Hormones and Social Affiliation: Menstrual Cycle Shifts in Progesterone Underlie Women's Attention to Signs of Social Support Saul Miller

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2011 Hormones and Social Affiliation: Menstrual Cycle Shifts in Progesterone Underlie Women's Attention to Signs of Social Support Saul Miller

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COLLEGE OF ARTS AND SCIENCES

HORMONES AND SOCIAL AFFILIATION:

MENSTRUAL CYCLE SHIFTS IN PROGESTERONE UNDERLIE WOMEN’S ATTENTION

TO SIGNS OF SOCIAL SUPPORT

SAUL MILLER

A dissertation submitted to the Department of Psychology in partial fulfillment of the requirements for the degree of Doctor of Philosophy

Degree Awarded: Spring Semester, 2011

The members of the committee approve the dissertation of Saul Miller defended on March 17, 2011.

______Jon K. Maner Professor Directing Dissertation

______Karin Brewster University Representative

______Colleen Kelley Committee Member

______Lisa Eckel Committee Member

______E. Ashby Plant Committee Member

The Graduate School has verified and approved the above-named committee members.

This dissertation is dedicated to Bill and Lois Miller.

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ACKNOWLEDGEMENTS

The author thanks Jon K. Maner for his guidance and mentorship; Colleen Kelley, Lisa Eckel, Ashby Plant, and Karin Brewster for their helpful comments and suggestions; his friends and family for their love and support; and his fiancée, Andrea, for much more than he could possibly list.

TABLE OF CONTENTS

List of Tables ...... vi Abstract...... vii 1. INTRODUCTION...... 1 1.1 Factors Shaping Affiliative Motivation ...... 1 1.2 An Evolutionary Perspective on Women’s Motivation...... 2 1.3 A Neuroendocrinological Perspective on Women’s Motivation...... 4 1.4 Lower-Order Cognition and Affiliation: Attention to Social Stimuli...... 5 1.4.1 The Social Monitoring System Hypothesis ...... 6 1.4.2 The Target-Specific Attentional Hypothesis ...... 6 1.5 Overview of the Current Research...... 8 2. METHOD...... 9 2.1 Participants...... 9 2.2 Procedure ...... 9 2.3 Progesterone Measurement...... 11 3. RESULTS...... 12 3.1 Preliminary Analyses...... 12 3.2 Facial Expression Dot Probe Task...... 13 3.3 Femininity Dot Probe Task...... 16 4. DISCUSSION...... 19 APPENDICES ...... 23

A. IRB APPROVAL...... 23

B. CONSENT FORM ...... 24

REFERENCES ...... 26

BIOGRAPHICAL SKETCH ...... 31

LIST OF TABLES

1 Mean (SD) salivary progesterone values (pg/ml)...... 13

2 Mean (SD) reaction time (ms) on the facial expression dot probe task ...... 16

3 Mean (SD) reaction time (ms) on the femininity dot probe task...... 18

ABSTRACT

The desire for positive social relationships is a fundamental motive shaping human cognition and behavior. In the current research, I integrate social cognitive, evolutionary, and neuroendocrinological theories to generate and test predictions about how female affiliative motives shift naturally across women’s menstrual cycles and how these shifts relate to functional changes in attention. Consistent with a social monitoring system hypothesis, during the luteal phase of their cycle, normally cycling women, but not women on oral contraceptives, displayed greater attentional attunement to social stimuli than non-social stimuli. Moreover, attention to social stimuli was associated with normally cycling women’s levels of progesterone – a hormone closely tied to affiliative motivation. The current research suggests that endocrinological mechanisms are functionally linked with lower-order cognitive processes designed to help foster positive social relationships.

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CHAPTER ONE

INTRODUCTION

Humans are a highly social species. “Social” because we rely on others every day of our lives for resources, support, and survival. “Species” because we are bound by the evolutionary pressures that shape all living creatures. Accordingly, human psychology and biology have been shaped throughout evolution to facilitate the pursuit of vital social needs. In the current research, I apply this “social species” model of human nature by exploring how biology influences cognitive processes designed to satisfy one of the most fundamental of human needs – the need for positive social relationships (Baumeister & Leary, 1995). In the current research, I integrate neuroendocrinological, evolutionary, and social cognitive perspectives on affiliation and social relationships to generate and test predictions about the ways in which natural hormonal fluctuations associated with women’s reproductive status relate to changes in lower-order social cognition. In particular, I examine how menstrual cycle changes in women’s reproductive status and levels of progesterone – a hormone closely tied to affiliative motivation (Schultheiss, Dargel, & Rohde, 2003) – shapes how women attend to their social world (DeWall, Maner, & Rouby, 2009; Gardner, Picket, & Brewer, 2000; Pickett, Gardner, & Knowles, 2004).

1.1 Factors Shaping Affiliative Motivation

Social relationships play a crucial role in helping people solve a variety of important adaptive challenges. Consequently, the need for friendship and positive social bonds is one of the most profound and fundamental of all human needs (Baumeister & Leary, 1995) – one that if not satisfied can lead to devastating consequences for psychological and social well-being (Baumeister, DeWall, Ciarocco, & Twenge, 2005; Leary, 1990). Although all people possess a desire for social closeness and friendship, the strength of this affiliative motivation is by no means constant across all situations and all people. For example, situational factors indicating that one’s affiliative goals are not being met (e.g., social rejection) cause people to increase their desire to form new social bonds and facilitate processes designed to increase the formation of positive social relationships (Maner, DeWall, Baumeister, & Schaller, 2007). Personality characteristics (e.g., a chronic need-to-belong) also influence

one’s desires for affiliation (Leary, Kelly, Cottrell, & Schreindorfer, 2005) and shape one’s sensitivity to other people in the social environment (Gardner, Pickett, Jefferis, & Knowles, 2005; Pickett et al., 2004). Thus, several factors shape the strength of one’s affiliative motivation and the degree to which people seek out potential sources of social connection. One factor that has received great attention among scientists interested in affiliative motivation is a person’s sex. Several studies suggest that affiliative motives are particularly strong among women. Women, for example, report greater concerns over relationship vulnerabilities such as negative social evaluations and interpersonal dependency than men do (Rose & Rudolph, 2006). Additionally, women tend to be more reactive to interpersonal stresses (e.g., social exclusion) than men are (Stroud, Salovey, & Epel, 2002; Stroud, Tanofsky-Kraff, Wilfley, & Salovey, 2000). Although on average women tend to have strong affiliative motives, affiliative responses vary considerably across individual women and across studies (Kajantie & Phillips, 2006). Indeed, whereas some studies reveal that interpersonal stressors lead women to have greater affiliative desires than men do (e.g., Stroud et al., 2000, 2002), other studies report no differences in affiliative responses between men and women (e.g., Maner, DeWall, et al., 2007). In the current research, I suggest that variability in women’s affiliative motives may be partially due to shifts in motivation across women’s menstrual cycles (Jones, DeBruine, Perrett, Little, Feinberg, & Smith, 2008). In the following sections, I review two theoretical models that provide a basis for predicting menstrual cycle shifts in women’s affiliative motivation. I then describe hypotheses for the types of lower-order cognitive processes that may be activated during those parts of a woman’s cycle when affiliative motivation is greatest.

1.2 An Evolutionary Perspective on Women’s Motivation

Women’s reproductive status varies greatly throughout the menstrual cycle. In particular, women’s fertility levels peak in the middle of their cycle around the time of ovulation (Wilcox, Weinberg, & Baird, 1995). From an evolutionary perspective, these fluctuations in women’s reproductive status should be associated with reproductively-relevant shifts in women’s psychology and behavior (Gangestad, Thornhill, & Garver-Apgar, 2005). Indeed, women display menstrual cycle shifts in mating motivation that correspond to the probability of ovulation, thereby maximizing reproductive benefits associated with peak levels of fertility (Gangestad,

Garver-Apgar, Simpson, & Cousins, 2007; Penton-Voak, Perrett, Castles, Burt, Kobayashi, & Murray, 1999). Just as women’s mating motives shift throughout the menstrual cycle, so too may women’s affiliative motives shift predictably across the cycle. In particular, female affiliative motivation may peak after ovulation during the luteal phase, due to the reproductive status of women during that part of their cycle. The luteal phase of a woman’s menstrual cycle is marked by her body’s tendency to prepare for pregnancy (e.g., by creating the corpus luteum and by increasing body temperature to incubate a fertilized egg) (Gilbert, 2000). This process occurs regardless of whether the woman is actually pregnant or not. That is, even if a woman has not conceived, after ovulation the body acts as if conception has occurred and begins to prepare for pregnancy, and it does so for several days until it is clear that the egg has not been fertilized. From an adaptationist perspective, the physiological changes that occur during the luteal phase to prepare for pregnancy should be accompanied by relevant psychological processes designed to overcome challenges associated with pregnancy (Conway et al., 2007; Fessler, 2002; Jones, Perrett, et al., 2005). Pregnancy increases metabolic demands and yet, historically, limited a woman’s physical capacity to gather resources. Moreover, pregnancy impairs a woman’s ability to protect herself from harm by hindering her physical ability to flee from or fight off a threat. Thus, women may display specific, adaptive processes for securing resources and protecting themselves from danger during pregnancy (Taylor, Klein, Lewis, Gruenewald, Gurung, & Updegraff, 2000). Throughout evolutionary history, social coalitions have served as one means by which people secure resources such as food and shelter, as well as protection from predators and other threats (Caporael, 1997). Consequently, when people’s abilities to gather resources and protect themselves from harm are minimized, they may seek out sources of social affiliation. Indeed, an emerging body of evidence suggests a close link between affiliative motivation and desire for resources (Zhou & Gao, 2008; Zhou, Vohs, & Baumeister, 2009). Social allies, therefore, may be particularly important for women during pregnancy (Taylor et al., 2000). Thus, during the luteal phase, just as women’s bodies begin to prepare for pregnancy, so too may women begin to prepare for pregnancy by strengthening social connections. The physiological shifts that occur during the luteal phase are therefore expected to facilitate the activation of affilitiave motivation,

and promote psychological processes designed to promote pursuit of social support (DeBruine, Jones, & Perrett, 2005; Jones, Little, et al., 2005).

1.3 A Neuroendocrinological Perspective on Women’s Motivation

The prediction that women’s affiliative motivation is highest during the luteal phase fits not only with adaptationist theories of social cognition, but also with existing neuroendocrinological research. In women, hormone levels vary dramatically across the menstrual cycle, and those hormonal shifts are associated with changes in female psychology (Garver-Apgar, Gangestad, & Thornhill, 2008; Roney & Simmons, 2008). The luteal phase of a woman’s cycle is marked hormonally by heightened progesterone levels. Increases in progesterone from the follicular phase to the luteal phase can range up to 1000% (Schultheiss et al., 2003). Those changes in progesterone are intrinsically connected to the biological changes that occur during the luteal phase to prepare for pregnancy. Recent endocrinological studies in humans and non-humans suggest that progesterone is closely linked with affiliative motivation. In female rats, for example, affiliative behavior is greatest during proestrus, when circulating levels of progesterone are at their peak (Frye, Petralia, & Rhodes, 2000). In humans, individual differences in implicit affiliative motivation are positively correlated with basal progesterone values (Wirth & Schultheiss, 2006). Experimental research also demonstrates that inducing or making salient affiliative motivation can lead to increased release of progesterone (Brown et al., 2009; Maner, Miller, Schmidt, & Eckel, 2010; Schultheiss, Wirth, & Stanton, 2004). In sum, several lines of work suggest a link between progesterone and affiliative motivation. Thus, the increased levels of progesterone observed during women’s luteal phase may serve as a catalyst not only for the biological changes that occur during the luteal phase to prepare for pregnancy, but also for luteal changes in affiliative motivation. To the extent that affiliative motivation is heightened when progesterone levels peak during the luteal phase, women should be expected to display psychological biases and attunements during the luteal phase that promote the formation and maintenance of positive social bonds. Indeed, some studies provide support for this hypothesis. For example, DeBruine and colleagues (2005) found that women reported greater liking for female faces resembling their own face (a putative kinship cue) during the luteal phase than during the follicular phase,

and these preferences for self-resemblance were correlated with estimated levels of progesterone. Furthermore, Jones, Little, and colleagues (2005) found that on the luteal days in which progesterone levels were expected to be highest, women reported increased preferences for femininity in other’s faces (a cue indicative of trustworthiness), as well as greater commitment to their romantic relationships. Thus, the luteal phase may be a critical period during which women are highly motivated to form and maintain positive social bonds with people, such as kin, romantic partners, and trustworthy others, who are likely to provide social support. Moreover, these affiliative processes may be related to the increases in progesterone that typically occur during the luteal phase. Although some previous research has hinted at a possible link between progesterone and affiliative processes during the luteal phase, limitations of this research have left several unanswered questions. First, previous research linking progesterone to menstrual cycle variations in affiliative processes (DeBruine et al., 2005; Jones, Little, et al., 2005) has relied upon estimates of progesterone levels (e.g., by using day of the woman’s cycle as an estimator), rather than actually measuring progesterone levels. Consequently, it remains to be seen whether actual levels of progesterone are associated with those psychological processes. Second, this research has focused almost exclusively on higher-order processes (e.g., explicit social preferences and judgments), leaving unexplored the more basic mechanisms presumed to underlie them. Early stage cognition provides the basic building blocks of higher- order psychology and behavior. From an evolutionary perspective, early-in-the-stream cognitive mechanisms should be adaptively tuned to one’s current motivational state (Maner, Miller, Rouby, & Gailliot, 2009). Accordingly, heightened levels of women’s affiliative motivation during the luteal phase of the menstrual cycle may promote basic cognitive attunements designed to facilitate the identification of and pursuit of positive social bonds.

1.4 Lower-Order Cognition and Affiliation

What kinds of cognitive attunements and biases might be expected in response to luteal phase affiliative motivation? Several lines of research suggest that one of the most basic processes influenced by motivational states is attention (Fox, Russo, & Dutton, 2002; Moskowitz, 2002; Öhman & Mineka, 2001). Because people’s mental resources are limited, they can only attend to certain aspects of their environment at any given time. Consequently, people

functionally allocate their attention to goal-relevant stimuli – stimuli that represent either opportunities for fulfilling their goals or threats to the satisfaction of those goals (Maner, Gailliot, Rouby, & Miller, 2007; McArthur & Baron, 1983). Attending to those stimuli facilitates other processes (e.g., remembering the stimuli, evaluating the stimuli in a positive or negative manner, approaching or avoiding the stimuli) that help people achieve their goal. Therefore, when progesterone levels peak during the luteal phase of the menstrual cycle, women may be expected to attend more to stimuli that are relevant for social support than to stimuli that are irrelevant for social support. Below I discuss two hypotheses pertaining to the types of stimuli that women may attend to when affiliative desires peak during the luteal phase.

1.4.1 The Social Monitoring System Hypothesis

People encounter a variety of different stimuli in their environment. Some of those stimuli (e.g., other people) are especially relevant to people’s affiliative needs. When people experience a heightened need to belong, they activate a social monitoring system – a psychological system that attunes individuals to socially relevant information in their environment (Gardner et al., 2000, Pickett et al., 2004). Previous research indicates that strong desires for social affiliation are associated with better memory for social events than non-social events (Gardner et al., 2000, 2005; Hess & Pickett, 2010). Additionally, when people feel lonely or rejected (and thus have a heightened desire to feel accepted by others) they attend more to and are better able at decoding the meaning of other people’s facial expressions and vocal tones (Gardner et al., 2005; Pickett et al., 2004). By activating the social monitoring system, people presumably are more aware of individuals who might help or hinder pursuit of their affiliative goals. Because a desire for social affiliation facilitates greater attunement to social stimuli than non-social stimuli, progesterone-mediated affiliative motives may be similarly associated with greater attention to social stimuli than non-social stimuli. In other words, during the luteal phase when progesterone levels are high, women may be more likely to engage in social monitoring and thus more likely to attend to social stimuli (e.g., other people who could help or hinder their desire for affiliation) than non-social stimuli (e.g., objects that are irrelevant to affiliation).

1.4.2 The Target-Specific Attentional Hypothesis

Although all people can potentially play a role in the pursuit of various social goals, some people are more likely than others to help satisfy one’s social goals. As a consequence, people’s

attention may be target-specific; people may attend specifically to those individuals who are most likely to help satisfy their current goals. For example, among heterosexual individuals, increases in mating motivation are associated with increased attention to attractive opposite-sex targets (those people who are most likely to help satisfy mating goals) but not same-sex targets or average-looking opposite-sex targets (Maner, Gailliot, et al., 2007). By focusing attention on those individuals who are likely to help satisfy a certain goal, people may be most likely to seek out and remember those individuals later on. Thus, rather than attending to all socially relevant stimuli in the environment (as the social monitoring hypothesis would suggest), people with a strong desire for positive social contact may attend only to those specific people likely to satisfy affiliative goals. People’s willingness to provide social support, and thus the degree to which they could potentially fulfill someone’s affiliative goals, is communicated via various cues. For example, substantial evidence suggests that interpersonal intentions are communicated through facial expressions (Parkinson, 2005; Ekman, 1971, 1982). Displaying an angry facial expression indicates that a person is currently motivated to fight and aggress against others (Lazarus, 1991; Shaver, Schwartz, Kirson, and O’Connor, 1987). Displaying a smile, on the other hand, signals more friendly, benevolent interpersonal intentions, and a desire for forming new social bonds (Horstmann & Bauland, 2006; Jones & Raag, 1989; Lundqvist & Öhman, 2005; Schneider & Josephs, 1991). Therefore, people who feel a strong desire to affiliate with others may seek out specific individuals displaying smiling facial expressions (DeWall et al., 2009). Previous research indicates that facial characteristics associated with masculinity and femininity are also perceived as indicators of different interpersonal intentions. For example, masculine facial characteristics (e.g., a wide jaw, long chin, and well-defined brow; Gangestad & Thornhill, 2003), are positively related to perceptions of violent and aggressive traits, as well as actual aggressive behavior (e.g., Carré, McCormick, & Mondloch, 2009; Stillman, Maner, & Baumeister, 2010). Conversely, feminine facial characteristics (e.g., high cheek bones and a small chin) are associated with perceptions of good parenting, trustworthiness, and warmth (Perrett et al., 1998) – characteristics signaling a high probability of social support. Thus, feminine characteristics in others may serve as another goal-relevant signal for individuals experiencing high levels of affiliative motivation.

To the extent that goal-driven attentional processes are target-specific, one might predict that people experiencing strong affiliative motivation attend more to feminine individuals and individuals displaying smiles than individuals lacking those cues of social support (e.g., DeWall et al., 2009). During the luteal phase, therefore, women might pay more attention to feminine faces and smiling faces than masculine faces or faces displaying different expressions.

1.5 Overview of the Current Research

The current study was designed to examine attentional biases during different phases of women’s menstrual cycles – attentional biases hypothesized to reflect women’s affiliative motivation. At various points of the menstrual cycle, normally cycling women and women on hormonal contraceptives performed dot probe tasks. The dot probe task is a common social- cognitive measure used to assess biases in attentional adhesion (how “glued” participants’ attention is to certain stimuli) (Fox, Russo, Bowles, & Dutton, 2001; Maner, Gailliot, et al., 2007). I hypothesized that during the luteal phase of their cycle when progesterone levels were high, normally cycling women would a) attend more to social stimuli than non-social stimuli (the social monitoring system hypothesis) or b) attend more to social stimuli signaling cues of social acceptance (e.g., smiling and feminine faces) than social stimuli lacking those cues (the target- specific hypothesis). Women on hormonal contraceptives served as a control group. Women on hormonal contraceptives do not experience regular changes in reproductive status and progesterone levels across their cycle; thus, attentional biases associated with progesterone and phase of the cycle were predicted only for normally cycling women.

CHAPTER TWO

METHOD

2.1 Participants

Ninety-four undergraduate women (age: 18-24) participated for course credit. Forty-nine participants were normally cycling (NC participants) and not taking any form of hormonal contraceptives; forty-five participants were taking hormonal contraceptives (HC participants). In a pre-testing session, all women indicated that they experienced regular menstrual cycles lasting approximately 28 days. A LH surge (indicating the onset of ovulation) was not observed for four NC participants, potentially indicating anovulatory cycles; their data were excluded from all analyses.

2.2 Procedure

During an initial session participants signed a consent form, filled out demographic information, and received information about the study. Participants were told that the study examined the association between hormones and various cognitive abilities such as attention and memory. Participants were given instructions to email the PI upon the start of their next menstrual cycle (i.e., at the start of blood flow or blood spotting). Additionally, NC participants were given ovulation predictor tests (from Clearblue Easy Ovulation Digital Test Kits) that measure LH in urine. A positive test indicates that ovulation will occur within 24-36 hours. Participants were told that the test sticks measured a certain hormone (no reference was made to LH or ovulation). Participants began using the test sticks 7 days after menstruation and emailed the PI when the test stick revealed a positive result. Four participants never received a positive result; the remaining NC participants experienced a LH surge, on average, 15.18 days (SD=3.33 days) after the onset of menstruation. Upon emailing the PI about the onset of menstruation, participants were scheduled for another session in the laboratory. Participants were randomly assigned to come into the laboratory during a particular menstrual cycle phase: follicular, ovulatory, or luteal. Follicular phase participants came into the lab 5-8 days after the onset of menstruation. Ovulatory phase NC participants came into the lab 0-1 days after their LH surge (indicated by the positive test

stick result). Women taking hormonal contraceptives do not experience a LH surge in the middle of their cycle; thus, the ovulatory phase for HC participants was defined as 13-15 days following the onset of menstruation. Luteal phase NC participants came into the lab 5-8 days after their LH surge; luteal phase HC participants came into the lab 19-22 days after the onset of menstruation. To prepare for each lab session, participants refrained from activities known to affect hormone levels, including exercising for 12 hours prior to coming into the lab, smoking for 6 hours prior to coming into the lab, eating for 2 hours prior to coming into the lab, and consuming caffeinated products for 2 hours prior to coming into the lab. During each session, participants provided a saliva sample by spitting into a collection vial (approximately 4 ml per sample). Participants then performed two dot probe tasks used to measure attentional adhesion to goal-relevant stimuli. Target stimuli consisted of man-made objects (non-social stimuli) and people’s faces (social stimuli). For the femininity dot probe task, stimuli consisted of 24 man- made objects and two versions (one masculine, one feminine) of each of 12 faces (6 male; 6 female) (Welling et al., 2007, 2008). For the facial expression dot probe task, stimuli consisted of 24 man-made objects and 24 faces (12 male, 12 female) varying in facial expression (8 smiling, 8 angry, 8 neutral) (DeWall et al., 2009). Participants first completed the femininity dot probe task, and then the facial expression dot probe task. On each trial of the dot probe tasks, a fixation cross first appeared in the center of the computer screen for 1,000 ms. Next, a target stimulus was displayed for 500 ms in one quadrant of the computer screen (upper left, upper right, lower left, lower right). Immediately following the disappearance of that stimulus, a categorization object (a circle or square) appeared in either the same location as the target stimulus (“filler trials”) or in a different location (“attentional shift trials”). Participants indicated via key press as quickly and accurately as possible whether the categorization object was a circle or square. The extent to which participants’ attention “stuck” to a target stimulus was indicated by their latencies on attentional shift trials. Greater latencies on those trials indicated that participants took longer to disengage their attention from the target stimulus. In other words, longer latencies on those trials indicated greater attentional adhesion to the target stimulus. After completing a block of practice trials (composed of neutral Chinese characters), participants completed 4 blocks of experimental trials. Each block consisted of 24 trials (6

“filler” and 18 “attentional shift”). The order in which stimuli and trials appeared was randomized.

2.3 Progesterone Measurement

Saliva samples were frozen at −20 °C. To precipitate mucins, samples were thawed and centrifuged at 4000 rpm for 10 min. The supernatant was stored at -20°C until assayed. Commercially available solid-phase Coat-A-Count125I radioimmunoassay kits provided by Siemens Medical Solutions Diagnostics (Los Angeles, CA) were used to measure concentrations of progesterone. Each sample contained 400 μl of participant supernatant. Standards and controls were diluted (1:40) with distilled water (analytical range: 2-1000 pg/ml). Tubes were incubated for 20 hours after adding radio-labeled tracer. All samples were processed in duplicate using a high throughput, automated gamma counter. The intra- and inter-assay CVs were 17.1% and 13.7%, respectively, which are commensurate with previous salivary measurements of progesterone (Liening, Stanton, Saini, & Schultheiss, 2010; Wirth, Meier, Fredrickson, & Schultheiss, 2007).

CHAPTER THREE

RESULTS

3.1 Preliminary Analyses

Preliminary analyses revealed that progesterone levels were positively skewed. Thus, consistent with previous research (Liening et al., 2010), progesterone values were log transformed for all analyses. One NC participant in the follicular phase had an extremely high progesterone value (greater than 3 SD above the mean NC follicular phase value); her data were excluded from analyses. Table 1 presents mean (non-transformed) salivary progesterone levels by phase of cycle among NC participants and HC participants separately. Analyses of progesterone values revealed a significant interaction between phase of cycle and contraceptive status, F(2,83)=13.45, p<.001, partial η2=.29. Consistent with hormonal changes across the menstrual cycle, NC participants in the luteal phase had significantly higher levels of progesterone than NC participants in the follicular phase, F(1,83)=33.94, p<.001, partial η2=.29, and NC participants in the ovulatory phase, F(1,83)=16.11, p<.001, partial η2=.16. NC participants in the ovulatory phase had marginally higher levels of progesterone than NC participants in the follicular phase, F(1,83)=2.83, p=.096, partial η2=.03. HC participants displayed higher levels of progesterone during the follicular phase than during the luteal phase, F(1,83)=4.16, p=.045, partial η2=.04, potentially due to the stoppage of oral contraceptive administration during the early part of the follicular phase; HC participants in the ovulatory phase did not differ in progesterone levels from either follicular or luteal phase HC participants, p’s>.10. Comparisons of NC and HC participants at each phase of the cycle revealed that NC participants had higher levels of progesterone than HC participants during the luteal phase, F(1,83)=62.61, p<.001, partial η2=.43, and ovulatory phase, F(1,83)=3.72, p=.057, partial η2=.04; there was no difference in progesterone levels among NC and HC participants in the follicular phase, F<1. Results are consistent with data demonstrating that oral contraceptives inhibit the secretion of endogenous progesterone and that salivary assays lack sensitivity to exogenous gestagens (Schultheiss et al., 2003).

Table 1: Mean (SD) salivary progesterone values (pg/ml).

NC participants HC participants

Follicular Phase 11.9 (7.8) 10.7 (3.4)

Ovulatory Phase 18.5 (7.3) 11.5 (7.7)

Luteal Phase 88.5 (53.8) 9.8 (8.9)

3.2 Facial Expression Dot Probe Task

The reaction time (ms) with which participants responded on attentional shift trials served as the dependent variable. Trials on which a participant’s latency was greater than three standard deviations away from his/her mean latency were excluded from analyses. On average, for each participant this resulted in 1.5% (SD=1.2%) of trials being exclude. One participant had an unusually high average response time (greater than 3 SD above the sample mean); her data were excluded from subsequent analyses. To test the prediction that during the luteal phase, NC participants, but not HC participants, would attend more to social stimuli than non-social stimuli (the social monitoring system hypothesis), average reaction time on the attentional shift trials was calculated separately for faces (social stimuli) and objects (non-social stimuli) for each participant. Using ANOVA, reaction time was predicted from stimulus type (social vs. non-social; within-subjects factor), contraceptive status (NC vs. HC; between-subjects factor), cycle phase (follicular vs. ovulatory vs. luteal; between-subjects factor), and all interactions. There was a main effect of stimulus type, F(1,82)=7.19, p=.009, partial η2=.08, indicating that, in general, participants attended more to social stimuli than non-social stimuli; however, this was qualified by the predicted three-way interaction between stimulus type, contraceptive status, and cycle phase, F(2,82)=3.51, p=.034, partial η2=.08. Follow-up analyses were conducted within NC and HC participants separately. No significant effects were observed among HC participants, all p’s>.10. Among NC participants, there was a marginally significant interaction between stimulus type and cycle phase, F(2,82)=2.39, p=.099, partial η2=.06. Consistent with the social monitoring system hypothesis,

13 during the luteal phase, NC participants attended more to social stimuli than non-social stimuli, F(1,82)=9.34, p=.003, partial η2=.10 (see Table 2). No effect of stimulus type was observed among NC participants in the follicular phase or ovulatory phase, p’s>.10. Additional analyses examined whether cyclical changes in progesterone underlie changes in attention to social stimuli. Separate GLM analyses were performed among HC and NC participants in which reaction time on attentional shift trials was predicted from stimulus type, salivary progesterone values (a continuous between-subjects factors), and their interaction. No significant effects were observed among HC participants, all p’s>.10. Among NC participants, there was a significant interaction between salivary progesterone and stimulus type, F(1,42)=4.30, p=.044, partial η2=.09. As seen in Figure 1, NC participants high in progesterone (1 SD above the mean) attended more to social stimuli than non-social stimuli, F(1,42)=10.65, p=.002, partial η2=.20; NC participants low in progesterone (1 SD below the mean) displayed no difference in their attention to social and non-social stimuli, F<1. Additionally, among NC participants, progesterone was significantly positively correlated with attention to social stimuli, r=.37, p=.015, but only marginally correlated with attention to non-social stimuli, r=.29, p=.054. Thus, results are consistent with the hypothesis that changes in progesterone are closely linked with changes in attentional processes associated with affiliative motivation. Although NC women displayed greater attention to social stimuli than non-social stimuli during the luteal phase when progesterone was high, it is possible that above and beyond the attention that is given to all social stimuli, NC women during the luteal phase pay particular attention to those specific social targets possessing cues of social acceptance (e.g., smiling faces) (the target-specific hypothesis). To test this hypothesis, using ANOVA, reaction time on attentional shift trials to social stimuli was predicted from target expression (happy vs. angry vs. neutral; within-subjects factor), target sex (male vs. female; within-subjects factor), participant contraceptive status, participant phase of cycle, and all interactions. No effects reached conventional levels of significance. To probe for potential effects of progesterone, separate GLM analyses were performed on HC and NC women in which reaction time was predicted from target expression, target sex, participant progesterone level, and all interactions. Among NC participants, there was a significant main effect of progesterone, F(1,42)=6.56, p=.014, partial η2=.14, indicating that higher levels of progesterone were associated with greater attention to all targets, regardless of facial expression and target sex. Notably, no other effects involving

progesterone were observed for either NC participants or HC participants. Thus, progesterone appeared to be unrelated to attention to any specific type of social stimuli; rather, progesterone was related to attention to social stimuli more generally. In addition to a main effect of progesterone, among NC participants, there was a main effect of target expression. NC participants attended more to neutral faces (M=567, SD=84) than happy faces (M=554, SD=85), F(1,42)=5.34, p=.026, partial η2=.11, and angry faces (M=556, SD=90), F(1,42)=3.18, p=.082, partial η2=.07; there was no difference in attentional adhesion to happy and angry faces, F<1. Among HC participants, there was an interaction between facial expression and target sex, F(2,41)=3.63, p=.036, partial η2=.15. Follow-up analyses revealed an effect of facial expression among male targets, F(2,41)=4.15, p=.023, partial η2=.17, but not female targets, p>.10. HC participants attend more to male angry faces (M=559, SD=95) than male neutral faces (M=540, SD=83), F(1,42)=7.34, p=.010, partial η2=.15; attention to male angry faces and male neutral faces did not differ from attention to male happy faces (M=546, SD=92), p’s>.10.

Figure 1. Attentional adhesion to social and non-social stimuli on the facial expression and femininity dot probe tasks.

Table 2: Mean (SD) reaction time (ms) on the facial expression dot probe task.

NC participants HC participants

Social Stimuli Non-Social Social Stimuli Non-Social Stimuli Stimuli Follicular Phase 523 (76) 525 (73) 562 (77) 544 (74)

Ovulatory Phase 565 (83) 554 (79) 531 (84) 534 (76)

Luteal Phase 580 (83) 559 (64) 556 (95) 549 (82)

3.3 Femininity Dot Probe Task

Similar analyses were performed on reaction times during attentional shift trials of the femininity dot probe task. On average, 1.4% (SD=1.0%) of trials were greater than three standard deviations away from participants’ mean latency and were thus excluded from analyses. One participant had an unusually high average response time (greater than 3 SD above the sample mean); her data were excluded from subsequent analyses. To test the social monitoring system hypothesis, an ANOVA was performed in which reaction time on attentional shift trials was predicted from stimulus type (social vs. non-social; within-subjects factor), contraceptive status (NC vs. HC; between-subjects factor), cycle phase (follicular vs. ovulatory vs. luteal; between-subjects factor), and all interactions. Significant interactions between stimulus type and cycle phase, as well as stimulus type and contraceptive status were observed, p’s<.05. However, those interactions were qualified by the predicted three- way interaction between stimulus type, cycle phase, and contraceptive status, F(2,82)=3.72, p=.028, partial η2=.08. Follow-up analyses were conducted within NC and HC participants separately. Among HC participants, there was a significant simple effect of stimulus type, F(1,82)=4.70, p=.033, partial η2=.05, such that HC participants attended less to social stimuli than non-social stimuli (see Table 3); no other effects approached significance, p’s>.50. Among NC participants, there was a significant interaction between stimulus type and phase of cycle, F(2,82)=8.54, p<.001, partial η2=.17. As can be seen in Table 3, NC participants in the luteal phase attended more to social stimuli than non-social stimuli, F(1,82)=25.39, p<.001, partial η2=.24, replicating the

pattern observed in the facial expression dot probe task; no difference in attention to social and non-social stimuli was observed among NC participants in either the follicular or ovulatory phases, p’s>.30. Additional analyses examined the role of progesterone in shaping attention to social stimuli. Separate GLM analyses were performed among HC and NC participants in which reaction time on attentional shift trials was predicted from stimulus type, salivary progesterone values (a continuous between-subjects factors), and their interaction. Among HC participants, there was a main effect of stimulus type, F(1,42)=4.15, p=.048, partial η2=.09; there were no main effects or interactions involving progesterone, p’s>.30. Among NC participants, there was a significant interaction between salivary progesterone and stimulus type, F(1,42)=5.13, p=.029, partial η2=.11. NC participants high in progesterone (1 SD above the mean) attended more to social stimuli than non-social stimuli, F(1,42)=14.30, p<.001, partial η2=.25; NC participants low in progesterone (1 SD below the mean) displayed no difference in their attention to social and non-social stimuli, F<1 (see Figure 1). Additionally, among NC participants, progesterone was significantly positively correlated with attention to social stimuli, r=.33, p=.028, but only marginally correlated with attention to non-social stimuli, r=.25, p=.094. Thus, these findings replicate those observed on the facial expression dot probe task, providing further evidence for the social monitoring system hypothesis. To test the target-specific hypothesis, indices of attentional adhesion to social stimuli were predicted from target femininity (masculine vs. feminine; within-subjects factor), target sex (male vs. female; within-subjects factor), participant contraceptive status, participant phase of cycle, and all interactions. A main effect of target femininity was observed, F(1,82)=6.77, p=.011, partial η2=.07; participants attended more to masculine faces (M=596, SD=100) than feminine faces (M=587, SD=94). No other effects were significant. To probe for potential effects of progesterone, separate GLM analyses were performed on HC and NC women in which reaction time was predicted from target femininity, target sex, participant progesterone level, and all interactions. Consistent with previous results, NC participants displayed a main effect of progesterone, F(1,42)=5.20, p=.028, partial η2=.11, indicating that higher levels of progesterone were associated with greater attention to all social targets. In addition to this main effect, among NC participants, there was an interaction between target sex and progesterone, F(1,42)=4.68, p=.036, partial η2=.10, and an interaction between target femininity and progesterone,

F(1,42)=5.59, p=.023, partial η2=.11. Follow-up analyses revealed that although there was a positive relationship between progesterone and attention to all social targets among NC participants, a somewhat stronger relationship between progesterone and attention to social targets was observed when those targets were male, F(1,42)=7.68, p=.008, partial η2=.16, or displaying masculine characteristics, F(1,42)=6.51, p=.014, partial η2=.13, than when they were female, F(1,42)=3.12, p=.085, partial η2=.07, or displaying feminine characteristics, F(1,42)=3.73, p=.06, partial η2=.08. An interaction between target femininity and progesterone was also observed among HC participants, F(1,42)=7.12, p=.011, partial η2=.14. Follow-up analyses revealed that HC participants who were relatively high in endogenous levels of progesterone (1 SD above the mean of HC progesterone values) attended more to masculine faces (M=607, SE=19) than feminine faces (M=590, SE=19), F(1,42)=11.59, p=.001, partial η2=.21; no effect of target masculinity was observed among HC participants low in progesterone, F<1.

Table 3: Mean (SD) reaction time (ms) on the femininity dot probe task.

NC participants HC participants

Social Stimuli Non-Social Social Stimuli Non-Social Stimuli Stimuli Follicular Phase 543 (90) 536 (88) 582 (94) 592 (106)

Ovulatory Phase 610 (117) 618 (118) 570 (77) 579 (86)

Luteal Phase 623 (95) 590 (75) 610 (94) 618 (102)

CHAPTER FOUR

DISCUSSION

Women’s biology shifts dramatically over the course of their menstrual cycle. Although a large literature indicates functional shifts in women’s psychology during the middle of their cycle around the time of ovulation (Gangestad et al., 2007; Penton-Voak et al., 1999), relatively few studies have examined whether psychological shifts occur at other points in their cycle. The current findings add to a small handful of studies (DeBruine et al., 2005; Jones, Little et al., 2005) indicating that, during the luteal phase of their cycle, women display psychological processes associated with a heightened desire for affiliation. Normally cycling women displayed greater attentional adhesion to social stimuli than non-social stimuli during the luteal phase of their cycle; this attentional bias was not observed among women on hormonal contraceptives, whose reproductive status is stable across the cycle; nor was it observed among normally cycling women during the follicular or ovulatory phases of their cycle. Greater attunement to the social environment reflects activation of the social monitoring system (Pickett et al., 2004). By monitoring one’s social world, one is better able to decode others’ true intentions, and thus better able to identify individuals likely to help or hinder pursuit of one’s affiliative goals (Gardner et al., 2005; Pickett et al, 2004). Therefore, during the luteal phase, just as a woman’s body begins to prepare for a nine-month pregnancy, so too may a woman display psychological processes designed to prepare for a long period marked by increased needs for social support. Changes in attention to social stimuli were associated with changes in progesterone. During the luteal phase, women experience an increase in progesterone that is linked to the biological preparation for pregnancy. Previous research has suggested a link between progesterone and affiliative desires and behaviors designed to promote social connectedness (Brown et al., 2009; Maner et al., 2010; Schultheiss et al., 2004; Wirth & Schultheiss, 2006). The current findings extend this previous research by demonstrating the association between progesterone and signs of affiliative motivation at lower-order levels of cognition. Attention provides the basic building blocks for higher-order cognition and behavior. What people attend to ultimately shapes what information is encoded and remembered, in turn affecting how people

evaluate and behave toward others in the environment. The current study, therefore, provides a particularly direct window into the lower-order cognitive consequences of naturally shifting levels of progesterone – consequences that could have a profound influence on subsequent social behavior. The current findings are consistent with a social monitoring system hypothesis of affiliative motivation. That hypothesis suggests that when people experience heightened needs for social support, they become especially attuned to social aspects of the environment (Pickett et al., 2005). Indeed, women in the current study displayed heightened attunement to social stimuli during the luteal phase of their cycle, a time marked by increased needs for social support due to potential pregnancy. In contrast, the current findings did not support the target-specific attentional hypothesis. Previous research has suggested that motivation promotes attention toward specific individuals who are most relevant for one’s goals (Maner, Gailliot, et al., 2007; Maner et al., 2009). For example, after being rejected, people experience a heightened desire for social contact (Maner, DeWall, et al., 2007), and subsequently attend more to people displaying smiling facial expressions – people who may be likely to provide social support and acceptance (DeWall et al., 2009). In the current study, however, luteal phase increases in progesterone were not associated with selective attention to smiling faces; nor were those increases in progesterone associated with selective attention to feminine faces, who might be perceived as a likely source of social support (Perrett et al., 1998). Thus, rather than being attuned to specific individuals who appear likely to provide immediate sources of social support, women during the luteal phase attended more generally to all social stimuli. The apparent inconsistencies in findings on how people respond to heightened affiliative motivation (i.e., general social attunement vs. target-specific attunement) may be due to variability in the sources of affiliative motivation. Affiliative motives prompted by acute social threats such as rejection may facilitate heightened attunement to specific social targets likely to provide immediate sources of help (e.g., smiling others; DeWall et al., 2009). In contrast, more general increases in affiliative motivation (such as those associated with heightened levels of progesterone) may be associated with a broader attunement to any social target who could eventually play a role in helping or hindering pursuit of affiliative goals. Indeed, previous research supporting the social monitoring system hypothesis has typically focused on individual

differences reflecting the general experience of affiliative motivation (e.g., Gardner et al., 2005; Pickett et al., 2004; cf. Hess & Pickett, 2010). Alternatively, general social monitoring and target-specific attunements may represent different stages of processing. Initially, a heightened affiliative motivation may lead to general social monitoring processes wherein people attend to all manner of social stimuli. Once those initial processes have been deployed, attention might subsequently target specific individuals who seem likely to provide realistic sources of positive affiliation. For example, rejection may initially lead people to attend to all social stimuli (Hess & Pickett, 2010), and then subsequently promote attention to specific targets likely to provide social acceptance (DeWall et al., 2009). Similarly, heightened levels of progesterone may cause women to attend to all social stimuli, and then cause those women to attend to specific people likely to help them during pregnancy. If this is the case, the lack of target-specific attunement in the current study may reflect the fact that women do not perceive strangers – even those displaying signs of friendship such as a smiling face – as realistic sources of long-term social support needed for pregnancy. Rather, during the luteal phase, women may focus attention on individuals they know well, such as romantic partners and kin, who have provided support in the past and who would likely continue to provide support in the future (DeBruine et al., 2005; Jones, Little, et al., 2005). Future research would benefit from examining attentional shifts to other types of targets (e.g., kin, romantic partners) across women’s menstrual cycles. Limitations of the current study provide several other useful avenues for future research. One limitation involves the correlational design of the study. Although progesterone values were correlated with attentional adhesion to social stimuli, I did not manipulate progesterone levels, and thus am limited in the ability to infer causality. Recent studies have begun to experimentally manipulate the administration of various hormones with promising results for social psychological researchers (van Honk et al., 2004). Future research on the endocrinological basis of social affiliation might explore the possibility of experimentally manipulating administration of progesterone prior to examining social monitoring processes. Another limitation involves the primary focus on only one cognitive process – attention. Although attention is a key lower-order cognitive process that shapes behavior in social interactions, a variety of other cognitive processes play important roles as well. For example, motivation can functionally influence who or what one remembers in the environment

(Ackerman et al., 2006; Becker, Kenrick, Guerin, & Maner, 2005; Maner et al., 2009). During the luteal phase, therefore, women may be expected not only to pay attention to social stimuli but also to remember those social stimuli. Examining menstrual cycle shifts in a range of cognitive processes associated with social affiliation should provide a clearer picture of the adaptive responses women display across the menstrual cycle. Throughout human history, people have recurrently faced various challenges associated with living in social groups. Consequently, people possess a variety of mechanisms designed to help them overcome those social challenges. The current research, in combination with an emerging literature on social neuroendocrinology and social cognition, indicates that those mechanisms are linked to basic biological and lower-order cognitive processes. The current findings suggest that natural shifts in progesterone underlie shifts in women’s affiliative motivation, in turn leading those women to attend selectively to social stimuli (i.e., other people) in the environment. The current research, therefore, reveals one mechanism by which women may solve a crucial adaptive challenge faced by members of all social species.

APPENDIX A

IRB APPROVAL

Office of the Vice President For Research Human Subjects Committee

APPROVAL MEMORANDUM Date: 9/16/2009 To: Saul Miller

Address: Dept.: PSYCHOLOGY DEPARTMENT From: Thomas L. Jacobson, Chair Re: Use of Human Subjects in Research Affiliation Across the Menstrual Cycle: Cognition Across Time

The application that you submitted to this office in regard to the use of human subjects in the research proposal referenced above has been reviewed by the Human Subjects Committee at its meeting on 09/09/2009. Your project was approved by the Committee.

The Human Subjects Committee has not evaluated your proposal for scientific merit, except to weigh the risk to the human participants and the aspects of the proposal related to potential risk and benefit. This approval does not replace any departmental or other approvals, which may be required.

If you submitted a proposed consent form with your application, the approved stamped consent form is attached to this approval notice. Only the stamped version of the consent form may be used in recruiting research subjects.

If the project has not been completed by 9/8/2010 you must request a renewal of approval for continuation of the project. As a courtesy, a renewal notice will be sent to you prior to your expiration date; however, it is your responsibility as the Principal Investigator to timely request renewal of your approval from the Committee.

You are advised that any change in protocol for this project must be reviewed and approved by the Committee prior to implementation of the proposed change in the protocol. A protocol change/amendment form is required to be submitted for approval by the Committee. In addition, federal regulations require that the Principal Investigator promptly report, in writing any unanticipated problems or adverse events involving risks to research subjects or others.

By copy of this memorandum, the Chair of your department and/or your major professor is reminded that he/she is responsible for being informed concerning research projects involving human subjects in the department, and should review protocols as often as needed to insure that the project is being conducted in compliance with our institution and with DHHS regulations.

This institution has an Assurance on file with the Office for Human Research Protection. The Assurance Number is IRB00000446.

Cc: Jon Maner, Advisor HSC No. 2009.3098

APPENDIX B

CONSENT FORM

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BIOGRAPHICAL SKETCH

Saul Miller received his Bachelors degree in Psychology from Bates College in the spring of 2004. Under the advisement of Jon K. Maner, he obtained his Master’s degree in Social Psychology in the spring of 2006 from Florida State University. He enrolled in the doctoral program in Social Psychology at FSU in 2006. Saul’s interests include social cognition, evoluationary psychology, and social endocrinology.