, for example, is not sufficient in itself to determine handedness because writing is a taught skill and can be influenced by teaching. Using a range of subjects' responses is a much better and more accurate method (Klar, 1999).

There are many handedness questionnaires that have been developed and used in different studies with different populations, such as The Dutch Handedness

Questionnaire designed by Strien (2002). However, the most often used are Crovitz and Zener (1962) questionnaire, the Annett questionnaire (Annett, 1970) and the

21 Edinburgh Handedness Inventory (EHI) (Field, 1971). These instruments are not reviewed here but it will be seen that EHI was used in the current study.

1.8.1.1 Handedness in Islamic societies

Because the current study was carried out in an Islamic society and with other

Islamic participants, this section presents a brief account of what handedness means to Muslims and how it is conceptualised and influenced by religious beliefs or inherited traditions.

Handedness means to prefer to use one hand more than the other. In Islamic societies, the “right hand” is a symbol of good things whereas the “left hand” is a symbol of bad things. Based on the Islamic sources, those who are doing good deeds are described as right-handed, and left-handed is a description of those involved in bad deeds. As a result of this, Muslims behave as right handed persons for most daily tasks, for example, greeting people, writing, eating, drinking and taking or giving things (Zverev, 2006). Therefore, the right hand is the preferred hand in nearly all of their activities. Interestingly, it is found in the Holy Qur’an that the “right hand” means ‘power’ that is, to perform an action strongly. Other meanings are also found in the Qur’an, involving oaths and blessings (Fakhr al-Dīn al-Rāzī, 2008).

Beliefs about the virtue of the right side are general in the Islamic culture. For instance, tinnitus is explained differently according to which ear it occurs in. If it is heard in the left ear, it means that you will have bad news and, if it is in the right ear, this means you will have good news. The same thing applies to eye twitches: twitching in the right eye means that you will meet a close or beloved friend but left

22 eye twitches portend the loss of one of your beloved relatives. Obviously, such beliefs are based on myth or superstition but they give some indications of how people in an Islamic society understand handedness and why people prefer to use the right hand for social activities. Though the right hand may have similar significance in other cultures (Mandal et al., 1999; Zverev, 2006), to our knowledge, Islamic societies are the most conservative with regards to people using their right hands to perform most things. Socially, it is not acceptable to drink, eat, pay or even wave to someone with the left hand, even if you are left-handed. Doing such things with the left hand is considered to be rude behaviour and, sometimes, it is taboo (Zverev,

2006). The question that arises from these observations is that, if the right hand is the preferred one in Islamic and other societies, how can we explain left-side cradling, and what is the contribution of handedness to this bias?

1.8.2 Mother’s heartbeat

The first researcher to suggest that left-side cradling cannot be explained by handedness was the American psychologist Lee Salk (1960; 1973), and this section discusses his heartbeat hypothesis. Based on Salk’s and other studies (e.g. Bourne and Todd, 2004), it might be concluded that handedness alone is unlikely to determine and explain the cradling behaviour of right- and left-handed mothers.

As detailed previously, Salk’s studies began after his casual observations of the behaviour if a rhesus macaque mother with her babies. After 42 follow-up visits, he found the mother monkey holding her infant on the left side of her body, close to her heart, on 40 occasions and only twice on the right side of her body. Therefore, Salk

23 concluded that this bias was not related to handedness because rhesus monkeys show no strong lateral preference for manual tasks. Instead, Salk explained this biased behaviour by referring to the imprinting of the mothers heart beat (Sieratzki and

Woll, 2002).

According to Salk’s suggestions, left-side cradling occurs in order to allow infants to be held close to the mother’s heart. His hypothesis was that mothers hold their infants over the pericardial area of the chest because the maternal heartbeat has been

“imprinted” on the foetus in the womb and it has a pacifying effect on the infant during the postnatal period. However, if this is correct, how can we explain left-side cradling of a doll, where almost the same bias was reported?

Another suggestion was that the sensation of having her own heartbeat “reflected” to her by contact with the infant’s body has the effect of reducing the mother’s own anxiety. This suggestion has relevance to the effects of a mother’s mood state on cradling side, which will be discussed in the following section.

However, Todd (2001) contradicted these findings by ruling out the heartbeat hypothesis. She argued that heartbeats cannot be heard when an infant is held upright near to the mother’s left shoulder. To prove this, she also carried out a study on a young mother diagnosed with ‘situs inersus’ and found that this mother showed the usual left-side cradling bias. With this condition, the mother’s heart is abnormally positioned to the right side of her body. This different positioning of the heart is called ‘dextrocardia’, and it is a rare condition that might be related to embryologic development, with an incidence estimation of one case in 12,019 pregnancies (Bohun et al., 2007).

24 In a longitudinal study on cradling preference, Todd and Butterworth (1998) recruited a 24 year old primigravida mother (a woman during first pregnancy) as a focal participant, along with her full-term, normally delivered, 40-day old boy infant.

Measured on 12 everyday tasks, the mother was considered to be right-handed.

Additionally, she had been diagnosed in childhood as having situs inversus with dextrocardia. The atypical position of the heart had been confirmed by her general practitioner. Another 20 right-handed primigravidae mothers (aged 26-41 years, mean age 32 years) were recruited as a control group. All participants were individually video recorded. Todd and Butterworth (1998) found that the focal participant held her baby to the left of the body midline in all trials in spite of the rightward positioning of her heart. The majority of 20 control participants also showed a left holding bias (16 of them held to the left), which is consistent with previous studies.

1.8.3 Depression and stress

The effect of stress and depression can be seen in our daily lives and it is very easy to note how our emotions can affect and guide our behaviours. Chapter 2 reviewed and discussed the literature on emotion. Emotions play a crucial role in our lives, and can be seen as enriching all our waking moments. Cacioppo et al. (2001 p.173) described their influence, proposing that “emotions guide, enrich and ennoble life; they provide meaning to everyday existence; they render the valuation placed on life and property.”

25 Although mood state affects all humans, research has demonstrated that it has specific and varied effects on mothers in particular. For instance, significant relationships have been found between infant cognitive development and maternal mood; Galler, Harrison, Ramsey, Forde and Butler (2000) carried out a longitudinal study of 226 women and their infants in Barbados, examining the relationship between infant feeding practices, maternal characteristics and infant outcomes over the first six months of life. The Zung Depression and Anxiety Scale was used to assess maternal depression and anxiety, and they found significant predictive relationships between mood and feeding practices.

A comparable study was carried out in South Bavaria, Germany, by Kurstjens and

Wolke in 2001. They found that maternal chronic depression has a significant effect on the cognitive development of children, and particularly on that of boys. In fact, maternal depression has also been considered as a risk factor for children's development in general, not only for their emotional development (Kurstjens et al,

2001).

There has also been found an association between maternal depressive symptoms and cradling side. Weatherill et al. (2004) found a significant left-cradling bias for mothers who were classified as non-depressed, and a non-significant right-cradling bias for those classified as depressed. However it has also been suggested that this bias might be due to stress rather than depression, as Reissland et al. (2009) found a right-side bias amongst 79 stressed mothers.

A reduction in left-side cradling in people with depression is likely to be because depression is known to induce a dysfunction of the right hemisphere. This is

26 indicated by a weaker left visual field advantage in the perception of chimeric faces by some people with depression (Donnot and Vauclair, 2007). Obviously, these findings show how depression can affect the right hemisphere, in which emotion is perceived.

Field (1984) found that the infants of depressed mothers show fewer positive facial expressions than negative ones, compared with infants of non-depressed mothers.

Reissland (2004) found that an infant’s emotional reactions can be affected by maternal depressed mood. In this study, infants of depressed mothers showed significantly fewer components of facial expression compared with infants of non- depressed mothers. Another interesting study carried out by Zekoski, O’Hara and

Wills (1987) showed how mothers' depressed moods can affect mother-infant interaction. They found that infants are sensitive to depressed moods and are less responsive to their mothers, who, in turn, are less successful in eliciting positive responses from their infants. This is in agreement with Hoffman and Drotar's (1991) study, in which they found lower positive interactions in mothers with depressed moods. Infants of depressed mothers were found to score significantly lower on corresponding interaction domains than infants of non-depressed mothers. The authors of this study argued that although mild to moderate symptoms of maternal depression may have been salient, these symptoms have selective effects on mother- infant interaction (Hoffman and Drotar, 1991).

Despite Weiland and Sperber's (1970) finding of an effect of anxiety on cradling bias, they concluded that anxiety is not the only factor that is responsible for that bias. Bogren (1984) supported these findings by suggesting that stress may lead to

27 rightward cradling. Additionally, Suter, Huggenberger and Schächinger (2007) found that stress reduced left cradling behaviour in female volunteers.

Reissland’s (2000) study of voice pitch in maternal vocalisation found that lower voice pitches were used while cradling to the left and had a soothing purpose while higher voice pitches tended to be used during cradling to the right side, and this had an attracting attention purpose. In that study, Reissland observed a left-side cradling bias among infants aged from birth to eighteen months old and found that mothers expressed their emotions to pre-verbal infants by using different pitches. Compared with the left cradler mothers, mothers who were right cradlers spoke with a higher mean pitch in order to attract their babies’ attention. The 18 mothers who cradled to the left had a mean pitch of 171.33 Hz (mean amplitude = 49.20 dB) while the 13 mothers who cradled to the right had a mean pitch of 221.11 Hz (mean amplitude =

55.78 dB) (Reissland, 2000).

In a three-year follow-up study on 35 right-handed mothers, De Chateau (1987) found a relationship between maternal anxiety and maternal parity. Consistent with previous studies (e.g. Weiland and Sperber, 1970; Bogren, 1984; Suter et al., 2009), the author suggested that cradling to the left reduces the mother’s anxiety.

It may be the case, then, that not only does mood status affect cradling side, but cradling side also affects mood status. In keeping with this, a review of studies carried out by Field (2010) found that postpartum depression has long-term negative effects not only on the infant’s health but also on his or her emotional, social cognitive and physical development. Infant-mother interaction is very important for infants' development. Less expressive language use and poor performance on

28 measures of cognitive–linguistic functioning has been found in infants of depressed mothers, resulting from affected early interaction (NICHD Early Child Care

Research Network, 1999). Additionally, depressed mothers have been found to be less sensitively attuned to their infants (Murray et al., 1996)

Also, Beardslee, et al. (1998), and Field (2010) found that parents’ depression can affect early interactions and may result in depressed children. Furthermore, the period of breastfeeding among depressed mothers tends to be reduced, with depressed mothers being reported to have significant breastfeeding problems and being unsatisfied with this feeding method (Dennis and McQueen, 2007).

1.8.4 Section summary

The effect of mood state is widely reported in the literature. The brain’s right hemisphere perceives and processes emotions, including the negative emotions of depression and stress. Studies have found a relationship not only between maternal depressed mood and infant cognitive development but also, as reported by Kurstjens et al. (2001), between maternal depression and infant development in general. The effect of depression on a mother’s behaviour has been observed during cradling her infant. Non-depressed mothers showed significantly greater left-side cradling behaviour compared to depressed mothers. Other studies suggested that stress is a better predictor than depression of cradling side. It could be inferred that the non- verbal communication between mother and her infant plays a critical role in infants’ early cognitive development. The absence of infant-mother interaction can lead to

29 depressed children and other child health problems (Dennis and McQueen, 2007;

Reissland, 2009)

1.9 Hemispheric specialisation

Another explanation of the left-cradling bias that has been investigated in previous studies is hemispheric specialisation. This explanation is not related to handedness and could be an alternative explanation for left-cradling bias. For instance, Sieratzki and Woll (1996) suggested that left-cradling facilitates the flow of affective information, and they proposed that the early mother-infant interaction is very important for both the mother and her infant (Sieratzki and Woll, 1996). Manning et al. (1997) and Reissland (2000) argued that the mother’s voice pitch is affected by her mood status. In their studies, they found that when a mother wants to soothe her infant, she uses a low voice pitch while cradling to the left.

It is possible that the reported left side cradling bias is a result of a specialisation of the right hemisphere of the brain for emotions, such as reported by Nicholl et al.

(1999); they found that the muscles on the left side of the face produce more intense emotional expressions than those on the right side. This is supported by a study conducted by Dimberg and Pettersom (2000). They showed pictures of angry and happy faces to 32 participants, and used facial electromyography (EMG) to detect resulting activity in the facial muscle regions of the participants. The participants’ responses showed larger zeugmatic EMG activity to happy facial stimuli and larger corrugator EMG activity to angry stimuli. These reactions were greater on the left side of the face, suggesting that the right brain hemisphere plays a predominant role

30 in the expression of negative emotions. Hauser (1993) found similar evidence using rhesus monkeys.

Although each hemisphere of the brain appears to have different information- processing abilities, emotions are thought to be processed in both the left and right hemispheres. However, there may still be specific roles for each hemisphere; it has been suggested that positive emotions are primarily expressed by the left hemisphere, whilst negative ones are associated with the right hemisphere (Fox and Davidson,

1986). This is not a unique situation; the laterality or cerebral hemispheric asymmetry of the brain, referring to both functional and biological differences, causes each hemisphere of the cerebral cortex to process information differently, resulting in, as Springer and Deutsch (1993 p. 13) put it, the “one-half of the brain directing behaviour”.

It is clear that facial expressions are a key method by which we convey all types of emotions, and this non-verbal mechanism is as important as verbal expression for human communication (Nandal and Ambady, 2004). The processing of facial expressions as a whole may also be somewhat hemisphere-specific. Mandal and

Ambady (2004), amongst others (e.g. Springer and Deutsch, 2003), concluded that the right hemisphere of the brain is most responsible for expressing and perceiving facial expressions (Manning and Chamberlain, 1991) while the left hemisphere is generally thought to be dominant for linguistic or verbal functions. If this is the case, then left-side cradling can be explained in terms of the specialisation of the right hemisphere for emotion processing due to the direct involvement of the right hemisphere.

31 The involvement of the right hemisphere in facilitating and enhancing auditory communication between mother and her infant has been investigated carefully.

Turnbull, Rhys-Jones and Jackson (2001) examined spontaneous leftward cradling in

53 hearing and deaf mothers. Although the involvement of the right hemisphere in processing prosody is well documented and well established, they argued that if the leftward cradling bias is related to the auditory content, then deaf mothers would not show that bias. Surprisingly, both the hearing and deaf groups, especially those who had been deaf from birth, showed a significant tendency towards left cradling. This finding does not support auditory content as a factor that determines left-side cradling.

Affective neuroscience is a new approach that can be considered as a reliable method for various investigations. For example, this method has allowed researchers to obtain reliable results when they examine visual and vocal communication between caregivers and infants. It has been found that this communication is facilitated by cradling to the left rather than to the right (Sieratzki and Woll, 1996; 2004). This suggestion is supported by the findings from a magnetic resonance imaging (fMRI) study of mothers responding to their young infants’ cries. More activity was found in the medial thalamus, medial prefrontal and right orbitofrontal cortices in healthy, breastfeeding, first-time mothers (Lorberbaum et al., 2002). Furthermore, a phonological task study was carried out using fMRI and it found a strong lateralised brain activation to the left in right-handed males, whereas this activity was distributed and bilateral in right-handed females (Shaywitz et al., 1995).

On the other hand, Bourne and Todd (2004) argued that gender has some influence on cradling side. They carried out an interesting study on 32 right handed university

32 students using a stimulus doll to examine the cradling side, and a chimeric faces task to test cerebral asymmetry. The authors found a relationship between cradling behaviour and lateralisation in women but not in men. However, the dominance of the right hemisphere for perception of facial expressions was found in right handed women with a left-cradling bias.

In agreement with Donnot and Vauclair's (2007) study on mothers in maternity hospitals, Vauclair and Scola (2009) argued that the left-holding bias is not a result of hemispheric specialisation in the perception of emotions in mothers. However, these findings seem to go against many previous studies (e.g. Sieratzki and Woll,

1996; Manning et al., 1997; Reissland, 2000). The role of the right hemisphere in the regulation of emotion, the significance of the left visual field (left visual advantage) and left auditory communication (left ear advantage) during infant-holder interaction, and finally the role of the right hemisphere in processing emotion can be taken as a coherent explanation of the left cradling bias, as has been confirmed previously by studies such as that of Harris et al. (2000).

From this discussion of the literature, it can be concluded that close emotional attachment is facilitated by the left cradling preference in healthy mothers. Logically, this can be inferred from women’s tendency to cradle to the left side of the body. The preferred left side for cradling is contralateral to the brain’s right hemisphere which is dominant for face and emotion processing (Bourne and Todd, 2004). More evidence comes from a supporting study that found that in positive and negative emotions, the left side of the face is more emotionally expressive than the right side

(Vauclair and Donnot, 2005).

33 On the other hand, no significant differences have been found in visual perception of affective signals between left and right cradlers in female students who cradled a doll, and it was suggested that other right-dominant functions could have a role in the left cradling bias (Lucas, Turnbull and Kaplan-Solms, 1993).

In addition to this, studies by Moscovitch and Olds (1982) and Davidson and

Schwartz (1976) demonstrated that men are less likely to show enhanced left-side facial expression than women. Thus, if the left cradling bias is associated with the lateralisation of emotion, if the perception of emotion is located in the brain’s right hemisphere, and if the contention that women exhibit more emotions than men

(Calni, 2002) is true, that would explain why a left cradling bias is found more among women than among men.

1.10 Experience in parenting

Parenting is an exclusive experience and it results in a special adult-infant relationship that can be enjoyed by those who are parents, live with a family with young children/infants or used to be parents. This is the understanding of parenting that will be used in the current study.

The role of childcare experience in cradling has previously been investigated by several researchers (e.g. Turnbull and Lucas, 1991; Bundy, 1979; De Chateau, 1983).

Turnbull and Lucas (1991) found that fathers (including new fathers) hold their children to the left side more often than non-fathers. This study reported that handedness, infant size, and previous experience in parenting do not contribute to the cradling preference in non-fathers. However, the authors concluded that the factors

34 that affect cradling side in fathers but not in non-fathers are not clear and fully understood, and need more investigation. Furthermore, there are some indications that cradling bias to the left-side of the body is weak or absent in males who are not parents (e.g. Turnbull and Lucas, 1990; De Chateau, 1983). In keeping with

Turnbull et al. (1991), Bundy (1979) claimed that women who were mothers cradled babies to the left more than non-mothers. If childcare experience affects cradling preference, it might also be the case that childhood experience of playing with dolls might also have a similar effect. Obviously this would be most notable in women, because men are less likely to have had this experience in their childhood. This idea is certainly not refuted by the finding that more men, especially non-fathers, hold babies to the right than do women (e.g. Turnbull et al., 1991).

Recently, Vauclair and Donnot (2005) have suggested that the brain’s right hemisphere has a leading role for the preferred side of holding an infant. They found significant correlations between the preferred holding side and the preferred visual field in right-handed-mothers and participants with care-giving skills. They assessed the relationship between holding side biases and hemispheric asymmetry in the processing of emotions displayed in faces by using two kinds of Chimeric Figures

Tasks. 210 university undergraduates were recruited. Most of them were under 25 years and the mean age was 22.4 years (S.D. = 4.92) for the men, and 21.9 years

(S.D. = 4.42) for the women. The effect of childcare skills was included as a factor by asking participants to report whether they had children of their own or had cared for sisters, brothers or other infants (Vauclair et al., 2005).

35 1.11 Summary and conclusion

This chapter has discussed lateralisation in the human brain and how, although the left and right hemispheres each have unique functions, they also work together. The tendency to cradle infants more to the left side of the body than to the right side of the body, even in non-human species, was then presented as an example of lateralised behaviour that demonstrates brain laterality. This phenomenon was reported to be independent of handedness, the gender of the holder, or even culture.

The incidence was found to be more frequent in women than in men, with infant size having some effect. Relying on previous studies, some suggestions were made about the factors responsible for producing or affecting the cradling side preference. These suggestions include the mother’s heart beat, handedness, mood state, hemispheric specialisation and experience in parenting. These factors, along with new factors investigated and examined in a different culture in the present study, will be further discussed in chapter 6.

36 Chapter 2

Lateralisation of Language and Emotion

2.1 Introduction

The use of the term ‘laterality’ in many studies leads us to look carefully at how it has been applied in the psychological literature in recent times in order to try to understand how it may relate to the current study. In fact, a clarification of the relationship between the structure of the nervous system and behaviour is one of the most important goals of neuroscience. However, ethical considerations restrict researchers from directly studying the nervous system during behaviour, and so indirect methods must be used. For the best understanding of laterality and the possible implications of hemispheric dominance, it is necessary to begin with a clear understanding of neuroanatomical concepts. The brain consists of two halves. These halves are called the right and left cerebral hemispheres. Although these hemispheres are connected by the corpus callosum, each of them has different functions (Springer and Deutsch, 1985), this will be discussed in Chapter 3.

The first observed differences between the functions of the two hemispheres were in motor control, that is, the fact that the left hemisphere controls the right half of the body and the right hemisphere controls the left half of the body (Sperry, 1968). This was reported during observation of paralysis patients, and these observations allowed researchers to assess the damage to specific hemispheres. However, the first scientific indication of laterality came through studying language processing. For

37 instance, in 1861, Paul Broca announced his discovery of the area that is responsible for the production of language, which is now known as Broca’s area. Damage to that area results in what is known as Broca’s aphasia. Finding this area was, in fact, the starting point for discovering its function. The detection of Broca’s area stimulated further investigations of brain lateralisation, and was followed by the discovery of what is called Wernicke’s area in 1874. Wernicke found that this area was directly involved in understanding written words. Broca’s and Wernicke’s areas are both found in the left hemisphere in about 90% of people. Despite the fact that each hemisphere is allocated certain functions, with the left hemisphere being dominant in the majority of people, this does not mean that the two hemispheres work independently. They communicate with each other via the corpus callosum.

2.2 Laterality of the human brain

The reason for reviewing studies on the laterality of the human brain is to obtain a clear understanding of the role of each hemisphere in cognition and emotion. This will help us to link our research findings to the results of previous studies and aid in understanding how bias in cradling might or might not be linked to interhemispheric biases for the processing of certain types of stimuli and the control of certain types of action.

As stated previously, the brain consists of two halves, and these halves are called cerebral hemispheres. The review of the literature in the current chapter will show that the first good evidence for the lateralisation of brain was produced by Sperry,

38 Hubel and Wiese (1960) after their research on split-brain patients. Brain lateralisation means that the left and right sides of the brain are different in their structure and cognitive functions; examples of such functions are the perception of external stimuli and motor behaviour. Lateralisation can be seen not only in human brains but also in the brains of some non-human species. Since it is widely believed that the study of atypical development can help us to understand typical development, it can be said that the most obvious evidence of this lateralisation is produced if damage occurs in one of the two brain hemispheres while the other remains healthy. These lesion studies, as they are called, can provide clear evidence of how certain brain functions are lost or impaired as a result of damage to particular brain regions. As an example of brain laterality, Williams and Evans (2003) argued that some forms of depression result from the involvement of specific lesions. They found some difficulties in assessing and diagnosing patients with depression after direct brain injury. They thought that some of the symptoms they found, such as frustration, fatigue, and poor concentration, are associated with damage in the right hemisphere, rather than being symptomatic of depression (Williams and Evans,

2003).

Gilmore (1998) found that damage to the right hemisphere can cause deficits in emotion recognition, as had been found in patients with disorders such as prosopagnosia (Heilman and Gilmore, 1998) and patients with acquired traumatic brain injury (TBI) (Green, Turner and Thomson, 2004; Ietswaart, Milders, Crawford,

Currie and Scott, 2008; McDonald, Bornhofen, and Hunt, 2009; Anderson and

Phelps, 2001; Sprengelmeyer et al., 1999; Calder, Lawrence and Young, 2001).

39 More evidence for the bilateral nature of the brain comes from split-brain studies, for example the study of the patient who underwent a corpus callosotomy for the treatment of epilepsy (Levy, Trevarthen and Sperry, 1972). By cutting some of the connections between the two hemispheres, interhemispheric communication was reduced and the two hemispheres were unaware of each other; Sperry (1968) suggests that the two hemispheres of the brain might be thought of as belonging to two different people. This means that the functioning of the patient’s brain was affected.

Despite the fact that each hemisphere of the brain has specific functional specialisations, there are some cognitive functions which are processed in both hemispheres, with each hemisphere processing some features of that function. A good example of this is language, where studies (e.g. Landis, 2006) showed that tones and prosody are processed by the right hemisphere whilst grammar is processed by the left hemisphere. This example shows that it seems that, although the different brain regions have different roles, but do not always act in isolation.

Recently, brain scans have been used to detect activation in particular areas of the brain and this has provided clearer evidence of how the human brain works. In such studies, a volunteer is exposed to a stimulus while a PET or a fMRI scan detects which part of his or her brain is activated; this indicates which part of the brain is responsible for the demonstrated behaviour. This method has enriched our understanding of many aspects of our psychology. Moreover, the discipline of affective neuroscience has not only made remarkable contributions to understanding emotion and mood but it has also gone beyond this by helping to explain the neural basis of emotion and its mechanisms.

40 Gazzaniga (1985) argued that the main function of the corpus callosum is to ensure that each hemisphere is aware of the activities of the other hemisphere. The function of each hemisphere is to control the body’s opposite side. For example, the right hemisphere controls the left hand and the left hemisphere controls the right hand.

Consequently, information received from one half of the body is transmitted to the opposite hemisphere (Andersen, Garrison, and Andersen, 1979).

It is believed that the main function of the corpus callosum is to connect the two hemispheres. However, alterations in its structure are found in psychiatric disorders such as schizophrenia and developmental disorders such as Down’s syndrome and developmental language disorders have also been found to be related to abnormalities in the size of the corpus callosum (Bloom, and Hynd, 2005).

In the last decade, the modular theory of the mind has been the most prominent in attempting to explain how the majority of people process information (Stacks and

Andersen, 1989). The modularity theory of the mind was first suggested by Jerry

Fodor (1983) and it holds that some brain functions, such as perception, language processing and language acquisition are modular, whereas other functions are not modular but controlled by a central processing system. However, despite the fact that this is a very popular theory among cognitive scientists, it is not universally accepted and there have been many criticisms levelled at it. One of these criticisms is related to the plasticity of the brain. Plasticity occurs when one region takes over the function of an injured region, especially in young people, as a “compensatory function”. Another criticism is that there appears to be communication between modules. For instance, watching someone’s lips while they speak is a good example of how the auditory module and the visual module can work together, especially in

41 people with hearing problems (Elman, Bates, Johnson, Karmiloff-Smith, Parisi,

Plunkett, 1996; Karmiloff-Smith, 1994; Prinz, 2006).

Thus, the two hemispheres are directly involved in processing some stimuli but they have different functions, and the corpus callosum acts as a mediator (Andersen et al.,

1979). This perspective, that is, the processing of information by both hemispheres, suggests that the brain is holistic in its processing of information (Floyd and.

Mikkelson., 2003) rather than modular. The majority of people and an even larger majority of right-handed people show standard hemispheric dominance (SD). That means that they have strong left hemisphere specialisation for language, and strong right hemisphere specialisation for other functions, including nonverbal communication (Geschwind and Galaburda, 1987). Geschwind and Galaburda

(1987) distinguished between standard and anomalous hemispheric dominance.

Although the concept of standard and anomalous hemispheric dominance contradicts the application of modular theory, the brain is still holistically processing information. That is, each hemisphere has its own function. However, the authors assumed that the distinction is not the same for every person; in some individuals these specialisations are reversed or symmetrical.

Additionally, the right hemisphere is responsible for the analogic, emotive, and holistic interpretation of incoming information, whereas the left hemisphere is responsible for the logical, analytical, and social interpretations of the same information (Stacks and Andersen, 1989). During conversation, for instance, people process the words spoken primarily in the left hemisphere, while the right hemisphere processes the nonverbal elements of the dialogue, such as facial expressions and gestures.

42 A third type of hemispheric dominance, suggested by Floyd and Mikkelson (2003) is mixed dominance (MD), a characteristic of people who share the marker characteristics of both standard and anomalous dominance. This group does not necessarily show evidence of a state that lies between standard and anomalous dominance, nor do they necessarily show a blend of left- and right-brained processing. Because only a little is known about MD individuals, MD is considered to be a default classification for people who have the markers of both SD and AD, but it is not a distinctive category in itself (Floyd et al., 2003).

Although there is a debate about which hemisphere is the more specialised for emotional memory, some studies have attempted to locate it even more specifically; for example, some studies have reported that the amygdala is strongly implicated in emotional memory. The amygdala appears to be responsible for the effect of emotion on perception by alerting us to events of which we are not aware (LaBar and Cabeza,

2006; Hardee, Thompson and Puce, 2008). The structures of the occipitotemporal neocortex, amygdala, orbitofrontal cortex and right frontoparietal cortices are responsible for the recognition of emotion. For instance, the amygdala can create the recognition of fear, while the basal ganglia and insula may play a role in disgust detection (Adolphs, 2002)

2.2.1 Handedness

Handedness, which means preferring to use one hand more than the other hand, is the most obvious result of human brain laterality. Handedness has been discussed in detail in chapter 1 as one of various factors that have been previously examined in

43 relation to the cradling bias. Different factors have been reported to underlie the development of handedness in humans, for instance, testosterone level (Tan, 1993), history of early brain injury (Rasmussen, 1977), age (Ellis et al., 1998), and maternal handedness and family history of sinistrality (Annett, 1999). However, an investigation of those factors is outside of the scope of this study. It suffices here to note this type of laterality as behaviour asymmetry.

2.2.2 Lateralisation of Language

The importance of language (both verbal and non-verbal) in facilitating communication between an infant and the person holding it has been reported in recent studies. Therefore, reviewing such studies could shed light on explanations of the cradling bias, especially given that, as will be shown later in this study, language is more likely to be processed in one hemisphere than the other and, hence, it may play a role in cradling bias.

The left and right hemispheres work as two control centres, with each hemisphere being responsible for certain functions. For example, the brain’s left hemisphere is mainly responsible for the processing of language, whereas the brain’s right hemisphere is specialised for nonverbal function (Gazzaniga, 1985; Levey et al.,

1972). The first of these observations is very relevant to the current study.

44

Figure 2.1

Broca’s and Wernicke’s areas

Moreover, Marangolo, Incoccia, Pizzamiglio, Sabatini, Castriota-Scanderbeg and

Burani (2003) have shown that patients with an injured right hemisphere respond to linguistic stimuli with overly literal interpretations. For accuracy purposes, the

Intracarotid Sodium Amytal Procedure (IAP) method is the most appropriate method for examining the dominant hemisphere for language. This technique is used to establish which cerebral functions are localised to which hemisphere (Westerveld,

Zawacki, Sass, Spencer, Novelly and Spencer, 1994). For instance, Rasmussen and

Milner (1977) reported that 96% of all right-handed and 70% of all left-handed participants in their study processed language in their left cerebral hemisphere;

Watson, Pusakulich, Ward and Hermann (1998) suggested that the remainder had right or bilateral hemispheric functions. This suggestion that the left side of the brain plays the dominant role in controlling speech has been examined and confirmed by

45 brain injury studies, and also by studies on language. The proportion of the left hemisphere's dominance for language has been estimated at between 92% and 99%

(Loring, Deador, Lee, Murro, Smith, Flaning, Gallagher and King, 1990). Loring et al. (1990) investigated the lateralisation of cerebral language in 103 patients undergoing an intracarotid amobarbital test that was part of their diagnostic preparation for epilepsy surgery. Generally, bilateral language representation was exhibited in most patients. Based on Wada memory difference scores, 79 of the 103 patients showed exclusive left hemisphere language representation and only two patients showed exclusively right hemisphere language representation. Additionally, the tests showed that language restricted to the right hemisphere was rare and it occurred only when left hemispheric language processing was completely absent.

The remaining 22 patients had “bilateral language“ representation, that is, language was represented in each hemisphere and, of these, 17 had “asymmetrical language” representation.

Studies (e.g. Knecht, Drager, Deppe, Drager, Bobe, Lohmann, Ringelstein, and

Henningsen, 2000) show that approximately 95% of healthy right-handed subjects have left-hemispheric dominance for language.

Although the pattern of cerebral language asymmetry is not very clear in mixed- handed patients, they are believed to have left cerebral hemisphere dominance for language. However, the incidence of atypical language lateralisation in healthy non- right-handed people is higher than in healthy right-handed subjects (22% vs 4–6%)

(Szaflarski, Binder, Possing, McKiernan, Ward, and Hammeke, 2002).

46 In a study on individuals with unilateral hemispheric lesions, Zaidel and Benson

(1985) calculated the incidence of aphasia in mixed and non-mixed-handed populations. They found that 60% of the mixed-handed patients with damaged left hemispheres developed aphasia, whereas only 32% of the non-mixed-handed group with left hemispheric damage developed language impairments. Additionally, only

2% of the mixed-handed patients with right brain injury become aphasic, compared with 24% of the non-mixed-handed (non-dextral) patients who had injury to the right hemisphere. Still looking at brain injury studies, Graves and Landis (1990) reported no aphasia or speech articulation difficulties in patients who had a large lesion in the right hemisphere. This lesion resulted in weakness of the muscles of the left side of the lower face, including the lip region. On the other hand, when the lesion was found in the left hemisphere, especially in Broca’s area, a weakness in the right side of the lower face was found, including the lip. This resulted in misarticulation and a failure to produce normal sentence structure and content (Graves and Landis, 1990).

The brain’s right hemisphere controls only the muscles on the left side of the mouth, and so it is possible to speak relatively normally with impairments in this area, although there may be some impact on articulation. However, it is not possible to speak normally without an intact left hemisphere, because the part of the brain that is responsible for speaking is located there.

47 2.2.3 Lateralisation of emotion

2.2.3.1 Processing positive and negative emotions

Emotion is very important in our daily life. Successful emotional communication results in better social interaction because the prosody or the tone of voice that we use facilitates our understanding of each other. During speech perception, for example, monitoring and rapid detection of mood are necessary in order to adapt our subsequent speaking behaviour to the circumstances. Intuitively, verbal and non- verbal language (e.g. prosody and intonation) contribute to our full understanding of others, because it does not make sense to use happy words with a very sad facial expression. They definitely do not go together!

The impact of the brain’s asymmetry on various aspects of functioning is well documented in the literature, but despite this, the lateralisation of emotion (as an aspect of this asymmetry) is still considered a controversial topic. For instance, the relationship between hemispheric asymmetry and face-recognition has a long history in psychology, but studies have only recently been conducted on the perceptual laterality of facial expressions (Moscovitch and Olds, 1982). The ways in which the asymmetrical nature of the brain could affect cradling bias in human beings as been discussed in chapter 1 but it is clear that human facial expressions are a gate to the brain side of the emotional states because more expressions have been reported an association between activations in the left side of the face-right side of the brain.

In Fox and Davidson’s study (1986), the responses of two-day-old infants, who were given sugar water and citric acid separately, were recorded by EEG. Greater activity of the left hemisphere was obvious after the infants tasted sugar water than after they

48 tasted citric acid. These findings support the hypothesis that the left hemisphere plays a role in perceiving positive emotions and that the right hemisphere plays a role in perceiving negative emotions.

Other studies have established that the right hemisphere is used for the perception of emotion (Campbell, 1982; Leventhall and Tomarken, 1986; Bloder, Bowers and

Heilman, 1991; Snow, 2000; Kucharska-Pietura et al., 2003, Smith and Bulman-

Fleming, 2005; Sim and Martinez, 2005; Ross, Prodan and Donnot, 2007).

But the question of whether the right hemisphere is used for the production of emotion is still controversial although Hauser (1993) argued that the left side of the face – and the right hemisphere - is involved in emotional expression.

Because emotional expressions, whether auditory or visual, can be regarded as patterns of social communication and emotional responses, it seems that the right hemisphere certainly influences the visual field and auditory communication factors.

This outcome has been confirmed in studies by Manning et al. (1991) and Sieratzki et al. (2002), as mentioned above.

Interestingly, Alves, Aznar-Casanova and Fukusima (2009) found that the right hemisphere is superior to the left hemisphere for processing facial expressions of fear and happiness after a stimulus is displayed in the left visual field. In addition, this study showed that positive expressions, such as surprise and happiness, were perceived more accurately and faster than negative ones (Alves et al., 2009).

Many studies have shown the role of the amygdala in the perception and experience of a negative affect (for example, Davidson and Irwin, 1999; LeDoux, 2003; Phelps and LeDoux, 2005) (for further details see chapter 3). Other studies have reported

49 that the amygdala is important in processing attention and memory (Irwin et al.,

2004) and also in the consolidation and retrieval of emotional memories (Canli and

Amin, 2002; Davidson and Irwin, 1999). Others have suggested that the amygdala may play a role in the perception of emotion, and go on to elicit other processes

(Adolphs, 2002; Williams, Weilman, and Geany, 2005).

Many theories and debates have been raised about the laterality of emotion, some stemming from empirical studies and others from philosophical enquiries. Of course, they may shed light on the majority tendency towards left-side cradling, and provide enlightenment for future studies. This factor, that is, the lateralisation of emotion, has been tested in many different studies, for example, Campbell (1982) and Leventall and Tomarken (1986). These studies have demonstrated the role of the right hemisphere in emotional monitoring.

Although Lucas, Turnbull, and Kaplan-Solms (1993) found no significant differences in the visual perception of affective signals between left and right cradlers in female students who cradled a doll, the lateralised perception of emotions has been reported in visual field studies (Bourne and Todd, 2004; Vauclair and Donnot, 2005).

There are two main theories of emotional asymmetry. The right hemisphere hypothesis suggests that the right hemisphere is dominant over the left hemisphere for all forms of emotional perception and expression. However, the valence hypothesis states that the left hemisphere is dominant for positive emotions, whereas the right hemisphere is responsible for negative emotions. This theory suggests that the hemispheric asymmetry depends on emotional valence regarding the expression and the perception of emotions (Hellige, 1993). In an attempt to reconcile these

50 theories, it has been suggested that the right hemisphere is dominant for emotional experiences and the level of activation of the right hemisphere determines either negative or positive emotional experience. Based on that, underactivation of the right hemisphere is associated with positive emotional experiences while overactivation of that hemisphere might be correlated with negative emotional experiences (Hellige,

1993).

Moreover, recent findings have claimed to reconcile the right-hemisphere and valence hypotheses, suggesting that the perceptual processing of both positive and negative emotions is a function of the right hemisphere (Sato, Yoshikawa,

Kochiyama, and Matsumura, 2004; Sato and Aoki, 2006) whereas the valence function is presented as another hemispheric specialisation for experiencing emotions and displaying facial expressions (Davidson et al., 2002; Gray, Braver and Raichle,

2002; Lennox, Jacob,Calder, Lupson, and Bullmore, 2004).

Thus, although each hemisphere of the brain appears to have different information- processing abilities and inclinations, emotions are processed in both the left and right hemispheres. It is suggested that the left hemisphere is used for expressing positive emotions, whereas the right hemisphere is responsible for the negative emotions, as mentioned in the second theory. This is supported by a study conducted by Fox and

Davidson (1986). It is well established that biological and functional differences between the right and left hemispheres of the brain cause each hemisphere of the cerebral cortex to process information differently, or, as Springer and Deutsch (1998, p.13) put it, the “idea of one-half of the brain directing behaviour”.

51 To examine the involvement of the right and left hemispheres in processing emotion, a study was carried out by Ross, Homan and Buck (1994) for neurosurgical purposes using the Wada test. Patients were injected with amobarbital into the right and left internal carotid arteries, and then asked to recall emotional life events. When the right hemisphere was deactivated, the subjects substituted the basic emotions they recalled with social emotions. Tamietto, Adenzato, Geminiani and Gelder (2007) suggested that the production of basic emotions occurs in the right hemisphere, and the left hemisphere is responsible for social emotions, especially positive emotional expressions, because such expressions have been attributed to social communication and conventions. In other words, it is good and polite to smile in public places rather than showing anger (Heller, 1997).

From a more theoretical standpoint, a similar explanation suggests that the right hemisphere is responsible for processing and activation of innate emotional schemata, whereas the left hemisphere is associated with control (Buck et al., 1992;

Gainotti, 2001).

Esslen, Pascual-Marqui, Hell, Kochi and Lehmanna (2004) conducted a study using low resolution brain electromagnetic tomography (LORETA) to identify the brain regions that are involved in emotional processing, and to follow the time sequence of this processing. They recruited 17 healthy, right-handed subjects with different emotional and neutral faces. The participants were shown emotional faces and asked to generate the same emotion that was presented in the shown faces. After presenting the stimulus, significant differences occurred in different time segments within the first 500 milliseconds. In addition to this, different patterns of activation were found in the different brain regions over time for each emotional condition. The interesting

52 finding was that the highest activation was in the right frontal areas in the majority of time segments, and the strongest activation was detected in extended fronto-temporal areas in the happy, sad and disgust conditions. In addition, activation was produced earlier in response to the sad, happy and disgust conditions than to anger and fear.

Given that these findings are consistent with the results of many brain-imaging studies using PET and fMRI, the LORETA imaging techniques that were used by

Esslen et al. (2004) provided the opportunity to follow the time sequence of emotion processing at a millisecond-range resolution.

There are two main methodological approaches used by researchers to investigate emotional functioning in the two hemispheres: the visual field technique for visual modality and the dichotic listening technique for auditory modality. Studies investigating visual modality have confirmed the role of the right hemisphere in the processing of emotion. Research by Sackeim, Gur and Saucy (1978) showed that emotions are more strongly expressed on the left side of the face, and other research has shown that emotional recognition is more accurate in the left-visual field ((Ley and Bryden, 1982; Indersmitten and Gur, 2003). These findings have been confirmed by use of the chimeric faces task, for instance in Levy, Heller, Banich and Burton's

(1983) study, which reported a significant right hemisphere arousal in right handed participants but not in left handed ones.

Nicholls et al. (1999) found that the muscles on the left side of the face produce a more intense emotional expression than those on the right side. This followed

Sackeim, Gur and Saucy’s (1978) suggestion that the right hemisphere is involved in the production of emotions. Supporting this is a study conducted by Dimberg and

Pettersom (2000) in which pictures of angry and happy faces were shown to 32

53 subjects. Facial electromyography (EMG) was used to detect resulting activity in the facial muscle regions. The subjects’ responses showed larger zeugmatic EMG activity to happy facial stimuli and larger corrugator EMG activity to angry stimuli.

These reactions were greater on the left side of the face than on the right side. Hence, it appears that the right brain hemisphere is predominant when negative emotions are expressed. Hauser (1993) found similar evidence for rhesus monkeys; he found that monkeys display fear grimaces on the left side of their faces earlier than on the right side. Likewise. Wallez and Vauclair (2010) found a strong and significant left hemimouth bias for screeching in Olive baboons, thus confirming the dominance of the right hemisphere for emotion processing. These animal findings were confirmed in Vauclair’s et al. (2005) study with humans in which they found that the left side of the face is more emotionally expressive than the right side for both positive and negative emotions. This supports the argument that, in humans, the right hemisphere has a crucial role in processing both positive and negative emotions expressed in faces (Szelpgl and Fersten, 1991).

Both verbal and non-verbal mechanisms are vital for human communication, and facial expressions are capable of conveying a wide range of emotions (Mandal and

Ambady, 2004). It can be concluded, therefore, that the right hemisphere of the brain is mainly responsible for expressing and perceiving facial expressions, whereas the left hemisphere is generally thought to be dominant for linguistic or verbal functions

(for example, Springer and Deutsch, 1998).

In the facial expression of emotion, both positive and negative emotions can be correctly identified, because emotion is disrupted more by injury to the right hemisphere than to the left hemisphere (Bowers et al., 1985). Also, prosody and

54 intonation of speech can be disrupted if the right hemisphere is injured, regardless of whether the emotion being expressed is positive or negative (Hellige, 1993).

Additionally, the earlier findings of asymmetry of facial expressions in the majority of the population led Moscovitch and Olds (1982) to conclude that the right hemisphere governs these expressions more than the left one does. The majority of clinical research into facial emotion has focused on differences in the size, intensity and mobility of expression between the left and right sides of the face (Campbell,

1982; Sackheim and Gur, 1978; Borod and Caron, 1980; Ekman, 1981; Kowner,

1995). Perhaps the most relevant finding, as mentioned earlier in this chapter, is that the left side of the face is significantly more expressive than the right side for posed and pleasant emotions.

Recently, the ability of humans to accurately decode facial expressions has been found to be affected by the nature of the display itself and by the character of the decoder. Considering handedness, familial sinistrality and immune disorders, Floyd and Mikkelson (2003) investigated the effects of biological sex and neurological hemispheric dominance on the ability of participants in their study to decode facial expressions accurately. In this study, participants were classified as having anomalous, standard or mixed hemispheric dominance. They found thattheir abilities to decode facial affect displays from photographs were influenced by sex and hemispheric dominance and interaction. In addition to this, the most accurate decoding of facial emotion was found in mixed hemispheric dominance females, whereas mixed hemispheric dominance males had the lowest accuracy (Floyd and

Mikkelson, 2003). These findings are consistent with previous studies, such as those of Yen (1975) and Sanders, Wilson and Vanderberg (1982).

55 In an interesting study conducted by Ross, Prodan and Monnot (2007), it was found that the facial blends of emotion could be more easily and accurately seen in the upper–lower than the right–left hemisphere. The lower facial emotions are processed preferentially by the left hemisphere, whereas the upper facial emotions are processed preferentially by the right hemisphere.

The human face does not only give us information about age, sex, race and other personal characteristics but also it can be used as a window into the inner feelings and moods. That is why we need to observe and record movements of facial muscles. Recently, some studies have used digital video cameras recording about 25 frames a second to enable researchers to identify all types of facial emotions easily and precisely.

Thus, the study of the asymmetry of facial expressions is considered a means by which to study the hemispheric lateralisation of emotions. However, it remains a controversial topic and different approaches may be needed in order to understand fully how facial expressions are modulated by the human brain. Nevertheless,

Bourne and Todd (2004) argued that gender has some influence, and Davidson and

Schwartz (1976), Moscovitch and Olds (1982) and Huang (2009) demonstrated that women are more likely than men to show enhanced left-side facial expressions.

2.2.3.1.1 Section Summary

From this chapter it can be concluded that emotion is very important in our lives.

Studies show that some regions in the human brain, such as the amygdale, are involved in emotion processing. More recent studies have focused on the

56 lateralisation of emotion and the role of the brain’s right hemisphere in processing emotion. The dominance of the right over the left hemisphere in the perception and expression of emotion forms one of the main theories concerning the processing of emotion. However, valence theory states that the right hemisphere is responsible for negative emotions and the left hemisphere is dominant for positive emotions. Studies have used both visual field and auditory field methodologies to investigate emotional function in the two hemispheres and, supporting the notion of right hemisphere advantage in emotion processing, emotional recognition has been found to be more accurate in the left-visual field. The facial expression of emotion has been found to be more accurate in the left than in the right hemiface, meaning that the left side of the face is more emotionally expressive that the right side for both negative and positive emotions.

2.2.3.2 Auditory field studies

Studies of laterality in the auditory domain (or 'auditory laterality') can provide other evidence of the pattern of human brain laterality. In the anatomy of the corpus callosum, the most famous method used to research auditory laterality is the dichotic listening task. This technique involves presenting two auditory stimuli to the left and right ears at the same time. The participant is asked to report which stimulus they perceive more clearly. The participant’s response reflects which hemisphere he or she uses to process that type of information. In cognitive neuroscience and neuropsychology, the dichotic listening task can be considered as an easy way of

57 studying brain laterality (Kimura, 1961). Since the work of Kimura in 1961, this technique has been widely used for both adults and children.

In distinguishing between auditory and phonetic levels of speech processing, a right ear advantage (REA) was reported by Studdert-Kennedy, Shankweiler and Pisoni

(1972). Recently, the REA for speech processing has been widely corroborated by numerous studies such as those of Pujol, Deus, Losilla and Capdevila (1999),

Foundas, Corey, Hurley and Heilman (2006), and Westerhausen and Hugdahl

(2008).

On the other hand, a left ear advantage (LEA) for emotional information processing is also well documented. For instance, Sim and Martinez (2005) concluded that a left ear advantage (LEA) was obtained for recalling emotional words rather than non- emotional ones. Sim and Martinez (2005) used dichotic word-pairs of emotion and non-emotion words to demonstrate with which ear emotion words can be remembered more accurately. In this study, 62 participants were asked to listen to emotion words and non-emotion words. A left ear advantage was found for the emotion words. That is, during the dichotic listening task, the ipslateral pathways may be suppressed, and all stimuli travel contralaterally to the opposite hemisphere because the contralateral pathways appear to be stronger than the ipslateral pathways

(Kline, 2009). This outcome confirms the view that the right hemisphere has a stronger memory for emotion words. This result also supports the importance of the role played by the right hemisphere in the perception of emotion.

In terms of auditory modality, most studies that have used listening tasks have relied on the pitch, length and loudness of vocalisations to import a prosodic feature.

58 Evidence of speech prosody being processed in the right hemisphere led Turnbull and Bryson (2001) to state that this finding is a key to understanding why mothers cradle their infants more to the left side of the body. However, this study was criticised by Sieratzi and Woll (2002) who stated that although there is an agreement about the role of communication between mother and infant, it was the auditory modality that mattered most. If this is true, how can other types of sensory modality between mother and infant, such as visual and skin-to-skin contact be explained?

Contradicting the importance of the auditory role, Sieratzi and Woll (2004) found that even deaf mothers showed as much left cradling as non-deaf mothers did. Even though Sieratzki and Woll have the right to defend their own theory in this context, the findings of Turnbull et al. (2001) still support the left ear advantage in emotional words (sounds) which are processed in the right hemisphere.

2.2.3.2.1 Section Summary

Human studies on auditory laterality have provided evidence on how the human brain is lateralised, even though the two hemispheres are connected via the corpus callosum. Dichotic listening tests are a widely used technique for detecting this laterality by presenting auditory stimuli to the left and right ears at the same time.

Participants’ reports about which stimulus they perceived more clearly helps the researcher to decide which hemisphere is most involved in that process.

Numerous studies have found a right ear advantage (REA) for speech processing, whereas left ear advantage (LEA) has been reported for emotional information processing. Additionally, emotion words have been reported to be remembered better

59 when heard through the left ear. Thus, there is much evidence for the role of the right hemisphere in the perception of emotion. The involvement of the right hemisphere in processing speech prosody has led some researchers to conclude that this could be an explanation for the marked tendency of mothers to cradle their infants to the left side of the body.

2.2.3.3 Visual field studies

In the 1960s, the studies by Sperry and colleagues (cited by Wade, 2009) on split- brain injury patients concluded that cortical commissures are critical for interhemispheric communication. When two pieces of information were presented to the different hemispheres (by means of the left and right visual fields), patients were unable to compare them with each other (Trevarthen, 1990). Livingstone and Hubel

(1988) justified their proposal of receptive field biases of the two hemispheres by referring to differences in the neural pathways that transfer the visual information from the retina to high levels of the visual system. These visual pathways are referred to as the transient (magnocellular) and the sustained (parvocellular) pathways, and the difference between them is that the neurons in the magnocellular pathway have larger receptive fields than the neurons in the parvocellular pathway. This means that more input is provided by the magnocellular neurons that are processed in the right hemisphere (Kosslyn, Chabris, Marsolek, and Koenig, 1992).

The role of the right hemisphere in processing information presented to the left visual field has been reported in several studies. For instance, Hellige (1996) concluded that a stimulus presented to the left visual field projects directly to the right hemisphere

60 and a stimulus presented to the right visual field projects directly to the left hemisphere.

Recently, a study by Sala, Darling and Logie (2010) supported the role of the left visual field in perception and also in remembering. The authors suggested that items are better remembered if they are presented in the left visual field, pointing to the involvement of the right hemisphere in this task. They concluded that their findings indicated a spatial asymmetry in retrieving or forming feature bindings in the visual short-term memory.

2.2.3.3.1 Section Summary

Since the 1960s work of Sperry and colleagues on split-brain injury patients, more recent studies have supported their findings. For instance, studies have reported that a stimulus presented to the left visual field projects directly to the right hemisphere of the brain and a stimulus presented to the right visual field projects directly to the brain’s left hemisphere.

Support for the involvement of the brain’s right hemisphere in processing left visual stimuli was found in observations that items are better remembered if they are presented in the left visual field. In non-human species, more attention was detected when a fearful stimulus was presented to the left-visual field. These findings lead to the conclusion that the brain’s right hemisphere is more involved in processing visual emotion than is its left hemisphere.

61 2.2.3.4 Lateralisation of emotion and infant holding side

The left-cradling bias of mothers when holding their infant children could be important evidence of the lateralisation of emotion. It can be said that, if the perception of emotion is located in the brain’s right hemisphere, then the left-side of the body is likely to be used for cradling infants.

Although there are inconsistent findings for the effect of gender on emotion, it is thought that the affective valence or intensity of the situation may lead to gender differences in the decoding and encoding of emotion. These inconsistencies include the verbal communication of emotions. For instance, Ickes, Gesn and Graham (2000) found no differences in women’s and men’s verbal expression of empathy in seven of the ten studies they reviewed. However, it might be that women show more behavioural displays than men (Wester, Vogel, Pressly and Heesacker, 2002), keeping in mind that women have been reported to show more emotional memories than men (Calni, Desmond, Zhao and Gabrieli, 2002). These inconsistent findings led Ekman (2003) to conclude that men and women experience the same emotions but differently. If women display more behavioural signs in emotional situations than men do, and if their emotional memories are stronger than those of men, this could explain why a left-cradling bias is found more amongst women than amongst men.

Furthermore, it is asserted that cradling to the left side – as an indication of lateralisation – facilitates the visual and vocal communication between the caregiver and the infant (Sieratzki et al., 1996; Sieratzki and Woll, 2004). This hypothesis is supported by magnetic resonance imaging studies, such as those of Lorberbaum,

Newman, Horwitz, Dubno, Lydiard, Hamner, Bohning and George (2002), who

62 found more activation to the right side of the mother’s brain when she listens to infant cries than when she listens to white noise. In addition, Reissland’s (2000) study of voice pitch in maternal vocalisation found that the voices of mothers cradling to the left had a mean pitch of 171.33 Hz whereas the voices of mothers cradling to the right had a mean pitch of 221.11 Hz. In general, stressed people used higher mean voice pitch than non-stressed did. Reissland (2000) concluded that, if the right side of the brain was affected by stress, then the cradling was affected accordingly and, thus, stressed mothers were more likely to cradle to the right rather than to the left.

From this discussion of the literature, it can be concluded that left-cradling may facilitate close emotional attunement with their babies by mothers with typical brain organisation. This is because women tend to cradle an infant on the side of the body that is contralateral to the brain hemisphere dominant for face and emotion processing (Bourne and Todd, 2004).

The lateralised perception of emotions has been found to be related to auditory field advantages in a left-handed student population (Donnot, 2007). Further to this,

Manning and Chamberlain (1991) have suggested that the mother is better able to monitor her infant in the left visual field (LVF), with the left auditory channel (left ear advantage) as another indication of laterality. As Sieratzki and Woll (2002) suggested in their study, the purpose of cradling an infant is to protect him/her and to facilitate mother–infant communication.

150 mothers with babies aged under 12 months participated in Manning and

Chamberlain’s (1991), experiment. The researchers based their study on three

63 conditions – control group, left eye occluded, and right eye occluded – to discover the effect of the visual field in perception. The members of the control group were asked to walk about five metres to the end of a cot, pick up the infant and return to their seats while holding the baby. The two other groups completed the same task, but the members of one group had the left eye covered, whereas the members of the other had the right eye covered. The results showed that when the left eye was covered, left-holding rates fell to 40 per cent from a baseline of 62 per cent in the control condition, whereas in the covered-right-eye condition, participants showed a left-holding rate of 64 per cent, which was similar to that of the control group.

Manning and Chamberlain (1991) interpreted these findings as evidence that cradling on the left side of the body helps the mother to monitor her infant in her left visual field (right hemisphere). Thus mother and infant can express and perceive each other’s emotions. Harris et al. (2001), Bourne and Todd (2004) and Vauclair and

Donnot (2005) found that the cradling of an infant to the left side of the body is related to the right hemisphere and that men are more strongly lateralised than women in the chimeric faces task.

Sieratzki et al. (2002) have argued that, if the processing of emotion is responsible for determining the preference of cradling side, then the real interaction between a mother and her infant would be the most valid situation to test. On the other hand, the emotional effect hypothesis has not been confirmed for right-handed mothers

(Donnot and Vauclair, 2007). The authors explained this result as being a factor of the holder–infant relationship. They have stated that the relationship between the mother and her infant is such that the infant can distinguish between parent and non-

64 parent holders. Actually, this is the only study that failed to confirm the role of lateralised emotion in holding behaviour.

Furthermore, Donnot (2007) tested the role of emotion–perception asymmetries in holding-side preferences among left-handed mothers and left-handed students while holding an infant. The participants had previously been tested with the Dichotic

Listening Task (DLT) and, in order to neutralise the influence of handedness, only left-handed volunteers were selected. The author found a significantly stronger left- side preference in the left-handed students than in the left-handed mothers. These results confirm the relationship between the auditory field advantage and holding- side preferences only for students, not for mothers. The researcher justified this result by stating that the newborn’s influence on the mother might have reduced the left- side preference. In addition, the mother might have cradled to the right as an adaptation to her infant's needs. This explanation supports Riessland’s (2000) study, in which she suggested that the mother, consciously or unconsciously, cradles to the left for soothing her infant and to the right for arousing him/her.

On the other hand, Reissland (2000) has argued that when a mother wants to soothe her infant, she uses a low voice pitch while cradling to the left. The voice pitch is affected by her mood status. This finding suggests that emotion is located in the right hemisphere, which brings to mind the study by Ross and Monnot (2008) on language lateralisation which concluded that the left hemisphere deals with the linguistic– phonetic/articulation aspects of language, whereas the emotional–attitudinal– affective prosodic aspects of language are lateralised predominantly to the right hemisphere. This study supported the research by Ross, Thompson and

YenkoskyMorais (1997) and Ladavas (1987) reported that the right ear is foremost

65 for processing linguistics, whereas the left ear is foremost for processing emotional prosody.

In a recent study, Reissland et al. (2009) found that mood state (depression or stress) can result in reducing left-side cradling bias in human mothers. They suggested that the effect of stress was stronger than that of depression in reducing the left cradling bias in mothers. This study agrees with the results obtained by Weatherill et al.

(2004) and Vauclair and Scola (2008) about the link between holding side and psychological state.

Since cradling bias is regarded as an indication of the lateralisation of emotion, it can be added here that because the brain’s right hemisphere is mainly responsible for recognising faces and interpreting facial expressions (Manning and

Chamberlain, 1991), parents who have right hemispheric dominance, and thus process emotions more easily, will tend to use the more intimate left-side cradling style.

2.3 Summary and Conclusions

This chapter has discussed a variety of issues related to human brain laterality. As has been well documented in the psychological and neuroscience literature, the brain has two hemispheres, and each has its own functions. Some of these functions are unilateral, such as language, though even language can be processed by both hemispheres through interhemispheric communication. Other functions, such as visual and auditory ones, have been found to be lateralised as well. The involvement of the right hemisphere in some brain functions has led many researchers to conclude

66 that stimuli that are presented to the left visual field are better remembered, and in many cases, result in faster response times. The right hemisphere plays a role in some cognitive functions; aspects of non-verbal language such as prosodic tones and emotional tone, especially relating to negative emotions, are processed in this hemisphere. Based on these findings, some researchers have argued that the cradling of an infant to the left side of the body is the best way to ensure emotional communication between the infant and the cradler. This is one of many explanations that have been reported in the literature in an attempt to understand the factors underlying left side cradling bias, which has been reported in Chapter 1.

To sum up, the lateralisation of the human brain is well documented, and its discovery allows us to have a greater understanding of human behaviour. The research records indicate that the study of visual perception has made more progress than any other area of cognitive science in the recent years. The functional specialisations in the human brain clearly explain how the human brain is lateralised.

For instance, emotion has been found to be processed by the right hemisphere, and emotional facial expressions appear more clearly on the left side of the face.

Language has been found to be primarily based in the left hemisphere, whereas non- verbal linguistic features, such as prosody, have been found to originate from the right hemisphere. Based on these findings, it could be suggested that the strong tendency for people to cradle infants more to the left-side of the body than to the right is another example of brain lateralisation. It is thought that cradling an infant to the left is the best way to ensure emotional communication between the held infant and the holder, and it allows each of them to see the other’s facial expressions clearly.

67 Chapter 3

Brain structure

3.1 Introduction

The human brain is the centre of the nervous system that controls the whole human body, either by triggering muscles or by triggering chemical secretions such as neurotransmitters or hormones. Although the brain is known to have a very complex biological structure and the way it works is far from being fully understood, there is good evidence about the involvement of some of its regions in specific human functions. Such evidence has been gleaned from genetic, evolutionary, cognitive and developmental approaches.

This chapter explores the roles in emotion processing of human brain regions such as the insula, amygdala, posterior cingulate cortex, dorsolateral prefrontal cortex, inferior frontal gyrus, orbitofrontal cortex and basal ganglia. Because these regions have been examined in studies on healthy subjects and in studies on people with brain injuries a greater understanding has been gained, for example, of the link between the absence of a function and the impairment of a region.

Thus, the sections that follow look at the emergence of the discipline of affective neuroscience, which has grown out of various other disciplines. They will then review studies that have examined regions in the brain that are believed to be responsible for the processing of emotion and that may, therefore, have implications for cradling bias. Finally, recent studies on gender differences in the brain will be reviewed.

68 3.2 The emergence of Affective Neuroscience

Affective neuroscience is a sub-discipline of the bio-behavioural sciences that investigates the underlying neural bases of emotion and mood. It is an interdisciplinary field that links neuroscience with the psychological study of mood, emotion and personality (Dalgleish, 2004). Affective neuroscience tries to answer questions such as which brain region is responsible for the processing of emotion? and are all types of emotions processed by the same region, or by different regions in the brain? (Dalgleish, 2004). The emergence of affective neuroscience can be traced back to Darwin’s (1872) book, The expression of emotions in humans and animals, and to the paper by William James (1884), What is an emotion?. The Darwinian ideas on evolution in general and on emotion in particular have had a profound influence on affective neuroscience by drawing scientists’ attention to the idea of carrying out research on animals for a better understanding of human emotions. Carl

Lange’s (1884) ideas on emotions were partnered with James’s (1884) theory to become one of the classic theories of emotion, now known as ‘The James-Lange theory of emotions’. This theory looks at the patterns of bodily changes that are involved in the experience of emotions (for review, see Dalgleish, 2004). This theory holds that changes in the body that we experience (emotions) are a result of our perception of the arousing event. It can be illustrated as follows:

Event Arousal Interpretation Emotion

69 In 1920, Walter Cannon (cited in Zimbardo and Weber, 1994; Dalgleish, 2004) provided four challenges to this theory after investigating (with Bard) how brain lesions affected the emotional behaviour of cats. First, the bodily changes are too slow to elicit emotions; emotion arousal is faster than any bodily change. Second, in animals, emotional behaviour is not impaired by the total surgical separation of the viscera in the brain. Third, there are similarities between the visceral reactions produced by different situations; for instance both feeling danger and doing exercise produce heart palpitations. Fourth, these reactions do not lead to the same emotion.

Consequently, it is not always easy to distinguish emotions according to their physiological components. This is what became known later as “The Cannon-Bard

Theory”

The James-Laing theory has also been challenged by two cognitive criticisms. One is that the intentionality of emotions cannot occur satisfactorily by means of feeling- centred conceptions, and the other one is that emotions themselves, as proper objects of rational assessment, cannot be satisfactorily represented by these feeling-centred perceptions (Deigh, 1994). Alternative theories have been presented but they do not fall within the focus of the current study.

Despite this early work, efforts to understand both human and non-human behaviour tended to be made by different disciplines individually until the closing years of the

20th century. The lack of an umbrella discipline to study the various aspects of the brain led Panksepp (1998) to call for a new perspective, which he suggested should be called “affective neuroscience”. He stated “I would suggest that a missing piece is a neurological understanding of the basic emotional operating system of the mammalian brain” (Panksepp, 1998, p.5).

70 The application of the affective neuroscience perspective has helped researchers to gain a better understanding of brain circuitry and to detect affective disorders.

Interestingly, the opportunity to detect these types of disorders allows researchers to link loss of function to specific parts of the brain. The use of functional magnetic neuroimaging (fMRI) and positron emission tomography (PET) techniques, for example, has helped psychological researchers to have a better understanding of many brain functions, including the way in which emotions are processed.

Such techniques (e.g., fMRI, PET) are now widely used in the psychological investigation of the processing of emotions and of emotional behaviour. Together with behaviour and self report measures, neuroimaging methods provide very significant types of information that cannot be achieved by other methods. PET allows researchers to investigate the neurochemistry of the brain and how behavioural changes can affect brain functions, while the actual time course of neural activation can be assessed by fMRI (Hugdahl and Davidson, 2003). PET uses the physics of radioactivity to trace chemicals in the brain. After giving a person a small dose of a non-toxic radioactive substance that will travel through the bloodstream, the brain regions involved in processing can be detected because a neurone will be active in that area. Thus, the active area (which contains more blood) is responsible for the function that the person’s brain carries out.

Functional Magnetic Resonance Imaging (fMRI), now more popular than PET, uses large magnets to create strong magnetic fields. The hydrogen atoms in the blood can be tracked by the magnetic field, leading to the detection of blood flow in the brain, thus also showing the active area (Median, Ross, and Markman, 2002). In sum, any type of system that uses blood flow around the brain to measure which parts of the

71 brain are being used to process information is called a homodynamic imaging system. Such techniques (e.g. fMRI, PET) are now widely used by psychologists in research on emotion. Together with behaviour and self-report measures, neuroimaging methods provide important types of information that cannot be collected by other methods.

Although affective neuroscience seems to be similar to cognitive neuroscience,

Davidson et al. (2002) argued that it focuses on the affective processes and is remarkably successful in breaking down the cognitive processes into different elements in order to allow their study in neural terms. For example, the main goal of research in laboratories of affective neuroscience is to investigate brain mechanisms in order to clarify the affective process in normal people as well as in participants with mood disorders, such as major depression (Davidson et al., 2002).

Thut et al.’s (1997) work can be considered to be the first published human neuroimaging study which used rCBF PET scans to examine the role of brain structure in reward processing. In order to measure regional cerebral blood flow, they asked 10 participants either to use their right index finger to press the button of a computer mouse, or to keep their finger on the mouse button without pressing it. This task contained six pairs of go–no-go stimuli, which were presented in 24 trials. All correct responses were rewarded with money or a simple ‘ok’ reinforcement from the experimenter. In agreement with non-human studies, they concluded that the subcortical components of the basal gangliathalamo-cortical system and the prefrontal lobe are involved in reward processing (Thut et al., 1997).

72 Cognitive neuroscience, on the other hand, investigates how higher mental functions, such as emotion, perception, attention, memory and decision-making are related to neural activity. Within this field, numerous studies (e,g, Shafritz, Collins, and

Blumberg, 2006) have reported the involvement of the neural circuitry in emotional processing and the interactions between emotion and other cognitive processes, such as working memory, long term memory, attention and decision-making.

3.3 Brain structure

The foregoing discussion on the emergence of affective neuroscience demonstrates that brain structure is one of the richest areas to investigate in relation to human behaviour, including left-side cradling, though it has to be acknowledged that more investigations are still needed because many questions remain to be answered. Thus, the neuroscience literature will be briefly reviewed. The following sections look at various parts of the brain that studies have associated with the perception and expression of emotion, and at the relevant studies. It is expected that these will provide a good starting point for a deeper understanding of emotion and of brain functions in general.

3.3.1 Amygdala

The amygdala has been investigated in many studies of asymmetric emotion. The term, coined from the Greek word for almond, was first used in 1819 by the anatomist Burdach to describe a mass of almond-shaped cells in the human temporal cortex (Davis and Whalen, 2001).

73 Despite a dramatic increase in studies on the amygdala, the nature of its function is still controversial. However, observations of the Klüver-Bucy syndrome have produced wide acceptance that the amygdala plays a role in many features of emotional processing (Maratos et al., 2009). The Klüver-Bucy syndrome is a rare behavioural disorder that occurs when both the right and left medial temporal lobes of the brain are impaired and, among others, Goscinski et al., (1997) and Kile et al.,

(2009) have reported the implication of the amygdala as its pathogenesis. Symptoms include inappropriate sexual behaviour, visual agnosia, absence of normal fear and anger responses, distractibility, memory loss, seizures, and dementia.

Figure 3.1.

Amygdala

74 The amygdala consists of several distinct groups of cells, and for this reason they were collectively called the basolateral amygdala. Traditionally, the central, medial and cortical nuclei are included in the ‘amygdaloid complex’ because they surround the basolateral amygdala. The basolateral amygdala and the surrounding structures constitute what have come to be called ‘the amygdala’ (Davis and Whalen, 2001).

To test the role of the amygdala in emotion processing, Rapcsak et al. (2000) conducted a ‘recognising fear’ experiment. They found that although amygdala damaged patients showed worse performance than normal participants in recognizing fear, both patients with focal brain damage and normal control participants performed significantly worse in recognising fear than in recognising other facial emotion. In addition, no association was found between amygdala lesions and impairments in fear perception even when the amygdala damage was bilateral. Based on these findings, Rapcsak et al. (2000) suggested that deficits in fear recognition might be related to task difficulty factors rather that neural damage in regions responsible for fear perception.

However, contrary to the finding of Rapcsak et al. (2000), the function of the amygdala in emotion perception (e.g. fear perception) has been reported in more recent studies. Balleine and Kilicross (2006) found that the amygdala played a role in reinforcement and reward processes in humans and animals. Urry et al. (2006), Irwin et al. (2004), Seminowicz et al. (2004) and Mayberg et al. (2008) all attributed depression to frontal region failure, that is, the failure of the rostral anterior cingulate cortex to regulate effectively the functioning of the amygdala. In addition, Adolphs

(2002) and Williams, Weilman and Geany (2005) have argued that the early perception of emotion involves the amygdala in eliciting further brain processing.

75 Other studies (e.g. Irwin et al., 2004) have reported that the amygdala is important in attention and memory processes. In studies on bilateral amygdala damage and functional imaging studies with intact people, Adolphs, Tranel and Denburg (2000),

Adolphs (2003), Labar and Cabeza (2006) and Murty et al. (2010) reported that the amygdala plays an important role in encoding emotionally arousing stimuli into the long-term declarative memory. Furthermore, it has been suggested that the amygdala is important in the consolidation and retrieval of emotional memories (Canli et al.,

2002; Davidson and Irwin, 1999) and it is necessary for the enhanced memory seen in patients with selective bilateral amygdala damage (Adalphs et al., 1999; Hamann,

1999). When stimuli are emotionally highly arousing, functional imaging studies have detected correlating activity in the amygdala and hippocampus during the encoding of emotional stimuli.

Some studies have tried to suggest more specific roles for the left and right amygdala. For instance, the meta-analysis study carried out by Baas, Aleman and

Kahn (2004) found that the left amygdala is generally more responsive than the right amygdala to emotional manipulations. They interpreted their findings as suggesting that the right amygdala may be more involved in what they called ‘global processing’ while the left amygdala may be more involved in ‘local processing’. Obviously, the role of the amygdala in emotion among humans needs more investigation.

An investigation of how the brain processes emotionally charged information, carried out by Vingerhoets, Berckmoes and Stroobant (2003), found that the left hemisphere of the brain is involved in decoding the literal meaning of external emotional messages. This finding suggests that the role of the left amygdala (located in the left hemisphere) is to decode emotion in order for it to be perceived by the right

76 amygdala. This suggestion is supported by many psycholinguistic studies (e.g. Ross, and Monnot, 2008). that show that the right hemisphere is responsible for the assessment of prosody and speech tone.

The authors measured the speed of blood flow to the tissues of the brain. When participants were asked to focus on the meaning of a sentence, their blood flow velocity increased significantly in the left hemisphere whereas when they were asked to focus on how the sentence was said, velocity increased in the right hemisphere of their brains. The authors suggested that patients with right hemispheric lesions could have problems in understanding the emotional prosody of a spoken message and may have difficulties in discriminating discrepancies in content and prosody.

These findings were supported by Glascher and Adolphs (2003) whose research suggested that the left and right amygdala have different functions in emotion processing; that is, the left may decode the arousal that is signalled by the specific stimulus, whereas the right may provide a global level of autonomic activation triggered automatically by any arousing stimulus. That means that the right amygdala is dependent on the decoding carried out by the left amygdala.

More recently, a meta-analysis of 385 PET and fMRI studies carried out by

Costafreda et al. (2008) provided further support for the above conclusions. They found that the right amygdala has a high-speed role in detecting unconscious stimuli, whereas the left amygdala is active when evaluation of language-related stimuli is needed.

In conclusion, these findings all suggest that it is the type of stimuli that is responsible for the involvement of the amygdala. For instance, if the stimuli are

77 associated with language, the left amygdala encodes the external information, but the perception of emotion is processed in the right amygdala. On the other hand, if the stimuli are not language-related and need more brain function, then the role of the right amygdala appears to be greater. However, these findings should still be viewed with caution because they may be influenced by complicated methodological differences, such as the method of analysis or fMRI magnet strength affecting the probability of amygdala activation.

One interesting study that used event-related fMRI, carried out by Fecteau et al.

(2007), investigated the neural changes, particularly in the amygdala, in response to emotional non-linguistic vocalisations. They found increased activity in the amygdala in response to negative emotions such as sadness and fear, especially in the right hemisphere. These findings are consistent with those of some previous studies that reported bilateral amygdala responses to vocalisations of sadness (e.g. Sander and Scheich, 2005) and right amygdala responses to vocalisations of fear (Phillips et al, 1998; Bach et al., 2008).

The involvement of the amygdala in processing positive information from other stimuli has been well documented. These stimuli include taste (O’Doherty et al.,

2002), olfactory (Buchanan et al., 2003) and erotic film excerpts (Bell et al., 2006).

Additionally, Bechara et al. (2000) and Fine and Blair (2000) found that deficits in processing positive stimuli can be attributed to impairments of the amygdala or wide damage in both temporal lobes, and in bilateral amygdala damaged patients (Fine and

Blair, 2000).

78 Finally, although a few studies, such as that of Morris et al. (1998), reported deactivations in the right amygdala for vocalisations of fear, these negative findings may be related to low power in detecting amygdala activity, rather than to an absence of activity (Costafreda et al., 2008).

3.3.2 Posterior Cingulate Cortex

The posterior cingulate cortex (PCC) is another region of the brain which has been linked to emotion, especially the perception of emotional components. The association between the perception and evaluation of stimuli and the PCC is supported by the findings of behavioural studies such as those using pictures (e.g.

Lane et al., 1997; Shin et al., 1997; Fischer et al., 1996; Kosslyn et al., 1996) and those involving emotional words (e.g., Beauregard et al., 1997; Maddock and

Buonocore, 1997; Shin et al., 1997).

There have been very few studies on lateralised PCC function. However, Maddock

(1999) reported in his meta-analysis that, of the 20 homodynamic imaging studies reviewed, all except one found more right than left-sided activation.

There are two theories concerning the role of the PCC in emotion or of its function in general. One of them suggests that the PCC is involved in visual spatial attention toward stimuli with a punishment or reward value. This activation was reported in

Small et al.’s (2001) study using chocolate as a stimulus. Participants were divided into two groups, one of which was highly motivated to eat chocolate and the other highly motivated not to eat chocolate. Compared to the control group, the authors

79 found that the posterior cingulated cortex was the only brain region that was active during both negative and positive conditions.

Figure 3.2

Posterior Cingulate Cortex

The other theory holds that the memory of emotional stimuli is modulated by the

PCC (Vogt, Abscher, and Bush, 2000; Fink, 2003; Pavlovic, and Pavlovic, 2010;

Maddock, Garrett, and Buonocore, 2003). For instance, more activation in the right

PCC was reported while subjects listened to sentences describing events from autobiographical memory or when they were presented with photographs related to their past experience (Fink 2003; Fischer, Wik and Frederikson, 1996).

80 3.3.3 Inferior Frontal Gyrus

Some studies have reported a critical role for the inferior frontal gyrus (IFG) in executive functions while others have related the IFG to tasks entailing the inhibition of learned responses (e.g., Garavan et al., 2002; Hampshire et al., 2010). In addition,

Herrington et al. (2005), Shafritz et al. (2006), and Chikazoe et al. (2007) found that during an emotional challenge some parts of the IFG were sensitive to response inhibition, and Shafritz et al. (2006) reported a greater activity in the IFG during a go/no-go task using stimuli containing emotional faces. In an emotional Stroop paradigm used by Mohanty et al. (2005) and Herrington et al. (2005), IFG activity was also observed. Moreover, IFG activity has also been detected in the perception of prosody (Aziz-Zadeh, Sheng and Gheytanchi, 2010) and during the perception of facial affect (Jabbi and Keysers, 2008). Recently, Nakic et al. (2006) found greater

IFG activity during the presentation of emotional words in a lexical decision task.

These studies have investigated the general role of the IFG and Shamay-Tsoory

(2010) suggested that the IFG participates in tasks that involve emotional empathy and emotional recognition.

However, other studies have examined the lateralisation of the IFG and reported a specific role for each half. For example, Konishi et al. (1999), Garavan et al. (2002),

Aron et al. (2004), and Wang et al. (2008) reported that the right IFG is sensitive when a participant wants to inhibit distracting information during task completion and Hayes et al. (2007) showed its role in distracting emotions in posttraumatic stress disorder.

81 Figure 3.3

Inferior Frontal Gyrus

These psycholinguistic studies suggest that a link between emotion and language can be logically inferred. It seems that the IFG is involved in the perception of emotion, and this can be in one or both sides, depending on the type of the emotional stimulus.

3.3.4 Dorsolateral Prefrontal Cortex

Recent studies suggest that the dorsolateral prefrontal cortex (DLPFC) is a region of the brain that functions asymmetrically for emotion and attention processes (Irwin et al., 2004; Seminowicz et al., 2004). This brain region is associated with tasks that require concentration. Additionally, the involvement of the DLPFC both in attention and emotion functions has been reported in several studies. Studies that have looked at attention and emotion functions together could help us to understand how these two functions may be integrated. For instance, Gray (2001) noticed that performance on a verbal working memory task was better when participants had been exposed to a

82 pleasant film clip. Herrington et al. (2005) detected quicker activity in the left

DLPFC than in the right DLPFC when participants were asked to identify the colour of pleasant and unpleasant words, and bilateral activity in the DLPFC was clearly detected for pleasant words using fMRI scans.

Figure 3.4

Dorsolateral Prefrontal Cortex

The involvement of the DLPFC in the selection of information has been reported in several studies using different techniques and methods, for example, PET scans

(Pardo et al., 1990), fMRI scans (Baass and Von Cramon, 2004), lesion studies

(Perret, 1974), and in studies with the Stroop task, where the participant must identify the ink colour of the presented word (Egner and Hirsch, 2005). Because

83 participants automatically read the words rather than identify the ink colour, this latter task is described as an attentionally demanding task.

It can be concluded here that these studies link the DLPFC to the maintenance and shifting of attention within the attentional demands framework (Banich, 2004;

Milham et al., 2003). Clinical studies support these findings. For instance, it was reported that patients with deficits in the function of their lateral frontal lobe experience difficulties in, for example, negotiating novel tasks, choosing a problem- solving strategy or dealing with unconstrained tasks (Banich, 2004).

3.3.5 Insula

One of the important parts of the brain that is thought to play a role in emotion circuitry is the insula. It is located within the cerebral cortex, beneath the frontal, parietal and temporal opercula. The function of the insula is the integration of autonomic information, and it is believed to be associated with social emotion

(Lamm, and Singer, 2010). Additionally, disgust-specific activation in the insula has been reported (Davidson, Irwin, 1999; Murphy, Nimmo-Smith and Lawrence, 2003; and Jabbi, Bastiaansen and Keysers, 2008) whereas (Barrett and Wager, 2006) found an association between insula activity and negative emotion.

It has been reported in previous studies that the regions of anterior insula/frontal operculum are involved in processing specific facial expressions of disgust.

However, a variety of disgust facial expression components which link to the disgust-eliciting stimulus have been suggested. For example, the opening of the mouth and tongue extrusion are associated with oral irritation and distaste; aversive

84 interpersonal contacts and certain moral offences as disgust stimuli were found to be associated mainly with upper lip curl, and finally offensive or irritating smells were predominantly linked to nose wrinkling (Rozin, Lowery and Ebert, 1994). This led

Curtis, Aunger, and Rabie (2004) to suggest that disgust emotion in human beings could be an evolved response to objects that were involved in producing threats of infectious disease.

Figure 3.5

Insula

Recently, using fMRI, Von dem Hagen et al. (2009) have found that activity in the anterior insula/frontal operculum is seen only in response to canonical disgust faces, displaying the upper lip curl and nose wrinkle. On the other hand, there was no activity found in response to facial expressions of distaste that display a mouth gape

85 and tongue protrusion (Von dem Hagen et al., 2009). Von dem Hagen and colleagues (2009) stated that activity in brain regions linked to social cognition produces the canonical disgust expressions; these regions include the posterior cingulate cortex, dorsal medial prefrontal cortex, temporo-parietal junction and superior temporal sulcus. The authors concluded by suggesting a significant role for appraisal processes in the insula activation to facial expressions of disgust.

3.3.6 Orbitofrontal cortex

The prefrontal cortex lies at the very front of the human brain, and contains the orbitofrontal cortex. It is called the orbitofrontal cortex because of its position above the eyes or orbits (Davidson, Scherer and Goldsmith, 2003).

Figure 3.6

Orbitofrontal cortex

86 These parts of the brain are thought to be important in emotion and motivation because they are the parts of the brain where the primary reinforcing value of stimuli is represented in primates, and because they perform pattern-association learning between potential secondary reinforcers and primary reinforcers (Rolls, 2000). As

Rolls (2000, p.286–287) said, “They are thus the parts of the brain involved in learning the emotional and motivational value of stimuli.”

During investigation of the neural substrates that might be responsible for abnormal behaviours in depressed patients, increased activity in both the orbitofrontal cortex and the rostral anterior cingulate gyrus to negative emotional stimuli was observed using an affective go/no-go task (Elliot, Rubinsztein and Sahakian, 2002).

3.3.7 Basal ganglia

Recently, subcortical areas such as the basal ganglia (BG) have been reported to play a role in processing emotional prosody (Pell, 2003; Van Lancker et al. 2006; and

Paulmann, Pell, and Kotz, 2008). Patient studies (e.g. Breitenstein, Lancker, Daum and Waters, 2001) and functional imaging studies with healthy people (e.g.,

Wildgruber et al., 2002) have provided good findings that support the role of the BG in emotional prosody processing.

Also, Meyer, Steinhauer, Alter, Friederici and Von Cramon, (2004) suggested that the BG plays a role in the sequencing of auditory affective information. Another suggestion that has been made is that reduced capability to encode emotionality from affective prosodic cue sequences is associated with impairments in the BG (Pell and

Leonard, 2003). Additionally, Schirmer and Kotz (2006) argued that, in order to

87 allow the evaluation of prosodic emotional cues, this process should interact with the cortical associative functions.

Figure 3.7

Basal ganglia

More questions have been asked about the extent to which BG patient studies can enrich our knowledge and to broaden our understanding of human behaviour. One of these studies has suggested that the basal ganglia may not play a compulsory role in the processing of implicit emotional prosodic information in healthy participants and in patients with BG problems. In patients with left BG damage, the results show that early rapid emotional prosodic deviance detection is not impaired, while off-line recognition of emotional prosodic contours is affected (Paulmann, et al., 2008).

88 3.3.8 Section summary

To sum up, the literature reports that there are various regions in the human brain that are involved in emotion and emotional modulation. These regions have been examined by different methods. However, the emergence of affective neuroscience has provided us with important information about brain structure, including the finding that some brain regions are involved in the perception and expression of emotion. One of these regions is the amygdala which, in observations of Klüver-

Bucy syndrome, has been found to play a role in many features of emotional processing. Studies show that the amygdala is responsible for recognising fear, for reinforcement and reward processes in humans and animals, for the negative effects of depression, and for eliciting further brain processing. Despite the increased activity in the amygdala in response to negative emotions, such as sadness and fear, studies also report that the amygdala processes positive information as well. Other studies have reported the role of the amygdala in attention, memory processes and the consolidation of emotional memories. Some studies have shown that the type of stimuli might be responsible for the involvement of the amygdala. Although the left and right amygdalae have different functions in emotion processing, they have also been found to have different functions for other processes, especially coding and decoding stimuli. Moreover, the left amygdala is generally more responsive than the right amygdala to emotional manipulations.

The perception of emotional components has been found to be associated with the posterior cingulate cortex (PCC). More right than left-sided PCC activation was found during listening to sentences describing events from autobiographical memory.

Two theories have been presented concerning the actual role of the PCC; one is that

89 the PCC is involved in visual spatial attention toward stimuli with a punishment or reward value and the second is that the memory of emotional stimuli is modulated by the PCC. Another brain region, the inferior frontal gyrus, has been found to be involved in executive functions, perception of prosody, perception of facial affect, presentation of emotional words in a lexical decision task, emotional empathy and emotional recognition.

The dorsolateral prefrontal cortex (DLPFC) is a region of the brain that functions asymmetrically for emotion and attention processes and it has been found to be associated with task that require concentration. Quicker activity in the left DLPFC than in the right DLPFC was detected when participants were asked to identify the colour of pleasant and unpleasant words.

The insula plays an important role in the emotion circuitry. For instance, a significant role for appraisal processes has been found in the insula’s activation in response to facial expressions of disgust, and this has been confirmed with observations of its involvement in the integration of autonomic information. Other studies have reported the association between the insula and social emotion, negative emotion, processing specific facial expressions of disgust, and response to canonical disgust faces.

The prefrontal cortex is a part of brain that is thought to be important in emotion and motivation. Studies have shown the involvement of this region in abnormal behaviours in depressed patients. An increased activity in both the orbitofrontal cortex and the rostral anterior cingulate gyrus to negative emotional stimuli has also been reported.

90 And finally, there is the basal ganglia (BG), which is believed to play a role in processing emotional prosody. Both patient studies and functional imaging studies with healthy people have provided good evidence to support this view.

3.4 Brain injury

First, it should be said here that studying atypical development allows us to shed light on typical development and helps us obtain a better understanding of human nature. For the current study, brain injury studies can be considered to be a good method of providing very important findings by determining which region of the brain is damaged. For instance, the nature of the loss of a particular function that can be detected by imaging techniques helps us to determine which region of the brain was responsible for that function. Thus, it can be inferred that emotion and health can affect each other reciprocally, that is, emotion can affect health, as can be seen in the effect of depression and anxiety on general health, and affected emotion can be found in unhealthy individuals, such as those with acquired brain injuries. The inability to identify people’s facial emotions can stem either from impairment caused by neurological disease or from brain injury. Research on certain brain injuries can be considered as the trigger for our rethinking of the functions of brain regions that underlie behaviour. Language is a good example here. It has been noticed that the ability to speak is severely affected if the lesions are located in the left hemisphere.

Moreover, the work of Roger Sperry and his colleagues in the 1960s on split-brain patients led to new findings on the functional specialisation of the two cerebral

91 hemispheres. This discovery began with cutting the connection between the two hemispheres in patients suffering from epileptic seizures, that is, cutting the corpus callosum to stop excessive signalling of nerve cells. By cutting this connection, the two hemispheres are prevented from communicating with each other and they are still able to learn, but separately (Sperry, 1968). This experiment shed light on other functions in the human brain, such as how emotion can be processed. The involvement of the left hemisphere in processing language was confirmed by the

19th century findings of Broca and Wernicke. What is now known as Broca’s area, that is, the left inferior frontal cortex, is involved in the production of language, or language outputs, and what is known as Wernicke’s area in the superior posterior temporal lobe is vital for the understanding of language, or language inputs (Binder,

Frost, Hammeke, Cox, Rao, and Prieto, 1997; Beharelle, Dick, Josse, Solodkin,

Huttenlocher, Levine and Small, 2010).

As will be discussed in Chapter 2, verbal input and grammar are processed in the left hemisphere, whereas prosody and the emotional context of language are processed in the right hemisphere. Words (e.g. “car” or “lion”) can be read with the left hemisphere and their content imagined in the right hemisphere. In recent decades, right hemisphere damage has been found to be involved in defects in emotion recognition. This is supported by the study of patients with disorders such as prosopagnosia (Christa, Stephan, Breen, and Caine, 2006; Lee, Duchaine, Wilson, and Nakayama, 2010). In recognising emotional content in human faces, depressed people performed worse than healthy people (Csukly, Czobor, Szily, Takács and

Simon, 2009; Douglas and Porter, 2010). More evidence came from the detection of an increase in hemodynamic flow in the right hemisphere during tasks of judging

92 emotional prosody, (Buchanan, Lutz, Mirzazade, Specht, Shah, Zilles and Jancke,

2000). Prosopagnosia is the most well known disorder in the psychology of vision.

People with this disorder are unable to recognise faces (even those of family members) or photographs of faces, but they can recognise non-face objects

(Williams, Berberovic and Mattingley, 2007). Green, Turner and Thomson (2004) found that patients with acquired traumatic brain injury (TBI) had an impaired ability to perceive facial emotion.

Further to this, defects in the perception of emotion are common in people with TBI and this can be observed through changes in their emotional and social behaviour.

For example, a longitudinal study was conducted by Ietswaart, Milders, Crawford,

Currie and Scott (2008) to examine the development of emotion recognition deficits.

They found impairments in emotion recognition in 37 patients with TBI compared to the control group either soon after injury or one year later (Ietswaart, Milders,

Crawford, Currie and Scott, 2008). Similarly, an experiment was carried out on 22

TBI people and 32 matched controls using the two strategies of mimicking relevant aspects of the facial expression, and focusing attention on the facial expression. It was found that a lack of emotion perception in TBI people leads to them failing to direct their attention towards some features of facial expression. They showed, instead, a decrement in performance and failed to mimic the facial expressions when asked to do so (McDonald, Bornhofen and Hunt, 2009).

Green et al. (2004) suggested that diffuse axonal injury (DAI) may cause deficits in the perception of facial emotion. These results support the findings of studies by

Spell and Frank (2000) and Mandal, Asthana and Maitra (1998) which showed that

93 participants without TBI scored higher than those with TBI in the recognition of facial expressions and vocal prosody.

In human lesion studies, it has been found that recognition of emotional facial expressions is impaired after bilateral amygdala damage (Anderson and Phelps,

2001; Sprengelmeyer et al., 1999; Calder, Lawrence and Young, 2001) and impairments in emotional memories and in recognising fear have been found in patients with bilateral amygdala lesions. They showed clear deficits in the emotional processing of facial expressions and prosody, in addition to an inability to recognise or remember emotional stimuli. Poor performance was also detected in patients with left lobectomies in tests of emotional memory, and in recognising disgust prosody

(Brierley, Medford, Shaw and David, 2004)

Adolphs and Tranel (1999) suggested that, in humans, there are extra-amygdalar structures in the right hemisphere of the brain that could play an important role in recognising emotional prosody. On a task of emotional prosody recognition, two subjects with complete bilateral amygdala damage and seven with unilateral amygdala damage were examined. One particular subject whose lesions were only in the amygdala had completely normal recognition of emotion in prosody on all tasks, whereas another, whose damage included substantial lesions especially in the right hemisphere, was normal on most, but not all, measures of recognising emotional prosody (Adolphs and Tranel, 1999).

It has been reported that depressed people have impairments of memory for emotional faces (Gilboa-Schechtman et al., 2002). Additionally, impairment in emotional memory has been linked to structural damage to the amygdala (Adolphs et

94 al., 2005; Buchanan et al., 2005) and this also seems to lead to impairment in encoding emotional faces (Boucsein et al., 2001).

Shaw, Lawrence, Radbourne, Bramham, Polkey and David (2004) investigated acquired damage to the amygdala by comparing early childhood amygdala damage with adulthood amygdala damage, and both of them with fully intact amygdalas.

Only participants with early acquired amygdala damage showed deficits in reasoning about the mental states of others, and they failed to show typical patterns of enhanced memory for emotionally arousing material. Furthermore, acquired amygdala damage resulted in impairment in recognition of facial expressions of emotions at both developmental stages. According to these findings, Shaw et al. (2004) concluded that the amygdala plays an important role in the recognition of facial expressions of emotions, and acquired damage results in emotional impairments.

However, other studies have shown that unilateral amygdala damage can lead to less serious impairments. For example, Boucsein et al. (2001) related the impaired ability to learn new emotional facial expressions to the extent of unilateral amygdala damage. In addition, Anderson et al. (2000), Adolphs, Damasio, Tranel, Cooper and

Damasio, (2000) Adolphs, Denburg and Tranel (2001) and Adolphs, (2006) concluded that impaired recognition of negative emotions from facial expressions can relate to damage to the right amygdala. In a CT and MRI scanning study by

Kucharska-Pietura et al. (2003), right hemisphere-damaged patients performed significantly worse than left hemisphere-damaged patients on an emotional task. The researchers concluded that this result supports the hypothesis that perception of emotion belongs to the right hemisphere, and contradicts the valence hypothesis, because the right hemisphere-damaged patients were significantly impaired in

95 perceiving both positive and negative emotions compared with both left hemisphere- damaged and healthy subjects.

Removing the amygdala and the neighbouring areas, such as the perirhinal and entorhinal cortices, can produce the same emotional symptoms as the Kluver–Bucy syndrome (Horel, Keating and Misantone, 1975; Davis and Whalen, 2001), such as a diminished fear response.

Strikingly, Davis and colleagues (2001) reported that memory impairments have been found after damage to the hippocampus and other structures, such as the anatomically related perirhinal and parahippocampal cortices, but no emotional behaviour impairment was noted. Additionally, damage to either the amygdala or hippocampus, that is, not combined damage, had a greater effect on memory or emotion than damage to both of them. This is because these two medial temporal lobe structures are linked to two independent memory systems. The amygdala can modulate both the encoding and the storage of hippocampal-dependent memories whereas the hippocampal complex can influence the amygdala response when emotional stimuli are encountered (Phelps, 2004).

Heywood and Cowey (1992) suggested that damage to the brain can take two forms of impairment. In humans, for instance, it can take the form of deficits in interpretation of emotion from facial expressions, or deficits in the recognition of the identities of seen faces (Rolls, 2008).

More evidence has been reported from studies on primates. Such studies show that different brain areas are responsible for processing facial identity and expression; cells whose responses are modulated preferentially by expression are located within

96 the monkey’s superior temporal sulcus, whereas cells which respond to the face’s identity tend to be located on the inferior temporal gyrus (Desimone, 1991;

Hasselmo, Rolls and Bayliss, 1989; Calder et al., 1996; Tsao, Schweers, Moeller and

Freiwald, 2008). These localisations of the aforementioned cells that work separately for different functions have been confirmed with PET scans (e.g. Sergent et al., 1994;

Calder et al., 1996).

Significant structural abnormalities have been found in affective disorders in the amygdala and hippocampus. For example, a review by Campbell et al. (2004) reported a reduced hippocampal size in patients with a major depressive disorder.

However, the structural abnormalities of the amygdala in affective disorders are controversial, and studies are still being carried out in this area. For instance,

Altshuler et al. (1998) and Savitz, Nugent, Bogers, Liu, Sills., Luckenbaugh, Bain,

Price, Zarate, Manji, Cannon, Marrett, Charney and Drevets (2010) found enlarged amygdala in patients with bipolar disorder whereas Mervaala et al. (2000) and Frodl,

Meisenzahl, Zetzsche, Born, Jäger, Groll, Bottlender, Leinsinger and Möller (2003) reported normal or reduced-size amygdala in patients over a broad age range and a longer duration of illness. Additionally, studies on depressive subjects with short disease duration have found enlarged amygdala (Lange and Irle, 2004). (For review see Drevets, Price and Furey, 2008; Holzel, Carmody, Evans, Hoge, Dusek, Morgan,

Pitman and Lazar, 2009).

Recently, a study of the assessment of the associative learning of objects and emotional faces by Weniger, Lange and Irle (2006) found significantly enlarged amygdalas and significantly reduced hippocampal size in depressive participants compared with a control group. Moreover, they were significantly impaired in

97 learning emotional facial expressions. In depressed participants, Weniger et al.

(2006) found that a poorer learning performance, and higher anxiety scores were significantly related to larger volumes in the left amygdala, whereas smaller left hippocampal volumes were related to higher anxiety scores. However, studies on the effect of amygdala size should be restricted to young people with short disease duration in order to have a clear idea about that effect. It was suggested that the antidepressant treatment might have an impact on amygdala over-activation

(Weniger et al., 2006).

3.4.1 Section summary

The work of Roger Sperry and his colleagues in the 1960s on split-brain patients showed the functional specialisation of the two cerebral hemispheres, including how emotion can be processed. Studying atypical development allows light to be shed on typical development and helps to obtain a better understanding of human nature. The nature of the loss of function that can be detected by imaging techniques helps to determine which region of the brain is responsible for that function. For instance, the inability to identify people’s facial emotions can stem either from impairment caused by neurological disease or brain injury. The involvement of the left hemisphere in processing language (the Broca and Wernicke areas) is a good example, and it is now known that language is severely affected by lesions in the left hemisphere.

Studies on prosopagnosia are an example of how right hemisphere damage is known to be involved in defects in emotion recognition. For example, studies showed that right hemisphere-damaged patients performed significantly worse than left hemisphere-damaged patients on an emotional task. Patients with acquired traumatic

98 brain injury showed an impaired ability to perceive facial emotion. Further to this, defects in perception of emotion are common in TBI people and diffuse axonal injury

(DAI) has been reported to cause deficits in the perception of facial emotion. Recent studies have confirmed the involvement of bilateral amygdala damage in impairments of the recognition of emotional facial expressions. Moreover, structural damage to the amygdala has been reported to result in impairment in emotional memory. Unilateral amygdala damage causes less serious impairments than bilateral damage. Finally, enlarged amygdala have been found in stressed and depressed people, and removing the amygdala and the neighbouring areas, such as the perirhinal and entorhinal cortices, can produce the same emotional symptoms as those found in patients with the Kluver–Bucy syndrome.

3.5 Gender differences in the brain

To begin with, it should be stated that gender differences are considered to be a substantial issue with many questions for discussion. However, bearing in mind the limitations of the current study, only those possible differences that are directly relevant to this study will be examined. It is believed that anatomical gender differences in structures, especially in the connection of the two cerebral hemispheres, could explain the known gender differences in cognitive function and cerebral lateralisation. Additionally, understanding the differences between men and women opens up the possibility of discovering individual differences within same- sex individuals.

Generally, females perform better on tests involving computation, whereas high scores on problem-solving or mathematical reasoning aptitude tests tend to occur in

99 men (Kimura, 1999). It could be the case that some differences appear at early stages, but the most marked differences should be obvious after puberty because of the change in sex hormones (Hayward, 2003). This leads to the conclusion that gender differences are very important in psychological research, including the current study.

Due to their importance to many aspects of human and non-human species, it will be useful to start with a review of the previous research that has reported differences between males and females in brain function, especially in the processing of emotion. For example, gender differences in the human brain provide evidence that the behavioural differences between males and females might result from the differences in the early development of the brain. Cooke, Tabibnia and Breedlove

(1999) argued that it is worth giving more attention to the concentration of circulating hormones during adulthood. In their study on rats they found that adult circulating androgen affected the volume of the posterodorsal nucleus of the medial amygdala. In the control group, male rats had a greater posterodorsal nucleus volume than females. However, after four weeks of adult castration, this difference disappeared. Moreover, androgen replacement caused males to retain the same volume of this region, whereas it increased in females (Cooke et al., 1999).

Regarding the role of sexual orientation, studies have reported some indications that the hypothalamic nuclei may differ in size between transsexual and heterosexual males (Zhou, Hofman, Gooren and Swaab, 1995) and between homosexual and heterosexual males (LeVay, 1991). That is, the brain structure of homosexual males resembled the female brain structure.

100 Based on the idea that transsexual males have strong feelings from early childhood that they have born as the wrong sex, these feelings could explain - in some way - why left-side cradling has been found more in females than males (that is, the effect of gender differences in the brain. On that basis, the similarities in some brain regions between heterosexual females and transsexual or homosexual males may shed some light on how brain size and gender differences in the brain can affect behaviour, bearing in mind the findings by Bishop and Wahlsten (1997) that adult males have a larger average brain size and a larger corpus callosum than do females

(Bishop and Wahlsten, 1997).

Although the difference between heterosexual individuals could explain why women have been reported to cradle to the left-side of the body more than men (see Chapter

1), more research needs to be carried out on homosexuals to obtain a better and clearer understanding of the role of gender differences in left-side cradling.

The fact that there are behavioural differences as well as cognitive differences between males and females could help us to understand how emotions are regulated in the human brain, and how different factors can affect the laterality of the human brain. Such an understanding could help in the explanation and interpretation of the main findings of this study.

The best understanding of any behaviour involves looking at evolutionary theory and seeing how other species developed similar behaviours. Typically, females have been characterised as being more sensitive to social cues and stresses (Smeets, Dziobek and Wolf, 2009). This has not only been found in human females, but also in most mammalian species (Lenroot and Giedd, 2010).

101 It has been reported that there are some differences between males and females in the size of their anterior commissure. This fibre was an average of 12% larger in females than in males (Allen and Gorski, 1991). In addition to this, statistically significant differences have been found between men and women in the size of the corpus callosum, with a greater size in men than in women (Ilayperuma, Nanayakkara and

Palahepitiya, 2009).

The better our understanding of the neuro-developmental processes that influence gender differences in social cognition, the better is likely to be our understanding of other aspects of gender difference during adolescence and adulthood. Major depression is a good example here. Before the onset of puberty, males and females have almost the same rate of depression (5%) but this percentage changes with the onset of puberty, doubling in females, while the male rate remains at approximately

5% (Angold, Costello and Worthman, 1998; Lenroot et al., 2010). Moreover, the development of the hypothalamic-pituitary-adrenal axis (HPA) is one of the prominent factors in gender differences. In more females than males, a greater hormonal reactivity to pharmacological stimulation with naloxone was detected, whereas greater HPA axis responses to a psychological stressor have been reported in males than in females (Uhart, Chong, Oswald, Lin and Wand, 2006).

The importance and significance of the role of the HPA axis in depression has been investigated in previous studies. Although the significance of HPA axis changes in depression remains unclear (as reported by Pariante and Lightman, 2008), a study by

O'Brien, Ames, Schweitzer and Tecrolma (1996) demonstrated that most depressed people showed HPA axis activation. In major depressive disorders, it was found that the association between anxiety and depression constitutes a major clinical factor,

102 and is associated with hypothalamic-pituitary-adrenal axis dysregulation (Meador-

Woodruff, Greden, Grunhaus and Haskett, 1990; Mello, Juruena, Pariante, Tyrka,

Price, Carpenter and Del Porto, 2007).

Moreover, the inferior-parietal lobule (IPL) has been found to be larger in men than in women (Frederikse, Lu, Aylward, Barta, and Pearlson, 1999).

3.5.1 Section summaryIt can be concluded from this section that gender differences found in the human brain provide evidence that the behavioural differences between males and females might result from the differences in the early development of the brain. Some gender differences appear at early stages but, due to the changes in sex hormones, the most marked differences are likely to be obvious after puberty. The gender differences in cognitive function and cerebral lateralisation can be observed from the anatomical sex differences in brain structures. It is well known that, on average, females perform better on tests involving computation, whereas men tend to do better than women in problem-solving and mathematical reasoning aptitude tests.

Researchers have paid attention to the concentration of circulating androgen hormones during adulthood. Moreover, similarities in some brain regions between homosexual males and heterosexual females have been reported. Other evidence of sex differences has shown that, on average, adult males have a larger brain size and they also have a larger corpus callosum than adult females. Evolutionary theory tells us that females are more sensitive to social cues and signs of stress and this is found in both human and non-human species. Differences have also been found between men and women in social cognition during adolescence and adulthood, and it is known that more females than males suffer from major depression after the onset of puberty. The contribution of the hypothalamic-pituitary-adrenal axis (HPA) in sex

103 differences is reported in more females than males, whereas a greater hormonal reactivity to pharmacological stimulation with naloxone, and greater HPA axis responses to a psychological stressor has been found more in males than in females.

3.6 Conclusion

This chapter started by discussing the importance of the emergence of affective neuroscience as a new approach that investigates and examines the underlying neural bases of emotion and mood. Next, it focused on specific brain regions and their roles in human emotion. The first region discussed was the amygdala and its role in fear recognition, followed by an investigation of the role of the posterior cingulate cortex in visual spatial attention toward stimuli and the memory of emotional stimuli. The dorsolateral prefrontal cortex is another brain region that is thought to play a role in emotion and attention processes. In addition, the inferior frontal gyrus is considered to be influential in executive functions and in allowing inhibition of learned responses. Another brain area mentioned was the insula, which was found to be associated with facial expressions of disgust. The orbitofrontal cortex is a part of the brain that is believed to be important in emotion and motivation. The last reported region was the basal ganglia, which is responsible for the processing of prosody. The last part of the chapter was devoted to reports of studies on brain injuries, and how such impairments have led to a greater understanding of the human brain. This discussion focused on gender differences in the human brain and how these differences might be responsible for different behaviours in males and females.

From the studies that were reported in this chapter, it can be concluded that affective neuroscience is a new approach that helps researchers to break down cognitive

104 processes into different elements to be studied in neural terms. Detecting activation in human brain regions allows us to decide which of these parts is responsible for which function and enable us to gain a better understanding of the brain functions that affect human behaviour. The result has been rich findings that have confirmed the involvement of the following regions in processing emotion: amygdala, insula, posterior cingulate cortex, dorsolateral prefrontal cortex, inferior frontal gyrus, orbitofrontal cortex and basal ganglia. Additionally, brain injury and split-brain studies have provided a further understanding by associating the absent functions with the impaired brain regions.

Finally, emotion is one of the brain’s functions that is processed in different ways by men and women, even when there are similarities in the expressed emotion, and this could be explained by gender differences in some brain regions. For example, women tend to cry more often than men, even though the emotion of “sadness” remains the same. Thus, men and women may behave differently in response to the same stimulus. One of the different behavioural tendencies that can be observed between men and women is in the cradling of babies and this difference may also be caused by the ways in which the different genders process emotion. Issues relevant to this tendency, such as how emotion and language are lateralised in the brain, have been discussed in the previous chapters. What evidence is there that gender differences in the brain’s functions, such as emotion, can result in behavioural differences? In other words, these chapters have examined the extent to which the tendency of women to cradle babies to the left side of their bodies and men to cradle babies to the opposite side can be explained by gender differences in the brains’ functions.

105 Chapter 4

Methodology

4.1 Overview

Having reviewed the relevant research literature in the previous chapters, this chapter considers the methodological issues that need to be addressed. These issues include the reasons for replicating and extending previous studies, the ways in which certain ethical problems (e.g. using a real infant as a stimulus) can be avoided, and what the contribution of the current study is to scientific research, and to the area of psychology in particular.

There are always reasons behind the design and structure of experimental studies.

For this experiment, however, these reasons limit the study somewhat, and can be summarised as follows:

1. Cognitive psychology is a new subject in the Arabic region. To my knowledge,

there have been no investigations in Arabic countries of either the left-side

cradling bias or the factors that could play critical roles in the lateralisation of

emotion in general.

2. Religious and cultural factors play a role in handedness in Arabic countries. In

short, Muslims must behave as if they are right-handed, even if they are

naturally left-handed. This means that, for this sample, the majority of tasks are

performed with the right hand. Additionally, the culture itself may affect

cradling preference, as has been found in previous studies. Therefore, we need

106 to investigate the way in which culture affects handedness and cradling bias. If

there is an effect, to what extent does this influence the results of the current

study?

3. Videotaping participants is a technique that leads to increased accuracy and

helps to obtain correct data in a natural manner. It is an ideal technique for

recording and, subsequently, analysing cradling preference. However, Saudi

Arabia is a conservative society and videotaping Saudi women, whether they

live in the country or abroad, is firmly prohibited by its Islamic law.

Consequently, Saudi mother participants in the current study could not be

videotaped. Nevertheless, since the videotaping of men is allowed, this

technique was used with male participants of this study.

4. Additionally, the current study is cross-national; it compares a Saudi sample

based in Saudi Arabia to a Saudi sample based in the United Kingdom. Hence,

it will provide rich data that may result in new outcomes.

5. As well as examining the cradling bias among Saudi mothers and non-mothers

using a questionnaire as the only available instrument, the present study

provides an opportunity to use videotaping to investigate the left-cradling bias

among non-fathers, which previous Western studies have found to be weak.

6. Finally, videotaping males and also asking them to fill in the same

questionnaire that the females completed enabled an investigation of the

difference between two types of cradling, that is, between spontaneous cradling

side and preferred cradling side. The first type was obtained by videotaping,

whereas the second one was obtained through answers to the questionnaire.

107 Videotaping (which is described in the “procedure” section of this chapter)

enabled the experimenter to gather clear evidence of the spontaneous cradling

side of male participants because they felt free to hold or cradle the object

(infant or doll) without any interference from the experimenter. On the other

hand, the questionnaire answers reflected the preferred cradling side because

participants had to think and imagine the way that they would cradle a doll or

their infant comfortably.

In connection with previous studies which have stated that the right hemisphere of the brain is involved in the perception of emotion, and that the right hemisphere of the brain controls the left side of the body, the current study hypothesises that mood state (depression and stress) may reduce left-side bias, that is, that depression and stress play a role in the lateralisation of emotion and this may affect the laterality of the cradling-side or infant-holding. It is possible that effects on or impairments of emotion recognition can contribute to changes in social behaviour, especially effects or impairments following traumatic brain injury (Kendall and Terry, 1996).

4.2 The hypotheses for the study

1. There is a significant left-side cradling bias in both males and females.

2. The preferred cradling side is related to the experience of childcare

(parenthood).

3. There is a difference between males and females in preferred cradling side

when holding an infant versus holding a doll.

108 4. There is a relationship between depression, stress, infant’s gender, holder’s

gender and cradling side.

5. The cradling side (of a real infant or a doll) is also related to handedness,

culture, parenthood, and footedness.

6. The preferred cradling side (of a real infant or doll) can be predicted from

handedness, footedness, depression, stress, the infant’s age, the holder’s

gender, the infant’s gender, and the participant’s status or culture.

7. The spontaneous cradling side (of a real infant or doll) can be predicted from

handedness, footedness, depression, stress, the infant’s age, the holder’s

gender, the infant’s gender, and the participant’s status or culture.

4.3 Ethical Considerations

This study was approved by the ethical committee of the Department of Clinical

Psychology, School of Health in Social Sciences, University of Edinburgh, and was signed and carried out according to the British Psychological Society’s revised

(2004) guidelines for work with children. Participants were contacted by e-mail, telephone or in person. Because the recruited sample for the current study were Saudi

Arabian, they were shown a letter of support for the study from the Saudi Arabian

Embassy in London as well as a supporting letter from Department of Clinical

Psychology, University of Edinburgh, before they agreed to participate (these letters are shown in the appendix). Both letters were translated into Arabic before being shown to the participants. Each participant also received a separate information sheet describing the study, along with an informed consent form and he or she was asked

109 to indicate agreement to participate by signing and returning the consent form.

Additionally, they were informed that all the information they gave would be used confidentially only for academic research purposes, and they were told that they had the right to withdraw from the study at any time. Those recruited to be holders of infants were only their fathers, relatives or very familiar and close friends. As mentioned previously, no women were recruited as holders of infants because this part of the experiment depended on videotaping, which is not allowed in Saudi

Arabia according to Islamic Law.

Before starting the experiments, all the materials were checked for safety. No data collected were discussed with participants, and participants were asked to not to do anything, during videotaping, that they would not normally do in their daily life. All videotapes were kept in a secure place with access restricted to the three people

(researcher, university supervisor and reliability coder) directly involved in the study, and, finally, the data will be destroyed after the PhD has been completed.

4.4 Methodology

The study used two methods, a questionnaire and videotaping, to collect the experimental data. The same questionnaire was used for both the Saudi Arabian based and UK based samples and for both the male and female participants. It contained a variety of measurements, and it commenced with two questions which identified the participant’s preferred cradling side for both the infant and the doll stimuli. The two questions were:

110 “Imagine you are holding/cradling an infant, to which side do you prefer? Left or right?” And, “Imagine you are holding/cradling a doll, to which side do you prefer?

Left or right?”

The videotaping was used to gather data on spontaneous cradling preference. As explained above, this was used only with the male sample, due to ethical considerations.

The information sheet, written in Arabic, given to participants had “Cradling Bias” as its title. But, in Arabic, this term means “to hold something” so it likely that the participants had no clear idea about for the purpose of the study. However, the consent form was in English but, again, the participants did not show any understanding of the meaning of “cradling bias”. Therefore, they appeared very normal during the experiments and some of them played freely with the held object.

All the male participants, fathers and non-fathers, were videotaped for one minute with each stimulus (infant and doll). Each participant’s cradling preference was determined by calculating the percentage of the two minutes that the infant or the doll was held to each side of his body.

If the participant held the object on one particular side for between 51% and 100% of the time, he was deemed to have a preference for that side. For example, if the participant cradled the object for 60% of time to the right and 40% to the left, then the participant was recorded as having a right preference. Anyone who held the object for 50% of the total duration on each side of his body was considered to show no cradling preference.

111 4.4.1 The cultural comparison

To obtain a cultural comparison, 234 participants (63.4%) were based in Saudi

Arabia and 135 participants (36.6%) were based in the United Kingdom.

The UK-based sample had been resident in the UK for more than five years. This period of time had offered these participants a chance to interact with British society and to integrate with the new culture. They are not isolated nor do they live in closed minorities because it is believed that learning the second language has cultural effects. Indeed, most of them are eager not only to pursue academic studies but also to involve themselves in the daily life of the new culture and they are in dynamic contact with it. It can be argued that residence in a foreign country has an acculturisation effect Al-Ansari, 2000; Jackson, 2009). Regardless of their heritage, culture and whether they are sojourns or refugees, newcomers tend to adapt to their new cultural environment (Ward, Bochner and Furnham, 2001). Their behaviour tends to be guided by their new environment and they are influenced by their social cognitions, such as the foods they eat, the clothes they wear, the people with whom they associate, and the values to which they adhere (Padilla and Perez, 2003).

A comparison of the results obtained from these two groups, all born and socialised in Saudi Arabia, was designed to examine the affect on cradling bias of living in another and very different country for a considerable period of time.

4.4.2 Stimuli types

Intuitively, the infant was the more 'normal' of the two cradling stimuli used in this experiment; therefore the second stimulus used with each participant was a real infant, aged between 1 month and 15 months (mean = 6.69, SD = 3.544). The

112 number of real infants used was 27, of whom 16 (59.3%) were males and 11 (40.7%) were females. Some of them were videotaped only with their fathers, and others were videotaped with their fathers and very close relatives or very close family friends. Thus, each infant was held only by people who were very familiar to it.

Using a real infant as a stimulus involves consideration of a number of issues. In addition to ensuring familiarity between the holder and the child, all video-tapes were recorded in the infants’ own homes (except for four cases which were videotaped at Aljadaani Hospital, Jeddah, Saudi Arabia), to ensure that the infants felt comfortable and were not upset by being in strange place. Two cases were dropped because the infants became upset while videotaping.

The second stimulus used was a doll. It was purchased from Reaitylworks and was not like a normal doll. It was made for educational purposes, especially for those who are planning to be parents or for new parents. The package contains a very useful training programme, such as how to soothe and feed. It is an infant-like doll of approximately the same size and weight (3.2 kg) as a newborn, and it is illustrated in figure 4.1. Because of its shape and design, and because of its clear similarity to a real infant, it was decided to use it as a stimulus in order to investigate how participants responded to a doll compared to how they responded to a real baby.

Although the doll could be animated, this feature was not used during this experiment. In other words, the experiment was designed to discover if participants exhibited similar or different behaviours while cradling a real baby and cradling a doll, and the contribution of the reality of the stimulus to the exhibited cradling side.

Using this type of stimuli provided a good opportunity to investigate what could be

113 considered as a hidden factor, that is, the real-ness of the cradling a doll compared to cradling an infant.

Figure 4.1

Infant-like doll designed and produced by REALITYWORKS company

4.4.3 Design

The study was conducted on a Saudi sample, part of which lived in Saudi Arabia and part of which lived in the UK. The design involved fathers, non-fathers, mothers and non-mothers. Two methods were used: videotaping and filling in a questionnaire.

Real infants and dolls were used as stimuli for establishing observed spontaneous cradling preferences in the male part of the sample. The questionnaire established self-reported cradling preference for all participants. All methodological considerations have been detailed previously.

114 Following some studies (e.g. Bundy, 1979; Sailing and Tyson, 1981) that have used dolls as stimuli and demonstrated that they can elicit a left cradling bias amongst young people in an imagination task, a baby-like doll was used in this experiment in order to eliminate the ethical problems that are associated with testing a real baby.

The second reason is that using a baby-like doll allowed us to investigate the role of real-ness of the cradled/held object.

4.4.4 Participants a total of 369 participants, all of whom grew up in Saudi Arabia, were recruited for this study. The names and addresses of potential participants were obtained from primary care centres in Saudi Arabia and from the Saudi Embassy in London. These numbered 900 and 431, respectively and they were contacted by telephone, e-mail, post or in person and they were shown a letter of support for the study from the Saudi

Arabian embassy. A total of 369 people agreed to participate in the study, of whom

234 (63.4%) were based in Saudi Arabia and 135 (36.6%) were based in the United

Kingdom. 102 (27.6%) were males and 267 (72.4%) were females. The age range of all participants was 16-59 (mean = 26.04, sd = 6.447), with the males’ ages ranging from 16 to 42 (mean=31.10, sd = 6.066) and the females’ ages ranging from 18 to 59

(mean =24.10, s.d = 5.47).

Both the Saudi-based and UK-based sub-samples for this study were chosen from the western part of Saudi Arabia. This was because the majority of Saudi people live in the capital (centre) and the western region due to its economic importance and the location there of the holy places of Makkah and Medina.

115 The UK-based sub-sample was recruited with the help of the Saudi Embassy in

London. The Embassy produced a list of 431 students from the western region of

Saudi Arabia, identified as such because they had been granted their scholarships by one of the three universities in that region, namely, Umm Al-Qura University

(Makkah), King Abdulaziz University (Jeddah) and Taibah University (Madina).All

431 were contacted and 135 agreed to participate in the current study. Obviously, no claim can be made that this sub-sample was representative of western region Saudis living in the UK, mainly because participation was restricted to students but also because the characteristics of the volunteers could not be compared with those of the non-volunteers.

For the Saudi-based sub-sample, we attempted to get a representative sample of the population of the western region of Saudi Arabia but this did not prove to be possible, mainly because females were more willing than males to participate and there was, therefore, a strong female bias in the sample. In addition, due to some data restrictions, it was not possible to obtain a full list of the names and addresses of all the clients of the primary care centres, even for research purposes. However, nine centres agreed to provide data for their first one hundred registered clients. Of the

900 persons subsequently contacted, 234 agreed to participate in the present study.

Obviously, this sub-sample may also not be representative of the population of the western region mainly, as stated, because of its female bias, but also because of restrictions on obtaining names and addresses from the primary care centres. Even without this problem, no information was available on how representative the clients of primary care centres are of the total population.

116 Figure 4.2

The graph above shows that 52 (51%) of the Saudi males were based in Saudi Arabia and 50 (49%) were based in the United Kingdom.

The sample included both people who were experienced in childcare (fathers and mothers) and people who were not experienced in childcare (non-fathers and non- mothers).The infants recruited for the experiment included both males and females.

The number and status of all the adult participants are shown in table 4.2.

4.4.5 Instruments

The following instruments were used in this study: the Beck Depression Inventory

(BDI - both Arabic and English versions), the Perceived Stress Scale (PSS – both

Arabic and English versions), the Waterloo Footedness Questionnaire-Revised

117 (WFQ-R), the Edinburgh Handedness Inventory (EHI - Arabic translation) and, for the pilot study, the dichotic listening task (DLT). The equivalence of the English and

Arabic versions of these instruments was confirmed, as detailed in chapter 6, because the first language of all the participants was Arabic. This test of the equivalence of the two versions of the instruments was essential because it enabled the study to be carried out using the appropriate version for each part of the sample. Only the Arabic versions were used with the Saudi based sample but both the English and the Arabic versions were used with UK based sample. With the latter group, we first used the

English versions because answering the questions in Arabic may not have reflected these participants’ real ability in English. Thus, we preferred to start with the English versions in order to avoid any possible effects. Later, the same participants were asked to fill in the Arabic versions and this allowed a comparison of the results of the two versions.

4.4.5.1 Beck Depression Inventory (BDI-II)

The BDI is a 21 multiple-choice question self-report inventory and it is one of the most widely used instruments for measuring the severity of depression ((Kogan, et al., 1994; Al-Musawi, 2001). Originally, it was designed for adults aged 17–80 to provide a quantitative assessment of depression intensity (Beck, Ward, Mendelson,

Mock and Erbaugh, 1961)

The BDI relates to symptoms of depression such as sadness, pessimism, sense of failure, dissatisfaction, guilt, expectation of punishment, dislike of self, self- accusation, suicidal ideation, episodes of crying, irritability, social withdrawal,

118 indecisiveness, change in body image, retardation, insomnia, fatiguability, loss of appetite, loss of weight, somatic preoccupation and low level of energy. It was one of the first self-rating scales for depressive symptomatology that attracted the attention of Arab psychometricians, such as Abdul Fatah Gareeb (1984), who translated it and developed the first simple standard Arabic version of the BDI (Abdel-Khalek, 1996).

To ensure internal consistency, 380 male and female undergraduate students were recruited from Kuwait, Saudi Arabia, Egypt and Lebanon. Cronbach’s Alpha scores for scale reliability were .89, .82, .77, and .67, respectively (Abdel-Khalek, 1996).

Before using this version in the current study, a pilot study of 31 participants was carried out to confirm its reliability for the current project. This produced a

Cronbach’s Alpha score of .813 and a spilt-half reliability of .842 (see table 4.3).

These reliability values indicated that the BDI Arabic version was a suitable instrument for assessing depression.

For each item, a participant was asked to choose one of four options that best described how he/she had felt in the past week. For each item, scores rank from normal (0) to severe (3) and the total score may range between 0 and 63. Different cut-offs have been used in previous studies, varying from 12 (Overby, 1994;

Weatherill, Almerigi, Levendosky, Bogat, Eye and Harris, 2004) to 22 (Kogan et al.,

1994). This study followed Al-Musawi (2001) and Abel-Khalek’s (1996) Arabic studies in considering participants who scored 18 or above as with high level of depression and anyone who scored 17 or below would be deemed to be non- depressed. Even though the above mentioned Arabic studies considered participants who scored 18 or above as depressed and anyone who scored 17 or below as non-

119 depressed, this was not based on clinical reference data. Therefore, we preferred to use in the present study high level of depression rather than depressed.

4.4.5.2 Perceived Stress Scale (PSS)

The PSS was designed by Cohen, Kamark and Mermelestein in 1983 to measure the level of stress that respondents feel they have experienced during the previous month. It is the most widely used instrument for this purpose (Ice and James, 2007).

The 14 items, each involving the choice of one of four statements which best describes the participant’s experience, are easy to understand and the responses are easy to mark (Remor, 2006). High measures of reliability and validity have been found by Cohen and various colleagues (1983, 1988) and others (Ramirez and

Hernandez, 2007). This instrument's 5-point scale ranges from 0 (never) to 5 (very often). A total score, which can range from 0 to 56 is obtained by adding together the score for each item, though the scores for items 4, 5, 6, 7, 9, 10 and 13 are reversed

(e.g. 0=4, 1=3 and so on).

In line with Cohen et al.’s (1983) proof that the PSS has good reliability, in the current study, the standardised Cronbach’s Alpha was found to be 0.866, and the split-half was 0.859.

There is no previously defined point at which the results of PSS can be dichotomized as stressed or not-stressed. As suggested by Morais, Maia, Azevedo, Amaral and

Tavares (2006), higher scores obviously indicate higher levels of perceived stress and previous studies, such as Cohen et al. (1983), reported almost the same mean scores for PSS that were found in this study, namely, 23.30 (SD = 8.99) with 20.93

120 (SD = 9.744) for males and 24.21 (SD = 8.53) for females. Although, the PSS is not a diagnostic instrument, in order to dichotomise the participants in this study, following Cohen et al. (1983) and Khayat (2007), it was decided that anyone whose score exceeded the mean score of 24 would be labelled as with high levels of stress and anyone with a lower score would be deemed to be not stressed.

4.4.5.3 Waterloo Footedness Questionnaire-Revised

For assessing the footedness preferences of the participants, the Waterloo Footedness

Questionnaire-Revised (Elias et. al., 1998) was used because it is relatively short (10- items), well known and has been previously used for such assessments. This questionnaire (WFQ-R2) asks for responses about two types of tasks. Five questions

(1, 3, 5, 7 and 9) ask about foot preference for manipulating an object (for example, kicking a ball, picking up a marble or pushing a shovel into the ground). The other five questions (2, 4, 6, 8 and 10) ask about which leg is likely to be used to provide support during an activity such as stepping up onto a chair or standing on one foot balancing on a railway track. A score of -1 means that the participant is left-footed whereas +1 indicates a right foot preference. To make sure that the WFQ-R was appropriate to use with the participants of this study, a good score for reliability was obtained in different ways. The Cronbach’s Alpha score was found to be (n = 39)

0.907, and the split-half (n = 39) was 0.920, using the Spearman-Brown equal length equation.

121 4.4.5.4 Edinburgh Handedness Inventory (EHI)

The Edinburgh Handedness Inventory (EHI) is one of the most famous instruments for measuring handedness and it has been used since 1971. It was developed by

Oldfield (1971), but was based on a thesis written by M. Humphrey, Oxford

University. In the original thesis, 1100 undergraduate students in Scotland and

England were recruited to answer a 20-item questionnaire, but Oldfield selected only

10 of these items for the final EHI questionnaire (Mandal, Bulman-Fleming and

Tiwari, 2000). Oldfield’s recommended scoring method for the EHI is based on hand performance and the scoring result is called the ''laterality quotient'' (L.Q. = range -

100 to +100).

However, there is an alternative scoring method developed by other studies, such as

Reissland (2009), and this was used in the present study. This method was preferred because the results are easily and quickly tabulated. The questionnaire consists of 10 questions which reflect ten activities that use the hands: writing; drawing; throwing; using scissors, a toothbrush, a knife, a spoon and a broom; striking a match; and opening the lid of a box. With use of the right hand being coded as 1, the use of both hands being coded as 2, and the use of left hand use being coded as 0, a total score of

20 indicates complete right-handedness, a score of 10 or above indicates that the subject is generally right-handed and a score of 9 or below indicates that the participant is generally left-handed.

Each participant was first asked to state whether he or she was left-handed or right- handed. In the second stage they were asked to fill in the EHI questionnaire. When participants' initial statements about handedness were compared with their EHI

122 score, the result was always found to be the same. That is, if a participant stated that he or she was left-handed, the EHI result reported that he/she was indeed left-handed, and vice-versa. There were no ambidextrous participants in the current study.

The scores obtained from 39 test subjects proved that EHI has a good reliability for this study sample since the standardised Cronbach’s Alpha was 0.966 and the split- half using Spearman-Brown’s equal length equation was 0.979.

Because both Arabic and English versions of these instruments (BDI, PSS, EHI, and

WFQ-R) were used in the current study, the equivalence of these instruments was examined. The results of this equivalence testing have been detailed in Chapter 6.

Because no Arabic versions exist for PSS, EHI and WFQ-R2, these instruments were translated by the author into Arabic and then reviewed by specialists in the translation department in King Abdulaziz University, Jeddah, Saudi Arabia who provided some suggested amendments. After checking the validity and adequacy of the translations, the final versions were used in the present study. Finally, and to make sure that the 10 item questionnaire (PSS) was culturally appropriate for the participants, it was vetted by reviewers from King Abdulaziz University, Jeddah,

Saudi Arabia and all the reviewers agreed that it is a good and reliable instrument.

4.4.5.5 Dichotic Listening Task (DLT)

The Dichotic Listening Task was used in the pilot study in order to determine which hemisphere is responsible for the emotional processing of auditory information. The first studies on brain laterality in humans investigated the effects of brain injuries,

123 and these were followed by split brain studies. These, and especially the latter, provided a rich source of information on brain functions since the connections between the two halves of the brain were broken and researchers were able to associate specific human behaviours to a specific brain hemisphere by using appropriate psychometric tests. However, the advent of the dichotic listening task provided a good and widely used method for investigating brain laterality in normal people by presenting stimuli to both ears simultaneously and then determining ear advantage (and thus demonstrating hemisphere laterality). This technique (DLT) is a non-invasive method that has been used to assess a variety of emotional processes.

The dichotic listening task used in the present study was designed by Donnot and

Vauclair (2007) and was considered to be a good instrument for our pilot study. The test has five imaginary language sentences presented in three emotional tones (angry, happy and neutral): “Oken floj manicha sobren”, “Fir asten monidar doke”, “At poricila doke´ro bramilan”, “Herna fitu coujarboque´”, and “Sim vobona surat ogarin”. There was also an additional sentence (“Turcafer adi goulnachu gorni”) that was used for familiarisation purposes.

This imaginary language was chosen and used in order to normalise and naturalise the participants' responses; that is, to ensure that the result would not be affected by the participants’ understanding the sentences. Only the emotional tone could be understood.

In each trial, the participant receives one of the three tones in one ear and another of the three tones in the other ear at the same time and at the same volume level. Each sentence consists of four words, and the duration of each sentence does not exceed

124 two seconds. All of the sentences start and end at the same time (Donnot and

Vauclair, 2007). In each of the thirty trials, the participant is asked to tell the experimenter which was the most clearly heard emotion.

A value of -1 is given if the tone presented to the left ear was the most clearly heard, and a value of +1 is given if the tone presented to the right ear was most clearly heard. After calculating the mean score, a negative mean indicates a left-ear advantage, and a positive mean indicates a right-ear advantage.

4.4.6 The equivalence of the Arabic and English versions

Before we report the main results of the current study, we should state that both the

Arabic and English versions of EHI, BDI-II, WFQ-R2 and PSS were used here. We examined their validity with a group of Saudis in the United Kingdom. The validity of the instruments that were used in the current study was discussed earlier in this chapter. Based on the validity outcomes, we examined the equivalence of the Arabic and English versions of each instrument.

As mentioned previously in the current chapter, the study sample was divided into two parts; one half of the sample was based in Saudi Arabia and the other half was based in the United Kingdom. The Arabic form of all questionnaires that were used in the current study was given to those who were in Saudi Arabia, because we had no evidence that participants in this area could read, understand and finally fill in the questionnaires in English. The English form was given to the second part of the sample, that is, those who live in the United Kingdom. All participants in this part were Saudis. They were undergraduate and postgraduate students in different British

125 universities. The fact that they were studying for degrees is good evidence that they were able to read, understand and, of course, fill in the questionnaires in English.

Anyone who did not achieve a certain level of English would not be accepted by any university due to standard rules of acceptance. Additionally, to be assured of the cross-cultural validity of the instruments for this sample, we examined the equivalence of the Arabic and English forms of the questionnaires.

To check for the adequacy and equivalence of the two versions of each instrument which were used in this study, and to be sure that the understanding of the items would have no effect on the result, the English versions of BDI-II, PSS-14, EHI and

WFQ-R2 were used with 53 Saudi participants in the United Kingdom. After filling in these questionnaires in English, the same participants were asked to repeat this task but with the Arabic versions (see instruments section in this chapter for how the instruments were translated). We started with the English versions because the first language of participants is Arabic. Doing them in Arabic may not reflect their real ability in English.

The Pearson correlations of the scores that were obtained from both versions were as follows: for the BDI-II, the correlation between the two versions (Arabic and

English) was n= 53, r = 0.938 (p < 0. 001), while the correlation between the two versions of the Perceived Stress Scale (Arabic and English) (PSS) was n= 53, r =

0.966 (p < 0.001). In terms of handedness, the Pearson correlation between the two versions of the Edinburgh Handedness Inventory EHI for both the Arabic and

English versions was n= 53, r = 0.989 (p < 0. 001). And, finally, the correlation between the Arabic and English versions of the Waterloo Footedness Questionnaire-

Revised (WFQ-R2) was n= 53, r =0.986 (p < 0. 001).

126 Thus, these significant results can be considered as good evidence of the cross- language equivalence of the two forms of the instrument. Therefore, we can proceed to the rest of the results.

4.5 Videotaping

Fathers and non-fathers were videotaped. Only the participants who consented to take part in the study were videotaped, and they were recorded while they cradled first a doll and then an infant aged between one month and fifteen months. Each participant was told to feel free to play freely (if he wished) using a soft toy with both the doll and the infant.

It has been suggested that stimulus presentation has an influence on cradling behaviour; Dagenbach et al.'s study (1988) demonstrated that the left cradling bias was weaker when the parent picked up the infant from a crib than when the infant was presented by the experimenter to the midline of the parent. Clearly, the expectations and handedness of the experimenter could affect the normality of the experiment. A good example of the influence of stimulus presentation is that mothers have been found more likely to hold to the left when they approach from the right side of the infant than when they approach it from the left (Vauclair et al, 2005). To avoid these types of effects and to examine spontaneous holding and cradling, both stimuli (i.e. infant and doll) were placed in a high chair at the midline of the participant’s body at a 3 metre distance in front of the participant. Thus, normality and spontaneity were ensured here by asking participants to pick up the stimulus

(infant or doll) from the high chair and then to hold or cradle it. This, of course, allowed the participants to be totally free to choose the side of approach.

127 First, each participant was asked to pick up, hold and then cradle the doll for a period of time, estimated at about sixty seconds. The doll was of the same size and weight as a real infant. Then, he was asked to do the same with an infant. The average time being videotaped was approximately two minutes for every male participant (one minute for each stimulus). The observed cradling preference was noted as being the spontaneous cradling-side choice.

All videotaped participants were asked to fill in the questionnaire, which was used for later analysis along with the recorded tapes. These analyses will be presented in detail in Chapter 8.

4.6 Procedure

The participants who had agreed to be videotaped were asked to answer the questionnaires relating to all the instruments described above before being videotaped. They were told exactly what to do, as described in the previous section.

During the videotaping task, the participant’s behaviour was observed and recorded according to the following questions: Is he cradling to the right or to the left? Is he changing the cradling from one side to the other? Does he cradle the doll in the same way as he cradles an infant?

All the videotaped subjects were first asked to hold/cradle a doll and then an infant.

The instructions were given to each participant on a piece of paper, which they had to read before carrying out the experiment. The piece of paper contained the following instructions.

128 “I would like to thank you very much for agreeing to participate. As you can see, there is a doll (infant) on that high chair. I need you to go and hold and cradle it.

Please remember that it is your right to go ahead or withdraw at any time. If you decided to participate, please feel free to play, speak or sing”.

This statement and the procedure were the same for the doll and the infant. The duration of time was controlled by the experimenter using a stopwatch, but the participants were not aware that they were being timed.

All fathers and non-fathers were videotaped with infants in very comfortable places, for example, the infant’s bedroom or a friend’s house in which the infant would feel comfortable and calm. Four of the infants were videotaped in Aljadaani Hospital,

Jeddah, Saudi Arabia.

4.7 Statistical analysis

The collected data were analysed with SPSS to see if there was any bias in cradling side and to discover whether there was any correlation between mood status

(depression, stress) and the cradling side, and whether there were any differences among participants owing to lateralisation of emotion, familiarity, gender, handedness, footedness or culture. The data analysis was designed to answer two sets of questions. Was there any bias in cradling due to the hypothesised factors i.e. depression, stress, footedness, handedness, culture, experience in parenthood, or the gender of the holder? Did depression, stress, footedness, handedness, culture, experience in parenthood, gender of the holder, infant gender, infant’s age or holder's age predict cradling side?

129 4.8 Terminology

Here, some of the terms that have been used in this thesis are defined with the aim of adding clarification to the study and avoiding any ambiguity that may lead to incorrect understanding. The cradling/ holding side preference was defined by calculating the percentage of time that the participant held the child/doll on each side of his body. Any side which scored 51% or above was deemed to be the preferred side. A score of 50% meant that the participant had no side preference. The terms

'leftward cradling' and 'left cradling bias' are used in the current and previous studies to describe the participant's preference for holding/cradling a doll/ an infant in the left arm and to the left side of his body while being tested.

The word 'cradle' is defined as ''to hold something or someone gently, especially by supporting with the arms'' (Cambridge Dictionary, 2005); therefore, 'cradle' comes from 'hold'.

The term 'handedness' is used in the current study to show the hand that the participant preferred to use for most tasks in his or her daily life. Handedness was measured by the Edinburgh Handedness Inventory (EHI).

The term 'footedness' means the foot that the participant prefers to use when the use of only one foot is required. Footedness was measured by the Waterloo Footedness

Questionnaire-Revised (WFQ-R).

The term 'earedness' means the ear (left or right) that is dominant in an individual when he or she hears emotional language or tone. (verbal and non-verbal language).

The Dichotic Listening Test (DLT) was used to demonstrate the preferred ear.

130 Participants were classified as showing either a left ear advantage or a right ear advantage.

4.9 Limitations

The current study has limitations due to its design and hypotheses. All the participants were Saudis, some of whom lived in the United Kingdom and some of whom lived in Saudi Arabia. All videotaped infants were with their fathers or another male who was very familiar to them.

All participants were asked to answer the study questionnaires. Only males were videotaped because only males are allowed to be videotaped according to the Islamic

Law in Saudi Arabia. Given that all male participants answered the questionnaire and were videotaped, these two different methods allowed us to obtain, respectively, the preferred and spontaneous cradling side for the male sample.

The effects of depression and stress on human behaviour were carefully examined in terms of the hemispheric localisation of emotion. Although several studies found no relation between handedness and cradling side, the factors of handedness and footedness were included in the current study due to the strong tendency to use the right hand that has been observed in Islamic societies (see Zverev, 2006).

The limitations of the current study involved the roles of parenthood or parenting experience, the gender of the holder/cradler, the gender of the infant, the age of holder, the age of the held infant, and effect of culture on the cradling side. As has been hypothesised, cultural factors could have an effect on the cradling side. The participants were of Saudi nationality, sharing the same culture and the same

131 traditions with the same religious beliefs and background. Hence, if there is any cultural effect on cradling side, it would be clear to observe. The main aims of this investigation were, firstly, to examine the cradling bias among Saudi males and females and how this can be affected by other factors. Secondly, we wanted to try to predict cradling side from these factors. Finally, both stimuli, that is, the real infant and the infant-like doll, were used with the sample, either in terms of being held physically or being imagined (by female participants).

One limitation of this study is that it looked only at adults from 16-59 years, and held infants of age 1-15 months. Infants aged 15 moths and above were not included as stimuli in the present study and school boys and girls under 16 years old were not included as holders. These excluded groups of infants and holders could have different cradling preferences from the sample used in this study. Therefore, it is recommended that further studies should be conducted to examine more factors.

Another limitation is that videotaping women is not allowed in an Islamic society, especially in a country like Saudi Arabia. This limited the investigation of spontaneous cradling side to the male part of the sample. Therefore, it is highly recommended that a further study should find a way to observe female cradlers, perhaps by surveying and manually recording their cradling behaviour in public places after getting ethical approval.

This study was carried out in the western region of Saudi Arabia because the people in this region are more liberal, friendly and willing to participate. Other regions were excluded due to difficulties of accessing them.

132 The familiarity between the participant and the held infant was very a important factor in videotaping them for the purposes of this study. Some cases were dropped because the infant was upset at the time. And finally, using a doll as a stimulus to elicit emotion could be extended in further studies. Although the doll used in this experiment could have simulated activities (animated nature) such as crying and laughing, there were not activated. These features could be used in future study.

133 Chapter 5

Pilot study

5.1 Dichotic listening Task

First, this chapter explains the reason for carrying out a pilot study and it describes that study. It then moves on to a description of the instruments and procedures that were used in the experiment before reporting on its results. The chapter concludes with a discussion of these outcomes in relation to other studies and to our theoretical position in the main study, namely, that the expression and perception of emotion may be located primarily in the right hemisphere (see Chapter 2).

5.2 Reasons for carrying out a Dichotic Listening Task

After looking at previous work on the lateralisation of emotion and language in chapter 2, it was decided that it was necessary to investigate if the results of that work could be replicated and applied in an Arabic sample. The results of this pilot study will, therefore, provide a base for the main investigation on the relation between the right brain hemisphere’s role in emotion processing and cradling bias in an Arabic sample.

5.3 Introduction

The brain’s asymmetry is related to the functional and structural differences between the two cerebral hemispheres. This section reviews, briefly, some previous studies that investigated this phenomenon (for a full review, see chapters 2 and 3). Several

134 studies (e.g. Bourne and Todd, 2004) reported the dominance of the right hemisphere of the brain in the reception and expression of emotion. Facial expressions were observed and it was found that the left side of the face is more expressive than the right side (e.g. Hauser, 1993). The first person to describe asymmetry in the sensory system was Ernst Heinrich Weber (1795–1878). Weber’s Law, as it was later known, described three areas of asymmetry, namely, the perception of weights, temperature and touch. Weber found that the left hand was more sensitive to these stimuli than the right hand (cited in Jerger and Martin, 2004). The first person to observe facial asymmetries during emotional expression was Darwin (1872), followed by Wolff in

1933, whose experiments involves creating chimerical faces. Wolff claimed that the right side of the face reflects the so called ''public side'' of an individual’s personality, whereas the left side reflects its ''private side''. These terms were somewhat vague and their meaning was not very clear, but actually these descriptions were good indicators of later studies that suggested that the left side of the face reflects a person’s introspective side whereas the right side of the face reflects his or her social side (Powell and Schirillo, 2009).

Karch and Grant’s (1978) study on facial asymmetry found that right facial composites could be judged to be more feminine, softer, more sickly, weaker, more passive, calmer, and more inclined towards the good direction on the good-bad scale.

On the other hand, left facial expressions were reported as being stronger, healthier, harder, more excitable, more active, and inclined towards the bad direction on the good-bad scale.

Additionally, studies of a combination of several neuropsychological factors support the proposed advantage for the right ear, and therefore the left hemisphere, in

135 processing language. For instance, Hugdahl (2003) and Rimol, Specht, Weis, Savoy and Hugdahl (2005) reported a left-hemisphere specialisation for the processing of syllables and Hugdahl (2003) found the predominance of cortical and subcortical pathways for right ear input. In 51 right and left-handed adults with the non-directed condition, Foundas, Corey, Hurley and Heilman (2006) reported a significant right- ear advantage in both handedness groups, with a stronger asymmetry in right- handers. They used dichotic listening performance of consonant vowel stimuli. More issues concerning asymmetrical brain processes for language were widely discussed in Chapter 2

More recent evidence for the asymmetry of sensitivity has been found in several studies. For example, hearing sensitivity was found to be better in the right ear than in the left ear (McFadden, 1993; McFadden and Mishra, 1993) and tinnitus has been found to be more prevalent in the left ear than in the right ear (Khalfa et al.,

1997). Additionally, a right ear advantage was demonstrated for some aspects of linguistics by presenting two different words simultaneously to the two ears in a dichotic listening paradigm. Words presented to the right ear were reported more accurately by the subjects than words presented to the left ear (Jerger and Martin,

2004).

Information received from both ears is represented in both hemispheres through the contralateral and ipsilateral auditory pathways (Fujiki, Jousmaki, and Hari, 2002).

However, each hemisphere seems to be specialised for certain functions. Some studies show a right ear advantage whereas others show a left ear advantage. This relates to the results generated from dichotic listening experiments; that is, different results are due to the different sorts of input (Kimura, 1967). Where the inputs are

136 verbal language, a right ear advantage (the left hemisphere is specialised for linguistics) is obtained but if the inputs are non-verbal (emotional language), a left ear advantage (the right hemisphere is specialised for emotion) is found.

Cowell and Hugdahl (2000) suggested that individuals vary in the manner in which such asymmetries interact with other higher order cognitive functions, even within healthy human participants. In 57 healthy men and women aged 20 to 72 years,they examined the sensitivity of dichotic listening performance, analysing the effect of certain factors, such as gender, age, and the interactions between the variables. They found that dichotic listening asymmetry scores varied as a function of gender, age, handedness, and family history of developmental language disorders. In other words, the right ear advantage has been found to decrease with age in women and increase with age in men.

In speech processing, dichotic listening is an indicator of laterality which is widely used in psychological studies (Hugdahl, Carlsson, Uvebrant and Lundervold, 1997;

Bethmann, Tempelmann, Bleser, Scheich and Brechmann, 2007). The consistent finding of a greater number of correct responses to syllables and words presented to the right ear compared with those presented to the left ear has led to the conclusion that the high right ear advantage (REA) indicates a greater degree of lateralisation in terms of perceptual asymmetry. For instance, Penna, Brancucci, Babiloni, Franciotti,

Pizzella, Rossi, Torquati, Rossini and Romani (2007) found that the right contralateral pathway strongly inhibited the left ipsilateral pathway. In contrast, the right ipsilateral pathway did not show the same inhibition by the left contraleral one

(Penna et al., 2007). The authors argued that the more competition that occurs between the right and left ears stimuli, the more inhibition can occur. Penna and

137 colleagues (2007) concluded that the neurophysiological based explanation that has been found can explain the involvement of the right ear in verbal dichotic listening tasks.

Dichotic listening tests in auditory studies provide rich and accurate data that allow researchers to test laterality or behavioural indicators of laterality in speech processing. Because laterality is one of the main fields of study in cognitive psychology, it has been investigated in several studies. For instance, Elias, Bryden and Bulman-Fleming (1998) argued that footedness is a better and more accurate predictor than handedness of cerebral lateralisation, especially among left-handed people, even though handedness is a more popular predictor. There are five features of lateral preference, which are well examined in the psychological literature: handedness, footedness, eyedness, earedness and facedness. Unlike the hands, feet, eyes, and ears, the face is a non-paired organ and it may exhibit different and more intense expression of emotion on its left side compared to its right side in both normal and brain-injured participants (Borod and Koff, 1990). Although footedness and handedness are the clearest manifestations of lateral preference and good predictors of laterality, studies on eyedness have produced considerable supportive findings. On the other hand, there have been few studies that have explored earedness in terms of lateral preference.

The five types of lateral preference, that is foot, hand, eye, face and ear, were first investigated by Strauss and Wada (1983). In this study, 73 patients were injected with sodium amytal, which contains amobarbital sodium, for speech testing.

Amobarbital is a bitter tasting white powder. It has no odour, and was first synthesised in Germany in 1923, where it was used for sleep disorders. It works by

138 increasing the activity of the neurotransmitter called GABA in the brain, leading to calmness and then sleep. Psychological and physical dependence can develop if it is taken for an extended period of time (Kim, Wan, Mathers and Puil, 2004). The drug has both diagnostic and therapeutic uses, such as testing hemispheric specialisation using intracarotid injections. The transient anaesthesia that can be induced by amobarbital on one cerebral hemisphere is a good method of helping towards an understanding of how the human brain works (Wada and Rasmussen, 2007).

Despite the fact that the findings were negative regarding eye and ear preference as a predictive factor, sodium amytal was found to be the best predictor of ear advantage in the dichotic listening test (Strauss and Goldsmith, 1986). Based on these findings, it can be argued that ear preference is worth further investigation.

To examine conscious and unconscious emotional stimuli, Smith and Bulman-

Fleming (2005) conducted research on 64 right-handed undergraduate students with normal vision at the University of Waterloo. Positive, negative or neutral words were presented for 17 ms to one visual field and, although the researchers found a right hemisphere advantage for conscious perception, they failed to find the same for unconscious perception.

One of the few studies that have demonstrated the natural expression of hemispheric asymmetries was conducted by Marzoli and Tommasi (2009). Their findings seem to be in agreement with previous studies, such as those of Kimura (1964) and Hugdahl,

Wester and Asbjornsen (1990), which were conducted on both differential hemispheric specialisation for approach/avoidance behaviour and right ear/left hemisphere advantage for verbal communication in both naturalistic circumstances

139 and the laboratory. They carried out a study in various discotheques to investigate ear preference in ecological situations by observing four types of interactions: a woman speaking to a man, a woman speaking to a woman, a man speaking to a man, and a man speaking to a woman. Unlike the previous studies, the individuals were observed unobtrusively during natural social interactions. The loud level of the background music encouraged participants to use either their right or left ear in verbal communication. They found that all interaction types were significantly biased and found to occur on the right side of the listener (Marzoli et al., 2009).

A final point to make here is that, although brain injury and brain lesion studies, along with studies on normal people, have reported lateralities in human and non- human species, genetic effects on laterality have not been confirmed. Studies on twins have failed to confirm a genetic hypothesis. For example, Reiss, Tymnik,

Kogler, Kogler and Reiss (1999) found that the genetic hypothesis of determination of sidedness in humans could not be confirmed. They conducted a study on 33 monozygotic (MZ) twin pairs and 67 dizygotic (DZ) twin pairs and found the incidence of non-right-handedness in twins is not higher than its incidence in singletons.

5.4 Gender differences in Dichotic Listening

The first point to note here is that studies have shown that gender differences can be detected as early as the second day after conception because male embryos have a higher metabolic rate and more cells (Ray, Conaghan, Winston and Handyside,

1995). Interestingly, Koopman (1999) reported that the development of the testes occurs as a result of interactions between Y and X chromosomes around six weeks

140 after conception. By producing the testicular hormones (e.g. testosterone) between weeks 12-16, a male foetus can develop its masculinity because the absence of these factors will result in the formation of a female foetus. Thus, this evidence confirms that gender differences occur early in human life and suggests that they lead to differences in subsequent human behaviour.

Recently, gender differences in dichotic listening tasks have been addressed and investigated widely. These investigations have stemmed from the importance of auditory asymmetry as a gate to brain laterality following hand and foot investigations.

Although previous studies have reported gender differences in dichotic listening tasks, the findings are inconsistent. For example, greater asymmetry has been found in men than in women (Cowell and Hugdahl, 2000), whereas Foundas, Corey,

Hurley and Heilman (2006) did not find this in their study. Moreover, it has been reported that the right ear advantage increased with age in men across the adult lifespan and decreased with age in women. This asymmetry was very obvious and prominent in older people compared to younger adults (Cowell et al., 2000).

Marzoli et al. (2009) used a quasi-experimental method on disco bystanders in order to provoke an ear orientating response. They found that when the data from observations of males and females were taken together, a right ear preference was evident but when the data for men and women were analysed separately, only the women showed a significant right ear preference. These findings (the role of gender in auditory asymmetry) are consistent with Hebbal and Mysorekar’s study (2003), which found that handedness and hearing acuity were significantly associated in

141 Indian students. In addition, a higher acuity in the right ear was found in the right- handed women than in the left-handers. Moreover, Ida and Mandal (2003) have found the same result; they observed a greater right-ear preference in women than in men in Japanese and Indian students.

The effect of age and gender on dichotic listening asymmetry has been reported and explained by the size of the corpus callosum (Westerhausen and Hugdahl, 2008) because a greater size of corpus callosum has been reported in men than in women

(Sullivan, Rosenbloom, Desmond and Pfefferbaum, 2001). Because of the wealth of the neural connections in this part of the brain, it is undoubtedly the most important part that connects the two hemispheres (Ilayperuma, Nanayakkaraand Palahepitiya,

2009).

It was thought that the size of the corpus callosum in elderly people might play a significant role in the separation magnitude of the two hemispheres. For example, in elderly people, the corpus callosum decreases in size, causing greater separation between the two hemispheres. This greater separation increases the right ear advantage (Sullivan, Rosenbloom, Desmond and Pfefferbaum, 2001).

Due to the role of the isthmus (a tissue that joins two larger organs or parts of an organ) in facilitating the contralateral auditory pathways of the association cortex

(Alexander and Warren, 1988), the decreased size of the area that contains the isthmus and the splenium (the posterior part of the corpus callosum) increases ear asymmetry (Gootjes, Bouma, Van Strien, Van Schijndel, Barkhof and Scheltens,

2006). Thus, the interhemispheric transfer of auditory information is affected by the reduced size of the isthmus. That is why ear asymmetry is affected here.

142 In sum, the bigger size of the corpus callosum in men compared to women has been found in the previous studies. It is believed that the size of the corpus callosum plays a significant role in the connection between the two-hemispheres: the greater the size, the greater the connections. Shrinking volume related to age leads to more separation between the two hemispheres. However, more investigations are needed in this matter for better understanding.

Studies on the effects of differences in the size of the corpus callosum have failed to prove any effect on handedness (Steinmetz, Jancke, Kleinschmidt, Schlaug,

Volkmann and Huang, 1995; Luders, Cherbuin, Thompson, Gutman, Anstey,

Sachdev and Toga, 2010). However, Allen, Richey, Chai and Gorski (1991) argued that, although there was no conclusive evidence of gender dimorphism of the corpus callosum, their study that investigated the gender difference in the shape of corpus callosum found that the splenium and the posterior region of the corpus callosum are more tubular-shaped in males and more bulbous-shaped in females. Interestingly, using magnetic resonance images (MRIs), these differences have also been detected in adults but not in children. Additionally, studies on the effect of age on the shape of the corpus callosum found that the differences in adult corpora callosa between men and women decreased significantly with age whereas a significant increase in this region was observed with age in children. Salat, Ward, Kaye,and Janowsky (1997) and Salat, Tuch, Greve, van der Kouwe, Hevelone, Zaleta, Rosen, Fischl, Corkin,

Rosas and Dale (2005) confirmed the effect of aging on the corpus callosum in the elderly, especially those exceeding age 55 years.

This led Allen and colleagues to conclude that their findings should be considered as a trigger to encourage more understanding of the gender related differences in both

143 neuropsychological and behavioural functions (Allen, Richey, Chai and Gorski,

1991). Recently, Wadnerkar, Whiteside and Cowell (2008) examined the effects of the menstrual period and gender differences on dichotic listening. 25 women and 20 men (aged 20-25 years) were recruited for this study. They used consonant-vowel

(CV) stimuli to administer dichotic listening and tested across three attention conditions. Men were tested only once, whereas women were tested in two phases during their menstrual cycle (Day 2-5: low oestrogen and progesterone/Low-EP

(mean = 4.04 days, SD = 0.93); Day 18-25: high oestrogen and progesterone/ High-

EP (mean = 20.84 days, SD = 2.46). Menstrual cycle and gender effects were used to analyse the performance average across the three attention conditions. Comparing the two phases, the authors found that women showed a greater right ear advantage

(REA) during the High-EP phase. When dichotic listening asymmetry was found in men, gender differences were found compared to women only during the Low-EP phase (Wadnerkar, Whiteside and Cowell, 2008). That is, men were found to display similar dichotic listening to women who were in the High-EP phase.

5.5 Summary

In general, studies have shown that gender differences occur early in human life and they lead to differences in subsequent human behaviour. Soon after conception, a higher metabolic rate and more cells can be observed in male embryos and the testicular hormones (e.g. testosterone) produced between weeks 12 and 16 enables a male foetus to develop its masculinity. Different studies have reported gender differences in dichotic listening tasks. For example, some studies have found more asymmetries in men than in women, whereas other studies have argued that women

144 show a significant right-ear preference. With age, the right ear advantage may increase in men across the adult lifespan and decrease in women. More evidence has come from the affect of the size the corpus callosum on the effect of age and gender on dichotic listening asymmetry. Recently, it has been reported that the corpus callosum tends to be larger in men than in women and this affects the connection between the two hemispheres. As its volume shrinks with age, there is more separation between the two hemispheres. Yet other studies have found that the size of the isthmus plays a role in ear asymmetry.

5.6 Pilot study

The pilot study addressed the following question: which brain hemisphere is more involved in emotional processing in a small Arab sample? This question investigates both the perception and expression of emotion. To determine which hemisphere is more involved in the emotional processing of auditory information, the pilot study asked each participant to report to the experimenter the clearest emotional tone he/she heard from the sentences that were presented simultaneously to both ears. In other words, was the speaker (in the software) happy, angry or neutral? This was designed to help to determine which brain hemisphere might be more involved in emotion processing, thereby leading to possible explanations for any cradling bias.

145 5.6.1 Methodology

5.6.1.1 Design

This pilot study was conducted, using the Dichotic Listening Task (DLT), on a sample of 51 male and female university students in the United Kingdom. A repeated measures design was used. DLT was designed for examining ear preference by detecting emotional tones, such as angry or happy, or emotionally neutral tones. Its administration is described in the Procedure section below Taking into account other factors, such as the gender, age and handedness of participants that may contribute to ear preference, the outcomes of this pilot study could help us to understand how humans perceive both negative and positive emotions.

5.6.1.2 Ethics

The experimental work of this thesis, including the pilot study, was approved by the

Ethical Committee of the Department of Clinical Psychology in the School of Health in Social Sciences, University of Edinburgh. Supporting letters from the Saudi

Embassy in London and from the Department of Clinical Psychology, University of

Edinburgh, were obtained and shown to the participants to ensure that they were aware of the nature of the study. They also received informed consent forms with information sheets describing the study. Each person who agreed to participate indicated this by signing and returning the consent form. Additionally, they were informed that all the information they gave would be confidential and would be used only for academic research purposes, and that they had the right to withdraw at any time. None of the data collected were discussed with participants; all of it is kept in a

146 secure place in the university and will be destroyed after the project is completed.

Before starting the experiments, all materials were checked for safety.

5.6.1.3 The sample

A total of 51 healthy Edinburgh University and Heriot Watt University students were recruited for this experiment. The sample was randomly chosen from different Arab nationalities: Saudis, Omanis and Egyptians. These included 28 (54.9 %) males and

23 (45.1 %) females (age = 19 to 38) with a mean age of 26.50 years (SD = 5.29).

The males were aged 19 to 38, with a mean age of 26.48 years (SD = 6.10), and the females were aged 19 to 35 with a mean age of 26.54 years (SD = 4.36).

With respect to handedness, 13 (25.5%) participants were left-handed whereas 38

(74.5%) were right-handed.

5.6.1.4 Apparatus

In order to determine which hemisphere is more involved in the emotional processing of auditory information, a personal computer (PC) was used to run a software programme called DLT designed by Donnot and Vauclair (2006) for a similar experiment but on a French sample. Before using this instrument in the current experiment, permission was obtained from the authors.

The test uses five imaginary language sentences: “Oken floj manicha sobren”, “Fir asten monidar doke”, “At poricila doke´ro bramilan”, “Herna fitu coujarboque´”, and

147 “Sim vobona surat ogarin”. Each sentence is presented in three emotional tones: angry, happy and neutral. There was an additional sentence (“Turcafer adi goulnachu gorni”) which was used for familiarisation purposes.

This imaginary language was used in order to normalise and naturalise the participant’s responses. That is, so that the result would not be affected by the understanding of the sentences, because they have no meaning. Only the emotional language is needed, which can be obtained from the three tones; anger, happy and neutral.

All the sentences are presented at the same volume, they are the same length, they start and end at the same time and they are delivered, in pairs simultaneously to both ears. The participant is asked to report the clearest emotion that he or she heard being expressed. There are thirty trials for each participant.

5.6.1.5 Procedure

In this pilot study, it was ascertained that the participant had no hearing problems by asking him or her. Then each participant was asked to sit for the experiment and listen carefully to a dichotic listening task over the provided headphones, using DLT software

The investigator recorded the responses on a separate sheet for each participant. If a participant reported that the speaker was angry when an angry tone was presented to the left ear and a happy tone to the right ear, this was marked as -1. This means that the subject showed a left ear advantage for detecting emotion. But if the subject

148 reported that the speaker was happy, then this response was marked as +1 because the participant showed a right ear advantage for detecting emotion. If the participant showed no preference, the response was marked as 0. The mean score for the 30 trials was then calculated for each participant. A negative mean indicated a left-ear advantage, and a positive mean indicated a right-ear advantage.

5.6.2 Results

67.5 percent of the sample showed a left ear advantage for recognising types of emotion, whereas only 23.5 showed a right ear advantage (mean = 0.235, SD =

0.428).

Table 5.1

t df Sig. (2-tailed) Mean Difference Ear Preference -3.978 50 .000 -3.647

Ear Preference Right / left

This result showed a significant left ear advantage (t (50) = 3.978, p < 0.001).

Moreover, the one-tailed Pearson correlation showed that ear preference and handedness were significantly negatively correlated (r = -0.312, p < 0.05).

A Chi-Square was run to determine if there was a bias according to gender and hand

2 factors. It was found that the left ear advantage was related only to handedness (χ =

4.963, df = 1, p <0.05); that is, the people who were right-handed were more likely

149 than left handers to have a left ear advantage. But there was no difference between right and left handed participants for right ear preference (see table 5.2).

The Pearson Chi-Square between ear preference and gender was non-significant

2 (χ = .152, df = 1, p>0.05) (see table 5.2).

Table 5.2

2 ear preference χ Sig Sex of participant .152 .474 Handedness 4.963 .036

Pearson Chi-Square for Sex/ Handedness and ear preference

The direction of this correlation was that the right-handed people tended to use their left ears more than the left-handed people did. Additionally, increasing scores in right-handedness related to increasing scores in left-earedness. (See graphs 5.1 and

5.2)

The contingency coefficients were obtained for ear preference for both the handedness and the gender of the participants. The first contingency coefficient showed that there was no relationship between ear preference and participants’ gender (contingency coefficient = 0.055, p> 0.05) whereas the second contingency coefficient showed that there was a relationship between ear preference and handedness (contingency coefficient = 0.298, p< 0.05).

150 Graph 5.1

Handedness and earedness

Graph 5.1 above shows that the left-ear advantage was found more in right-handed participants than in left handed participants. However, the scores for the right ear were found to be the same for both left and right handers.

Graph 5.2

Ear

preference and gender of the participants

151

Graph 5.2 (above) illustrates that males demonstrated more left ear accuracy than did females in detecting the clearest emotion in the DLT tests, whereas females showed more accuracy than males in using their right ears in the same task. No significant correlation was found between gender and ear preference.

For further investigation, paired sample t-tests were run to examine the clear detection of the three types of emotion: anger, happiness and neutral. The sample was divided into three-paired groups: angry-neutral with neutral-angry; angry-happy with happy-angry; and happy-neutral with neutral-happy. Table 5.3 shows the means and standard deviations for all three pairs.

Table 5.3

Std. Std. Error Mean N Deviation Mean Pair 1 total angry-neutral -1.3137 51 2.63431 .36888 total neutral-angry 1.4314 51 2.04211 .28595 Pair 2 total angry-happy -1.0588 51 2.32733 .32589 total-happy-angry -1.3922 51 2.08881 .29249 Pair 3 total happy-neutral -1.2157 51 2.30055 .32214 total neutral-happy .0588 51 2.66392 .37302

Means and SD for the paired samples

152

Table 5.4

Paired Differences Sig. t df Std. Std. (2-tailed) Mean Deviation Error Mean Pair Angry-Neutral -2.745 3.35168 .46933 -5.84 50 .000 1 neutral-Angry Pair Angry-Happy .333 3.22903 .45216 .737 50 .464 2 Happy-Angry Pair Happy-Neutral -1.274 3.49330 .48916 -2.60 50 .012 3 Neural-Happy Comparing mean scores of the emotion types

Table 5.4 shows a significant left ear advantage for detecting the negative (anger) emotion (t = 5.84, df = 50, < 0.005) and a significant left-ear advantage for detecting the positive (happy) emotion (t = 2.60, df = 50, < 0.005). These types of emotion were significantly detected when positive/negative and neutral emotions were dichoticaly presented. However, no preference was found when the emotion types were negative and positive or positive and negative (t = 0.737, df = 50, > 0.05).

Although both the angry and happy emotions were significantly detected by the left ear, the mean score for the angry emotion (mean = 1.3137) was higher than the mean score for the happy emotion (1.2157). In terms of the difference between detecting the negative and positive emotions via the right ear, it was found that the mean score for detecting the negative emotion was significantly higher than that for detecting the positive one (t=3.674, df= 50, p<0.05).

153 5.6.3 Discussion

In this pilot study, we tried to investigate which hemisphere of the brain is more involved in processing emotional information in an Arab sample. Thus, the goal of the pilot study was to determine whether or not there was any difference between an

Arab sample and the results reported by previous studies about which ear may be dominant when normal participants receive emotional information. Based on these results, we can carry out further investigations.

In agreement with previous studies that report a left ear advantage (right hemisphere of the brain) for emotional information processing, our results show that 39 participants (76.5%) showed a significant left ear advantage for detecting emotional tones, whereas only 12 (23.5.%) participants had a right ear preference. We found a significant right ear advantage for identifying a negative emotion, namely anger.

However, even though participants showed a significant left ear advantage for detecting all types of emotion, the mean score for the angry emotion was higher than the mean score for happy one, though this difference was not significant. Therefore, our findings support the results of a study by Erhan, Borod, Tenke and Bruder (1998) that found a tendency to show greater left-ear advantage in identifying negative emotions than in identifying positive emotions. Thus, even though our sample was obviously not representative of all Arab peoples, the results of our pilot study provide no indication that there is a significant difference between Arabs and other populations in the brain processing functions that were tested.

Additionally, our findings are consistent with previous studies by Broadbent (1954), and Kimura (1961), Studdert-Kennedy, Shankweiler and Pisoni (1972), Carmon and

154 Nachshon (1973), Sackeim, et al. (1978), Blonder et al. (1991), Haucer (1993),

Nagae et al. (2002), Sim and Matinez (2005, 2006) and Donnot (2007). The latter found that the brain’s right hemisphere is specialised for emotion and correlated with left-side cradling in lefthanders. The findings of Sato and Aoki’s study (2006) provided behavioural evidence supporting the dominance of the brain’s right hemisphere in processing negative emotions, especially unconscious negative emotions.

Similar evidence was obtained in our study. Based on this result, it appears that presented emotional information is processed in the right hemisphere of the brain because this hemisphere is specialised for processing such information. This result may help us to understand better, and explain, why most people cradle to the left side of their body rather that the right side. This issue of cradling infants to the left side of the body will be further discussed in chapter 6.

The dichotic listening task was used in the present study because it is non-invasive and a good instrument that can be used to investigate emotional tones presented to both ears. Intuitively, it is possible to respond to any meaningful sentence due to its meaning rather that the tone itself. However, in this study, this effect was ruled out by using meaningless sentences. Additionally, all participants confirmed that they had no lack of hearing or other relevant medical problems. Thus, we carried out this experiment in the confidence that we had eliminated any effect other than tone. Also, all participants were able to distinguish clearly between the three tones (angry, happy and neutral) during the familiarisation phase.

155 We found that our findings are in line with the previous dichotic listening studies that confirmed the involvement of the right hemisphere (i.e. the left ear advantage) in emotion processing such as recalling emotional words better than recalling non- emotional ones. This hypothesis has been strengthened by work which asked participants to recall emotional words presented in the left visual field (LVF). Nagae and Moscovitch (2002) concluded that the perception of both emotional and non- emotional words was more dependent on the left hemisphere but explicit memory for emotional words was dependent more on the right hemisphere.

The LEA findings in the present study and in the literature are also supported by studies on facial expressions in human and non-human species that reported the superiority of the brain’s right hemisphere in processing emotional inputs. (e.g.,

Sackeim, Gur and Saucy, 1978; Hauser, 1993; Wallez and Vauclair, 2010).

The role of the right hemisphere of the brain in processing emotion is supported by clinical data from studies on people who have had brain injuries. No effect on emotion and intonation of speech was detected when the damage was to the left hemisphere (Heilam, Scholes and Watson, 1975; Zaidel, Kasher, Soroker and Batori,

2002), but impairment in emotional prosody and facial expression has been reported in patients with right hemisphere damage (RHD) (Blonder, Bowers and Heilman,

1991). These studies can be taken as strong evidence that confirms the role of LEA

(the right hemisphere) in processing emotional inputs because studying abnormal situations, such as brain damage, can often be useful and fruitful (see Chapters 1 to

3). It can be inferred that the sudden absence of a particular function (e.g. processing emotion) is related to the damage incurred, if we know that the participant had no medical or psychiatric problems prior to the damage.

156 The emergence of affective neuroscience has also provided supportive findings. For example, it has been found that the contralateral auditory pathways are dominant, and more rapid and numerous than the ipsilateral ones (Penna et al., 2007). Recently,

Marzoli’s and Tommasi study (2009) confirmed such outcomes. Because the language process is localised in the brain’s left hemisphere, this confirms the role of the contralatral, rather than the ipsilateral pathway, in sending faster and stronger signals to the appropriate hemisphere of the brain. This result supports findings of right ear advantage in a verbal DL task, and other behavioural studies reviewed and discussed in this chapter and in Chapter 2.

Another issue that needs to be addressed here is that, in general, the right ear may be more accurate than the left ear when quick responses (either emotional or linguistic) are required. This was reported in a quasi-experimental study by Marzoli and

Tommasi (2009) in natural social interactions. This right advantage can be explained as arising from a need to understand fully what the speaker wants to say.

Based on these studies and other previous ones, it seems that although healthy people usually hear with both ears, each ear has its own specialised functions. To prove this, music played through one earphone in the right ear would definitely be heard unless there was a problem in that ear. The same test could be applied to the left ear. If “the end justifies the means”, then the specialised hemisphere of the brain will choose the most suitable pathway through which to perceive auditory information.

In conclusion, it seems that emotional information is more likely to be processed in the brain’s right hemisphere. This has been reported in several studies using different methods. Our pilot study, which found a significant left ear bias for the presentation

157 of emotional content, especially negative emotion, supports and confirms the previous findings. Thus, we can proceed with confidence onto the next chapter, which reports the results of the main study. This investigates whether or not mood state or stress, can affect the dominant role of the right hemisphere of the brain in emotional processing and, if so, how such an effect might occur.

158 Chapter 6

6.1 Overview

Before the results of the present study are considered, it is good to start with a summary of the methodology that was used. Therefore, this chapter contains a brief summary of the methodology that was used, followed by a presentation of the results from the main project, together with the data description, analysis and interpretation.

As was mentioned in detail in chapter 4, two types of methods were used; questionnaire and video-tape. Saudi male and female participants were recruited, half of them were based in their home country and the other half were in the United

Kingdom. Due to restrictions on videotaping women in Saudi Arabia and in the

Islamic culture, only the males were video-taped. For this reason, we had to use a self-report questionnaire for the female participants.

Ethically, the restrictions of the Islamic law and the decision of the participant to participate or refuse were respected. All ethical considerations are considered later in the ethical approval section.

A total of 369 Saudi males and females were recruited the current study using two types of stimuli; one is a real infant and the other an infant-like doll. The representative sample that was selected from different cities was divided into two groups; one based in Saudi Arabia and the second group was based in the UK.

159 Additionally, cradling as a human behaviour was divided into two types; preferred and spontaneous.

A questionnaire was used in order to assess what preferred side that participant would use. The second type of cradling is the spontaneous one which was assessed by videotaping participants with both the baby and the doll. All participants were asked to fill in a set of self-report instruments; BDI, PSS, EHI and WFQ-R2. These instruments were used for assessing depression, stress, handedness and footedness.

Other variables that were included were holder’s age and sex, infant age and sex, and finally culture. The role of cultural context was also investigated in the current study, by comparing the two recruited samples that is, 234 (63.4 %) in Saudi Arabia and

135 (36.6 %) in the UK.

The first stimulus was a real infant, aged between 1 month and 15 months (mean =

6.69, SD =3.54). The second stimulus was an infant-like doll of the same size and weight as a newborn baby (3.2kg) purchased from Realityworks.

Four instruments were used for the current study: the Beck Depression Inventory

(BDI - both Arabic and English versions), the Perceived Stress Scale (PSS – both

Arabic and English versions), the Waterloo Footedness Questionnaire-Revised

(WFQ-R) and the Edinburgh Handedness Inventory (EHI - Arabic translations). The cut-offs, scoring method, and the equivalence of the Arabic and English versions of these instruments are widely discussed in chapter 4.

160 The questionnaire results

6.2 Questionnaire results

As shown in Table 6.1, 282 (76.4 per cent) participants reported that they preferred to cradle a real infant to the left side of their body whereas only 87 (23.6 percent) participants reported a right side preference on the same task. This data is further illustrated in Figure 6.1.

Table 6.1

Cradling side Frequency Percent

Left 282 76.4 Right 87 23.6 Total 369 100.0

Total number and percentage of preferred cradling-side (stimulus: Real Baby)

Figure 6.1

Baby cradling preference (whole sample)

161 As shown in Table 6.2 and Figure 6.2, when asked about cradling an infant-like doll,

257 (69.6 per cent) participants said they would cradle it to the left side of their body and 112 (30.4) said they would have a right side preference.

Table 6.2

Cradling side Frequency Percent Left 257 69.6 Right 112 30.4 Total 369 100.0

Total number and percentage of preferred cradling side (stimulus: Doll)

Figure 6.2

Doll cradling preference (whole sample)

Of the 102 males in the sample, 70 (68%) said they would cradle an infant to the left side of their body whereas 32 (31.4%) said they would cradle to the right side of the body. When they imagined cradling a doll, 68 (66.7%) of the males expressed a left cradling preference and 34 (33.3) stated a rightward cradling preference.

162 Among the 267 female participants, 212 (79.4%) imagined cradling the infant to their left whereas 55 (20.6%) thought that they would cradle it to the right side of their body. When asked to imagine cradling a doll, 189 (70.8%) of the female participants said they would cradle it to the left while 78 (29.2%) of them expressed a rightward cradling preference.

Table 6.3 shows the frequencies of stress, depression, handedness and footedness.

Table 6.3

Factor Frequency Percent

Stress High levels of stress 117 31.7 Non-stressed 252 68.3

Total 369 100.0 High level of 89 24.1 depression Depression Non-depressed 280 75.9 Total 369 100.0 Left 33 8.9 Handedness Right 336 91.1 Total 369 100.0 Left 32 8.7 Footedness Right 337 91.3 Total 369 100.0

Frequencies of stress, depression, handedness and footedness.

Table 6.3 indicates that about 32% of the sample showed high levels of stress and that 24% were with high levels of depression. The percentages of handedness and footedness are almost the same as those reported in previous studies (see chapter 1).

163 6.1.1 Was there a bias in the side of cradling real infants?

We ran a Chi-Square on the data from cradling a baby and the factors that we hypothesised could affect the cradling side. First, we examined the relationship between cradling a real infant and the following factors: culture, infant gender, participant’s gender, depression, stress, handedness and footedness.

In line with previous studies, in order to convert the data to dichotomous values, a value of 0 was assigned to the following variables: high level of depression, high level of stress, left-handed and left-footed, and a value of 1 was assigned to the following variables: non-depressed, non-stressed, right-handed and right-footed. The cut-offs for depression, stress, handedness and footedness were, therefore, calculated as follows.

For depression, anyone who scored 18 or above on the BDI was considered as with high level of depression and anyone who scored 17 or below was considered a non- depressed participant.

For stress, any participant who scored 24 or above on the PSS was considered to have a high level of stress whereas anyone who scored 23 or below was considered to be a non-stressed person.

As was detailed in the instruments section, a score of 10 or above on the EHI was considered to indicate right-hand preference and a score of 9 or below was considered to indicate left handedness. From the WFQ-R2 footedness questionnaire, a score of -1 was taken to mean that the participant was left-footed whereas a score of +1 indicated a right foot preference in the participant. A score of 0 indicated no foot preference.

164 It was found that there is no relationship between cradling a real baby and cultural

2 2 factors (χ = 0.305, df = 1, p = 0.334), no relationship with handedness (χ = 1.428,

2 df = 1, p = 0.164), no relationship with footedness (χ = 1.230, df = 1, p = 0.188),

2 and no relationship with infant gender (χ = 0.079, df = 1, p = 0.438). On the other hand, there is a relationship between cradling a real infant and the participant’s

2 2 gender (χ = 4.754, df = 1, p <0.05), stress (χ = 12.499, df = 1, p<0.05), and

2 depression (χ = 5.281, df = 1, p <0.05).

Each participant's status was one of six categories: father of the held infant, mother of the held infant, father of another infant, mother of another infant, non-father, and non-mother. By running a Chi-Square, it was found that there is a relationship between the participant's status and cradling a real infant except for two of the categories because the assumption of Chi-Square was not met in that some cells had expected values of less than 5. Therefore, the contingency coefficient was obtained instead and the cradling side preference for a real infant and father of the held infant was found to be significantly correlated (c = 0.116, p < 0.05). A significant correlation was also obtained between cradling a real infant and mother of someone else’s infant (c = 0.128, p < 0.05).

2 The results for the other categories were as follows: mother of the infant (χ =

2 7.705, df = 1, p < 0.05), father of another’s infant (χ = 8.329, df = 1, p < 0.05),

2 2 non-father (χ = 4.466, df = 1, p < 0.05), and non-mother (χ = 5.222, df = 1, p <

0.05). According to the Pearson Chi-Squares, there is a significant relationship

165 between each of the above categories and cradling a real infant. Tables 6.4 and 6.5 summarise these results.

Table 6.4

2 Real infant Cradling χ Exact Sig. (1-sided) participant group .305 .334 handedness 1.428 .164 footedness 1.230 .188 infant gender .079 .438 participant's gender 4.754 .022 stress 12.499 .000 depression 5.281 .017 mother of the infant 7.705 .003 father of other's infant 8.329 .005 non-father 4.466 .03 non-mother 5.222 .017 parenthood 11.589 .001

Pearson Chi-Square of real baby cradling and the examined factors

Table 6.5

Real infant Cradling Contingency Sig. father of the infant .116 .025 mother of other's infant .128 .013

Contingency Coefficient of real baby cradling preference and other examined factors

166 In terms of cradling bias, there is a relationship between cradling a real infant and

2 parenting experience χ = 11.589, df = 1, p <0.05 (see table 6.25) and for cradling

2 doll, χ = 14.417, df = 1, p <0.05.

6.1.2 Was there a bias in cradling an infant-like doll?

The results show that there is no relationship between cradling a doll and cultural

2 2 factors (χ = 0.058, df = 1, p = 0.449), or the participant's gender (χ = 0.593, df =

1, p = 0.259). A value that only approached significance was found between cradling

2 a doll and stress (χ = 2.492, df = 1, p = 0.073).

2 There was a relationship between cradling a doll and handedness (χ = 3.961, df = 1,

2 2 p <0.05), depression (χ = 8.455, df = 1, p < 0.05) and parenting experience (χ =

14.417, df = 1, p <0.001). Because one cell in the footedness cross-tabulation had an expected value of less than 5, the contingency coefficient was therefore obtained instead (c = .139, p <0.05).

A Chi-Square run to examine the relationship between cradling a doll and the participant's status, produced results that varied according to the status.

There is a relationship between cradling a doll and being the father of the infant according to the contingency coefficient (c=0.121 p <0.05). The Chi-squares

2 obtained for the rest of the categories are as follows: mother of the infant (χ =

2 4.906, df = 1, p <0.05), non-father (χ = 6.839, df = 1, p <0.05), and non-mother

2 (χ = 5.702, df = 1, p <0.05). But there is no relationship between cradling a doll

167 2 and being the father of another infant (χ = 0.330, df = 1, p = 0.339) or the mother

2 of another infant ((χ = 1.997, df = 1, p = 0.107). These results are summarised in

Tables 6.6 and 6.7.

Table 6.6

2 Doll Cradling χ Exact Sig. (1-sided) participant group .058 .449 handedness 3.961 .032 participant's gender .593 .259 stress 2.492a .073 depression 8.455a .003 mother of the infant 4.906 .017 father of other's infant .330 .339 mother of other's infant 1.997 .107 non-father 6.839 .009 non-mother 5.702 .012 parenthood 14.417 .000

Pearson Chi-Square of dol cradling and the examined factors

Table 6.7

Doll Cradling Contingency Sig. father of the infant .121 .020 footedness .139 .007

Contingency Coefficient of doll cradling preference and other examined factors

168 6.3 Discussion

This study investigates the incidence of left-side, non-feeding cradling by Saudi males and females using two stimuli: a real infant aged between one month to 15 months, and an infant-like doll. The reason for using Saudi Arabian participants was to examine whether cradling bias in an Arabic Islamic country was similar to the cradling behaviour reported from other environments, and to assess how mood state and other factors could affect that bias. An important part of this study was to examine the effect of culture on cradling because some studies have claimed that left-side cradling is universal, whereas other researchers have argued that it is not universal. Studies in Sri Lanka (Bruser, 1981) and in South Africa (Saling and

Cooke, 1984) are examples of the former while Nakamichi’s (1996) study in

Madagascar is an example of the latter.

Consistent with previous studies that were conducted in different parts of the world, such as the USA (Dagenbach et al., 1988), Sri Lanka (Bruser, 1981) and South

Africa (Saling and Cooke, 1984), our study found no relationship between cradling a real infant and culture. The results obtained from participants based in Saudi Arabia

2 and participants based in the United Kingdom was very similar (χ = 0.305, df =1, p

2 > 0.05). Similar results were also obtained from the two groups in doll cradling (χ =

0.058, df =1, p > 0.05). These findings are in agreement with those reported by Salk

(1973), who emphasised the universality of left side cradling, especially in females.

As cited in chapter 3, there is evidence of the incidence of this phenomenon in mothers and new fathers. In addition, this bias was also found in women who were not mothers (De Chateau et al., 1978). Clearly, from the range of studies that have

169 been carried out in different parts of the world and cited above, and the cross-cultural studies of Finger (1975) and Manning (1991), there is a near-consensus that left-side cradling bias is a universal phenomenon.

Chapter 1 explained and emphasised the strong tendency in Islamic societies to use the right hand for most daily tasks and raised the question about whether this might affect cradling bias. It was argued that, if there was an effect of handedness on cradling behaviour, it would be clearly observed in this study’s sample due to the strong right handed tendency within the culture. It was found that Saudi Arabian traditions and religious beliefs about handedness did not affect the cradling bias. Our results showed that cradling bias did not relate to handedness or footedness. This result provides strong support for the proposition that the left cradling bias is universal.

In agreement with previous studies (e.g. Salk, 1973), the phenomenon of left-side cradling was found to be present irrespective of handedness. Other studies that have reported such a bias have all also found it to be unrelated to handedness preference

(e.g. Manning and Chamberlain, 1990; Turnbull and Lucas, 1991; Reissland, 2000;

Harris et al., 2001; Bourne and Todd, 2004; Vauclair and Donnot, 2005; Vauclair and Scola, 2008; Reissland, 2009; Donnot and Vauclair, 2010).

This study did not find any relationship between cradling a real infant and the gender of the infant. This finding contrasts with Lockard, Caley, and Gunderson's (1979) observation of populations in the United States and the Wolof tribes in Africa. They found that women carry to the left side more often with male infants than with female infants. This may be explained by Bogren’s (1984) study which found that

170 left-cradlers were more likely to be of the same gender as the infant whereas the opposite is likely to be true for right-cradlers. In other words, a mother is more likely to cradle a female infant to the left, and a male infant to the right while, for fathers the opposite is true. Our findings confirm the effect of the holder’s gender on cradling side by finding that the female sample showed more left-side cradling preference than males did. It might be that females are faster than males to perceive an emotional stimulus presented in the left visual field (Burton and Levy, 1989). This finding might explain the weakness of the left-side cradling bias in men. However, no difference was found in cradling a doll. This could be explained in terms of the reality and vividness of the held object because imagining holding a real infant might be not the same as imagining holding a doll.

The experience in parenthood may have an effect on cradling preference because it has been previously reported that fathers showed a significantly greater left holding preference than non-fathers (De Chateau, 1983). However, Scola and Vauclair

(2010) reported that, regardless of parental experience, handedness, and asymmetry in emotion perception, a left side preference for holding newborn infants (for calming and soothing purposes) was found in 65% of new fathers. Our findings for our female sample are almost in agreement with Scola’s and Vauclair's study whereas, as reported above, we found that, of the 102 male participants, 70 (69.6%) cradled to the left and 32 (31.4%) cradled to the right.

The results of this study for the effects of depression and stress on cradling side were consistent with those of previous research. We found that participants who were with high level of depression or who had a high level of stress tended to cradle or hold

171 infants to their right-side, and this points to a possible impact of mood state on cradling behaviour.

An association between stress and cradling bias has been previously reported

(Bogren, 1984). In Bogren’s study, some mental health problems were found prior to pregnancy in women who cradled to the right, along with concerns about the pregnancy, delivery and health of the child at birth. Studies such as that of Reissland

(2000) detected a higher voice pitch and amplitude when mothers cradled to the right in comparison with when they cradled to the left. However, for soothing infants, they used a lower pitch. Reissland (2000) concluded that the demands of the situation determined the side of cradling. In another study, Reissland et al. (2009) suggested that stress could have more effect than depression on cradling bias. Consistent with this, Vauclair and Scola (2009) reported frequent right-side cradling in mothers with affective symptoms. Finally, Vauclair and Scola (2010) confirmed these findings by concluding that the holding bias might be affected by cradler stress and/or depression.

Clearly, if the right hemisphere is affected by mood state, the cradling side could be affected too because stress, for instance, affects the right hemisphere where emotion may be processed more. The role of the right hemisphere in processing emotion is widely documented, as discussed in Chapter 2, and this hemisphere controls the left side of the body. Logically, any effect in this hemisphere will result in an effect on the left side of the body, and this is what was found in the current study, supported by previous research, such as that of Reissland (2009), Huggenberger (2010) and

Vauclair and Scola (2010). Furthermore, this study found that the cradling side of dolls as well as the cradling side of real infants was affected by depression. Indeed,

172 we found that, as the depression score increases, the less left-side cradling was exhibited.

In examining the side bias for cradling a doll, a Pearson’s Chi-Square was used. This showed that there was a relationship between cradling a doll and handedness, footedness, depression, being the father of the held infant, being the mother of the held infant, being a non-father, being a non-mother, and parenting experience. There was a relationship approaching significance between cradling a doll and stress

2 (χ =2.49, df= 1, p = 0.073), but no relationship was found between cradling a doll and cultural factors, the participant's gender, being the father of another infant, or being the mother of another infant. These results confirm those reported in previous studies (e.g. De Chateau, 1976; Bunday, 1979).

Additionally, it was found that parenting experience affected left-sided cradling of a doll. This finding means that experience in parenting could have an effect on

2 cradling side (χ =14.417, df= 1, p < 0.05). Intuitively, being skilled in carrying out any task is better than being non-skilled. Hence, parents should have good experience in parenthood, and this applies especially those who have more than one infant. To make this point more specifically, mothers are the people to whom infants are normally primarily attached, because most of an infant’s needs are provided by their mothers. Thus, mothers may show more laterality than fathers, or mothers’ holding styles should be more biased to the left than fathers’ styles.

However, left-side cradling was found to be unrelated to parenting experience, as had previously been found in a study of pre-school girls holding of an infant-like doll

(Todd, 1995). It can be said that a comparison of the parents group with the non-

173 parents group in this study appears to confirm the effect of the experience of parenting. But Todd’s (1995) study confirms a similar incidence even in pre-school girls. More evidence that showed a strong tendency to cradle the doll to the left side of the body was found in 5-year old girls (Saling and Bonert, 1983) and 6-year old girls (De Chateau and Anderson, 1976). However, a bias towards left side cradling was also found in boys of 2-16 years old although this bias was weaker in the older group (De Chateau and Anderson, 1976). These studies showed that experiments using an infant-like doll successfully elicited left-side cradling.

Surprisingly, we found a relationship between cradling side with the doll and handedness, and between cradling side with the doll and footedness. This result supports Meer and Husby's (2006) finding that dolls were cradled in the non- dominant arm; thus, it could be concluded that the real-ness of the held object affects the cradling bias. Previously, Almerigi, Carbary and Harris (2002) proposed that cradling to the left side of the body might be unique with infants. They found that

81% of 300 university students imagined holding a vase to the right side, whereas only 34% of them imagined holding an infant to the right side. Finally, non-fathers and non-mothers showed a tendency to hold the doll to the left. This suggests the innateness of a cradling bias in human beings, despite the holder’s gender and experience in parenting, as reported above.

Not surprisingly, we found no relationship between cradling a doll and being the father of another infant, or the mother of another infant. A number of factors should be taken into account here, because they could contribute to this result. These factors are the infant being real, the infant being a newborn, being parents, being in a good mood, and being very close to and familiar with the held infant. We believe that all

174 these factors have a direct or indirect effect on cradling bias. Thus, the reason why no relationship was found between cradling a doll and being the father or mother of another infant might be because the held object (doll) was not a real infant, and the holders were not its parents.

6.4 Summary and conclusion

This chapter has reported the results of the incidence of cradling bias in a Saudi

Arabian sample. This study found a clear left-side cradling preference for both a real infant and a doll. Pearson Chi-Square calculations showed that there is a relationship between left cradling bias with a real infant and the participant’s gender, stress, depression, parenting experience, being the father of the held infant, being the mother of the infant, being a father holding another’s infant, being a mother holding another’s infant, being a non-father, and being a non-mother.

In terms of doll cradling preference, Pearson Chi-Square calculations showed that there is a relationship between doll left cradling bias and handedness, depression, parenting experience, footedness, being a non-father, and being a non-mother. In addition, a relationship approaching significance was found between doll cradling bias and stress.

The next chapter will discuss how the preferred cradling side can be predicted from factors such as stress, depression, handedness and culture.

175 Chapter 7

STATISTICAL ANALYSIS OF QUESTIONNAIRE RESULTS

7.1 Introduction

In Chapter 6, the findings from the questionnaires used in this study were reported and they were analysed by running Pearson’s correlations between the variables, followed by an examination of the cradling side bias using cross-tabulation and Chi- square analysis. In this chapter, the main results will be tested by an examination of the independent variables that might predict cradling side for both stimuli, first for a real infant and secondly for an infant-like doll.

In order to predict the preferred cradling side from other variables, logistic regression was carried out because it “is multiple regression but with the outcome variable that is categorical dichotomy and predictor variables that are continuous or categorical”

(Field, 2005, p.218).

After the results of these two analyses have been reported, they will be discussed in the light of the results of previous studies.

7.2 Analysis of Preferred Cradling Side for a Real Infant

This section addresses the following question: can the preferred cradling side of a real infant be predicted from these variables: the participant’s age, the infant’s age, the participant’s group, the participant’s gender, the infant’s gender, infant-like cradling, depression, stress, handedness, footedness, and the cradler’s status?

176 First, a logistic regression was run on the results of the questionnaire about the cradling side that respondents imagined they would use when cradling a real infant.

The cradling-side was the dependent variable, and the predictors were the participant’s age, the infant’s age, the participant’s ‘group’, the participant’s gender, the infant’s gender, depression, stress, handedness, footedness, and the cradler’s status. The assumptions of logistic regression were met because the outcome variable

(cradling side) is a binary variable, which was measured as left or right. Cradling to the right side was coded “1” and cradling to the left was coded “0”.

Data were collected from a total of 369 participants, with no missing cases, and the sample size was adequate to allow logistic regression to be carried out. There were no outlier cases, the dependent variable is binary, the logistic regression model fitted correctly with no multicollinearity in the model and the data met the assumptions for logistic regression. These assumptions are shown in the relevant tables in the appendices.

Additionally, due to inflation in standard error for some variables, collinearity statistics were carried out. These showed that there were some problems with those variables regarding tolerance and variance inflation factors (VIF). Although “perfect collinearity is rare in real-life data” (Field, 2005, p.174), those variables that exceeded a value of 10 for VIF and less than 0.1 for tolerance were removed, as they may have indicated serious problems with tolerance, and could have led to biased regression results (Field, 2005). Therefore, problematic variables were removed and the analysis was rerun and rerun until the analysis was carried out for the last trial.

177 In the beginning block of logistic regression, -2 log likelihood (-2LL) was accounted for at 403.064, which gives the “Goodness of Fit of the model”. It took 4 iterations of the data to locate the goodness-of-fit. It has been suggested that a smaller -2LL value means that the model fits the data better (George and Mallery, 2006; Brace, Kemp and Snelgar, 2003), and a perfect model is assumed when the -2LL value is close to

0. The block 0 of the logistic regression equation is generated with only a constant, and no other independent variables were included in the equation. Of the total participants, 282 cradled to the left and the model correctly classified 76.4%, which means that the cradling side can be predicted at an accuracy of 76.4%.

For the coefficient of the logit equation, the constant value is -1.176 and the odd ratio is Exp (B) = 0.309. Therefore, the odds ratio of cradling to the left side is 0.309:1.

The residual chi-square was not calculated due to redundancies. Therefore, by adding one or more variables to the model, its predictive power will be significantly affected (Field, 2005).

The predictive variables related to cradling side preference are included at this stage of logistic regression using Enter as a method. It took 5 iterations of the data to locate a good fit and the -2 LL was accounted for at 341.789. Thus, the resulting value is lower than the previous one and, hence, it shows an improvement in predicting the cradling side preference to the left. In addition, the Omnibus test demonstrates a chi- square value of 61.275 at a significant level, p = <0.001; this means that the model accurately predicted the left cradling preference in this task of “cradling a real infant”, and the inclusion of more variables in the equation produces more accurate results than using only a constant.

178 The Cox and Snell R2 0.153, and the Nagelkerke R2 0.230 values show that the model fits the data adequately. A non-significant Chi-square Hosmer and Lemeshow test supported this good result. This Chi-square is considered more robust than the traditional chi-square test. Moreover, it produced a chi-square of 3.663 at a non- significant level of p>0.05. This result suggests that there is no difference between the observed and model-predicted values.

Table 7.1

Predicted

Observed Baby cradling preference Percentage Left Right Correct

Baby cradling Left 270 12 95.7 Step 1 preference Right 65 22 25.3 Overall percentage 79.1

Classification table

Table 7.1, above, shows an improvement and it correctly predicts 25.3% of the sample as right-cradlers and 95.7% as left-cradlers. It also shows the overall percentage of cradlers in a real infant cradling task, meaning that it is possible to accurately predict the side of cradling a real infant at 79.1% from the predictive variables that were added in Block 1. Overall, the inclusion of the predictive variables using the Enter method gave the model a better prediction.

The next step was to remove the non-significant variables, starting with the large p- valued variables, and going down to the small ones until we were left with only the significant variables. Upon doing that, the remaining predictive factors were the age

179 of the infant, doll cradling behaviour, stress, being the mother of the held infant, and being the mother of another infant. Additionally, based on the Wald Chi-square test, other variables needed to be removed from the rerun of the analysis. It was decided to observe caution in removing these non-significant variables, since the Wald Chi- square has been criticised for being too conservative (George and Mallery, 2006).

Normally, removing the non-significant variables will affect the results. However, according to the Wald Chi-square test, the non-significant variables should be removed from the equation. Hence, the non-significant variables were removed and the analysis rerun. Now, the overall cradling side could be accurately predicted at

79.4%, which is slightly greater than the previous result before removing the non- significant variables. However, as shown in Table 7.2, the accuracy of right-side cradling prediction increased to 26.4% compared with the classification of 25.3% before removing the non-significant variables. The accuracy of predicting left-side cradling (95.7%) did not change between the two results. Additionally, when we considered stress as a predictor, the coefficient was negative (-0.843), meaning that being with high levels of stress reduces the probability of cradling to the left side of the body. However, the rest of the significant predictors had positive coefficients, meaning that increasing each factor leads to an increase in left-side cradling. The -

2LL was 346.052, Omnibus Chi-square was 57.012, Cox and Snell R Square test was

0.143, Nagelkerke was 0.215, and finally there was a non-significant Hosmer and

Lemeshow Chisquare.

180 Table 7.2

Predicted Observed Baby cradling preference Percentage Correct Left Right

Step 1 Baby cradling Left 270 12 95.7 Preference Right 64 23 26.4 Overall percentage 79.4

Classification table

The five predictors are infant age, cradling doll, stress, mother of the held infant and mother of another infant.

The classification plot shows the predicted probabilities of cradling side in the cradling a real infant task. The model is considered to fit the data perfectly when the cases for which the event has occurred are clustered at the far left and right sides.

The graph in Figure 1 shows that most of the cases (Left) are clustered to the left side, meaning that many cradlers preferred to cradle to the left side during this task.

The following question is now considered. Which variable could be considered to be the best predictor? To answer this question, the forward: LR method was used to put the predictors in the order of their strength. It can be inferred here that the first predictor was side of cradling an infant-like doll, the second was stress, the third was being the mother of the held infant, the fourth was being a mother holding another’s infant, and the last was infant age because this had the lowest significance of all the predictors.

Finally, in order to check the assumption of no multicollinearity, the tolerance and variance inflation factor (VIF) were carried out. The tolerance was below 0.2 and

181 VIF no greater than 10, which suggested that there was no cause for concern (Field,

2005; Myers, 1990; Menard, 1995). The loading of each factor appeared as follows: the “cradling a doll” variable had 90% of variance on dimension 2, the infant’s age

(in months) had 76% of variance on dimension 5, “mother holding another’s infant” had 72% of variance on dimension 6, stress had 47% of variance on dimension 3 and

“mother of the held infant” had 42% of variance on dimension 4.

7.3 Analysis of Preferred Cradling Side for a Doll

This section addresses the following question: can the preferred cradling-side of a doll be predicted from the variables of the participant’s age, the participant’s ‘group’, the participant’s gender, the infant’s gender, real infant cradling behaviour, depression, stress, handedness, footedness, and the cradler’s status?

The questionnaire used in this study provided data on the side of the body that respondents imagined cradling a doll. A total of 369 cases were included in the data analysis with no missing cases. The dependent variable was “doll cradling side”, with cradling to the right coded as “1” and cradling to the left coded as “0”. Logistic regression was carried out and it was found that it took three iterations in the first step with -2 LL at 452.999

With the inclusion of only the constant, the classification table shows that the cradling-side could be accurately predicted 69.6% of the time using a doll as the stimulus. The constant value is (-0.831) and the odds ratio Exp (B) = 0.436 with the residual Chi-square = 53.813, p = <0.0001.

182 The next block of the test took 20 iterations with -2LL at 395.059. This means that adding some variables to the equation will improve the model. The value of -2LL in this block is smaller than the previous one. However, before proceeding, a test of collinearity statistics had to be carried out as the table of variables in the equation showed inflation of the standard error in some variables (see the appendices). Hence, these variables should be excluded and the analysis rerun.

All variables with tolerance problems were removed and the test was rerun. Although a -2LL of 406.302 with 5 iterations is bigger than the previous one, there is no concern regarding the tolerance and VIF after removing those variables.

The significance levels were calculated by the Omnibus Tests of Model Coefficients.

The findings show that the model adequately fits the data with a Chi-square of

46.697. In addition, the non-significant result of the Hosmer and Lemeshow Test

2 supports these findings (χ = 6.546, df = 8, p > 0.05). Despite the facts that the value of -2LL is big, and the Nagelkerke R Square of 0.168 is low, the Hosmer and

Lemeshow Test produced a reasonably good model fit, as reported earlier.

The classification table (see appendices) shows an improvement compared to the beginning block. It is possible to predict the cradling-side at an accuracy of 32.1% to the right and 91.1% to the left. The overall percentage prediction accuracy is 73.2%.

When all the independent variables were included in the equation as predictors, the

2 Wald χ test suggested removing the non-significant independent variables. On that basis, all the non-significant independent variables were removed except for WFQ because this approached a significant value (p = 0.058). Thus, this variable was

183 included in the equation because it was thought that footedness might relate to doll-

cradling preference. Table 7.3 shows the final refined test after removing all

problematic variables that had been suggested by the Wald test Chi-square.

Table 7.3

B S.E. Wald df Sig. Exp(B) Step (a) Baby cradling preference 1.293 .263 24.106 1 .000 3.645 Depression -.609 .269 5.117 1 .024 .544 Footedness 1.449 .627 5.340 1 .021 4.258 Constant -2.096 .653 10.318 1 .001 .123

The suggested predictors

After removing all non-significant independent variables except WFQ, the model

summary shows an increase in -2LL to 411.845 compared with 406.302 in the

previous one which included all variables. In addition, the Nagelkerke R Square of

0.149 was less than the previous one of 0.168. Furthermore, the classification table

indicates that, overall, it is possible to accurately predict the doll-cradling side at a

level of 72.4%: 41.1% to the right side of the body and 86.0% to the left.

Here, there are three significant predictors. They are cradling side with a real infant,

depression and footedness. An increase in cradling a real infant to the left is

associated with an increase in cradling a doll to the left.

In conclusion, since the infant-like doll was the stimulus and the cradling side

preference was the dependant variable, the B value of depression means that an

184 increase in the depression score leads to a decrease in the left side preference. In terms of footedness, right-footedness is associated with an increase in cradling to the left. In terms of which variable is the best predictor of doll cradling side, our model suggests that the cradling behaviour exhibited with a real infant is the best predictor, followed in strength by footedness and then depression.

Since the assumption of no multicollinearity was tested in the previous experiment, the tolerance and variance inflation factors (VIF) were applied. It was found that there was no cause for concern, for the tolerance was below 0.2 and VIF was no greater than 10. The loading of each factor was found as follows: the cradling of a real infant variable had 90% of variance on dimension 2, footedness 85% of variance on dimension 4, and depression 82% of variance on dimension 3 (see appendices).

7.4 Excluding doll cradling in the prediction of infant cradling and vice versa

An important issue needs to be addressed here. It might be argued that including or excluding doll cradling as a predictor may affect the predicted side of cradling a real baby. When this factor was excluded from the equation and the analysis was rerun, the results show that the new predictive factors for cradling a real infant are the participant’s age, the infant’s age, stress and parenthood. Comparing this result to the previous analysis, and after removing all non-significant predictors, two predictors, namely, mother of the infant and mother of another infant, are removed. However, two new predictors, namely the participant’s age and parenthood appear. (See the table 7.4)

185 Table 7.4

B S.E. Wald df Sig. Exp(B)

Participant’s age .060 .023 6.735 1 .009 1.062

Infant’s age .090 .037 6.122 1 .013 1.095

Stress .054 .015 13.230 1 .000 1.056

Parenthood 1.221 .301 16.449 1 .000 3.391

Constant -5.251 .865 36.841 1 .000 .005

Predictors after excluding “doll cradling” as a predictor from the equation

The same procedure was carried out to predict the cradling-side of a doll. Baby cradling as a predictor was excluded from the equation and the new predictive factors for doll cradling-side are only depression and footedness. A comparison of this new result with the previous results demonstrates that differences between them occur only when the infant cradling predictor is excluded or included. (See the table 7.5 below)

Table 7.5

B S.E. Wald df Sig.

Footedness 1.537 .621 6.128 1 .013

Depression -.734 .257 8.168 1 .004

Constant -1.736 .633 7.510 1 .006

Predictors after excluding “infant cradling” as a predictor from the equation

186 7.5 Discussion

This chapter has reported the findings of various statistical analyses to investigate which, if any, of the variables could predict cradling side. These analyses were performed on the results, reported in Chapter 6, of two experiments carried out using different stimuli, a real infant and an infant-like doll, with the same participants.

There were two investigations, one for real infant cradling and one for doll cradling.

The first investigation looked at the possibility of predicting the cradling side for real infants from the following variables: the participant’s age, the infant’s age, the participant’s ‘group’, the participant’s gender, the infant’s gender, doll cradling behaviour, depression, stress, handedness, footedness and the six categories of the participants’ status. According to the outcomes of logistic regression, the first block showed that cradling side could be predicted with 76.4% accuracy. After inputting all the predictors into the equation, there was a predictive accuracy of 95.7 % for participants who cradled to the left side but of only 25.3 % for participants who cradled to the right, with a 79.1 % accuracy overall. In the end, the analysis suggested that only five significant variables could be used to predict left-side cradling. They are doll cradling side, the infant’s age, stress, being the mother of the held infant, and being a mother holding another’s infant.

Despite the fact that there was a difference between the two stimuli (doll and infant), as we expected, cradling a doll was still a significant predictor for cradling a real infant. This is intuitive, because the two experiments were run in the same manner, and the held objects were approximately the same size.

187 The variables of ‘cradling a real infant’ and ‘age of the held infant’ were positively and significantly correlated. This means that an increase in the infant’s age led to a decrease in left-side cradling. This result is consistent with previous studies (e.g.

Lockard, Daley and Gunderson, 1979; Dagenbach, Harris and Fitzgerald, 1988), which suggested that the left cradling bias decreases with increasing infant age because of the effect of infant size. Additionally, this occurs not only in humans; it was found that rhesus monkey infants showed a significant preference for their mothers’ left nipples during the first week after birth. This bias decreases from the third week onwards (Tomaszycki et al., 1998). Weatherill et al. (2004) found that the percentage of mothers who held their 11-15 month old infants on the left was lower than those with young infants or newborns.

It would appear that the increase in the size of the held infant affects the left cradling bias because the right arm is typically stronger than the left, and this could also explain why a left cradling bias was found to be weaker in men. For instance, in

Saudi society, men tend to carry infants only when they are older (say, over 7 months) while very young infants tend to be cared for only by women. Based on

Saudi cultural beliefs and norms, caring and nurturing infants, especially when they are very young, is considered to be a woman’s job because she is thought to be more patient and sensitive than her husband. However, when the family goes outside the home, it tends to be the man who carries the infant and he uses his right side (right arm) to do this as it is stronger than the left arm. It could be said that if the holder is just holding the infant rather than cradling and engaging with it, the left side bias is likely to be weak or even absent, and the left side bias is likely to be strong only if the holder of the infant is also caring for it and responding to its needs.

188 Bearing in mind possible predictors of left-side cradling, being the mother of the held infant or the mother of another infant was found to show a stronger left-sided cradling bias than being a father. This is in agreement with well documented studies that reported that the majority of mothers prefer to hold their infants to the left side of their body, especially when calming or soothing them (e.g., Salk, 1960; Reissland,

2000).

Concerning stress as a significant predictor, our results showed that there is a negative correlation between left-side cradling and stress. That is, an increase in stress scores reduced the incidence of cradling to the left side of the body. This result is in agreement with previous studies, such as those of Vauclair and Scola (2008) and

Suter et al. (2009).

Gender differences play a significant role in many aspects, as discussed in Chapter,

2, 3 and 5. Here, the most relevant point is that the mother is the closest person to the held infant; she can understand the infant's feelings and emotions and then respond to his/her needs. The strong tendency to cradle to the left side of the body can be explained by the findings of Calni (2002), Brebner (2003), van Middendorp, Geenen,

Sorbi, Hox, Vingerhoets, van Doornen and Bijlsma (2005) and McRae, Ochsner

Mauss, Gabrieli and Gross (2008); in these papers it was argued that women exhibit more emotions than men do. This finding supports the role of emotional processes and explains the emotional communication between the holder and the held infant.

Logically, the more the emotion expression, the greater is the tendency to cradle to the left due to the advantage of the right hemisphere in emotion processing.

Therefore, a stronger left cradling bias was found in women than in men.

189 The second statistical investigation looked at the possibility of predicting the cradling side for a doll from the results of the self-report questionnaires completed by the same participants about their preferred side for cradling a doll. By including all predictors in the equation, 91.1 % accuracy was obtained for those who preferred to cradle to the left side, whereas an accuracy rate of only 32.1% was obtained for those who preferred the right side, and the overall accuracy was 73.2%. The three significant predictors proved to be cradling side of a real infant, footedness and depression. Although in this experiment the held object was not a real infant, participants still showed a left cradling bias, as found previously by, for example,

Lucas et al. (1993), Almerigi et al. (2002) and Bourne and Todd (2004).

The results of the current study showed that right-footedness is associated with left- side cradling. One possible explanation is that the body-balance needs this association; we can see how people walk or run and how the right arm is associated with the left foot, and how the left arm goes with the right foot. Clearly, this motor skill allows the body to be balanced and enables us to perform any task comfortably.

Our results confirm previous research in which it was found that the proportion of crossed hand-foot preference was higher in men than in women (Dargent-Paré, De

Agostini, Mesbah and Dellatolas, 1992) and higher in left-handers than in right- handers (Dargent-Paré et al., 1992; Kang and Harris, 2000). This provides an understanding of the relationship between right-footed preference and left-side cradling.

Finally, depression did not predict preferred cradling side when the object was an infant. However, it did so when the held object was a doll. This might be due to the

190 cradler-infant interaction, which could elicit emotional communication leading to the left-side bias.

As has been reported in many studies, emotions affect cradling side, especially the negative emotion of depression. People with high levels of depression may show no emotion or not understand others’ emotions and, therefore, they cannot respond to their facial expressions (Jaeger, Borod and Peselow, 1986; Fu, Williams, Brammer,

Suckling, Jieun, Cleare, Walsh, Mitterschiffthaler, Andrew, Pich and Bullmore,

2007; Joormann, 2010). The localisation of emotion in the right hemisphere might explain why people with emotional problems tend to shift their cradling from the left side to the right side of the body (Reisland, 2009). If the right hemisphere is affected, the cradler may change cradling side to the right (Abel, 2010). This is confirmed by the absence of the cradling bias in those with a disorder of emotional relatedness, such as autistic children (Ballroom and Foyer, 2011).

7.6 Summary and Conclusions

Preferred cradling side, as reported by participants of this study in a questionnaire, was examined in this chapter to see whether or not cradling side can be predicted from various factors. Separate analyses were performed on the two types of stimulus presented to the participants. For predicting the preferred cradling-side of a real infant, logistic regression showed that the best predictor was cradling side of an infant-like doll, while stress, being the mother of the held infant, being the mother holding another’s infant and infant age were also important. In terms of the preferred

191 cradling-side of a doll, the cradling side of a real infant was the best predictor, followed by footedness and then depression.

192 Chapter 8

RESULTS AND ANALYSIS OF SPONTANEOUS CRADLING

EXPERIMENT

8.1 Introduction

The previous two chapters reported on and analysed the results of data obtained through a self-report questionnaire in which respondents imagined cradling a real infant and a doll and said which side of their body would be used for such cradling.

In this study, this is called the ‘preferred cradling side’. This chapter reports on and analyses a videotaped experiment in which participants were asked to physically pick up and cradle a real infant and then an infant-like doll. We call this spontaneous cradling and the side of the body to which the participant cradled these stimuli is called the ‘spontaneous cradling side’. After reporting the results of these observations, an attempt will be made to predict cradling side from a number of independent variables using multiple regression because this analysis “allows us to go a step beyond the data that we actually possess” (Field, 2005, P.144). The independent variables for spontaneous infant cradling are the infant’s age, the participant’s age, stress, depression, footedness and handedness. The independent variables for spontaneous doll cradling are the same, except that the infant’s age is excluded. All the participants used the same infant-like doll so this was not a variable.

193 8.2 Methodology

8.2.1 Design

In this experiment, we first collected data, through a questionnaire, on the participants’ ages, status (whether or not they were a parent), stress level (using

PSS), depression level (using BDI), footedness (using WFQ-Revised) and handedness (using EHI). Then, an appointment was arranged with each participant so that he could be videotaped holding and cradling first an infant and then an infant- like doll. All the collected data were entered into SPSS for analysis.

Real infants were recruited from the families of those who agreed to participate in the experiment. Each participant was videotaped for about a minute while he picked up and cradled the infant. The participants were told that they could speak to and/or play with the infant while they were holding and cradling it.

The doll, purchased from REALITYWORKS, was designed an educational and training instrument for those who are about to be new parents. The doll was the size and shape of a real infant about three months old. It had some animated features, such as crying, laughing and making sounds, but these were not activated in the current study. The same doll was used by all the participants in the experiment.

8.2.2 Ethics

This experiment was carried out after receiving the consent forms from the participants showing their willingness and agreement to be videotaped with their own infant or with another’s infant and with a doll. Before signing the consent form, they were shown a letter of ethical approval from the School of Health, University of

194 Edinburgh and a letter from Saudi Embassy in London titled “certificate of comfort”

(see Appendix 1). These letters allowed all participants to participate with confidence. Ethically, it was not possible to videotape females because that is prohibited in Saudi society. Therefore, there were no female participants in this part of the study. The familiarity of the cradler/holder with the held infant was also taken into account so that only the fathers of the recruited infants and others who were very familiar with these infants were included in the experiment.

8.2.3 Participants

102 male participants were recruited for videotaping. 23 (22.5%) were the fathers of the recruited infants, 45 (44.1%) were fathers but not the father of any of these infants, and 34 (33.3%) were non-fathers. Table 8.1 summarises these data.

Table 8.1

Frequency Percent Valid Percent Valid Father of the infant 23 22.5 22.5

Father of other's infant 45 44.1 44.1

Non father 34 33.3 33.3

Total 102 100.0 100.0

Sample frequencies

195 8.2.4 Procedure

A Sony digital hand camera was used for videotaping the participants with real infants and with the doll. One minute was allocated for videotaping each participant, first with a real infant and then with the doll, making a total of approximately 2 minutes for each participant. However, due to difficulties in managing the exact 60 seconds duration for each stimulus, and for the sake of data accuracy, the different behaviours of each participant were calculated as percentages of the videotape duration and these were used in subsequent calculations.

8.3 Results

Tables 8.2 shows the minimum and maximum duration times for left and right cradling with both the infant and the doll, with means and standard deviations for each variable. Because it was difficult to manage exactly 60 seconds for each experiment, and for more accuracy, percentages of total time was used instead.

Table 8.2

Std. N Min Max Mean Deviation Duration of baby 102 .00 145.00 32.49 28.42 left cradling Duration of baby 102 .00 307.00 23.60 37.35 right cradling Duration of Doll 102 .00 84.00 26.54 24.72 left cradling Duration of Doll 102 .00 83.00 17.04 21.78 right cradling

Mean duration of cradling time

196 Table 8.3

Mean Std. Deviation N BABY left cradling 58.47 44.03 102 Stress 21.10 9.57 102 Depression 11.22 8.21 102 Infant's age 9.37 3.88 102 Participant's age 31.10 6.06 102 Footedness 8.35 6.27 102 Handedness 16.21 3.83 102

Mean and SD for the sample

8.4 Analysis of results for spontaneous infant cradling

The first question raised here is whether or not there was a difference between fathers and non-fathers in cradling a real infant to the left side. According to the one- tailed t-test, there was no difference between them since t = .571, df =100 and p>.05.

Therefore, the variable “parenthood” was excluded from the later regression equation.

To compare the means of the three categories, that is, father of the infant, father of another's infant and non father, in the spontaneous cradling of a real infant, a one- way ANOVA was run and a difference was found between these groups in spontaneous cradling side with a real infant, and this was mainly between the ‘father of the held infant’ group and the other two groups. This suggests that being the father of the held infant had a significant effect on cradling side of a real infant (F(2,99) =

4.821, p<.05). However, the participant’s status was not included in the later regression equation because this factor did not improve R significantly.

197 There are some other issues that should be addressed before going ahead with the regression analysis. First, the sample size was adequate for generating regression using a Stepwise method. It has been suggested by several statisticians, such as Field

(2005), that 15 participants per predictor is a sufficient sample size to carry out regression. The current study had 17 participants per predictor (102/6= 17). To use

Enter as a regression method, the number of cases per predictor was also adequate, as the minimum should not be less than 5:1. However, to use Stepwise, a minimum of

25 participants per predictor (25:1), with at least 40:1 being preferred, has been suggested. Therefore, four predictor variables were included to reach the minimum required case number of predictor variables in order to be able to run simple or multiple regression analyses. In the current experiment, there were 102 participants and four predictors so there were 25.5 participants per predictor (102/4). These four predictors were chosen according to their closeness to significance, as indicated by the Enter method. The second step was to run the Mahalanobis test, the distance measure for standardised residuals. It showed that no cases exceeded the value of 25.

Based on that result, there was no problem with the distance of cases from the means of the predictors. Thirdly, to check the standardised residual, no cases were found to be greater than 3. For the fourth step, there were no concerns regarding collinearity, because none of the predictors had a tolerance of more than 1, and the variance inflation factor (VIF) was less than 10. Thus, multiple regressions could be run to examine these factors as predictors of left-side cradling. Enter was the first method used here for regression analysis. For this, all the predictors were included in the equation and nothing was removed. (see table 8.4)

198

Table 8.4

Unstandardised Standardised Collinearity Coefficients Coefficients Statistics Model T Sig. Std. B Beta Tolerance VIF Error 1 (Constant) 115.156 31.091 3.704 .000 Stress. -.445 .566 -.097 -.786 .434 .632 1.582 - Depression -.693 .681 -.129 .312 .594 1.684 1.017 - Infant's age -1.871 1.135 -.165 .103 .953 1.049 1.649 Participant's -.151 .736 -.021 -.205 .838 .932 1.073 age Footedness .372 .765 .053 .487 .628 .806 1.241 Handedness -1.257 1.277 -.109 -.985 .327 .776 1.289

Collinearity Statistics

The model summary table (see the appendices) displays the R Square which is .090 and the adjusted R Square is .032. In other words, this was the proportion of the variance of left-side cradling accounted for by the predictors. Here the model told us that we could interpret 3.2% of the left-side cradling by the included predictors. That was a very low value and, thus, it was considered that there might be some hidden factors that could explain the other 96.8 %.

From Enter to Stepwise

Statistical procedures should be used with caution because minor variations in the data can have a large effect on the order in which variables are entered. Therefore, a large number of independent variables are simultaneously entered in the model to

199 find out which of them will be a best predictor using Enter as a safest method. The next stage is that method should be changed from Enter to Stepwise because the

Stepwise method always results in the most parsimonious model. Other advantages of using Stepwise are; it is efficient in finding the regression equation with only significant regression coefficients, only independent variables with significant regression coefficients are entered into the equation, and finally the steps involved in building the regression equation are clear (Brace et al., 2003).

Because of that long list of independent variables, the regression method was changed to Stepwise because this selects a subset of variables entirely by statistical criteria. This method minimises the number of predictor variables according to a case-variable ratio. Therefore, by excluding one variable and including another, a good prediction can be obtained (Field, 2005). Consequently, the Stepwise method was then used, and the analysis was rerun.

Using the Stepwise method with the same variables, the standardised beta coefficients showed that the only significant predictor was the ‘infant's age in months’ variable (Beta = -2.03, p < .05). All the other variables were then excluded from the equation because they did not improve R significantly. The model summary showed that R Square = 0.041 and adjusted R Square = 0.032. This indicated that regression accounted for 3.2% of the variance of left-side cradling. This was also a low value for a predictive equation. The only predictor that could explain the spontaneous baby left-side cradling for an infant was ‘infant’s age’, although the values for stress and depression approached significance.

200 Although the stress and depression variables did not produce changes in R value and did not significantly strengthen the model, they were considered as predictors due to the approaching significance they showed in the regression equation. The Pearson correlations that found significant negative correlations between spontaneous cradling side and both stress (r= -.192, n=102, p<0.05) and depression (r= -.201, n=102, p<0.05) are shown in Table 8.9.

An attempt was made to check these results by running regressions first by removing

“footedness” and then by removing “participant's age” and finally by removing

“handedness” from the regression equation. However, the same result was obtained, that is, that increase in infant age, depression scores or stress scores reduced the left side cradling tendencies of men when they spontaneously cradled a real infant. The next two tables show how this happened. Stress and depression had approaching significance values in predicting the left-side cradling of a real infant; therefore, these factors should be taken into account.

One more thing worth mentioning here is that, after entering “doll left-side cradling” as a predictor, the model showed a significant improvement in R. with R Square =

0.363 and adjusted R Square = 0.357. This means that regression accounted for 35 % of the variance of left-side cradling, which was much better than in the previous model.

8.5 Analysis of results for spontaneous doll cradling

This experiment was carried out to examine the factors that might explain spontaneous cradling behaviour when the stimulus is a doll rather than a real infant

201 and whether the significant variables were the same or different to those found in the spontaneous cradling of a real infant.

This experiment used the same variables as those used in the previous experiment, except that the ‘infant’s age’ was excluded because all the participants used the same doll, which simulated a three-month old infant. .

A comparison of the spontaneous cradling behaviour of the three groups of holders, that is, father of the infant, father but not of the held infant and non father, was made using one-way ANOVA. This showed that there were differences between the groups, especially between the ‘father of the held infant’ group and the ‘non-father’ group. This suggests that there was a significant effect of cradler status on the cradling side of a doll (F (2, 99) = 3.728, p<.05). But, because the participant’s status did not improve R significantly, it was not included in the regression equation.

Before reporting on the multiple regression analysis, the descriptive statistics for all the variables are shown in Table 8.21 and this is followed by an examination of the assumptions of regression.

Table 8.5

Mean Std. Deviation N Doll left cradling 56.9551 46.78872 102 percentage Stress 21.1078 9.57297 102 Depression 11.2255 8.21603 102 Handedness 16.2157 3.83219 102 Footedness 8.3529 6.27686 102 Participant's age 31.10 6.066 102

Descriptive statistics

202 For the Enter method, the sample size was 20 participants per variable (102/5= 20.4) and, for the subsequent Stepwise method, it was 25 (102/4= 25.5), after removing one variable (depression) as it had the lowest significance (p = 0.820). The residuals were not greater than 3 and the Mahalanobis value was not greater than 25.

The Shapiro-Wilk test suggested that the standardised residuals were not normally distributed and the graph showed that the relationship between the dependent variable and the independent variables was not linear. Regression requires normality of standardised residuals and a linear relationship between the examined variables.

For the inter-correlations between variables, Pearson correlations showed that stress

(r = -.269, n=102, p<0.05) and depression (r = -.130, n = 102, p= 0.096) were negatively correlated to the spontaneous cradling side.

The model summary in Table 8.25 shows the R Square was .125 and the adjusted R

Square was .080. That is, only 8% of doll left-side cradling could be explained by the included predictors. Although this is a very low percentage, it is higher for cradling the doll than for cradling the real infant.

The ANOVA table above contains the f ratio which is significant here (F (5,101) =

2.754, p< 0.05) meaning that the model is significant. The coefficients table suggested that stress was the only significant predictor and negative (Beta = .280, p<0.05), and that the age of the participant approached a positive significance (Beta

= .168, p = 0.091). Although the age of the participant was not significant, it was noted that an increase in holder’s age led to a greater left cradling side tendency.

The next step was to change the regression method from Enter to Stepwise and rerun the analysis because Stepwise minimises the number of predictor variables according

203 to a case-variable ratio and because it selects a subset of variables entirely by statistical criteria. This method excludes any variable that has no effect on the regression equation. The Stepwise outcomes were as follows. The model summary showed no improvement in the model. R Square was .072 and the adjusted R Square was 0.063. The standardised beta coefficients showed that the stress variable was the only significant predictor (Beta = -.269, p<0.05). The other variables were excluded from the equation one by one but this did not show any other significant variable and did not improve R significantly. Despite having no problem with tolerance, the doll left-side cradling could not be explained by excluding the variables other than those that approached significance.

Finally, when “cradling of real infant” was included as a predictor, the model showed an improvement in R (.650) and R Square (.422) suggesting that the cradling side of a doll can be predicted at 40 % of accuracy according to adjusted R Square. This model shows that spontaneous cradling behaviour with a real infant, stress and the holder’s age are the significant predictors for spontaneous cradling behaviour with a doll.

Next, we asked if there was any relationship between of the preferred cradling side and the spontaneous cradling side. The results for the preferred cradling side came from the questionnaire and were reported in Chapter 6. The results for spontaneous cradling side were obtained from videotaping and are reported in this chapter. This relationship can be explored only with the male sample since, for the reasons already explained, only men could be videotaped. Pearson Chi-square tests were run and they showed that there is a relationship between the two types of cradling; for cradling a

204 2 2 real infant it was (χ = 67.849, df = 1, p <.05) and for cradling the doll it was (χ =

76.787, df = 1, p <.05). These results are shown in Table 8.6.

From these results, it can be concluded that the effect of cradling an imagined object is not like the effect of cradling a physical one, and the effect of cradling a real infant is not like the effect of cradling a doll. Therefore, we assumed that the spontaneous cradling side was more accurate than the imagined (preferred) one and that a real infant elicited emotion more than a doll did.

Table 8.6

2 Exact Sig. Baby Cradling from videotape χ (1-sided) Baby Cradling from questionnaire 67.849 .000 2 Exact Sig. Doll Cradling from videotape χ (1-sided) Doll Cradling from questionnaire 76.787 .000

The relationship between the two types of cradling

205 8.6 Discussion

Previously, we have distinguished between two types of cradling side, preferred and spontaneous. The preferred sifde was assessed by a questionnaire and the results were reported in Chapters 6 and 7. In this chapter, we have examined the spontaneous cradling side, which was assessed by videotaping male participants. 102 male-participants were recruited and classified as being ‘the father of the held infant’, ’a father but not of the held infant’, or ‘a non-father’.

The aim in this chapter was to predict the spontaneous cradling side from the variables of stress, depression, the infant’s age, the holder’s age, footedness and handedness. Because the participant’s status did not improve R significantly, this factor was excluded. After running multiple regressions, only one significant predictor (infant age in months) was found for spontaneous left-side cradling of the real infant; that is, all the other variables did not show significant changes to the R value, and so were excluded from the equations. In addition, stress and depression approached negative significance as predictors of spontaneous left-side cradling of a real infant so they cannot be ruled out as predictive variables. On the other hand, this experiment confirms that stress can significantly predict the spontaneous cradling side of doll (p<.05) and that the holder’s age approaches significance (p =.099),

Therefore, both of these variables can be considered as possible predictors for spontaneous doll cradling behaviour.

In the era previous to the last few decades, men in Saudi Arabia tended to be out of the house for most of the day, either for work or social activities, while their wives stayed at home caring for children and doing the housework. This could explain why

206 some studies have reported an absence or weakness of cradling bias in males (De

Chateau, 1983; Turnbull and Lucas, 1990).

In the modern era, women in Saudi Arabia have participated positively in their society and they have succeeded in striking a balance between this and being housewives and mothers. Consequently, men and women share home and family responsibilities. Both may have jobs, but they have enough time to care for their children due to the facilities provided by the Saudi government. The absence of both parents during a period of time (for example, during working hours) could increase the cradling bias, especially when the infant is very young. Perhaps that is why our findings showed an effect of infant’s age on cradling side, and that an infant’s age can be used as a predictor for the cradling side in male participants. Thus, the intensity of emotion that resulted from the absence of the father for most of the day, along with the age of the infant, might be the reason behind the increase in left-side cradling.

In contrast with previous findings that reported an absence or weakness of cradling bias in males, we found a strong left-side bias in males. The absence of both parents during a period of time (for example, during working hours) and the age of the infant that had been left behind in nursery, for example, might increase this bias.

In terms of stress as a potential predictor of cradling bias, studies have reported that it could help to explain cradling behaviour (Bogren, 1984; De Château, 1991;

Weatherill et al., 2004; Suter, Huggenberger, Blumenthal, and Schachinger, 2009;

Vauclair, Scola, 2008; Reissland et al., 2009). Bogren (1984), who studied the effect of stress on cradling, concluded that mothers who were anxious about their

207 pregnancy had a tendency to cradle to the right, meaning that cradling to the right- side can be predicted by stress, as anxiety is the normal reaction to stress (Ehlert,

2006) and stressful events lead to anxiety (Baranyi, Bakos Haller, 2005). Finally, the findings of this study showed that stress can predict the spontaneous cradling side of a doll, and that the holder’s age had an effect that approached significance.

8.7 Conclusion

Based on the findings reported in this chapter and the findings that were reported in

Chapter 7, it can be concluded that cradling-side predictors differ according to the particular cradling side, and according to the type of stimulus. Although more predictors were reported in Chapter 7 than in this chapter, we should distinguish between the two types of cradling-side. In addition, the predictive variables vary according to the type of cradling and the type of the held object. And finally, we believe that videotaping participants is a more accurate method than using questionnaires, and that the spontaneous cradling side is more realistic and more accurate than the preferred one obtained from self-report questionnaires. These techniques were therefore used in the present study.

208 Chapter 9

General Discussion

9.1 Discussion of experiment and findings

This study was carried out to investigate the cradling bias phenomenon, which is a behaviour that is considered to reflect the lateralisation of the human brain. Despite the pioneering works of Sperry, Hubel and Wiese (1960) on split-brain patients, this type of study is new to the Arabic region and for that reason we were confident that it would obtain new results. As has been discussed widely in this thesis, Saudi Arabia is a conservative society due to its religious and traditional background. This type of society allowed us to examine handedness and cultural effects more clearly in two ways. The first was because we compared two very similar Saudi samples, one based in Saudi Arabia and the other in the United Kingdom. The second was because Saudi

Arabians' strong belief in using the right hand in most daily tasks helped us to examine the involvement of handedness in cradling behaviour. If there was any effect of one or both of these factors, it would appear clearly. Other factors were examined and the results were reported in detail.

We started by carrying out a pilot study to investigate how people process their emotions (perception). A left ear advantage (LEA) was shown for emotional information processing, thus demonstrating the role of the right hemisphere in emotion processing and confirming the previous findings in the literature. Even though participants showed a significant left ear advantage for detecting all types of emotion, the mean score for the angry emotion was higher than the mean score for

209 the happy one, which suggests that this kind of emotion (anger) is processed more in the right hemisphere. Because of the hypothesised role of the right hemisphere in emotion processing, and because this role has been widely reported in the literature and confirmed in the present study, we took this result as good starting point for further investigation.

As cradling can be taken as a feature of the laterality of the human brain, we, therefore, tested this behaviour by using two types of stimuli, real infants and a doll, in two different studies. In one study, 369 Saudi male and female participants were asked, through a self report questionnaire, to imagine cradling first a real infant and then to imagine cradling an infant-like doll and to report on which side of their body they would do this. This reported behaviour was labelled ‘the preferred cradling side’. In the second study, 102 Saudi male participants were videotaped physically cradling first a real infant and then an infant-like doll. This observed behaviour was labelled ‘the spontaneous cradling side’.

On the questionnaire, each participant was asked to state his or her gender, age and whether their imaginary cradling had been with their own child or that of a friend.

Thus, there were six categories of participants, namely, father of the cradled infant, mother of the cradled infant, father cradling a friend’s infant, mother cradling a friend’s infant, non-father and non-mother. In addition, each participant was asked to complete BDI, PSS, EHI and WFQ-Revised self report questionnaires, and these enabled us to make an assessment of his or her level of stress, level of depression, handedness and footedness, respectively.

210 Our results showed that the preferred cradling side of a real infant had a left arm bias and this was related to the holder’s gender, depression, stress, parenting experience, and all the six participant categories. The same cradling bias and the same relationships were found when respondents imagined cradling a doll but here handedness and footedness also appeared as factors. We concluded that cradling side is affected by different factors, according to stimulus type.

Our findings did not find any relationship between real infant left cradling preference and the holder’s age. This was not surprising because the left cradling preference has also been found in pre-school girls (De Château & Andersson, 1976; Saling &

Bonert, 1983) and in never-pregnant women (Saling & Tyson, 1981).

The effects of handedness and footedness on cradling side for the doll were surprising, because previous studies had reported that the incidence of cradling to the left side of the body was independent of handedness. However, this result reflects the strong belief, based on the traditions and religion of the participants that the right hand should be used for this activity rather than it being a spontaneous response. This emerged when they were asked which side they would prefer to use when holding or cradling a doll. However, when they were videotaped adopting a spontaneous cradling side, the recordings showed that handedness had no effect on cradling side either for the real infant or the doll. Thus, our findings here are consistent with previous research that showed no correlations between cradling-side and handedness or footedness.

Using the data gathered through the questionnaires for preferred cradling side and through videotaping for spontaneous cradling side, and using these as dependent

211 variables, this study tried to predict cradling side from a number of independent variables. For the preferred cradling side, these independent variables were the participant’s age, gender, parenting experience, the six categories of relationship to the cradled infant, stress, depression, handedness and footedness. For the spontaneous cradling side, the same variables were used, except that, because only men were involved, there were only three categories of relationship to the cradled infant, namely, being the father of the held infant, being a father but not of the held infant, and non-father.

For spontaneous cradling side, the significant variables varied according to the stimulus type; if the stimulus was a real infant, then the age of the infant was a significant variable, with the effects of depression and stress approaching significance. However, if the stimulus was a doll, stress was significant, with the holder’s age approaching significance.

For the preferred cradling side, when a real infant was the stimulus, then cradling side for a doll, stress, being the mother of the infant, being a mother but not of the held infant, and infant’s age were the predictors. However, with the doll stimulus, the best predictors were the cradling side of a real infant, footedness and depression.

Thus, depression was a predictor of the spontaneous cradling side when the object was a real infant and of the preferred cradling side when object was a doll. Stress was a predictor of both spontaneous and preferred cradling sides when the stimulus was a real infant but not of the preferred side when the stimulus was a doll.

Consequently, the present study confirms previous findings (e.g. Galler et al., 2000) that depression affecting the right hemisphere of the brain has negative effects on

212 child developmental and cognitive and social health. Additionally, footedness was found to be a predictor, suggesting that a right foot preference correlates to an increasing tendency to cradle to the left side.

Moreover, the effects on cradling side of stress and infant’s age were confirmed in the present study, as reported in chapter 6. Because stressed people have been found to be more likely to cradle to the right side of the body (Reissland, 2009), and because cradling to the left side is known to decline as an infant gets older, logically, the size of infant and stress can predict cradling side.

It was also concluded that depression and stress can affect human cradling side by reducing the left side cradling bias. The specialisation of the right hemisphere in auditory emotional input processing, which is reflected in the left ear advantage

(LEA) in this process, was confirmed in the pilot study. In addition, a faster response was detected if the stimulus was presented to the left visual field.

Our findings confirm those of previous studies in this respect, such as effect of stress reported by Reissland et al. (2009) and the effect of depression detailed by

Weatherill et al. (2004). Reissland et al. (2009) found that stressed but not depressed mothers showed a significantly reduced left-sided cradling bias, whereas Weatherill et al. (2004) found that depressed and stressed mothers tended to cradle on the right side. Our findings suggest that stress and depression affect cradling side, probably due to their direct effect on the right hemisphere that controls the left side of the body.

These findings, along with those in the previous literature, show the role of the right hemisphere in processing emotion. Thus, the present study suggests that depression

213 and stress, as signs of affected emotion, reduce the left-side cradling bias. If the left side of the body is controlled by the right hemisphere, where emotion is more processed, then it can be suggested that left side cradling will be reduced due to the effect of depression or stress on that hemisphere. In addition, an increase in the left- side bias correlates with an increase in the holder’s closeness to the held infant, that is, as its mother or father rather than the other four status categories, more so than other factors. Although the present study found no difference between males and females in cradling a doll, our findings confirm the mean difference between men and women in cradling side when cradling a real infant, pointing to the fact that cradling bias is found more in women than in men. This might explain why the difference between the two held objects led to different results. Moreover, no difference was found between the Saudi-based sample and the UK-based sample, either in cradling a real infant or in cradling a doll. A cultural effect was not found in this study, thus confirming previous studies that argued that left cradling side is universal in humans and non-human species.

9.2 Further research and implications

The Arabic region is a rich environment for more psychological studies, especially in the field of cognition, due to the rarity of such studies. Therefore, more studies are needed to produce more useful and up-to-date findings.

Further work on cradling side could embrace some factors that are, not included in the present study but which may have effects, such as attachment because more uncertainty about the relationship between mothers and their infants has been reported in right-cradler mothers (DeChateau, 1987).

214 Studying how such factors influence cradling could establish a deeper understanding of human behaviour and cognitive functions. In addition, further studies could lead to more understanding of gender differences in terms of how cognitive functions are processed and how emotion is regulated and expressed.

If a female researcher was able to obtain permission to observe mothers holding their infants in surgery clinics, for example, and if the mothers agreed to participate, it would certainly be interesting to replicate this study to examine the spontaneous cradling-side for Saudi women. In such a study, it might be useful to include education level as a factor that could affect cradling side to discover potential differences between mothers who terminated their formal education after high school and those who enrolled in a university. And finally, investigating gender differences in perceiving auditory and visual information could provide new explanations for the weakness or absence of the cradling bias in men because it has been suggested that women are more brain lateralised than men (Abel, 2010).

It is hoped that the findings of this study could stimulate other types of future research, especially on the effects of maternal stress and depression. For example, this study provides some possible indicators of maternal depression, and depression is known to have strong effects on human health and, in some cases, to lead to more serious problems. Our findings showed that stress and depression can predict cradling side; by reversing this finding, it can be inferred that it is possible to take right side cradling as a possible indicator of depression or stress. This does not mean that all those who show right-side cradling are stressed or depressed, but it can be used as an indication. The findings of previous studies, and of this study, that the brain’s right hemisphere is clearly involved in emotion processing, and especially in

215 processing negative emotions, help us to understand how people regulate their emotions and how the affected emotion contributes to human behaviour. It is known that women are more vulnerable than men to depression, and this difference is greater after giving birth. Cradling a new born baby to the right side of the body could be an indicator of postpartum depression and prompt doctors to look for other indicators with the aim of making a quick intervention to help such mothers, if necessary. This is especially important because maternal depression has been found to affect infant development, especially cognitive development, and that is why Beck

(2006) described it as “The thief that steals motherhood.”

9.3 Limitations

The limitations of the present study were determined mainly by the restrictions that a conservative society placed on its sample and its conduct. These restrictions cannot be ignored in Saudi Arabia and, although the current study obtained the necessary permissions, it was conducted according to Islamic Law. This precluded a male researcher from observing women in intimate situations with children and from video-taping their spontaneous cradling behaviour.

The laterality of human brain was investigated by examining cradling-side behaviour. Two stimuli were used, a real infant aged between one and fifteen months and a doll. We divided cradling side into two types, preferred and spontaneous, and examined them using questionnaire and videotaping methods, respectively. We were able to examine the preferred cradling-side in the total sample but spontaneous cradling side could be examined only in the 102 male participants. Additionally, all participants were Saudis, some based the UK and some in Saudi Arabia, and no other

216 nationalities were involved. The similarity between the two samples allowed us to examine the cultural factor. Moreover, the strong traditional and religious significance of using only the right hand for most everyday tasks allowed us to examine the handedness factor that was thought to affect the cradling-side.

Concerning the representativeness of the sample, Saudi Arabians are very homogeneous in their language, religion, beliefs, and traditions so it is likely that any selected sample would be representative on these variables, and this would be especially so in a sample selected entirely from the western region of the country.

However, there were factors that undermined the intended representativeness of the recruited sample. Firstly, the UK-based sub-sample was based entirely of students, who may not be representative of all Saudis living in the UK. Secondly, there is no way of knowing if the 135 volunteers who comprised this sub-sample were representative of the 431 students whose details were supplied by the Saudi Embassy in London. Consequently, it cannot even be claimed that this sub-sample was representative of Saudi students in the UK. The representativeness of the Saudi- based sub-sample also turned out to be flawed. Firstly, the recruitment of participants relied on client data from primary care centres. Although all Saudi citizens have access to these centres, it could be that their users might not be representative of the population as a whole. Then, only nine centres agreed to cooperate with this study and each of these restricted provision of names and addresses to the first 100 clients on their registers. Of the 900 people subsequently invited to participate, only 234 did so. These volunteers may or may not be representative of the population of the western region. Secondly, this recruitment process produced a strong female bias, since 182 (77.8 %) of the total were women.

217 Because of these problems of sample representativeness, it is strongly recommended that a further study should be carried out which will measure the same variables used in this study but with truly representative samples of the populations, firstly of the western region and then of other parts of the country. It is not easy to see how this might be accomplished. In many countries, the electoral register might serve as a basis for a representative sample but, as yet, women in Saudi Arabia are not allowed to register to vote. However, there is a strong movement among women for voter rights and, recently, the Shoura Council (a quasi-legislative body) called for women to be allowed to vote, at least in municipal elections. Given a full electoral register, a number of representative locations (cities, towns and rural areas) could be identified and their electoral registers used as a basis for random sampling.

Another limitation of this study is that anxiety was not measured. This is because it has been reported that anxiety is the normal reaction to stress (Ehlert, 2006) and stressful events lead to anxiety (Bogren, 1984; Baranyi and Bakos Haller, 2005). It might be useful to include measuring anxiety in a further study as a factor that might affect cradling side in humans.

A further limitation was the inability of the researcher to observe and film women actually holding their own or other infants and consequently the research had to rely on self-reports. Given the complete ban in Saudi Arabia, and in Saudi culture, on men filming women in such situations, only a female researcher would be able to obtain the necessary permission. Thus, it is recommended that a female researcher

218 might attempt to replicate the aims of this study by seeking permission to observe mothers spontaneously holding their infants in surgery clinics.

The final limitation of this study is that the cut-off score for depression was not based on clinical reference data. Instead we followed previous Arabic studies in using a cut-off score of 18 for BDI. These, also, were not based on clinical reference data, therefore, we used a reasonable assumption that anyone who scored 18 or above might be considered to have a high level of depression. However, it would obviously have been better to have based the cut-off on clinical reference data and further investigations in this area should attempt to correct this limitation.

9.4 Summary and conclusions

This study was carried out to investigate the incidence of cradling bias in Saudi people. Consistent with previous studies, it was found that this phenomenon occurs more in women than in men, with 65%-86% of mothers cradling to the left side of the body. This strong incidence was found to be absent or weak in men. The same cradling bias has been observed in some non-human species. Different explanations have been offered in numerous studies to interpret this behaviour, including factors such as mother’s heartbeat, handedness, communication, advantages of auditory and visual fields, and hemispheric specialisation. We tried to examine as many factors as possible that might affect cradling side in humans; our study included the factors of culture, the holder’s age and gender, the infant’s age and gender, depression, stress, handedness, footedness and experience in parenting. Two types of stimuli, a real infant and a doll, were used to examine both the preferred and the spontaneous

219 cradling side. By running Pearson’s correlations between the variables, we obtained initial outcomes. Depression, stress, the infant’s age, the holder’s gender, the participant’s status and doll cradling behaviour correlated to real infant cradling preference, whereas depression, handedness, footedness, and real infant cradling correlated to doll cradling preference.

In cradling a real infant, the cradling bias was found to be related to parenthood, the holder’s gender, depression, stress and the six categories of participants’ status.

There was a statistical relationship between doll cradling bias and handedness, footedness, depression, being the father of the infant, being the mother of the infant, being a non-father and being a non-mother. Although we found a significant difference between males and females in cradling a real infant, no difference was found between them in cradling a doll. The cultural factor did not have any effect on cradling side, either for a real infant or for a doll.

For predicting the preferred cradling side for a real infant, we found that the predictors, in order of significance, were cradling-side of a doll, stress, being the mother of the held infant, being the mother of another infant, and the infant’s age.

For predicting the preferred doll cradling side, we found that the predictors, in order of significance, were cradling-side of a real infant, footedness and depression. For the spontaneous cradling side with a real infant, the age of the infant was the only significant predictor, though stress and depression approached significance. For predicting cradling side with a doll, stress was found to be the only significant factor.

From these results it was concluded that both Saudi men and women showed a clear left-side cradling bias in cradling both a real infant and a doll.

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