The Impact of Absorption on Common Mental Health Problems and Auditory Hallucinations

The impact of absorption on common mental health problems and auditory hallucinations

A thesis submitted to The University of Manchester for the degree of Doctor of Clinical Psychology in the Faculty of Biology, Medicine and Health

2018

CHARLOTTE ASPINALL

School of Health Sciences

Division of Psychology and Mental Health

Contents

List of Tables and Figures ...... 5 Paper 1: Systematic Review ...... 5 Paper 2: Empirical Study ...... 5 Thesis Abstract ...... 6 Declaration ...... 7 Copyright and Ownership Statement ...... 7 Acknowledgments ...... 8 Paper 1: Systematic Review ...... 9 Abstract ...... 10 Introduction ...... 11 Method ...... 14 Eligibility criteria...... 14 Search procedure and selection ...... 14 Data extraction ...... 17 Quality Assessment ...... 17 Results ...... 18 Overview of reviewed studies ...... 18 Relationship between absorption and mental health difficulties ...... 19 Discussion...... 33 References ...... 38 Paper 2: Empirical Study ...... 44 Abstract ...... 45 Introduction ...... 46 Method ...... 48 Design ...... 48 Participants ...... 48 Measures ...... 49 Procedure ...... 52 Calibration Phase ...... 52 Screening ...... 52 Main study ...... 53 ...... 54 Statistical Analysis ...... 55 Results ...... 55 2

Manipulation check...... 55 Hypothesis test ...... 56 Discussion...... 57 References ...... 60 Paper 3: Critical Appraisal ...... 63 Introduction ...... 64 Paper 1: Systematic literature review ...... 65 Rationale for the topic ...... 65 Search terms ...... 65 Inclusion and exclusion of papers ...... 67 Quality Assessment ...... 68 Synthesising data ...... 69 Paper 2: Empirical paper ...... 70 Development of the research question ...... 70 Participants ...... 70 Recruitment ...... 71 Voice Hearing Task ...... 71 Absorption and relaxation manipulations ...... 72 E-Prime program ...... 72 Analyses ...... 73 General discussion ...... 73 Future clinical and research implications ...... 74 References ...... 75 Appendices ...... 77 Appendix A: Journal of Psychology and Psychotherapy: Theory Research and Practice Guidelines ...... 78 Appendix B: NICE Guidance on Common Mental Health Disorders ...... 82 Appendix C: Downs and Black Quality Checklist ...... 88 Appendix D: Quality Assessment ...... 94 Appendix E: Author guidelines for the journal ‘Psychosis’ ...... 101 Appendix F: Letter of Ethical Approval ...... 112 Appendix G: Revised hallucinations Scale ...... 115 Appendix H: Poster Advertisement ...... 117 Appendix I: Voice Hearing Task ...... 119 Appendix J: Quartile cut off data for the RHS ...... 126

Appendix K: Tellegen Absorption Scale ...... 128 Appendix L: Dissociative Experiences Scale ...... 131 Appendix M: Relaxation and absorption pilot scores ...... 134 Appendix N: Participant Information Sheet ...... 136 Appendix O: Consent Form – Screening ...... 141 Appendix P: Consent Form – Main Study ...... 143 Appendix Q: Demographic Information ...... 145 Appendix R: Manipulation Scripts ...... 147 Appendix S: Statistical SPSS Output ...... 150

Word Count

Main text Figures/Tables References Total Paper 1 6,243 1747 2547 10537 Paper 2 5329 272 919 6520 Paper 3 4622 0 820 5443 Total 22,500

List of Tables and Figures

Paper 1: Systematic Review

List of Tables

Table 1 Study Characteristics ...... 21 Table 2 Summary of Correlations ...... 32

List of Figures

Figure 1 PRISMA flow diagram ...... 16

Paper 2: Empirical Study

List of Tables

Table 1 Median absorption ratings ...... 56 Table 2 Median absorption ratings ...... 56 Table 3 Median false alarm rates at time 1 and 2 in the absorption and relaxation condition ...... 57 Table 4 Median hit rate at time 1 and 2 in the absorption and relaxation condition ...... 57

List of Figures

Figure 1 Experiment procedure ...... 54

Thesis Abstract

This thesis was completed by Charlotte Aspinall for the degree of Doctor of Clinical Psychology (ClinPsyD) at The University of Manchester. The thesis title is ‘The impact of absorption on common mental health problems and auditory hallucinations’. This thesis was submitted on the 27th of April 2018 and is comprised of three papers. Papers 1 and 2 have been prepared for submission to Psychology and Psychotherapy: Theory Research and Practice and Psychosis respectively.

Paper 1 presents a systematic review on the evidence for the relationship between absorption and common mental health difficulties. A literature search was completed to identify empirical papers using the following electronic data bases: PsycINFO, MEDLINE, CINAHL and Web of Science. Twenty papers were identified that satisfied inclusion criteria for the review. Evidence supported a relationship between absorption and common mental health difficulties, suggesting absorption is a clinically relevant form of dissociation. Absorption was more strongly related to anxiety experiences across all anxiety disorders, which may potentially be due to a reduction in metacognitive awareness when absorbed.

Paper 2 presents an experimental study investigating if state absorption has a causal impact on voice hearing. To explore this, we tested whether non-clinical, hallucination-prone individuals exposed to an absorption manipulation (n = 36) exhibited a significantly greater increase in auditory false alarms during a laboratory voice hearing task than a comparable group exposed to a relaxation control manipulation (n = 37). The absorption and relaxation conditions showed no increase in false alarms following manipulation. There was no significant difference in false alarm rates between participants in the absorption condition compared to the relaxation condition, when controlling for false alarms pre-manipulation. There was also no significant relationship between change in state absorption and change in false alarms from pre- to post- manipulation. This study indicates that absorption does not have a strong effect on voice hearing, however should be interpreted with caution due to limitations in the design and effect of manipulations.

Paper 3 provides a critical appraisal of the systematic review, the empirical paper and the research process as a whole. Strengths and limitations of the presented research are discussed as well as future clinical and research implications.

Declaration

No portion of the work referred to in the thesis has been submitted in support of an application for another degree or qualification of this or any other university or other institute of learning

Copyright and Ownership Statement i. The author of this thesis (including any appendices and/or schedules to this thesis) owns certain copyright or related rights in it (the “Copyright”) and s/he has given The University of Manchester certain rights to use such Copyright, including for administrative purposes.

ii. Copies of this thesis, either in full or in extracts and whether in hard or electronic copy, may be made only in accordance with the Copyright, Designs and Patents Act 1988 (as amended) and regulations issued under it or, where appropriate, in accordance with licensing agreements which the University has from time to time. This page must form part of any such copies made. iii. The ownership of certain Copyright, patents, designs, trademarks and other intellectual property (the “Intellectual Property”) and any reproductions of copyright works in the thesis, for example graphs and tables (“Reproductions”), which may be described in this thesis, may not be owned by the author and may be owned by third parties. Such Intellectual Property and Reproductions cannot and must not be made available for use without the prior written permission of the owner(s) of the relevant Intellectual Property and/or Reproductions. iv. Further information on the conditions under which disclosure, publication and commercialisation of this thesis, the Copyright and any Intellectual Property University IP Policy (see http://documents.manchester.ac.uk/display.aspx?DocID=24420), in any relevant Thesis restriction declarations deposited in the University Library, The University Library’s regulations (see http://www.library.manchester.ac.uk/about/regulations/) and in The University’s policy on Presentation of Theses.

Acknowledgments

I would like to thank my supervisors Dr Richard Brown and Dr Filippo Varese for their support, patience and expert knowledge throughout the research process. I also extend my thanks to Dr Akib Ul Huque for his advice and saving the day with programming.

I’d like to give a very special thankyou to my family and friends for their endless love and encouragement, and to my cohort which ClinPsyD training wouldn’t have been the same without. Finally, thanks to Dan for being my rock all the way through and for all the cups of coffee.

Paper 1: Systematic Review

The relationship between absorption and common mental health difficulties:

A systematic review

The following paper has been prepared for submission to ‘Psychology and Psychotherapy: Theory Research and Practice’. The guidelines for authors can be found in Appendix A.

Abstract

Purpose

The aim of this review is to identify, synthesise, describe and critically evaluate the evidence for a relationship between absorption and anxiety disorders, depression, obsessive compulsive disorder, post-traumatic stress disorder, and specific phobias.

Absorption is characterised as a disposition or personality trait where an individual has episodes of ‘total attention’ completely absorbed in an internal or external experience, reducing responsiveness to distraction and stimuli in the environment. Absorption is considered a ‘nonpathological’ form of dissociation, however has been found to positively correlate with proneness to auditory hallucinations. Evaluating the relationship between absorption and common mental health difficulties will develop our understanding of the clinical relevance of this form of dissociation, particularly whether absorption is specifically related to psychotic phenomena or to distress more generally.

Methods

Electronic data bases PsycINFO, MEDLINE, CINAHL and Web of Science were used to review empirical papers from 1974 to the present day, on absorption and common mental health difficulties as defined by National Institute of Clinical Excellence guidelines (2011) (Appendix B).

Results

Searches identified twenty papers meeting inclusion and exclusion criteria. A variable, but positive relationship was found between absorption and common mental health difficulties. Absorption correlated more consistently with anxiety related disorders than depression. Methodological quality varied across studies.

Conclusions

This review supports a relationship between absorption and common mental health difficulties, suggesting absorption is a clinically relevant form of dissociation. Absorption is more strongly related to anxiety experiences across all anxiety disorders, which may potentially be due to a reduction in metacognitive awareness when absorbed. These findings could have implications for psychological interventions for, and the prevention of, common mental health difficulties. Future research into the direction of causality between absorption and common mental health difficulties would enable to us better understand if absorption is a predictor or consequence of mental health.

Introduction

Absorption belongs to the construct of dissociation, which is characterised by an individual feeling disconnected from themselves, or the world around them, leading to a detachment from reality (Cardeña, 1994; Tellegen & Atkinson, 1974). Absorption is characterised as a disposition or personality trait where an individual has episodes of ‘total attention’ completely absorbed in an internal (i.e. imagination, a day dream) or external experience (i.e. a movie, reading a book, listening to music), reducing their responsiveness to distraction and stimuli in their environment. This total attention increases a sense of reality towards the representational resource and decreases consciousness, sense of self and what is actually real (Tellegen & Atkinson, 1974). For example, some people may become so absorbed in a daydream, that they lose awareness of what is happening around them.

Absorption can be considered in both state and trait terms (Roche & McConkey, 1990). As a personality trait, absorption is characterised by an individual’s predisposition and capacity for absorbing and self-altering experiences, whilst state absorption is a shorter lived, momentary experience where total attention is focused on a stimuli (external or internal), without distraction (Tellegen & Atkinson 1974; Carleton et al., 2012). Trait absorption is thought to be at least partly genetic (Tellegen et al.,.,, 1988). Absorption is most commonly assessed using the Tellegen Absorption Scale (TAS: Tellegen & Atkinson, 1974) which is a 34-item, self-report questionnaire, answered on a true or false basis. The scale aims to assess a range of absorbing experiences such as absorption in thoughts and imaginings, re-experiencing the past, cross-modal experiences and altered consciousness, with higher scores indicating higher levels of absorption (Tellegen & Atkinson, 1974).

Absorption is a form of dissociation, which can be characterised by an altered, disrupted state of consciousness, changes to, or fragmentation of memory, or changes in perception of the self (identity) or an individual’s environment (American Psychiatric Association, 2013). Dissociation has been previously been viewed by Pierre Janet (1887) as a discontinuous experience, qualitatively distinct from ordinary experiences (van der Hart & Horst, 1989). Others have viewed dissociation as a ‘normal’ universal experience (Hilgard, 1977), with only some individuals going on to develop more severe forms of dissociation, such as a dissociative disorder (Putnam, 1989). Dissociation is now best understood on a continuum ranging from experiences commonly experienced by the general population, such as absorption, followed by experiences such as dissociative amnesia, through to forms such as Dissociative Identity Disorder (DID) (Bernstein & Putnam, 1986).

Experiences on the dissociation continuum are variable in duration, their associated distress and the level of impact they have on an individual’s life. Dissociation can at times be precipitated by traumatic life experiences, for which it may become a way of coping with distress (Lynn et al., 2014). Certain dissociative experiences, such as amnesia and depersonalization- derealisation, are considered more debilitating, thus being referred to as ‘pathological 11 dissociation’. This review specifically focuses on the phenomenon of absorption, which research has shown is a common experience, reported at a relatively high frequency in the general population and therefore considered ‘non-pathological’ dissociation (Roche & McConkey, 1990; Butler, 2006).

A similar but distinct construct to absorption is the concept of flow (Csíkszentmihályi, 1975; Wild et al., 1995). Flow is characterised by a complete focus and absence of self-conscious thought, resulting in a decreased sense of the passage of time and sense of space (Csikszentmihalyi, 1990). Flow differs to absorption due to the intrinsic enjoyment that is experienced alongside the effortless concentration on a task (Csíkszentmihályi, 1997). The task needs to require an optimal level of skill or challenge in order for the individual to encounter flow, with these types of experiences often being associated with sports, games and work (Csikszentmihalyi & LeFevre, 1989). Despite these differences the characteristics of the flow experience are similar to those of state absorption, and proneness to flow and absorption experiences are both thought to promote life satisfaction and positive psychological well-being (Asakawa, 2004, 2010; Snodgrass & Lynn, 1989). The two concepts seem to share features such as a sense of deep involvement, an absence of reflective self-conscious and a decreased sense of the passage of time (Csikszentmihalyi et al., 2005).

There is also phenomenological overlap between absorption and so-called imaginative involvement (Roche & McConkey, 1990), both of which form part of the assessment on the TAS (Tellegen & Atkinson 1974). Hilgard (1974) describes imaginative involvement as an individual being open to experience, having states of becoming highly involved in imagination and experiencing an altered sense of reality. Whilst absorption and imaginative involvement remain separate constructs, they share similar characteristics such as being highly immersed in internal stimuli (e.g. thoughts, daydreams, imagination) and experiencing a sense of disconnection from the surrounding environment (Waller et al., 1996). Imaginative involvement is a common experience, although like absorption, may predispose an individual to more severe forms of dissociation when an individual has experienced traumatic life experiences (Levin et al., 2004) and can be a way for the individual to cope with psychological distress (Barabasz et al., 1983).

Pathological dissociation has been linked to various mental health difficulties. The relationship between dissociation and psychosis has been the focus of increasing research interest in recent years, with studies finding psychotic experiences are more positively associated with pathological dissociation (Kilcommons & Morrison, 2005) than they are with absorption (Perona- Garcelán et al., 2016). Absorption in contrast is often thought to be a positive experience that predisposes to wellbeing; however, there is evidence from a number of studies suggesting that it may also be linked to psychopathology and proneness to experiencing auditory hallucinations (Glicksohn & Barrett, 2003; Morrison & Perterson, 2003; Perona-Garcelán et al., 2014). Studies have also found positive relationships between pathological dissociation and common mental health difficulties. Higher rates of dissociation have been found in individuals experiencing anxiety disorders, mood disorders and post-traumatic stress disorder (Mulder et al., 1998). Evidence has also suggested that pathological dissociation is the strongest predictor of 12 symptoms in OCD (Paradisis et al., 2015) and is experienced as nine times higher in depressed than non-depressed individuals (Maaranen et al., 2005).

The relationship between absorption and common mental health difficulties such as depression, generalised anxiety disorder (GAD), panic disorder, phobias, post-traumatic stress disorder (PTSD) and obsessive compulsive disorder (OCD), is less well understood. Studies have identified positive associations between absorption and obsessive-compulsive symptoms (Soffer-Dudek, 2014), post-traumatic stress symptoms (Carleton et al., 2012), and health anxiety (McClure & Lilienfeld, 2002). Moreover, dissociation theory suggests that the underlying mechanisms of absorption, such as an involuntary narrowing of consciousness and the resulting reduction in awareness, identity, perception and memory, might be a psychological defence to help manage overwhelming stimuli, and that this is particularly characteristic of individuals experiencing mental health difficulties (Janet, 1887; Putnam, 1989). It therefore seems important to understand if absorption is related to mental health difficulties as well as positive experiences of wellbeing. With that in mind, the aim of this systematic review is to evaluate the evidence for a relationship between absorption and a range of common mental health difficulties.

Evaluating the relationship between absorption and common mental health difficulties will develop our understanding of the clinical relevance of this form of dissociation. It will allow us to understand if absorption is specifically related to psychotic phenomena such as auditory hallucinations, or if it is relevant to the wider experience of distress. Understanding this association is important to help inform the clinical practice of healthcare professionals, for which absorption might be formulated as a risk factor for, or possibly a symptom of, common mental health difficulties. In so doing, the review will develop our understanding of the underlying causes, prevention and treatment of common mental health difficulties. We have chosen to explore a range of common mental health difficulties together, to enable us to distinguish and compare if a relationship is pertinent to different types of experiences, rather than one independent disorder. As it would be unrealistic to assess every diagnostic mental health disorder, we focus on common mental health difficulties, as these are most experienced by the general population. Numerous studies have been completed on absorption and common mental health difficulties but to date, no review of those studies has been made. This is necessary to understand if absorption is specific to particular disorders or a transdiagnostic correlate.

Method

This systematic review aims to understand if there is a positive relationship between absorption and common mental health difficulties.

Eligibility criteria

Inclusion criteria were empirical articles that 1) used quantitative research methodology; 2) were published in an English language peer-reviewed journal; 3) included a measure of absorption as defined above; 4) included a measure of at least one of the following: depression, low mood, anxiety, worry, panic disorder, obsessive compulsive disorder, post-traumatic stress disorder, social anxiety, health anxiety, a specific phobia or other anxiety disorder symptoms; and 5) reported a correlation between absorption and at least one of these common mental health difficulties. Exclusion criteria included 1) research solely on psychosis, bipolar disorder, personality disorder, schizophrenia, eating disorders or broadly defined ‘stress’; 2) case studies, single case designs and/or case series; and 3) papers not presenting primary data e.g. reviews and editorials. The search period was from 1974 when the concept of absorption was first articulated (Tellegen & Atkinson 1974), to the present day.

We elected not to include studies on self-focused attention or fantasy proneness, which may be related to, but distinct from, absorption.1

Search procedure and selection

In conducting the review, we sought to identify every article correlating a measure of absorption, flow or imaginative involvement with at least one measure of a common mental health problem (depression, anxiety/worry/generalised anxiety disorder [GAD], panic disorder, obsessive compulsive disorder [OCD], post-traumatic stress disorder [PTSD] and specific phobias), as defined within National Institute of Clinical Excellence guidelines (2011). For the purpose of this review, due to their similarities and overlap, we encompass the constructs of flow and imaginative involvement when discussing absorption and its relationship to mental health.

Electronic data bases PsycINFO, MEDLINE, CINAHL and Web of Science were used to review the literature, along with hand searching Google Scholar and reference lists. Two sets of search

1 Exclusion of studies on self-focused attention and fantasy proneness is discussed further in the critical review paper. This decision was based on evidence suggesting self-focused attention is a conscious self-evaluative process to regulate affect and manage self-presentation, often in social situations (Duval and Wicklund, 1972; Clark and Wells, 1995). This differs to absorption where total attention is given to an internal resource, reducing awareness of the self and consciousness of external stimuli. Fantasy proneness was excluded due to evidence suggesting it belongs to a more pathological form of dissociation, often characterised by hallucinations, paranormal and out of body experiences (Irwin, 1990; Rauschenberg & Lynn,1995; Merckelbach et al, 2001).

14 terms encompassing absorption and common mental health problems were linked with the Boolean operator ‘AND’. Terms were searched in titles and abstracts. Terms pertaining to the concepts of flow and imaginative involvement were included in the search because of their similarities with absorption. Terms were mapped to relevant Medical Subject Headings (MesH) for PsychINFO and MEDLINE and to ‘subject headings’ for CINAHL. The following terms encompassed the concept of absorption: 1) absor* OR flow OR imaginative ADJ involvement OR Tellegen OR TAS OR Tellegen ADJ Absorption ADJ Scale. Common mental health problems were encompassed by the following terms: 2) depress* OR generalised ADJ anxiety ADJ disorder OR anxi* OR panic OR agoraphobi* OR obsessive ADJ compulsive ADJ disorder OR post ADJ traumatic ADJ stress OR trauma* OR PTSD OR social ADJ anxiety OR phobi* OR hypochondria* OR illness ADJ anxiety OR worry OR low ADJ mood OR stress OR obsession$ OR compulsion$.

The reference manager Mendeley was used to organise all citations and remove duplicates. The screening process is outlined in Figure 1 and was guided by the Preferred Reporting Items of Systematic reviews and Meta-Analyses (PRISMA) approach (Shamseer et al., 2015). After the removal of duplicates, titles and abstracts were first screened for reference to absorption and mental health disorders. Full texts were then sourced for potentially eligible papers and inclusion and exclusion criteria were applied, resulting in the final selection.

Figure 1 PRISMA flow diagram

Data extraction

Papers included in the review were read and data relevant to the review question were extracted using a form developed for this purpose. Table 1 provides an overview of relevant study characteristics.

Quality Assessment

The Downs and Black Checklist (Downs & Black, 1998) was used to assess the methodological quality in all final papers, identifying strengths, weaknesses and providing insight into methodological factors that may have influenced the results of the studies (National Health Service Centre for Reviews, 2009). The tool includes 27 items and has five subscales including external validity, internal validity (control of bias), internal validity (confounding), reporting and power. Each item is rated as 1 for ‘yes’, 0 for ‘no’ and 0 for ‘unable to determine’.

The checklist (Appendix C) was modified for this review to ensure that it was appropriate for the review question. A number of items could not be answered, due to a lack of information resulting from the main focus of studies not being the relationship between common mental health difficulties and absorption, but instead a secondary finding of the initial study aims. 18 items were used from the original checklist and one further question asking if participants were recruited from a clinical sample was added with the same scoring system applied. The 18 items used were further modified to ensure items related specifically to the review question. For example, the wording for question 6 was changed from ‘are the main findings of the study clearly described?’ to ‘are the findings on the relationship between absorption and mental health clearly described?’ A further example, in question 13 pertaining to outcome measure qualities, an additional rating of 0 was added for papers which had used the Dissociative Experiences Scale (DES) to measure absorption, but not used factor analysis to inform which items of the DES were used. This is because the DES is not a standardised measure of absorption. A ‘not applicable’ rating was added for questions which were only applicable to case control studies.

Questions assessing the quality of an intervention or manipulation were only rated for studies either directly manipulating absorption or providing an intervention for a mental health difficulty to observe the impact on absorption and included in the search terms, but not questionnaire based studies. Scoring was adjusted appropriately to account for this by calculating a total percentage score for each study, with higher percentages indicating a higher quality paper. More significance was given to the clinical studies in conjunction with the quality ratings regarding conclusions drawn; rather than the quality ratings alone.

Two independent researchers separately rated five randomly selected papers in the first instance to ensure inter-rater reliability (Appendix D). Substantial agreement between the two assessors (k= 0.72) confirmed that the scale was reliable (Landis & Koch, 1977). Any discrepancies were identified and discussed to identify consensus ratings. Once reliability of the quality assessment was established, one researcher rated the remainder of the papers. 17

Results

Overview of reviewed studies

A summary of included studies and their characteristics are summarised in Table 1. Studies were completed in a range of countries with the majority conducted in America (n= 7). Sample sizes ranged from 30 participants (Aardema et al., 2010) to 950 participants (MacSwain et al., 2009). The majority of studies recruited from a student population (n = 11), followed by a clinical population (n =6), healthcare professionals (n = 2) and the general population (n = 1). There were only minor differences between the average effect found in clinical (r=0.27) and non- clinical populations (r=0.23). Quality of studies ranged from 26% (Wolfradt, 1997; Gomez-Perez et al., 2013) to 42% (Wolfradt & Meyer, 1998; Gick et al., 1997; Perona-Garcelan et al., 2014). No studies mentioned completing a power calculation to inform sample size. One study explored the impact of a mental health intervention on absorption (Rufer et al., 2006) and one study explored the impact of an absorption manipulation on mental health (Gómez-Pérez et al., 2013). One case control study had a control group comparing participants with anxiety disorders with non-anxious case controls, on anxiety and absorption measures (Wolfradt & Meyer, 1998), whilst the remaining papers were questionnaire based studies with cross sectional designs.

Eight different measures of absorption were used, with the majority of studies using questions specific to absorption from the Dissociative Experiences Scale (n =9). It is not possible to identify if all studies used the same items to measure absorption on the DES. An example question taken from the DES to measure absorption in one study (Aardema et al., 2010) is ‘Some people find that when they are watching television or a movie they become so absorbed in the story that they are unaware of other events happening around them’. This is similar to questions measuring absorption on the Tellegen Absorption Scale (n = 6), such as ‘while watching a movie, a TV show, or a play, I may become so involved that I may forget about myself and my surroundings and experience the story as if it were real and as if I were taking part in it’ and ‘I find that when I am watching television or a movie I become so absorbed in the story that I am unaware of other events happening around me’ on the imaginative involvement subscale from the Attentional Resource Allocation Scale (n = 1). The Work Related Flow Inventory measure differed to others, in that it measured experience directly related to work only, for example ‘when I am working, I think about nothing else’ (n = 1). The absorption subscale from the Absorption, Intellectance and Liberalism Questionnaire (n =1) bases its measurement of absorption on the absorption scale from the Multidimensional Personality Questionnaire (MPQ; Tellegen, 1982) with questions such as “It is sometimes possible for me to be completely immersed in nature or in art and to feel as if my whole state of consciousness has somehow been temporarily altered”. The imagination subscale of the Dissociative Processes Scale (n= 1) and the 8-item absorption subscale of the Curious Experiences Survey (n = 1) were also used. One study used the Multidimensional Inventory of Hypochondriacal Traits to measure both absorption and mental health difficulty. There were 23 separate

18 measures of mental health difficulty for depression, anxiety, health anxiety. PTSD, OCD and phobias, with the Beck Depression Inventory (n=5) and State-Trait-Anxiety Inventory (n=5) being the most commonly used measure.

Relationship between absorption and mental health difficulties

Findings between absorption and common mental health difficulties varied between small (r=0.1), medium (r=0.3) and large effects (r=0.5) (Cohen, 1988). Associations varied from strong negative (r=-.62) to strong positive associations (r=0.74) between studies on absorption and depression, anxiety, health anxiety, OCD, PTSD and specific phobias (Table 2).

Studies on obsessive compulsive disorder revealed the strongest relationship with absorption, finding an overall medium effect ranging from 0.14 to 0.49. Studies on OCD had higher quality ratings (see Table 1) due to recruiting from a clinical sample, reporting specific probability values and when, using the DES to measure absorption, making explicit reference to factor analysis to derive the items. The relationship between absorption and OCD did not change over time when measured in a non-clinical population (Soffer-Dudek et al., 2015), whereas the relationship increased from a small to medium effect after clinical participants received Cognitive Behaviour Therapy (CBT; Rufer et al., 2006), suggesting that the intervention had an effect on the correlation between absorption and OCD. A stronger relationship between OCD and absorption post treatment, might be explained by the true relationship between absorption and high levels of OCD being obscured by unusually high levels of OCD symptoms pre- treatment.

There was a very variable relationship between depression and absorption, with correlations ranging from strongly negative, r= -0.68 (Aardema et al., 2010) to medium positive effects, r= 0.36 (Levin & Spei, 2004). Overall a very weak relationship was found between absorption and depression, with two studies reporting non-significant findings. One of these non-significant findings may potentially be due to minimal levels of depression being experienced in the non- clinical undergraduate sample. The same study found a significant small to medium effect between absorption and anxiety (Berntsen & Rubin, 2007), suggesting absorption relates to anxiety, but not depression. The second non-significant finding used the Absorption, Intellectance and Liberalism Questionnaire, to measure absorption (Garrido & Schubert, 2015). Whilst some of these questions are based on an absorption scale (MPQ; Tellegen, 1982), it is unclear what the other items are based on, potentially measuring something different to absorption. Interestingly, a large negative effect (Aardema et al., 2010) and medium positive effect (Levin & Spei, 2004) were found in studies utilising the same outcome measures for absorption and depression in non-clinical populations, suggesting little trend between absorption and depression in non-clinical samples. In a higher quality paper using the TAS, absorption and depression correlated weakly in a clinical sample (Gick et al., 1997), suggesting depression may not be a predictor of absorption in clinical samples also.

Anxiety studies showed considerable variability in correlations. Whilst there was a medium effect overall, correlations ranged from negative, r= -0.20 (Datu et al., 2017) to large effects, r= 0.74 (Wolfradt & Meyer, 1998). Papers on anxiety included the lowest quality rated studies in the review, for various reasons including no explicit reference to factor analysis when using the DES, interventions not being clearly described and non-specific probability values being reported when less than 0.05. Datu et al., (2017) reported the lowest correlation, which may be explained by participants being counsellors and absorption being measured in relation to work only using a flow measurement. Wolfradt and Meyer (1998) found a medium effect between absorption and anxiety, with anxious participants reporting higher levels of absorption than non- clinical matched controls (r=0.63). However, only a weak correlation was found in other studies using a clinical sample (Gick et al., 1997). The only study to manipulate absorption found a moderate association between state anxiety and absorption induced via a cold pressor task.

Health anxiety was measured using non-clinical participants only and again showed great variability in results from small negative, r=-0.1 (McClure & Lilienfeld, 2002) to large positive, r=0.64 effects (MacSwain et al., 2009), however this strongest correlation should be interpreted with caution, as distinct outcome measures were not used for the separate variables, possibly resulting in a stronger relationship because the same items measured absorption and health anxiety (MacSwain et al., 2009). The relationship between PTSD and absorption varied across measures, ranging from small, r= 0.1 to medium, r= 0.36 effects (Amdur & Liberzon, 1996). When measured using the TAS, correlations ranged from r=0.18 to r=0.23; however when measurement of absorption was measured by imaginative involvement scales the relationship strengthened to medium and large effects (Berenbaum et al., 2008; Carleton et al., 2012). When measured overtime following a pregnancy loss, absorption and PTSD correlations remained constant, suggesting the frequency of absorption does not fluctuate in the months following a traumatic experience (Engelhard et al., 2003). The relationship between phobias and absorption was weak (r=0.15).This finding comes from one paper alone, using a clinical sample experiencing a range of mental health difficulties rather than phobias specifically (Gick et al., 1997).

Table 1: Study Characteristics

Author and Quality Country Participant Measure of mental Measure of Correlation between Date of Rating health difficulty Absorption absorption and mental Information Study health measure

Depression

Garrido & 32% Australia 335 university students (199 females, POMS- SF- Profile of Absorption, POMS: r=0.14, NS Schubert mean age of 21.1 years) Mood States Short Form Intellectance and (2015) (Curran et al., 1995) Liberalism

Questionnaire

(Glisky & Kihlstrom, 1993)

Levin & Spei 37% America 376 volunteers recruited by university BDI- Beck Depression Dissociative BDI: r=.36, p<.001 (2004) students. 223 females, 151 males, 2 Inventory–II (Beck et al., Experience Scale- unknown. Mean age = 30.7 (SD= 12) 1961) Absorption Subscale

Aardema et 37% Canada 30 hospital employees. BDI- Beck Depression Dissociative BDI: r= - 0.62, p<0.001 al., (2010) Inventory (Beck et al., Experience Scale- 14 females, 16 males. Average age 1996) Absorption Subscale 33.1 years (SD=8.2).

Berntsen & 32% USA 188 undergraduate students taken BDI- Beck Depression Tellegen Absorption BDI: r=0.07, NS Rubin (2007) from ‘Study 1’ of 2 studies reported. Inventory – II (Beck et al., Scale 1961)

Soffer-Dudek 37% Israel 184 undergraduate psychology BDI- The Beck Dissociative BDI: r=.26, p<.001 et al., (2017) students, 130 females, mean age = 23 Depression Inventory Experience Scale-

years (SD= 1.45). Absorption Subscale

Gick et al., 42% USA 281 participants with a primary mental BSI- Brief Symptom Tellegen Absorption Dep: r=.11, p=.05 (1997) health difficulty including anxiety, Inventory (Derogatis & Scale depression, chronic pain, habit. Mean Melisaratos, 1983)

age = 38.29 years. 69% female.

Average of all depression correlations r= 0.05

Anxiety

Wolfradt & 42% Germany 37 patients with DSM-IV anxiety STAI- State-Trait-Anxiety Tellegen Absorption Absorption for the entire Meyer (1998) disorders and 44 matched controls. 45 Inventory (Spielberger & Scale sample correlated with: female, 37 male, mean age =36, range Gorsuch, 1983) (Tellegen & Atkinson, State anxiety: 20 -56 years. 1974)

r= 0.65, p < 0.001.

Trait anxiety:

r = 0.74, p < 0.001.

Anxious patients had higher absorption scores (M=60.02 SD= 27.87) than non- anxious controls M=24.67, SD=14.01) (r= 0.63)

Wolfradt 26% Germany 269 university students. 143 female, STAI- State-Trait-Anxiety Dissociative Trait anxiety: r = 0.19, p, (1997) 126 male, mean age 22.4 years. SD Inventory Experience Scale- 0.01 not reported. Absorption Subscale

(Bernstein & Putnam, . 1986)

Gómez- 26% Spain 101 female undergraduate students, STAI-S- State Subscale Dissociative State anxiety: r= 0.301, Pérez et al., mean age = 20.53 (SD= 3.15) of the State and Trait Experience Scale- p<.01 (2013) Anxiety Questionnaire Absorption Subscale

(Marteau & Bekker,1992)

Datu et al., 32% Philippines 133 Filipino guidance counsellors (108 STAI- 6-item version of Work-Related Flow State anxiety: r= −.20, (2017) females) with a mean age of 34 years. the Spielberg State-Trait Inventory p<.01 Anxiety Inventory (Bakker et al., 2008)

Levin & Spei 37% America 376 volunteers recruited by university STAI- Spielberger State- Dissociative STAI-State: (2004) students. 223 females, 151 males, 2 Trait Anxiety Inventory Experience Scale- r=.34, p<.001 unknown. Mean age = 30.7 (SD= 12) Absorption Subscale

STAI–Trait:

r=.30, p<.001

Aardema et 37% Canada 30 hospital employees. BAI - Beck Anxiety Dissociative BAI: r= 0.49, p<0.01 al., (2010) Inventory (Beck et al., Experience Scale- 14 females, 16 males. Average age 1988) Absorption Subscale 33.1 years (SD=8.2).

Soffer-Dudek 37% Israel 184 undergraduate psychology BAI- The Beck Anxiety Dissociative BAI: r=.25, p<.001 et al., (2017) students, 130 females, mean age = 23 Inventory Experience Scale-

years (SD= 1.45). Absorption Subscale

Gick et al., 42% USA 281 participants with a primary mental BSI- Brief Symptom Tellegen Absorption Anx: r=.13, p=.03 (1997) health difficulty including anxiety, Inventory (Derogatis & Scale

depression, chronic pain, habit. Mean Melisaratos, 1983)

age = 38.29 years. 69% female.

Average of all anxiety correlations r= 0.32

OCD

Rufer et al., 32% Germany 52 adult patients with diagnosed and Y-BOCS - The Yale- Dissociative YBOCS Pre-treatment: r= (2006) treated with CBT for OCD, as Brown Obsessive- Experience Scale- 0.14, NS outpatients or inpatients. 34 female, Absorption Subscale Compulsive Scale YBOCS Post-treatment: r = mean age = 34.5 (SD = 8.0) (Goodman et al., 1989) 0.33, p =. 0.03

Soffer-Dudek 37% Israel 265 psychology students completed a TPI - The Padua Dissociative TPI Time 1: r=0.48, p<.001 et al., (2015) questionnaire (Time 1), which was Inventory (Sanavio, 1988) Experience Scale- TPI Time 2: r=0.49, p<.001 repeated 3 months later (Time 2) by Absorption Subscale

206 participants.

Aardema 37% America 377 undergraduate students, 55.6 % SCOPI - Schedule of Dissociative SCOPI: r= .41, p<.05 (2011) women, mean age 19 years, range= Compulsions, Experience Scale- 18-39). Obsessions, and Absorption Subscale Pathological Impulses (Watson & Wu, 2005)

Soffer-Dudek 37% Israel 184 undergraduate psychology MOCI- The Maudsley Dissociative MOCI: r=.30, p<.001 et al., (2017) students, 130 females, mean age = 23 Experience Scale- Obsessive-Compulsive years (SD= 1.45). Absorption Subscale Inventory (Hodgson & Rachman, 1977)

Gick et al., 42% USA 281 participants with a primary mental BSI- Brief Symptom Tellegen Absorption OCD: r=.18, p=.00 (1997) health difficulty including anxiety, Inventory (Derogatis & Scale

depression, chronic pain, habit. Mean Melisaratos, 1983)

age = 38.29 years. 69% female.

Average of all OCD correlations r= 0.33

Phobia

Gick et al., 42% USA 281 participants with a primary mental BSI- Brief Symptom Tellegen Absorption Phobic anxiety: (1997) health difficulty including anxiety, Inventory (Derogatis & Scale r= .15, p= .01 depression, chronic pain, habit. Mean Melisaratos, 1983)

age = 38.29 years. 69% female.

Average of all phobia correlations r= 0.15

Health Anxiety

McClure & 32% USA 212 undergraduate students.78% IAS: Illness Attitudes Tellegen Absorption IAS Disease Phobia: Lilienfeld female. Ages ranged from 17 to 31 Scale (Kellner, 1986) Scale r =.14; p < .05. (2002) years (M= 19:13; SD = 1:38).

IAS Effects of Symptoms:r

= .14; p < .05.

IAS Health Habits: r = -.01, NS

IAS Bodily Preoccupation:

.13, NS

Disease Phobia and Effects of Symptoms became non- significant when negative emotionality was controlled for. Effect sizes not reported.

MacSwain et 37% Canada 950 undergraduate psychology MIHT- Multidimensional Absorption was Correlations were reported al., (2009) students (674 Inventory of measured using the based on gender: Hypochondriacal Traits MIHT, which was also females) with a mean age of 18.98 (Longley et al., 2005) used to measure years (SD = 2.39). health anxiety. Women: r=.64, p < .001.

(MIHT; Longley et al.,

2005) Men: r=.59, p < .001.

Average of all health anxiety correlations r = 0.27

PTSD

Engelhard et 37% Netherlands 118 women (M=31 years, SD=4) PSS- Post-Traumatic Tellegen Absorption PTSD score one month al., (2003) completed questionnaires 1 month Stress Disorder Symptom Scale post loss: after a pregnancy loss and 104 of Scale (Foa et al., 1993) r= 0.23, p<0.05 these completed questionnaires at 4

months post pregnancy loss.

PTSD score four months post loss:

r=0.22, p<0.05

Perona- 42% Spain 318 students, mean age of 21.41 (SD TQ- Trauma Tellegen Absorption Trauma Questionnaire: Garcelan et = 5.78), 79% were female. Questionnaire Scale r=.18, p < .01 al., (2014) (Davidson et al., 1990)

Amdur & 32% America 129 male Vietnam combat veterans DES Absorption MMPI-2 PTSD Subscale Liberzon diagnosed Subscale r=.22, p<.05 IES- Impact of Event (1996) with PTSD. Mean age 45.17 Scale (Horowitz et al., The Mississippi Scale (SD=7.15) 1979) r=.36, p<.01

M-PTSD- Mississippi Scale for Combat- Combat Exposure Scale: r Related PTSD (Keane et =0.1, NS al., 1988) Impact of Event Scale MMPI-2-PTSD- (Intrusive) r=.20, (Avoidant) Minnesota Multiphasic r= .18, NS Personality Inventory – 2 - PTSD Subscale (Keane et al., 1984)

CES- Combat Exposure Scale (Gallops et al., 1981)

Carleton et 37% Canada Two samples consisting of: PCL-C- The PTSD ARAS-II- Attentional PCL: r= 0.51, p<0.01 al., (2012) Checklist – Civilian Resource Allocation

Version (Weathers et al., Scale – Imaginative

1. 30 participants meeting diagnostic 1994) Involvement Subscale criteria for PTSD.

( ARAS; Carleton et 2. 222 participants reporting a al., 2010) traumatic event but not diagnosticallyassessed.

Berenbaum 32% America 303 adults (53.1% female) between CAPS- PTSD - Clinician- Imagination subscale et al., (2008) the Administered PTSD of the Dissociative Correlations were reported Scale (Blake et al., 1995) Processes Scale ages of 18 and 89 years (M=43.2). based on gender: (DPS; Harrison & Recruited via telephone directory. Watson, 1992)

Women: r=.32, p<.05.

8-item Absorption subscale of the Curious Experiences Men: r=.21, p<.05. Survey (CES; Goldberg, 1999)

Berntsen & 32% USA 188 undergraduate students taken PCL- Post-Traumatic Tellegen Absorption PCL: r=0.22, p<0.05 Rubin (2007) from ‘Study 1’ of 2 studies reported. Stress Disorder Checklist Scale

(Blanchard et al., 1996)

(PTSD)

Average correlation of all PTSD correlations r= 0.25

= significant correlations

Table 2: Summary of Correlations

Correlation between Author and Date of Study absorption and mental health Depression Garrido & Schubert (2015) r=0.14, NS Levin & Spei (2004) r=.36, p<.001 Aardema et al., (2010) r= - 0.62, p<0.001

Berntsen & Rubin (2007) r=0.07, NS Soffer-Dudek et al., (2017) r=.26, p<.001

Gick et al., (1997) r=.11, p=.05 Anxiety r= 0.65, p < 0.001. Wolfradt & Meyer (1998) r= 0.74, p < 0.001. Wolfradt (1997) r = 0.19, p, 0.01 Gómez-Pérez et al., (2013) r= 0.301, p<.01 Datu et al., (2017) r= −.20, p<.01 r=.34, p<.001 Levin & Spei (2004) r=.30, p<.001 Aardema et al., (2010) r= 0.49, p<0.01 Soffer-Dudek et al., (2017) r=.25, p<.001 Gick et al., (1997) r=.13, p=.03 OCD Rufer et al., (2006) r= 0.14, NS r = 0.33, p =. 0.03 Soffer-Dudek et al., (2015) r=0.48, p<.001 r=0.49, p<.001 Aardema (2011) r= .41, p<.05 Soffer-Dudek et al., (2017) r=.30, p<.001 Gick et al., (1997) r=.18, p=.00 Phobia Gick et al., (1997) r= .15, p= .01 Health Anxiety r =.14; p < .05. McClure & Lilienfeld (2002) r = .14; p < .05. r = -.01, NS r= .13, NS MacSwain et al., (2009) r=.64, p < .001. r=.59, p < .001.

PTSD Engelhard et al., (2003) r= 0.23, p<0.05 r=0.22, p<0.05 Perona-Garcelan et al., r=.18, p < .01 (2014) r=.22, p<.05 Amdur & Liberzon (1996) r=.36, p<.01 r =0.1, NS r=.20, r= .18, NS Carleton et al., (2012) r= 0.51, p<0.01 Berenbaum et al., (2008) r=.32, p<.05. r=.21, p<.05. Berntsen & Rubin (2007) r=0.22, p<0.05

Discussion

The evidence of a relationship between absorption and common mental health difficulties has been evaluated through the identification of 20 papers including a measure of absorption, flow or imaginative involvement and a measure of a common mental health difficulty. Overall, the review included low quality papers identifying a variable relationship between common mental health difficulties and absorption, tending to correlate more highly with anxiety related disorders, but not depression.

There are two broad explanations for the apparent relationship between absorption and anxiety. Firstly, it might be that absorption serves as a risk factor and predictor for developing anxiety. Secondly, absorption might be a consequence and symptom of having a difficulty with anxiety. When considering the latter, experiencing a heightened preoccupation with compulsions or unwanted thoughts or imaginings is a common symptom of anxiety, which may increase the amount of time an individual spends absorbed in internal stimuli. The individual may then feel an urge to act on their unwanted thoughts, engaging with further absorbing internal or external stimuli in the hope that it helps. If this is the case, absorption could be understood as a consequence, or symptom of having a mental health difficulty such as OCD. Indeed, the one study in the review to manipulate absorption found evidence to suggest that state anxiety might be a vulnerability factor for absorption, with anxiety predicting absorption in a subsequent cold pressor task.

Reduced metacognition could be a possible explanation for associations across anxiety disorders and absorption. Meta-cognitive consciousness involves an individual monitoring their own thoughts, being aware when spontaneous thoughts occur and acting on shifting their focus of attention (Wells, 1995). The narrowing of consciousness and changes in perception associated with absorption could increase the tendency for an individual to become engrossed in internal anxieties, with wider attention not being paid to safety cues or information which challenges their unhelpful beliefs. The individual’s metacognitive awareness is therefore compromised, reducing insight and reflection into their own thinking, lacking the ability to regulate cognition and diminishing the capacity to problem solve their anxieties. Similarly, when all consciousness is narrowed onto an experience of a traumatic memory, the salience and reality of that symptom may increase, and as an individual’s detachment from themselves, the environment or reality increase, so the symptom may be experienced as increasingly real.

The same process could describe anxieties specific to physical health. Absorption may serve as a risk factor or symptom for a narrowed preoccupation on bodily sensations which are then consequently misinterpreted as harmful, due a distorted sense of reality, reduced consciousness and reduced metacognition. Absorption may therefore be a predictor for experiencing somatic sensations, leading to excessive and difficult to control worries about ill health. Previous research has discussed links between health anxiety and the benefits of Attention Training Treatment (ATT) to develop skills in controlling attention with the aim of reducing focus on internal stimuli and increasing meta-cognitive control (Papageorgiou & 33

Wells,1998). This review found mixed evidence for a relationship between absorption and health anxiety, one study finding weak non-significant associations and the other a large effect between absorption and health anxiety. This relationship should be approached with caution as it is unclear if the same items were used to assess both variables, increasing the likelihood of an effect.

One intervention study found that outcomes for cognitive behavioural therapy were poorer in individuals who experienced higher levels of absorption prior to treatment for OCD, which suggests absorption could be a vulnerability or risk factor for OCD symptoms, rather than a consequence. Absorption could be associated with poorer outcomes in treatment due to an increased narrowing of attention onto threats and a decreased sense of control, impacting on the individual’s capacity to benefit from therapy techniques that require metacognitive awareness, such as thought challenging.

Absorption was found to be consistent over time in a clinical population experiencing pregnancy loss; however it is difficult to determine the impact of the trauma on absorption, due to no baseline data being collected. Mixed effect sizes were found between absorption and PTSD outcome measures in one study on combat veterans. Almost no effect was found between absorption and the Impact of Event Scale, for which items seem to measure more avoidant symptoms of distress, such as trying not to think about things, avoiding being upset and trying to remove events from memory. It is possible that absorption showed little relationship with PTSD on this measure, due to a lack of items measuring preoccupation in thought and decreased metacognitive awareness (i.e. I am thinking about my past, so I am going to distract myself). Symptoms of PTSD measured by The Mississippi Scale used in the same sample, showed a medium effect with absorption. These items were more characteristic of preoccupation in thought, for example using substances as a way of forgetting, having trouble concentrating on tasks and daydreams feeling real, which might explain the stronger relationship with absorption.

The processes described across anxiety related difficulties might also be expected to apply to rumination in depression; however a relationship with absorption does not seem to be shared with depression, showing almost zero effect. Whilst experiences of depression and anxiety often overlap, symptoms of depression such as numbness to experience, a sense of loss, absence of positive experiences, difficulty concentrating and negative beliefs about the self, world or others, could possibly impede openness to absorption, compared to experiences of anxiety. Depression was the most studied correlation, being measured seven times across both clinical and non- clinical samples. The samples recruited to measure this relationship may have impacted the results in some instances. For example one clinical sample recruited participants with a range of primary mental health difficulties, for which the true relationship between depression and absorption might be obscured by a range of competing symptoms, resulting in a very small effect.

Negative correlations were found in all studies recruiting healthcare professionals. Depression may reduce in hospital employees when absorption increases, possibly due to differences in their interpretation of the items on depression scales and regarding experiences of absorption in a positive way, therefore associating higher levels of absorption with reduced levels of depression. Alternatively, symptoms of depression may increase as absorption reduces, due to diminished opportunity to escape from the reality of stimuli experienced as depressing. In Filipino guidance counsellors, a negative relationship between anxiety and absorption may have been found, due to using a measure of flow, which is generally regarded as a positive experience. Experiences of anxiety may decrease as intrinsic enjoyment from states of flow increase. Likewise, anxiety may increase, when flow experiences are reduced.

Non-significant associations between absorption and common mental health difficulties were found in both clinical and non-clinical studies. With the exception of two studies (Gómez-Pérez et al., 2013; Wolfradt, 1997), lower quality papers were more likely to report non-significant findings compared to papers of the higher quality. This might be related to the possible lack of power to detect an effect resulting from no power calculations informing sample sizes, the predominant assessment of mental health difficulties in non-clinical populations and potentially unreliable and inaccurate assessment of absorption and mental health difficulties.

The studies reviewed had a range of methodological limitations. The majority of papers reported correlations as secondary findings rather than as a specific focus of the study, which could explain some of the inconsistent findings. Ninety percent of studies were cross-sectional surveys, precluding conclusions about causality. Outcome measures for absorption and mental health difficulties were completed at the same time, in the same context, increasing the chance of an association being found for purely spurious reasons (Roche & McConkey, 1990). The majority of studies were not conducted in clinical populations (n=14), representing a narrow understanding of the relationship between common mental health difficulties and absorption. Only one study included a direct manipulation of absorption, which was not specific to absorption, but dissociation more generally, and only one study provided a direct intervention for a single common mental health condition, which had a small sample size. Both studies did not have a control group.

Assessment of mental health difficulties was limited by measures which did not specifically assess one particular mental health condition. For example, the Brief Symptom Inventory (BSI) was used to measure OCD, depression, anxiety and phobias. Whilst the BSI is viewed as a reliable measure of general psychological distress, the validity of measuring separate mental health symptom subscales is poor (Ruiperez et al., 2001; Hayes et al., 1997). Correlations between common mental health difficulty varied across different measures of absorption (TAS: r= 0.18; DES-AS: r=0.25; ARAS: r=0.51; DPS-IS & CES-AS: r=0.27; AIT: r=0.14; WRFI: r= -.20), suggesting absorption measures could potentially be measuring different constructs. The only measure specifically designed to measure absorption, the Tellegen Absorption Scale (Tellegen & Atkinson, 1974), was used in just 30% of papers, raising questions about the validity of the associations found across studies not using this measure. Nearly half of the papers used the 35

‘absorption factor’ on Dissociative Experiences Scale (Bernstein & Putnam, 1986) to measure absorption. The correlation between the TAS and the absorption questions on the DES are highly variable (Stockdale, 2002; Frischholz, 1991), casting doubt on the validity of studies using the latter as a measure of absorption (Carlson & Putnam, 1993). Where studies have completed a factor analysis to identify absorption items, it remains a possibility that different factor analyses have identified different sets of items on the ‘absorption’ factor, making it difficult to draw comparisons between studies using such a scale to measure this construct. This is a criticism of current studies and underlines the importance of using a standardised measure of absorption, such as the Tellegen Absorption Scale, in future studies.

Future research and clinical practice would benefit from specific studies directly examining the relationship between absorption and common mental health difficulties as the main aim of their paper. Studies using clinical populations, with adequately powered sample sizes, would contribute towards a fuller understanding of the experience of mental health conditions in relation to absorption. Studies assessing the impact of an absorption manipulation on a common mental health difficulty, or the impact of treatment for a common mental health problem on absorption would provide more meaningful evidence to support a relationship between the two variables.

Further research into the direction of causality between absorption and common mental health difficulties would enable to us better understand if absorption is a predictor or consequence of mental health. Further research could also explore whether absorption correlates with other psychological experiences of distress, such as eating disorders. The current findings suggest that it may also be important for mental health practitioners to enquire about experiences of absorption when working with individuals presenting with common mental health difficulties. The nature of absorbing stimuli and the frequency of absorption experiences could provide useful assessment information to gain a deeper understanding of the context of an individual’s distress. It may also inform expectations for how well an individual may progress in therapy and help to identify barriers to treatment, such as becoming absorbed in session and possible ways to overcome these. Clearer case formulation could be achieved by including the role of absorption in the maintenance of psychological distress, for example, when affecting the achievement goals or maintaining preoccupation with distressing thoughts or images. Due to the possible decrease in metacognition when experiencing a state of absorption, interventions could be aimed to reduce unhelpful patterns of absorption and preoccupation in thoughts which lead to the maintenance of psychological distress. Attention Training Technique (Wells, 1990; Wells et al., 1997) is an example of an intervention that could be used to help individuals experiencing a common mental health difficulty and absorption become more aware and conscious of the present moment. It aims to reduce self-focused attention through building capacity to monitor and control the source of an individual’s attention building skills in switching and dividing attention.

Identifying absorption in internal or external stimuli early, could lead to the greater prevention of common mental health difficulties and inform relapse prevention strategies. Early intervention could be provided to assist in the identification of warning signs that an individual is becoming absorbed in distressing content and provide ways to cope with this experience, such as grounding techniques. Administering the TAS throughout treatment, may also inform the progress of therapeutic input, if absorption is a symptom of their mental health condition. Psychoeducation on the role of absorption and how it relates to client mental health difficulties may also lead to better outcomes in therapy and prevent relapses in the future.

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Paper 2: Empirical Study

The impact of absorption on auditory hallucinations during a voice hearing task

The following paper has been prepared for submission to ‘Psychosis’. The guidelines for authors can be found in Appendix E.

Abstract

The impact of absorption on auditory hallucinations during a voice hearing task

A tendency to experience episodes of ‘total attention’ (I.e., absorption) has been associated with hallucination proneness and experiences of auditory hallucinations in non-clinical populations. Whether state absorption has a causal impact on voice hearing remains unknown, however. To explore this, we tested whether non-clinical, hallucination-prone individuals exposed to an absorption manipulation (n = 36) exhibited a significantly greater increase in auditory false alarms during a laboratory voice hearing task than a comparable group exposed to a relaxation control manipulation (n = 37). The absorption and relaxation conditions showed no increase in false alarms following manipulation. There was no significant difference in false alarm rates between participants in the absorption condition compared to the relaxation condition when controlling for false alarms pre-manipulation. There was also no significant relationship between change in state absorption and change in false alarms from pre- to post-manipulation. This study indicates that absorption does not have a strong effect on voice hearing, however should be interpreted with caution due to limitations in the design and effect of manipulations. Development of a paradigm to manipulate and maintain absorption is needed for further experimental research.

Keywords: absorption, dissociation, auditory hallucinations, voices, psychosis

Introduction

Auditory hallucinations are typically experienced as internal or external voices or sounds in the absence of any external stimulation, whilst in a fully conscious state (Beck & Rector, 2003). Although experienced in non-clinical samples, auditory hallucinations are most commonly reported in individuals with mental health difficulties and diagnoses such as schizophrenia or bipolar disorder (Goghari & Harrow, 2016). The tendency to hear voices is best described on a continuum, from those that are experienced as part of everyday functioning, to those which cause the individual psychological distress (van Os et al., 2000). Auditory hallucinations experienced as negative are predominantly reported in clinical samples, whilst positive experiences are mainly reported in non-clinical samples (Daalman, 2011).

Dissociation is a multi-faceted construct, comprising different domains such as absorption, detachment and compartmentalization, which lead an individual to feeling a sense of disconnection from themselves and reality, to varying extents (Bernstein & Putnam, 1986). Absorption is a form of dissociation, referred to as the tendency to enter a state of ‘total attention’, where an individual becomes fully immersed in internal (i.e. thoughts or imagination) or external stimuli (i.e. music or a film), reducing their distraction to contextual information and heightening a sense of reality towards their representational field (Tellegen & Atkinson, 1974). Absorption is typically understood as a widely experienced, normative phenomenon and whilst forming part of the domain of trait dissociation, has been argued to have less clinical relevance than the clinical dissociative constructs of detachment (i.e. depersonalisation-derealisation) and compartmentalization (i.e. amnesia) (Brown, 2006; Holmes et al., 2005). Associations between clinical dissociative constructs and auditory hallucinations are well evidenced in both clinical and non-clinical populations (Pilton et al., 2015, Varese et al., 2011, Kilcommons & Morrison, 2005).

Despite this, absorption has been associated with hallucinatory experience in clinical (Perona- Garcelan et al., 2012) and non-clinical populations (Humpston et al., 2016). In non-clinical populations, high hallucination proneness has been significantly associated with higher levels of absorption compared to individuals with medium or low hallucination proneness (Perona- Garcelan et al., 2013; Glicksohn & Barrett, 2003). The cause of this relationship is not well understood, however. One possibility is that a reduction in metacognitive awareness due to being absorbed might decrease source monitoring, which is the capacity for an individual to correctly discriminate between events that are internal or external (Bentall, 1991).

When in a state of absorption, total attention is dedicated to the stimuli an individual is experiencing (e.g. memory of a conversation), narrowing all consciousness to that resource (Roche & McConkey, 1990). As total attention is focused on the individual’s subjective experience, external contextual information recedes from awareness and meta-cognitive awareness of the source of the experience (i.e., “this isn’t really happening to me”) is reduced. Such a reduction in objective meta-cognitive awareness may therefore increase the likelihood of 46 an individual reporting an auditory hallucination, due to misattributing internal sources of the information to an external cause (Morrison & Petersen, 2003).When an individual fails to source monitor in this way, internal speech is misattributed to an external event, rather than an individual’s own cognitions, resulting in the experience of hearing voice which is not their own (Johnson, 1993). To achieve successful source monitoring, and individual must be experiencing a level of meta-cognitive awareness, which is compromised when absorbed (Brookwell et al., 2013).

Previous research has found a positive association between suggestibility and auditory hallucinations, which may be related to a reduction in source monitoring (Alganami et al., 2017). According to the early theories of Pierre Janet, absorption is thought to increase responsivity to suggestions due to the subconscious parts of an individual’s personality being more open to suggestion, as an individual’s field of consciousness is narrowed, reducing the capacity to critically evaluate their own cognitions and experiencing (Van der Hart & Horst, 1989). If this view is correct, then an increase in absorption should lead to a decrease in the ability to source monitor, therefore increasing openness to suggestion, resulting in an auditory hallucination. In previous studies, absorption has been found to increase an individual’s responsivity to suggestions after exposure to an absorption manipulation (Brown, 2001). It is possible that absorption may not have a direct impact on auditory hallucinations, but instead might be an underlying mechanism in creating a suitable condition for voice hearing to occur. Total absorption in an internal or external event could potentially mediate a relationship with reduced metacognitive awareness, source monitoring or suggestibility, leading to an increase in voice hearing. Despite evidence suggesting hallucinatory experiences may be precipitated by absorption (Glicksohn & Barrett, 2003), research investigating the causal impact of absorption on voice hearing is limited by the majority of studies being questionnaire based. No previous studies have used experimental designs to observe the effect of an absorption manipulation on auditory hallucinations.

A range of auditory paradigms have been developed and used to assess the rate at which individuals report hearing auditory stimuli that are not present, with a view to enhancing studies researching the mechanisms of auditory hallucinations in non-clinical participants. When asked to identify if a voice was heard within 5 second trials of white noise, non-clinical participants with high hallucination proneness reported hearing significantly more voices that were not present, compared to average and low hallucination prone participants (Barkus et al., 2007). This supports previous findings in non-clinical participants (Huque et al., 2017; Merckelbach & van de Ven, 2001). The mechanisms of auditory hallucinations can be studied using voice hearing tasks, with previous research using them to monitor the impact of exposure to stressful stimuli on rates of auditory misperception (Wong, 2018).

Further investigation is needed to increase our understanding of the relationship between absorption and auditory hallucinations. The current study aims to explore the impact of an absorption manipulation on auditory hallucinations. This study recruited a sample of non-clinical, hallucination-prone participants, who were randomised to an absorption or relaxation 47 manipulation. The impact of the manipulation on false alarms (hearing a voice which isn’t there) during a Voice Hearing Task (VHT) was compared. We predicted that participants in the absorption condition would report more false alarms on a voice hearing task at time 2, controlling for false alarms at time 1, compared to participants in the relaxation condition. We also predicted that change in state absorption would be associated with a change in false alarms on the voice hearing task.

Method

Design

The current study employed a 2x2 factorial design. Group condition was the between participants variable with participants in the experimental condition listening to recorded instructions designed to induce an absorbed state and those in the relaxation control condition listening to instructions designed to induce a similarly relaxed but non-absorbed state. The choice of conditions was based on previous research by Brown et al., (2001) which found that relaxation instructions followed by absorption instructions had a significantly greater impact on the tendency to respond to suggestions than relaxation instructions alone. The same scripts were used in this study, but adapted removing a hypnotic context and reference to the word ‘focused’. The relaxation condition controlled for feelings of relaxation that are thought to accompany absorption, but not an actual absorbed state, such as calmness and freedom from tension and factors such as being given instructions that the person expects will have effects on their mental state. The relaxation condition differed to the absorption condition, which aimed to create increased absorption, a reduction in metacognitive awareness and a complete immersion in internal or external stimuli, with reduced distraction to contextual information.

Time (pre-recording [time 1] vs. post-recording, [time 2]) was the within participants variable. The dependent variable was the number of false alarms exhibited during an experimental voice hearing task (VHT; see below for details). Ethical approval was gained from the University of Manchester, Research Ethics Committee 4 (Appendix F).

Participants

A power calculation assuming an alpha level of 0.05 indicated that 66 participants (33 in each group) would be required to have 80% power, to detect a medium to large effect size of 0.70, which was expected on the basis of previous research (Faul et al., 2007; Cohen, 1988). This is a preliminary study, using a novel task under experimental conditions. An outcome of the research will be an estimate of the effect size for following studies.

One hundred and sixty nine individuals participated in an initial screening process. Potential participants were provided with a website link directing them to the Revised Hallucinations Scale (RHS) screening questionnaire (Appendix G). Inclusion criteria included being eighteen

48 years or older, having a good understanding of written and spoken English, normal or corrected to normal hearing and a score within the top quartile on the RHS, indicating high hallucination proneness. Exclusion criteria included having a self-reported diagnosis of psychosis and uncorrected hearing impairment.

This study recruited participants with a high hallucination proneness to maximise the potential for voice hearing, as previous studies have found that low hallucination prone individuals report hearing fewer voices on auditory paradigm tasks (Barkus et al., 2007). A clinical sample was not recruited both for practical reasons and to avoid causing distress. It may have also been more difficult to increase absorption in a clinical population, due to a ceiling effect.

Seventy-three non-clinical participants completed the main study, including 67 females (92%) and six males (8%) with a mean age of 20.87 (SD= 3.26, range 18-33). Participants were recruited from the University of Manchester via poster advertisements (Appendix H) and an undergraduate research credit system. Participants were predominantly psychology undergraduates who received research credits for participating. Non-psychology students received monetary reimbursement.

Participants in each condition for the main study had comparable scores on measures of hallucination proneness, trait absorption and dissociative experiences, with a mean RHS score of 9.58 in the absorption condition (SD= 1.78) and 9.95 (SD=1.73) in the relaxation condition. The mean Tellegen Absorption Scale (TAS) score in the absorption group was 19.44 (SD=5.46) and 19.57 (SD=5.97) in the relaxation condition. The mean Dissociative Experiences Scale (DES) score in the absorption group was 25.14 (SD= 14.4) and 25.62 (SD=12.87) in the relaxation condition.

Measures

Voice Hearing Task (VHT, Huque et al., 2017)

The Voice Hearing Task (Appendix I) consists of a 4 minute 30 seconds recording of white noise over which are embedded 18 nonsense voice stimuli. Participants were asked to listen to the recording and press the spacebar on a keyboard each time they heard a voice. Previous research has shown the task correlates with hallucination proneness, with participants often report hearing a voice, when no stimuli are present (Huque et al., 2017). In this study, participants completed the task on two occasions, once before the experimental or control recording and once after. A calibration phase of the voice hearing task was completed by eighteen volunteers prior to recruitment, to determine the amplitude of voice stimuli required for the laptop and headphones being used.

The VHT assessed the amount of voices participants reported hearing, both when no voices were present (false alarms) and when voices were present (hits). Prior to the first presentation of the main VHT, an initial practice task lasting one minute was completed by each participant. 49

This allowed for the calculation of individual variability in reaction times, which was then used to differentiate between false alarms and hits in the main tasks. The mean and standard deviation of participant’s reaction time to correctly identifying stimuli in the practice was taken. In the main task, a false alarm was counted as a reaction above or below two standard deviations from their practice mean and a hit was counted as a reaction within two standard deviations from their practice mean.

A false alarm average and hit rate average were calculated to inform an exploratory analysis. False alarm average was calculated to explore the relationship with trait absorption scores on the TAS and with the DES, to inform if the VHT was valid in our sample. Average hit rates were calculated to help establish whether the state induced in each condition was similar or not.

State absorption measure

A purpose made, single item measure of state relaxation was completed electronically before and after the experimental/control manipulation. Participants rated their level of state absorption between 0 and 100, with 0 being ‘not at all absorbed’ and 100 being ‘completely absorbed’ using the following wording:

‘We are interested in how absorbed you feel right now. Absorption is a state where you feel totally immersed and engrossed in what you are doing right now. How absorbed are you right now, at this moment (where 0 is not absorbed at all, and 100 is totally and completely absorbed)?’

An absorption change variable from time 1 to time 2 was calculated to explore if change in absorption and change in false alarms from time 1 to time 2 were associated.

State relaxation measure

A purpose made, single item measure of state relaxation was completed electronically on two occasions, pre-manipulation and post manipulation. Participants rated their level of relaxation between 0 and 100, with 0 being ‘not at all relaxed’ and 100 being ‘completely relaxed’, using the following wording:

‘We are interested in how relaxed you are feeling right now. Relaxation is a state where the body and mind feels free from tension and anxiety. How relaxed are you currently feeling (where 0 is not relaxed at all and 100 is totally and completely relaxed)?’

Revised Hallucinations Scale (RHS; Morrison et al., 2000)

The Revised Hallucinations Scale is a 5-item self-report scale measuring predisposition to auditory hallucinations. The scale was adapted to measure questions pertaining to auditory hallucinations only, which has shown satisfactory internal reliability (α=.73) in previous studies (McCarthy-Jones & Fernyhough, 2011). Questions are measured on a 4-point frequency scale (1-4), ranging from ‘never’ to ‘almost always’. Participants completed the RHS electronically and those scoring within the top quartile (8 or over), indicated high hallucination proneness and were eligible to participate. This cut off was estimated on a sample of 210 University of Manchester undergraduate students, conducted as part of a separate investigation by members of the research team (Appendix J).

Tellegen Absorption Scale (TAS; Tellegen & Atkinson, 1974)

The Tellegen Absorption Scale (Appendix K) is a 34-item questionnaire measuring trait absorption and the tendency to become involved in absorbing stimuli. Participants rate each item as ‘true’ or ‘false’ in regards to their own experience. It is scored by the amount of items the subject rated as true, with higher scores indicating higher trait absorption. It has good psychometric properties with alphas ranging from .85 to .88, and a 30-day test–retest reliability of .91 (Tellegen, 1982). Participants completed the TAS electronically at the end of the experiment, to assess the relationship between absorption and false alarms.

Dissociative Experiences Scale (DES; Bernstein & Putnam, 1986)

The Dissociative Experiences Scale (Appendix L) consists of 28 self-report items, measuring symptoms of dissociation including the subscales absorption, imaginative involvement, depersonalization, derealisation, and amnesia. Each item is answered on an 11 point frequency scale, between 0% (never) and 100% (always). It is scored by totalling the percentage answered for each question and dividing by 28. The DES has good psychometric properties (Bernstein et al., 1993). Participants completed the DES electronically at the end of the experiment to assess the relationship with false alarms.

Procedure

Calibration Phase

To ensure the amplitude of the voice hearing task was calibrated to the laptop and headphones being used in the study, eighteen volunteers, aged 18 – 32, were recruited to complete a calibration exercise determining auditory thresholds. This involved listening to a series of trials playing a nonsense voice whilst looking at a laptop screen displaying two green arrows marked 1 and 2, flashing consecutively one after the other. Participants were required to identify on which arrow the nonsense voice was played, by pressing either 1 or 2 on the keyboard. Correctly identified voices resulted in the volume being reduced on the next trial and incorrectly identified voices resulted in an increase in volume on the following trial. Participants were offered a rest after 80 trials and completed a maximum of 250 trials. The auditory threshold for each participant was determined as the amplitude of voice they could correctly identify 75% of the time. Participant’s thresholds ranged from -5800 to -6300 decibels. An average volume of - 5900 decibels was used as the amplitude for the main study. This ensured that the stimuli in the VHT created a sufficient level of ambiguity, whilst still remaining audible to the participant.

Once amplitude for the study was determined, a pilot of the whole program was completed, firstly to ensure the main program provided sufficient instructions for participants to follow the program on their own, and secondly to ensure participants’ ‘hit’ and ‘false alarm’ rates were comparable to the median expected (Huque et al., 2017) when the volume was set to -5900. Six volunteers completed the program which confirmed voice stimuli were set to the correct volume. The pilot did, however, highlight that the absorption manipulation did not increase levels of absorption more than the relaxation condition (Appendix M). In an attempt to address this, the instructions in the absorption condition were adapted such that the word ‘focused’ (i.e. “allow yourself to become completely focused”) was replaced with ‘absorbed’ (i.e. “allow yourself to become completely absorbed”) where appropriate. A second pilot of the program was then completed on six volunteers, which showed the absorption manipulation successfully increased levels of absorption in the absorption condition, more than the relaxation condition.

Screening

Screening was administered using the University of Manchester’s Clinical Psychology questionnaire platform. Participants read a participant information sheet (Appendix N), completed a consent form (Appendix O) and the Revised Hallucinations Scale. Eligible participants were taken to an automated booking system to select a date and time to participate in the main study. Those excluded from participating were informed they had not scored within the required range to participate.

Main study

Participants completed the experiment on one occasion lasting 45 minutes, in a testing cubicle at the University of Manchester. After reading a participant information sheet, informed consent (Appendix P) and demographic information (Appendix Q) was gained. Participants were allocated to one of two conditions, based on a random sequence generated prior to recruitment. Seventy three participants were recruited, 36 in the absorption condition and 37 in the relaxation condition.

The entire experiment was completed electronically on a windows-based laptop with volume on maximum output, wearing Sony MDR-ZX310 over the ear headphones, using a program developed in E-Prime 2.0 software. The program was designed to guide participants through the experiment, displaying instructions between the practice task, main voice hearing tasks, manipulations and outcome measures. The recordings for each condition (Appendix R) were verbal absorption and relaxation instructions, based on manipulations in a previous study by Brown et al., (2001). These were pre-recorded and built into the E-Prime 2.0 program. Recordings ensured manipulations were consistent between participants within each condition. E-prime 2.0 software automatically recorded responses electronically for ‘hits’ and ‘false alarms’ on the VHT, state absorption, state relaxation, and TAS and DES measures. The experimental procedure is described in Figure 1.

Screening measure completed via internet link: Revised Hallucination Scale (RHS) N= 169

High hallucination prone participants randomly assigned to condition (n = 73)

Relaxation Condition Absorption Condition N=37 N=36

Practice Voice Hearing Task Practice Voice Hearing Task

Practice Task (Time 1) Practice Task (Time 1)

Manipulation check 1: How absorbed are you now, at this moment (where 0 is not absorbed at all and 100 is totally and completely absorbed)?

How relaxed are you now, at this moment (where 0 is not relaxed at all and 100 is totally and completely relaxed)?

Voice hearing task (Time 1) Voice hearing task (Time 1)

Listen to absorption instructions Listen to relaxation instructions

Manipulation check 2: How absorbed are you now, at this moment (where 0 is not absorbed at all and 100 is totally and completely absorbed)?

How relaxed are you now, at this moment (where 0 is not relaxed at all and 100 is totally and completely relaxed)?

Voice hearing Task Time 2 Voice hearing Task Time 2

Complete TAS Complete TAS

Participation Complete DES Complete DES complete

Figure 1 Experiment procedure

Statistical Analysis

Seven missing questionnaire items (0.13% of the overall data) were replaced with that condition’s mean score for that item. Z-scores were then calculated to identify outlying values, and those less than -3.29 or more than 3.29 (n= 7) were replaced with the next highest value plus or minus one (Tabachnick & Fidell , 2007).

The Shapiro-Wilk test of normality identified non-normally distributed variables, which were successfully transformed using the square root. Successfully transformed variables included hits (time 1 & 2), false alarms (time 1 & 2), total DES and total TAS scores. State absorption (time 1 & 2) and state relaxation measures (time 1 & 2) were transformed using reflection and square root. The false alarm average variable was successfully transformed using the log 10 transformation. The absorption change variable was non-normal but could not be successfully transformed; it was therefore analysed non-parametrically.

A check was first performed to assess whether we had been successful in manipulating absorption using a 2x2 repeated measures analysis of variance (ANOVA).

For Hypothesis 1, an analysis of covariance (ANCOVA) was used to test if participants in the absorption condition exhibited significantly more false alarms on the voice hearing task at time 2, compared to participants in the relaxation condition, controlling for performance at time 1. Wilcoxon signed ranks tests were also used to test the change in false alarms from time 1 to time 2, separately for the absorption and relaxation condition.

For Hypothesis 2, a Spearman’s correlation was used to assess whether change in self- reported state absorption from time 1 to time 2 was associated with change in auditory false alarms on the voice hearing task from time 1 to time 2.

A Pearson’s correlation assessed the relationship between average false alarm scores and the TAS and DES. A Spearman’s correlation was therefore used to assess if the change in state absorption from time 1 to time 2 correlated with trait absorption. Statistical outputs can be found in Appendix S.

Results

Manipulation check

The median absorption ratings and inter quartile ranges at time 1 and time 2 are reported in Table 1.

There was a significant increase in absorption from time 1 to time 2 in the absorption condition F(1,35)= .26.8, p=.00, partial eta²=.434, as predicted; contrary to expectation, however, a comparable increase in absorption in the relaxation condition was also found F(1,36)= 12.97, p=.001, partial eta²=.265 . There was no significant effect of the absorption manipulation

55 between groups, indicating that change in absorption ratings from time 1 to time 2 was comparable across the two conditions F(1,71)= .60, p=.81, partial eta²=.001.

Similarly, both conditions exhibited a significant increase in relaxation (absorption: F(1,35)= 82.04n , p=.00, partial eta²=.701; relaxation: F(1,36)= 89.47, p=.00, partial eta²=.713) from time 1 to time 2, and this was also comparable across conditions, F(1,71)= 0.21, p=.70, partial eta²=.003. The median relaxation ratings and inter quartile ranges at time 1 and time 2 are reported in Table 2.

A Spearman’s correlation indicated that there was no significant relationship between changes in state absorption from time 1 to time 2 and the TAS, in the absorption (r= .22, p=.20) or relaxation group (r=-.11, p=.51).

Table 1 Median absorption ratings

Time 1 Time 2

Absorption condition (n = 36) 75.00 (IQR=20) 87.50 (IQR=18.25)

Relaxation condition (n = 37) 75.00 (IQR= 21) 85.00 (IQR= 22)

Table 2 Median relaxation ratings

Time 1 Time 2

Absorption condition (n = 36) 67.50 (IQR=29) 90.00 (IQR=18)

Relaxation condition (n = 37) 70.00 (IQR=20) 90.00 (IQR=11)

Hypothesis test

There was no significant difference between the absorption condition and the relaxation condition, on false alarm rate at time 2, when controlling for false alarms at time 1, F(1,70) =.51, p=.48, partial eta²=.007. However, a significant difference was found between hit rates at time 2 in the absorption condition compared to the relaxation condition, when controlling for hit rate at time 1, F(1, 70) = 6.77, p=.01, partial eta²=.088.

There was no significant change in false alarm rates between time 1 and time 2, in the absorption condition Z=-.858, p=.391 or the relaxation condition Z=-.807, p=.420.

Table 3 Median false alarm rates at time 1 and 2 in the absorption and relaxation condition

Time 1 Time 2

Absorption condition (n = 36) 10.00 (IQR=8) 9.00 (IQR=7)

Relaxation condition (n = 37) 6.00 (IQR=5.5) 7.00 (IQR=7)

Table 4 Median hit rate at time 1 and 2 in the absorption and relaxation condition

Time 1 Time 2

Absorption condition (n = 36) 5.00 (IQR=5) 7.50 (IQR=7)

Relaxation condition (n = 37) 6.00 (IQR=4) 4.00 (IQR=4)

There was no significant relationship between change in absorption and change in false alarms from time 1 to time 2 (r = -0.32, p=.72).

A Pearson’s correlation coefficient indicated there was no significant relationship between false alarm average and TAS (r=.06, p=.59) or DES scores (r=.23, p=.06), although the latter approached significance.

Discussion

This study aimed to investigate if 1) exposure to an absorption manipulation increased false alarms on a voice hearing task at time 2, controlling for false alarms at time 1 and 2) if change in state absorption is associated with change in false alarms on a voice hearing task, from time 1 to time 2. Contrary to expectation, no significant differences were found for hypothesis 1 and no significant relationship was found for hypothesis 2. On the face of it, these results seem to suggest that absorption does not have a strong effect on voice hearing in hallucination-prone non-clinical participants. If this is a valid finding, then it provides support for absorption not being a clinically relevant form of dissociation or impacting the frequency of auditory hallucinations. Whilst it remains possible that the predicted finding is simply absent and the proposed link between absorption and voice hearing is wrong there are a number of methodological reasons to consider before firm conclusions are drawn.

First, the increase in absorption was the same in the two conditions, despite piloting the absorption and relaxation instructions. This finding might be because state absorption was not successfully captured in the outcome measures, or it could be because the manipulations between the two groups were too similar. Both the absorption and relaxation manipulations

57 included initial instructions to relax, which may have influenced participants in a similar way, leading to a comparable effect. These findings are inconsistent with a previous study using similar manipulations, which found different effects between absorption and relaxation groups on response to suggestion (Brown et al., 2001). A distinct difference in the current study is that we did not present the instructions in a hypnotic context, which may be a crucial ingredient of any subsequent increase in suggested responding. Future research should consider whether there are alternative control conditions that might be more suitable. It may be the case that an individual does not have to be relaxed to be absorbed, for example an individual may feel stressed and become absorbed in their thoughts. Research has shown absorbed-like states can be achieved whilst riding an exercise bike (Banyai & Hilgard, 1976), suggesting it might be a beneficial implication for future research to develop ways of inducing an absorbed-like state, without increasing relaxation in order to create an optimal control condition.

As previous research has shown a positive association between high hallucination proneness and absorption in non-clinical populations (Glicksohn & Barrett, 2003), it is seems that the high hallucination prone participants in the relaxation condition may have experienced stimuli in the relaxation manipulation as equally absorbing as the absorption manipulation. If absorption in the relaxation group was also increased, this might explain why no significant differences were found between groups in false alarm rates at time 2. Notably, however, neither group showed a significant increase in false alarm rate from time 1 to time 2, suggesting that there was either no increase in actual absorption in either condition, or that absorption simply had no impact on auditory hallucination on the VHT. Supporting the former interpretation, there was no significant relationship between changes in state absorption from time 1 to time 2 and the TAS. It is possible that participants’ expectancy that they would become absorbed, or the social demand to report that they had, influenced their absorption ratings, rather than them reflecting an actual increase in state absorption. This study has relied on self-report data to capture state absorption, which impacts the validity of results. Further consideration in future research should be given to alternative ways of measuring absorption, for example, using brain imaging or other biomarkers of absorbed states in the laboratory.

To successfully induce a state of absorption, the manipulation needed to narrow the participant’s attention and their representational (i.e. perceptual, imaginative) resources (Tellegen & Atkinson, 1974), to experience an altered state of consciousness during the VHT at time 2. Whilst it is possible that we did not successfully increase absorption, it is also possible that participants did become more absorbed during the manipulation, but that this diminished by the time they completed the VHT at time 2, perhaps as a result of them having to complete experimental measures. This could have led to an increased sense of reality and metacognitive awareness and might explain why the two conditions showed no significant differences between false alarms rate following the recordings. The development of a manipulation to increase and maintain state absorption is an important implication for future research.

Despite finding no significant difference between the absorption condition and the relaxation condition on false alarm rates, a significant difference was discovered between the two 58 conditions in ‘hit’ rates. The finding that hit rates in the absorption condition were significantly different to the relaxation condition, suggests that there was something unique about the absorption manipulation. It does not seem that hits increased due to an increase in state absorption, as there was no difference in self-reported absorption between the groups. One possibility is that this increase in correctly identifying voices reflects an increase in participant concentration in this group, perhaps because they misinterpreted the instruction to become ‘completely absorbed’ and ‘totally immersed and engrossed’ as needing to be alert, conscious and aware, and to focus on identifying as many voices as possible.

Results also found that whilst the relationship between false alarms and scores on the DES approached significance, no significant relationship between false alarms and scores on the TAS was found, suggesting false alarms on the voice hearing task are not related to absorption or dissociation, in non-clinical samples with high hallucination proneness. This is inconsistent with evidence from previous studies, which have found a relationship between auditory misperception on voice hearing paradigms in individuals with high hallucination proneness (Huque et al., 2017; Merckelbach & van de Ven, 2001). A possible explanation for this inconsistency would be if the VHT did not reliably detect false alarms, perhaps due to a lack of sensitivity or the time-frame determining what is calculated as a false alarm being too small. This might support recent findings using the same voice hearing paradigm as this study, which found the VHT did not detect a relationship between false alarms and hallucination proneness (Wong et al., 2018). A particular strength of the voice hearing paradigm used in this study is that it did account for individual differences in reaction times compared to other tasks available which do not (Feelgood & Rantzen, 1994).

The results of this study found no significant difference in false alarm rates after exposure to an absorption manipulation, however found a significant difference between hit rate and absorption when compared to a control group. Absorption and relaxation manipulations shared similarities, with implications for future research to manipulate and increase in absorption, without increasing relaxation. Additionally, further consideration should be given to the design of control groups, to prevent an increase in absorption occurring in both conditions. The full extent of the absorption manipulation may not have been captured in this study. The development of better manipulations to increase and maintain levels of absorption would benefit further experimental studies, along with developing ways to capture state absorption more meaningfully. Absorption may not be a predisposing factor in the development of voice hearing, however could potentially underlie impairment in source monitoring. These results suggest that absorption could have clinical implications on the underlying mechanisms which make individuals vulnerable to experiencing auditory hallucinations.

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Paper 3: Critical Appraisal

Critical Appraisal

Introduction

This paper provides a critical appraisal of both the systematic review and empirical study described within this thesis.

The first paper consisted of a systematic review which aimed to evaluate the evidence for a relationship between trait absorption and related constructs (flow and imaginative involvement) and common mental health difficulties. In conducting the review, we sought to identify every article including an individual difference measure of absorption, flow or imaginative involvement and an outcome measure of a common mental health problem, as defined by NICE clinical guidance on the identification of common mental health disorders. Over 20,000 articles were identified, of which 20 were included in the final analysis. The quality of papers varied, with the majority of studies being cross-sectional correlational surveys. Results were variable but generally supported a relationship between absorption and anxiety, but not depression.

The second paper investigated if state absorption has a causal impact on voice hearing in hallucination prone, non-clinical participants. An experimental design was used to measure if exposure to an absorption manipulation resulted in a significantly greater increase in auditory false alarms during a laboratory voice hearing task than a comparable relaxation control manipulation. Neither the absorption or relaxation group showed a significant increase in false alarm rate following manipulation and no significant difference in false alarm rates between conditions, when controlling for false alarms pre-manipulation was found. There was also no significant relationship between change in state absorption and change in false alarms from pre- to post-manipulation.

Paper 3 will provide reflections on the strengths and limitations of Papers 1 and 2, including issue pertaining to the process of systematically reviewing the literature for paper 1, and the methodological design and interpretation of the results for Paper 2. Clinical implications and suggestions for future research are discussed.

Paper 1: Systematic literature review

Rationale for the topic

The initial review topic was guided by the focus of the empirical paper, and was to investigate the relationship between absorption and auditory hallucinations. An initial scope of the literature found that the relationship between dissociation and psychosis was well researched (Kilcommons & Morrison, 2005). Studies also indicated a positive relationship between absorption and experiences of auditory hallucinations (Morrison & Perterson, 2003; Perona- Garcelán et al., 2013), although this was evidently a less well researched area. A review of the literature investigating a relationship between absorption and auditory hallucinations seemed ideal to compliment the empirical paper. After consulting with another trainee, however, it emerged that a systematic review focusing on psychosis symptomology (including auditory hallucinations) and how they related to different aspects of dissociation (including absorption) was already in progress. It was therefore decided that it would be redundant to review the relationship between absorption and auditory hallucinations and an alternative review was needed. This led to the consideration of reviewing how absorption relates to common mental health difficulties, beyond experiences of psychosis, with the aim of understanding if trait absorption is an exclusive correlate of psychosis/voice hearing, or whether this relationship extends to other mental health difficulties.

Previous research has suggested that absorption is a common experience in the general population, associated with wellbeing and having less clinical relevance that other more ‘pathological’ forms of dissociation such as amnesia and depersonalization-derealisation (Roche & McConkey, 1990; Butler, 2006). Despite this, a number of studies had found evidence showing absorption is related to proneness to experiencing auditory hallucinations (Glicksohn & Barrett, 2003; Morrison & Perterson, 2003; Perona-Garcelán et al., 2014), suggesting that experiences of absorption might also be clinically relevant to mental health. To better understand if this relationship was exclusive to hallucination proneness only, the decision was made to systematically review if absorption had a positive relationship with common mental health difficulties.

Search terms

One of the challenges in the review was defining the search terms used to capture papers on absorption and common mental health difficulties. The keywords used in relevant papers to describe absorption and common mental health difficulties were variable. Terms needed to be comprehensive and sensitive enough to ensure all relevant papers were identified, however specific enough to ensure the studies being captured were effective and meaningful.

The intention was to identify all papers relating to common mental health difficulties with the exclusion of psychosis, which raised the question of what constitutes common mental health difficulty and what does not. The evidence was therefore explored searching articles through Google scholar. Although there was extensive research into separate mental health difficulties, it was difficult to find research that defined what was experienced as ‘common’. Clinical guidance was then searched from The National Institute for Health and Care Excellence (NICE) which identified evidence of the identification and treatment of common mental health disorders. For the purpose of this review, search terms for common mental health difficulties were therefore based on those recognised in NICE (2011). Clinical practice guidelines were chosen to define eligibility criteria for common mental health problems, as they are developed in a systematic way from research evidence (Mann, 1996).

On reflection, a limitation of using this approach was that studies describing mental health difficulties not listed in this guidance, such as eating disorders, were excluded from the review. These may have provided further insight into how the construct of absorption relates to different types of mental health difficulties and could be a topic for further exploration in future research. Despite this, the search terms used already captured a high amount of papers and it would have been unrealistic to include every mental health difficulty listed in the DSM-IV (First et al., 2002). Focusing the review on common mental health difficulties was therefore chosen and enabled a comparison to previous research on absorption and severe mental health difficulties, such as hallucinatory experiences. As absorption is considered a common experience within the general population, it also seemed that the search terms used to capture the experience of being absorbed also required some consideration, with the research team discussing what defined the experience of absorption and similarities to other constructs which are described.

Absorption is a distinct construct, although it has similarities to others constructs discussed in the review (Tellegen, 1974). We explored the similarities and differences between absorption, flow, imaginative involvement, self-focused attention and fantasy proneness, deciding to exclude the latter two. To achieve a state of flow, a task with an optimal level of challenge is first required (Csíkszentmihályi, 1975); however, once a flow state is achieved, it shares subjective features of absorption such as a sense of deep involvement, an absence of reflective self- conscious and a decreased sense of the passage of time (Csikszentmihalyi et al., 2005). Including flow in the search terms enables us to better understand why absorption might be related to mental health, as flow is most commonly associated with life satisfaction and positive psychological well-being, therefore helping us to understand if it is certain types of absorbing experiences that relate to mental health, rather than absorption itself. Imaginative involvement differs to some extent from absorption in that it is mainly characterised by imagination and altered reality, but shares similarities such as being highly immersed in internal stimuli and experiencing a sense of disconnection from the surrounding environment (Hilgard, 1974). Due to their similarities, both flow and imaginative involved were included in the search terms.

The decision was made to exclude studies on self-focused attention and fantasy proneness because the constructs shared more differences than they did similarities. Evidence suggests 66 that self-focused attention is a self-evaluative process which involves an individual feeling the need to consciously observe themselves, often in social situations, to monitor the way they behave in order to reach a certain goal. By focusing on the self, the individual’s engagement in metacognition is increased and they are more able to regulate affect and manage self- presentation (Duval and Wicklund, 1972; Clark and Wells, 1995). This differs to the construct of absorption, where total attention is narrowed to either an internal or external resource and engagement with metacognition is diminished. Self-focused attention does not diminish consciousness of external stimuli, and increases, rather than decreases awareness of the self, and was therefore excluded from the search terms.

Fantasy proneness was also considered as a search term to capture experiences of absorption. Similarities include a reduced sense of reality and a deep and profound involvement in fantasy and imagination, however the term was excluded based on characteristics such as out of body experiences and paranormal beliefs, such as healing and telepathy abilities (Irwin, 1990; Rauschenberg & Lynn, 1995; Merckelbach et al., 2001). Fantasy proneness was also reported as being experienced in as little as 4% of the general population (Wilson & Barber, 1982), whereas absorption is considered as a common experience, widely reported in the general population (Butler, 2006). This systematic review was interested in exploring the ‘normal’ dissociative construct of absorption and including fantasy proneness would have muddied the waters in this respect. Considering the relationship between fantasy proneness and absorption retrospectively, strong associations ranging from r=0.68 – 0.75 have been found, suggesting fantasy proneness should have been included in the review (Levin, 2001; Council, 1990).

The Tellegen Absorption Scale (Tellegen, 1974) was included in the search terms to ensure all studies using this measure were captured. The Dissociative Experiences Scale (Bernstein & Putnam, 1986) was not included in the search terms, as including it would lead to a significant increase and unrealistic amount of studies to review. Papers measuring absorption using the DES were assumed to be captured through absorption terms. On reflection, it might have been beneficial to include this measure within the search terms and exclude papers which did not use it to measure absorption. Similarly, more studies may have been identified if the term ‘nonpathological adj dissociation’ was included, however this could have also identified studies measuring a range of dissociative experiences, not just absorption. Including these terms would have resulted in a more comprehensive review and whilst it may have captured more studies, the variation in methodology, quality and design may have impacted on quality, to the detriment of the review.

Inclusion and exclusion of papers

There was a large amount of papers to screen at title stage after duplicates were removed. This was due to the large amount of search terms used to capture the mental health difficulties being studied. The vast majority of papers were easily identified as not being related to the review question, for example, referring to absorption of medication and could be excluded from full text 67 review based on the title. Papers included in the full text screening were over inclusive based on abstract screenings. When abstracts referred to absorption or a common mental health difficulty, but did not describe looking at a relationship between the two, they were included for full paper screen. The rationale behind this was that the relationship between absorption and mental health difficulties often being reported as a secondary finding, rather than the main focus of papers. An initial scoping exercise of the absorption literature helped to identify this prior to the main review being completed. This over inclusivity led to many papers being excluded during the full text screen due to irrelevance, followed by not including measures of mental health difficulty or absorption, flow or imaginative involvement. The process of searching through over 20,000 titles was extremely labour intensive, however necessary in order to capture all studies. If the search terms had been widened further to include more mental health difficulties or experiences relating to absorption, the number of articles identified would not have been a feasible review.

Quality Assessment

The Downs and Black Checklist (Bernstein & Putnam, 1986) used in the systematic review was adapted to assess the methodological quality in all final papers. The majority of designs in the current review were cross-sectional, however many items on the checklist referred to qualities such as randomisation, intervention groups, control groups and blinding subjects to conditions. A ‘not applicable’ option was added to the criteria, to account for studies which these items did not pertain to. Additional guidance specific to each quality rating was added to the quality checklist, to ensure items were rated reliably in relation to the specific review question. This additional clarity on the quality assessment, enabled substantial agreement to be reached between two assessors ensuring inter-rater reliability (k= 0.72), based on twenty-five percent of the papers being co-rated.

Ratings differed on seven items, three of which related to the validity and reliability of outcome measures questioning ‘were the main outcome measures used accurate and reliable?’ Additional adjustment had been made to the criteria for this question, with studies using a ‘subscale’ of the DES to measure absorption, only being rated ‘yes’ if explicit reference was made to selecting the items based on factor analysis. This is because there is no explicit absorption scale within the DES; therefore if studies had not based their measurement of absorption taken from the DES on factor analysis, they could be measuring different constructs to absorption. On reflection, including factor analysis does not necessarily resolve issues with reliability of measurements, as different studies may have based their analysis on different factors, therefore potentially measuring different constructs, some of which might not have been related to absorption at all.

Disagreement occurred once measuring ‘was there adequate adjustment for age and gender in the analyses from which the main findings were drawn’, once measuring ‘have actual probability values been reported for the correlation between absorption and mental health difficulty, except 68 where the probability value is <0.001?’ and twice measuring ‘are the characteristics of the subjects included in the study clearly described?’. Items which were more concrete were rated more consistently between raters. It was likely that some items left more room for subjectivity than others, leading to disagreement; however difference may have also arisen due to misidentification information on occasion, for example when identifying probability values.

Synthesising data

A narrative synthesis was completed on the final papers. A meta-analysis would have been a superior technique calculating the magnitude of effect (Garg et al., 2008); however, due to time constraints, this was considered unfeasible. Once the data were collected, a challenge for the trainee was to present the findings in such a way that was clear and coherent for the reader. Numerous different outcome measures were used for both absorption and common mental health difficulties, which made it difficult to make meaningful comparisons between absorption measures and specific mental health measures alone.

The decision was made to report findings by different mental health categories, i.e. depression, anxiety, PTSD, OCD, phobias, health anxiety and their relationship with absorption in the results section. Average correlations were made available in a summary table for the reader to see, although were not drawn upon throughout the text, as they obscured the range of variability in correlations between studies. Caution was also taken reporting average correlations due to the variability between outcome measures and samples used. For example, the relationship between absorption and PTSD was measured using eight separate PTSD outcome measures and five separate measures of absorption in five distinct samples. Instead, average correlations were made available within the results section, but were considered alongside the range of effects found, exploring potential methodological explanations for variance in effect.

Paper 2: Empirical paper

Development of the research question

The research question aimed to explore the impact of absorption on auditory hallucinations, to better understand if absorption is in fact a clinically relevant form of dissociation, despite being argued as having less clinical relevance than other forms of dissociation such as detachment and compartmentalization (Brown, 2006; Holmes et al., 2005). Research identified absorption as being significantly associated with high levels of absorption (Perona-Garcelan et al., 2012) and hallucinatory experiences (Humpston et al., 2016). After reviewing the literature, it was clear that the cause of the relationship between absorption and auditory hallucinations was not well understood, and no studies to date had attempted to manipulate a state of absorption and observe the impact on voice hearing.

An experimental design was therefore chosen for the study, in an attempt to directly manipulate absorption and monitor its effect on voice hearing. We chose to use a voice hearing paradigm designed specifically for studies on voice hearing (Huque, 2017), and manipulations which had shown an effect in previous research (Brown et al., 2001).

Participants

A number of possibilities were considered for which participant sample to recruit from. In an attempt to cause minimal distress, it was felt that exposing a clinical sample of voice hearers to an absorption manipulation which could potentially increase auditory hallucinations, would be an unethical choice. It may have also impacted the likelihood of absorption increasing during the manipulation phase, if participants’ levels of absorption were already very high. Previous research had shown that high hallucination proneness is significantly associated with higher levels of absorption compared to individuals with medium or low hallucination proneness in non- clinical samples (Perona-Garcelan et al.,. 2012; Glicksohn & Barrett, 2003). Non-clinical, high hallucination prone individuals were therefore considered and subsequently recruited, as this sample was both most representative of a voice hearing population, and more likely to respond to stimuli designed to absorb them.

In the development of the design for this study, consideration was given to recruiting both high and low hallucination prone participants. This would have provided further insight into whether the effect of absorption on voice hearing was specific to individuals prone to hearing voices. This would have significantly increased the amount of participants required for screening and increased the time spent on recruitment. It was therefore felt that in order for a sufficient amount of data to be collected in the amount of time available, recruiting high hallucination prone participants only, was the most effective and feasible option.

Recruitment

Recruitment was initially from a student sample with the view to widen advertisement to the general population, if rates of interest were low. If this was not successful, the reduction of hallucination proneness would be considered. Incentives for participation were explored. Reimbursement through monetary reward or course credits was considered the most effective incentive for participation, compared to participating for free or entry into a prize drawer only. To maximise incentives to participate, individuals in this study were also entered into a prize draw. This approach could be criticised due to participant motivation and the impact this might have on fully engaging with the experiment. Utilising an online screening platform and participation booking system worked effectively, with 100% of students being recruited through this system fairly quickly. All participants were students recruited from the University of Manchester. This has implications for the generalisability of results due to a lack of diversity, however it meant scores for hallucination proneness remained in the top quartile, rather than reducing to the top tertile as in previous studies measuring hallucination proneness in non-clinical samples (Varese et al., 2011).

Voice Hearing Task

The Voice Hearing Task (VHT; Huque et al., 2017) was used to detect false alarms and hit rates in response to auditory stimuli. The VHT was chosen over other auditory paradigms (Galdos et al., 2011; Feelgood & Rantzen, 1994) as it took into account each individual reaction time on a practice task, to provide increased precision in identifying hits and false alarms during participation in the main task. The results suggest that hit rate on the VHT did not significantly correlate with absorption. Whilst this could be due to the limitations in the design of the manipulation, it might also be due to issues with the audible volume of stimuli.

The author of the VHT advised on the calibration phase in this study and suggested calculation of individual auditory thresholds for each individual participant would increase sensitivity to hit and false alarm rates. This approach would have added 30 minutes, to the one hour long participation time previously approved by an ethics committee. It would also have implications on the redesign of the E-Prime program and timescales to begin recruitment. The average auditory threshold was therefore calculated in a calibration phase recruiting 18 volunteers, rather than individual calibration for each participant. This approach may have reduced the sensitivity of the task, particularly if the hearing of participants in the calibration phase was significantly different to those completing the main experiment. Since the completion of this study, recent evidence using the VHT reported no correlation between false alarms and hallucination proneness (Wong et al., 2018). This might suggest that the VHT requires further validation. Evidence that high hallucination prone individuals often misattribute internal stimuli as external stimuli, due to difficulties monitoring the source of events, suggests higher rates of false alarms would be expected on the VHT. Individual calibration in future research may improve sensitivity and development of this novel task.

Absorption and relaxation manipulations

The manipulation scripts used in this study were based on those in previous research which found relaxation instructions with the addition of absorption instructions, had a significantly greater effect on suggestibility, than relaxation alone (Brown et al., 2001). It was identified during a pilot of the E-Prime program that levels of absorption in the absorption condition were no greater than levels of absorption in the relaxation condition. The most probable explanation for this was the use of the word ‘focused’ in the absorption condition, possibly increasing, rather than narrowing awareness. The pilot was completed on six volunteers, three in each condition and although these findings could not be generalised, they did identify a potential issue with the manipulations, for which time was not accounted for to enable major modifications to the manipulations and programming software. A new absorption manipulation was recorded, with language changing from the word ‘focused’ to ‘absorbed’. A further brief pilot of these instructions was completed on six further volunteers, which showed a higher increase in absorption scores in the absorption condition, than the relaxation condition. If time had allowed, a larger pilot of the manipulations would have been beneficial for this study to ensure they were sufficiently different.

Relaxation was chosen as a control group for absorption, to control for experiences of relaxation which might accompany but not define an absorbed state, such as feeling calm, at ease and free from tension, as well as being given instructions to follow which the person might expect are going to have an impact on their mental state. Despite attempting to control for these confounding variables, absorption was found to increase in both groups. This raises the question of whether it is possible to increase relaxation, without increasing absorption, and what an optimal control condition would be if relaxation is inherent to absorption. A key question is whether an individual needs to be relaxed to become absorbed. If it is possible for someone to become absorbed in stimuli when feeling anxious (which is one interpretation of paper 1) then there may be potential for developing alternative control groups for absorption in future research.

E-Prime program

In an initial design of the program, consideration was given to verbally reading out manipulation instructions to participants during each experiment, providing verbal instructions between voice hearing tasks and administering paper copies of outcome measures at the correct intervals. There were concerns that this approach would impact the participant’s ability to relax or become absorbed. A focus on social interaction would occur for the participant, due to relying on the researcher for prompts and having to switch their attention between computer, paper and researcher based tasks. This had the potential to increase metacognitive awareness (i.e. ‘what should I say to the researcher at the end of this task?), reducing the ability to become fully absorbed in the experiment. Manipulation instructions being read to every participant would 72 unlikely be delivered in a consistent way, therefore impacting the validity of the results. For this reason, it was agreed that the best way guiding participants through the experiment, whilst giving full opportunity to become absorbed or relaxed, was through developing a computer program on E-Prime software. This was potentially the most challenging aspect of this study overall.

The aim of the program was to create an experience where the participant could complete the experiment, without any distraction to the experiment, from the moment after they provided written consent, until the end of the experiment. This involved designing two programs, one for absorption and one for relaxation, which built in the practice voice hearing task, main voice hearing task, manipulation recordings, outcome measures and the instructions which linked these together. A considerable amount of time was spent designing the program and over 6 months was spent creating the software with computer programmers. Some of the original design was changed in order to fit E-Prime software, for example a sliding analogue scale for measures of state absorption and state relaxation was unsuccessfully programmed, leading to ratings being collected by participants typing a number instead. This way of measuring state absorption and state relaxation was avoided, in the hope that participants would not be able to remember what number they provided between 1 and 100, reducing the impact of expectancy effects and demand characteristics on the next rating.

Significant difficulties with the effectiveness of the program (i.e. manipulation recordings not playing, data not being recorded, and instructions freezing) were overcome through discussion and additional programming input from an additional external contributor. The final e-prime program worked reliably and effectively, with participants being able to follow all instructions on their own, with no direction needed from the researcher. An initial pilot of the program helped with this process.

Analyses

Analysis of the data was a smooth process, however as the relationship between absorption and false alarms was not as expected, some additional variables were computed to better understand the impact of the manipulations on hit rate, which were supplementary to the main analysis.

General discussion

The results of the systematic review exploring absorption and mental health difficulties, together with the findings of the empirical paper exploring absorption and auditory hallucinations share similarities in the underlying mechanisms of how absorption may have an impact on an individual’s mental health. The systematic review found evidence towards absorption possibly serving as a risk factor for developing anxiety related difficulties, or in fact to be a symptom of 73 anxiety, but did not find the same relationship for depression. Although the findings from the empirical paper did not show an effect between absorption and auditory hallucinations, the previous research discussed suggests evidence for one. This raises the question of what is similar about anxiety and auditory hallucinations, which is not present in depression that may interact with absorption. It could perhaps be that both anxiety and auditory hallucinations are related to feelings of threat, danger and fear (Mathews & MacLeod, 1985), whereas depression is typically characterised by loss, subdued mood and reduced interest (Hamilton, 1960). There might have a causal role between threat perception and absorption, due to the characteristics of absorption (i.e. reduced consciousness) leading to difficulties monitoring the source of reality, therefore misattributing stimuli and leading to feelings such as threat or fear. Absorption reduces the ability for metacognition, which in turn would make it more difficult for an anxious or hallucination prone individual to correctly source monitor and attribute internal stimuli experienced when absorbed, as being just that, rather than an external source. When an individual’s field of consciousness is narrowed, with capacity to evaluate their own cognitions and source monitoring reduced, this may lead to an increased responsivity and openness to suggestions, therefore making it more likely for an individual to report hearing a voice which isn’t there, or perceive danger which is not real.

Future clinical and research implications

Identifying absorption in internal or external stimuli early, could lead to the greater prevention of common mental health difficulties and inform relapse prevention strategies. Psychoeducation on the role of absorption and how it relates to source monitoring, suggestion, metacognition and threat perception may lead to a better understanding of the impact of absorption, better outcomes in therapy and prevent relapses in the future. Intervention could be provided to assist in the identification of warning signs that an individual is becoming absorbed in distressing content and provide ways to cope with this experience, such as developing ways to monitor attention, developing metacognition and grounding techniques.

Future research would benefit from investigating the impact of an absorption manipulation on a common mental health difficulty, or the impact of treatment for a common mental health problem on absorption would provide more meaningful evidence to support a relationship between the two variables. The development of better manipulations to increase and maintain levels of absorption would benefit further experimental studies, along with developing ways to capture state absorption more meaningfully as an alternative to self-reports. Further research into the relationship between absorption and auditory hallucinations may benefit from controlling for fear.

References

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Brown, R. J. (2006). Different types of “dissociation” have different psychological mechanisms. Journal of Trauma & Dissociation, 7(4), 7-28.

Brown, R. J., Antonova, E., Langley, A., & Oakley, D. A. (2001). The effects of absorption and reduced critical thought on suggestibility in an hypnotic context. Contemporary Hypnosis, 18(2), 62-72.

Butler, L. D. (2006). Normative dissociation. Psychiatric Clinics, 29(1), 45-62.

Clark, D. M., & Wells, A. (1995). A cognitive model of social phobia. Social phobia: Diagnosis, assessment, and treatment, 41(68), 00022-3.

Council, J. R., & Huff, K. D. (1990). Hypnosis, fantasy activity and reports of paranormal experiences in high, medium and low fantasizers. British Journal of Experimental & Clinical Hypnosis, 7(1), 9-15.

Csikszentmihalyi, M. (1975). Play and intrinsic rewards. Journal of humanistic psychology.

Duval, S., & Wicklund, R. A. (1972). A theory of objective self-awareness.

Feelgood, S. R., & Rantzen, A. J. (1994). Auditory and visual hallucinations in university students. Personality and Individual Differences, 17(2), 293-296.

First, M. B., Spitzer, R. L., Gibbon, M., & Williams, J. B. (2002). Structured clinical interview for DSM-IV-TR axis I disorders, research version, patient edition. SCID-I/P.

Garg, A. X., Hackam, D., & Tonello, M. (2008). Systematic Review and Meta-analysis: When One Study Is Just not Enough. Clinical Journal of the American Society of Nephrology, 3(1), 253-260.

Galdos, M., Simons, C., Fernandez-Rivas, A., Wichers, M., Peralta, C., Lataster, T., ... & van Os, J. (2010). Affectively salient meaning in random noise: a task sensitive to psychosis liability. Schizophrenia bulletin, 37(6), 1179-1186.

Glicksohn, J., & Barrett, T. R. (2003). Absorption and hallucinatory experience. Applied Cognitive Psychology, 17(7), 833-849.

Hamilton, M. (1960). A rating scale for depression. Journal of neurology, neurosurgery, and psychiatry, 23(1), 56.

Hilgard, J. R. (1974). Imaginative involvement: Some characteristics of the highly hypnotizable and the non-hypnotizable. International Journal of Clinical and Experimental Hypnosis, 22(2), 138-156.

Irwin, H. J. (1990). Fantasy proneness and paranormal beliefs. Psychological Reports, 66(2), 655-658.

Kilcommons, A. M., & Morrison, A. P. (2005). Relationships between trauma and psychosis: an exploration of cognitive and dissociative factors. Acta Psychiatrica Scandinavica, 112(5), 351- 359.

Levin, R., & Fireman, G. (2001). The relation of fantasy proneness, psychological absorption, and imaginative involvement to nightmare prevalence and nightmare distress. Imagination, Cognition and Personality, 21(2), 111-129.

Mathews, A., & MacLeod, C. (1985). Selective processing of threat cues in anxiety states. Behaviour research and therapy, 23(5), 563-569.

Morrison, A. P., & Petersen, T. (2003). Trauma, metacognition and predisposition to hallucinations in non-patients. Behavioural and Cognitive Psychotherapy, 31(3), 235-246.

Rauschenberger, S. L., & Lynn, S. J. (1995). Fantasy proneness, DSM-II—R Axis 1 psychopathology, and dissociation. Journal of abnormal psychology, 104(2), 373.

Roche, S. M., & McConkey, K. M. (1990). Absorption: Nature, assessment, and correlates. Journal of personality and social psychology, 59(1), 91.

Tellegen, A. & Atkinson, G. (1974). Openness to absorbing and self-altering experiences ("absorption"), a trait related to hypnotic susceptibility. Journal of Abnormal Psychology, 83, 268-277.

Varese, F., Barkus, E., & Bentall, R. P. (2011). Dissociative and metacognitive factors in hallucination-proneness when controlling for comorbid symptoms. Cognitive Neuropsychiatry, 16(3), 193-217.

Wilson, S. C., & Barber, T. X. (1982). The fantasy-prone personality: Implications for understanding imagery, hypnosis, and parapsychological phenomena. Psi Research.

Wong, S., Bucci, S., Huque, A. U., Hartley, S., Brown, R. J., & Berry, K. (2018). An analogue study investigating voice-hearing following exposure to stressful material. Psychosis, 10(1), 55- 57.

Appendices

Appendix A: Journal of Psychology and Psychotherapy: Theory Research and Practice Guidelines

Appendix B: NICE Guidance on Common Mental Health Disorders

Appendix C: Downs and Black Quality Checklist

Question Score Description 1. Is the hypothesis/aim/objective yes=1, no=0 of the study clearly described? 2. Are the main outcomes to be yes=1, no=0 If the main outcomes are first measured clearly described in the mentioned in the Results section, the introduction or methods section? question should be answered no. 3. Are the characteristics of the yes=1, no=0 In cohort studies and trials, inclusion patients included in the study and/or exclusion criteria should be clearly described? given. In case-control studies, a case- definition and the source for controls should be given. 4. Are the interventions of interest yes=1, no=0 Treatments and placebo (where clearly described? ‘Are the relevant) that are to be compared interventions or manipulations of should be clearly described. *This item interest clearly described?’ is only applicable if the absorption manipulation or mental health intervention is directly related to the review question. Manipulations and interventions (where relevant) should be clearly described. 5. Are the distributions of principal yes=2, A list of principal confounders is confounders in each group of partially=1, provided. patients to be compared clearly no=0 described? *not rated 6. Are the main findings of the yes=1, no=0 Simple outcome data (including study clearly described? ‘Are the denominators and numerators) should findings on the relationship be reported for all major findings so between absorption and mental that the reader can check the major health clearly described?’ analyses and conclusions. (This question does not cover statistical tests which are considered below). *Data should be reported on the correlation between a measure of absorption and a measure of mental health difficulty. This may not be the main finding of the study and cold be a secondary component. 7. Does the study provide yes=1, no=0 In non normally distributed data the estimates of the random inter-quartile range of results should variability in the data for the main be reported. In normally distributed outcomes? *not rated data the standard error, standard deviation or confidence intervals should be reported. If the distribution of the data is not described, it must be assumed that the estimates used were appropriate and the question should be answered yes. 8. Have all important adverse yes=1, no=0 This should be answered yes if the events that may be a consequence study demonstrates that there was a of the intervention been comprehensive attempt to measure reported? *not rated adverse events. (A list of possible adverse events is provided).

9. Have the characteristics of yes=1, no=0 This should be answered yes where patients lost to follow-up been there were no losses to follow-up or described? *not rated where losses to follow-up were so small that findings would be unaffected by their inclusion. This should be answered no where a study does not report the number of patients lost to follow-up. 10. Have actual probability values yes=1, no=0 been reported (e.g., 0.035 rather than <0.05) for the main outcomes, except where the probability value is <0.001? *‘Have actual probability values been reported (e.g., 0.035 rather than <0.05) for the correlation between absorption and mental health difficulty, except where the probability value is <0.001?’ 11. Were the subjects asked to yes=1, no=0, The study must identify the source participate in the study unable to population for patients and describe representative of the entire determine=0 how the patients were selected. population from which they were Patients would be representative if recruited? they comprised the entire source population, an unselected sample of consecutive patients, or a random sample. Random sampling is only feasible where a list of all members of the relevant population exists. Where a study does not report the proportion of the source population from which the patients are derived, the question should be answered as unable to determine. 12. Were those subjects who were yes=1, no=0, The proportion of those asked who prepared to participate unable to agreed should be stated. Validation representative of the entire determine=0 that the sample was representative of population from which they were would include demonstrating that the recruited? distribution of age and gender was the same in the study sample and the source population. 13. Were the staff, places, and yes=1, no=0, For the question to be answered yes facilities where the patients were unable to the study should demonstrate that the treated representative of the determine=0 intervention was representative of treatment the majority of patients that in use in the source population. receive? The question should be answered no * not rated if, for example, the intervention was undertaken in a specialist centre unrepresentative of the hospitals most of the source population would attend. 14. Was an attempt made to blind yes=1, no=0, For studies where the patients would study subjects to the intervention unable to have no way of knowing which they have received? determine=0 intervention they received, this should 90

*In studies with an absorption n/a be answered yes. manipulation or mental health * This item only applies to studies with intervention, was an attempt a manipulation to induce/reduce made to blind subjects to the absorption or studies directly looking condition they received? at the effect of a mental health intervention on absorption. For studies where the subjects would have no way of knowing which intervention or manipulation they received, this should be answered yes. 15. Was an attempt made to blind yes=1, no=0, This item only applies to studies with a those measuring the main unable to manipulation to induce/reduce outcomes of the intervention? * In determine=0 absorption or studies directly looking studies with an absorption n/a at the effect of a mental health manipulation or mental health intervention on absorption. intervention, was an attempt made to blind those measuring the main outcomes? 16. If any of the results of the yes=1, no=0, Any analyses that had not been study were based on “data unable to planned at the outset of the study dredging,” was this made clear? determine=0 should be clearly indicated. If no *not rated retrospective unplanned subgroup analyses were reported, then answer yes. 17. In trials and cohort studies, do yes=1, no=0, Where follow-up was the same for all the analyses adjust for different unable to study patients the answer should yes. lengths of follow-up of patients, or determine=0 If different lengths of follow-up were in case-control studies, is the time adjusted for by, for example, survival period between the intervention analysis the answer should be yes. and outcome the same for cases Studies where differences in follow-up and controls? * not rated are ignored should be answered no. 18. Were the statistical tests used yes=1, no=0, The statistical techniques used must to assess the main outcomes unable to be appropriate to the data. For appropriate? determine=0 example nonparametric methods * Were the statistical tests used to should be used for small sample sizes. assess the relationship between Where little statistical analysis has absorption and mental health been undertaken but where there is no difficulty appropriate? evidence of bias, the question should be answered yes. If the distribution of the data (normal or not) is not described it must be assumed that the estimates used were appropriate and the question should be answered yes. 19. Was compliance with the yes=1, no=0, Where there was non compliance with intervention(s) reliable? *not unable to the allocated treatment or where rated determine=0 there was contamination of one group, the question should be answered no. For studies where the effect of any misclassification was likely to bias any association to the null, the question should be answered yes.

20. Were the main outcome yes=1, no=0, For studies where the outcome measures used accurate (valid and unable to measures are clearly described, the reliable)? ‘Were the main determine=0 question should be answered yes. For outcome measures used accurate yes=1, no=0, studies which refer to other work or (valid and reliable)? If a subscale used DES that demonstrates the outcome of the DES is used to measure without measures are accurate, the question absorption, explicit reference reference to should be answered as yes. should be made to using items factor based on factor analysis.’ analysis = 0 unable to determine=0 21. Were the patients in different yes=1, no=0, For example, patients for all intervention groups (trials and unable to comparison groups should be selected cohort studies) or were the cases determine=0 from the same hospital. The question and controls (case-control studies) n/a should be answered unable to recruited from the same determine for cohort and casecontrol population? ‘For intervention studies where there is no information studies, were the subjects in concerning the source of patients different included in the study. intervention/manipulation groups (trials and cohort studies) or were the cases and controls (case- control studies) recruited from the same population?’ 22. Were study subjects in yes=1, no=0, For a study which does not specify the different intervention groups unable to time period over which patients were (trials and cohort studies) or were determine=0 recruited, the question should be the cases and controls (case- n/a answered as unable to determine. control studies) recruited over the same period of time?’ For intervention studies, were study subjects in different intervention groups (trials and cohort studies) or were the cases and controls (case-control studies) recruited over the same period of time?’ 23. Were study subjects yes=1, no=0, Studies which state that subjects were randomized to intervention unable to randomised should be answered yes groups? determine=0 except where method of n/a randomisation would not ensure random allocation. For example alternate allocation would score no because it is predictable. 24. Was the randomized yes=1, no=0, All non-randomised studies should be intervention assignment unable to answered no. If assignment was concealed from both patients and determine=0 concealed from patients but not from healthcare staff until recruitment staff, it should be answered no. was complete and irrevocable? * not rated

25. Was there adequate yes=1, no=0, This question should be answered no adjustment for confounding in the unable to for trials if: the main conclusions of the analyses from which the main determine=0 study were based on analyses of findings were drawn? treatment rather than intention to treat; the distribution of known confounders in the different treatment groups was not described; or the distribution of known confounders differed between the treatment groups but was not taken into account in the analyses. In nonrandomised studies if the effect of the main confounders was not investigated or confounding was demonstrated but no adjustment was made in the final analyses the question should be answered as no. 26. Were losses of patients to yes=1, no=0, If the numbers of patients lost to follow-up taken into account? unable to follow-up are not reported, the *not rated determine=0 question should be answered as unable to determine. If the proportion lost to follow-up was too small to affect the main findings, the question should be answered yes. 27. Did the study have sufficient no power Sample sizes have been calculated to power to detect a clinically analysis detect a difference of x% and y%. important effect where the completed = probability value for a difference 0, power being due to chance is less than analysis 5%? ‘Did the study conduct a completed = power analysis to determine the 1 power sample size needed to detect a analysis significant difference in effect size completed for outcome measures on and reported absorption? If so, did the study sample size meet the required sample size?’ met = 2

Appendix D: Quality Assessment

Quality Assessment Levi Aardema Aardema Amdur & Berenbau Carleton Datu & Engelhar Garrido & Gick Gomez- n McSwain Perona- Rufer Soffer- Soffer- Wolfr Wolfradt McClure & Bernst et al., & Wu Liberzon m et al., et al., Mateo d et al Schubert (199 Perez et (200 et al., Garcelan et et al., Dudek Dudek et adt & Meyer Lilienfeld en & Question (2009) (2011) (1996) (2008) (2012) (2017) (2001) (2013) 7) al., (2013) 3) (2009) al., (2013_ (2006) (2017) al., (2015) (1997) (1997) (2002) Rubin 1. Is the hypothesis/aim/objecti ve of the study clearly described? 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2. Are the main outcomes to be measured clearly described in the introduction or methods section? 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3. Are the characteristics of the subjects included in the study clearly described? 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 4. Are the interventions or manipulations of interest clearly described? n/a n/a n/a n/a n/a n/a n/a n/a n/a 0 n/a n/a n/a 0 n/a n/a n/a n/a n/a n/a 5. For case control studies, are the distributions of age and gender in each group of subjects to be compared clearly described? n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a 6. Are the findings on the relationship between absorption and mental health clearly described? 1 1 1 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 1 1 7. (10) Have actual probability values been reported (e.g., 0.035 rather than <0.05) for the correlation between absorption and mental health difficulty, except where the probability value is <0.001? 1 1 0 0 1 0 0 1 1 0 1 1 1 1 1 1 0 1 0 1 8. (11) Were the subjects asked to participate in the study representative of the entire population from which they were recruited? 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 950

9. (12) Were those subjects who were prepared to participate representative of the entire population from which they were recruited? 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 10. (14) In studies with an absorption manipualtion or mental health intervention, was an attempt made to blind subjects to the condition they received? n/a n/a n/a n/a n/a n/a n/a n/a n/a 0 n/a n/a n/a 0 n/a n/a n/a n/a n/a n/a 11. (15) In studies with an absorption manipualtion or mental health intervention, was an attempt made to blind those measuring the main outcomes? n/a n/a n/a n/a n/a n/a n/a n/a n/a 0 n/a n/a n/a 0 n/a n/a n/a n/a n/a n/a 12. (18) Were the statistical tests used to assess the relationship between absorption and mental health difficulty appropriate? 1 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 1 1 1 1 13. (20) Were the main outcome measures used accurate (valid and reliable)? If a subscale of the DES is used to measure absorption, explicit reference should be made to using items based on factor analysis. 1 1 0 0 0 0 1 0 1 0 1 0 1 0 1 1 0 1 1 0 14. (21) For intervention studies, were the subjects in different intervention/manipulat ion groups (trials and cohort studies) or were the cases and controls (case-control studies) recruited from the same population? n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a 0 n/a n/a n/a n/a n/a n/a

15. (22) For intervention studies, were study subjects in different intervention groups (trials and cohort studies) or were the cases and controls (case-control studies) recruited over the same period of time? n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a 0 n/a n/a n/a n/a n/a n/a

16. (23) Were study subjects randomized to their group condition? n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a 17. (25) Was there adequate adjustment for age and gender in the analyses from which the main findings were drawn? (e.g. stratification, ANCOVA, Logistic Regression) 0 0 0 0 1 1 0 0 0 0 0 1 0 0 0 0 0 0 0 0 18. (27) Did the study conduct a power analysis to determine the sample size needed to detect a significant difference in effect size for outcome measures on absorption? If so, did the study meet the required sample size? 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 19. Were participants recruited from a clinical population? 0 0 1 1 0 0 0 0 1 0 0 0 0 1 0 0 0 1 0 0

Second researcher Question Aardema Aardema Carleton et Wolfradt Berenbau et al., & Wu al., (2012) (1997) m et al., (2009) (2011) (2008) 1. Is the hypothesis/aim/objective of the study clearly described? 1 1 1 1 1

2. Are the main outcomes to be measured clearly described in the 1 1 1 1 1 introduction or methods section? 3. Are the characteristics of the subjects included in the study clearly 1 0 1 1 1 described? 4. Are the interventions or manipulations of interest clearly described? n/a n/a n/a n/a n/a

5. For case control studies, are the distributions of age and gender in each n/a n/a n/a n/a n/a group of subjects to be compared clearly described?

6. Are the findings on the relationship between absorption and mental health 1 1 1 1 1 clearly described? 7. (10) Have actual probability values been reported (e.g., 0.035 rather than 1 1 0 0 0 <0.05) for the correlation between absorption and mental health difficulty, except where the probability value is <0.001?

8. (11) Were the subjects asked to participate in the study representative of 0 0 0 0 0 the entire population from which they were recruited?

9. (12) Were those subjects who were prepared to participate representative 0 0 0 0 0 of the entire population from which they were recruited?

10. (14) In studies with an absorption manipualtion or mental health n/a n/a n/a n/a n/a intervention, was an attempt made to blind subjects to the condition they received? 11. (15) In studies with an absorption manipualtion or mental health n/a n/a n/a n/a n/a intervention, was an attempt made to blind those measuring the main outcomes? 12. (18) Were the statistical tests used to assess the relationship between 1 1 1 1 1 absorption and mental health difficulty appropriate?

13. (20) Were the main outcome measures used accurate (valid and reliable)? 1 1 1 1 0 If a subscale of the DES is used to measure absorption, explicit reference should be made to using items based on factor analysis.

14. (21) For intervention studies, were the subjects in different n/a n/a n/a n/a n/a intervention/manipulation groups (trials and cohort studies) or were the cases and controls (case-control studies) recruited from the same population?

15. (22) For intervention studies, were study subjects in different n/a n/a n/a n/a n/a intervention groups (trials and cohort studies) or were the cases and controls (case-control studies) recruited over the same period of time?

16. (23) Were study subjects randomized to their group condition? n/a n/a n/a n/a n/a

17. (25) Was there adequate adjustment for age and gender in the analyses 0 0 0 0 0 from which the main findings were drawn? (e.g. stratification, ANCOVA, Logistic Regression)

18. (27) Did the study conduct a power analysis to determine the sample size 0 0 0 0 0 needed to detect a significant difference in effect size for outcome measures on absorption? If so, did the study meet the required sample size?

19. Were participants recruited from a clinical population? 0 0 1 0 0

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Appendix E: Author guidelines for the journal ‘Psychosis’

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Appendix F: Letter of Ethical Approval

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Appendix G: Revised hallucinations Scale

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Appendix H: Poster Advertisement

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Appendix I: Voice Hearing Task

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VOICE-HEARING TASK

Features of the white noise

Audacity 2.0.5 for Mac was used. Maximum output volume was used.

Monophonic audio (a single track of audio), 44100Hz, 32-bit floating point audio.

Gain: 0 db

Duration: 5 minutes

Normalized maximum amplitude to: -55 db

Nonsense words

Primary list. Total 70 nonsense words, each composed of seven letters, were created with

PassMaker version 1.2. A text to speech converting software programme called the Balabolka v

2.9 was used to create wav files in male voice (IVONA 2 Brian) for each of these nonsense words. The voice parameters during creating the sound files were as follows: rate = 0, pitch =

0, and volume = 100.

Ratings for similarity with actual English words. The 70 nonsense words were played (with maximum volume both on the laptop and headphones) in a quiet room to 10 native English raters (PhD students and faculty members of the University of Manchester) to decide on whether they sound very similar, a little bit similar, or not at all similar to actual English words.

Eight (80%) raters identified 17 and seven (70%) raters identified 16 words not at all similar to actual English words. The 17 words with 80% rating were selected for the main test and 16 words with 70% rating were used in the practice test.

Volumes of the sound files

The amplitude of sound files used in the auditory task was based on auditory thresholds of 20 individuals. A computer algorithm called the parameter estimation by sequential testing

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(PEST) was used to determine thresholds. One of the participants, aged 46 years, was excluded from the analysis for not satisfying the age criterion for the final study which was 18 – 40 years. The thresholds found (on an E-Prime programme) for 19 participants are given below:

Participant ID Threshold 4LR -6100.00 5YX -6000.00 0H5 -5900.00 7CN -6000.00 7M7 -5900.00 2ND -5700.00 D83 -5900.00 E81 -5700.00 5S6 -5700.00 J9C -6100.00 KL7 -5900.00 8IH -6000.00 MO7 -5900.00 D38 -5700.00 F3T -6100.00 L05 -5900.00 N7O -6000.00 U2R -6300.00 WPH -6000.00 Mean threshold -5936.8421 SD 160.591 Minimum -6300.00 Maximum -5700.00

The following features were considered to decide on the volumes of the main experiment sound files:

1. The volumes should spread over a range of frequencies such that participants will hear some of the voices but miss others. More specifically, voice amplitudes should lie on the both sides

(i.e. above and below) of participants’ auditory thresholds. As auditory threshold will not be determined for individual participants, using a range of volumes surrounding the mean

121 auditory threshold for the pilot sample increases the likelihood that auditory thresholds of participants in the main experiment will lie somewhere in that range. This is to ensure that the voices are neither too loud (that participants hear all of them) nor too faint (that participants hear none of them).

2. Participants should find the task sufficiently ambiguous (in terms of amplitude of sound files) so that they are likely to respond even when they are not absolutely sure about hearing voices. It was expected that this would facilitate the top-down processes related to auditory perception and thus would generate false alarms (i.e. hearing of voices or believing that a voice was presented when actually there was no voice).

To satisfy the above features, the central (i.e. mean) volume was set to -5900 (which is near the mean threshold for the pilot sample, -5936.8421). Other intensities constituted volumes up to 3 steps (1 step = -150 which is close to the SD calculated for the threshold sample) above and 2 steps below the central value. Thus following volumes were used for the voice detection task:

-5450, -5600, -5750, -5900, -6050, -6200

The practice task consisted of the above sound amplitudes as well as much higher ones (i) to make participants familiar with the task and (ii) to determine their general reaction time to clearly audible voices which later is used to decide on the criterion for false alarms in the main task.

The following 18 amplitudes were used in the practice task:

-1000, -1500, -2000, -2500, -3000, -3500, -4000, -4500, -4700, -4900, -5000, -5200, -5450, -

5600, -5750, -5900, -6050, -6200

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When do the voices (i.e. nonsense words) appear during the test?

Voices appear in a random sequence in both the practice and main task.

Practice test. The following features were considered to decide on the time intervals between the voices in the practice test:

1. The intervals should not be too short that the sound files would hear overlapping with

one another.

2. The intervals should not be too long that the total duration would increase

unnecessarily.

To satisfy the above requirements, it was decided to use a random interval between a minimum of 1 second and a maximum of 2 seconds in-between two successive sound files.

Thus Microsoft Office Excel random number generator function was used to get the following

18 intervals to randomly pair with 18 volume levels:

Intervals between two successive sound files in the practice test (milliseconds)

1869 1806 1660

1300 1205 1685

1876 1411 1956

1108 1377 1568

1618 1123 1407

1682 1063 1330

Main test. A randomly selected 3 to 10 seconds time gap (generated with Microsoft Excel) was used between two successive voices, thus there was a minimum gap of 3 seconds and a maximum gap of 10 seconds between two voices.

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Intervals between two successive sound files in the main test (seconds)

3 9 2

9 4 3

8 6 10

10 7 6

10 3 10

5 3 3

How many times the sound files were played during the tasks?

Practice test. A sound file (out of total 17 sound files which 70% of the raters rated not at all similar to meaningful English words) was randomly selected to use twice and the other 16 files were used once to cover all the 18 volume levels. Given the intervals between two successive sound files, it was found that an approximately one-minute practice trial would require 24 voices. To get the additional voices, six of the 18 sound files were randomly selected to run twice.

Main test. The main test composed of total 18 voices with 16 nonsense words played once and one was played twice. These were the 17 sound files that 80% of the raters identified not at all similar to the actual English words.

Duration for the sound files

All the sound files were played for about 800ms in both the practice and main tasks.

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Procedure to test a participant

The voice detection task consists of threshold and suprathreshold nonsense voices that randomly appear against continuous background white noise. Participants task is to press the spacebar as soon as they hear a voice. Headphones are used to present the stimuli.

1. The task is described to participants in a very simple language.

2. Participants do the practice test which takes around one minute. At the end of the task, participants are asked whether they heard very faint voices like whispers. They are then informed that the main test consists of only whispers and they may find it difficult to detect them.

3. Participants are given the main test which takes around 4m 30s. At the end, participants are asked whether they heard voices and what they think about the task and whether there was anything that influenced their responses.

Reference

Huque, A. U., Poliakoff, E., Brown, R. J. (2014). Effects of learning on somatosensory and

auditory decision-making and experiences: Implications for medically unexplained

symptoms. Unpublished manuscript.

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Appendix J: Quartile cut off data for the RHS

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Statistics RHS_total RHS_auditory N Valid 210 210 Missing 42 42 Mean 12.0619 7.2143 Median 11.0000 7.0000 Mode 9.00 5.00 Sum 2533.00 1515.00 Percentiles 25 10.0000 5.0000 33.33333333 10.0000 6.0000 50 11.0000 7.0000 66.66666667 12.0000 8.0000 75 13.0000 8.0000

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Appendix K: Tellegen Absorption Scale

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Please indicate whether each of the following statements is generally true or generally false for you by circling the relevant response Sometimes I feel and experience things as I did when I True False was a child. 2. I can be greatly moved by eloquent or poetic True False language. 3. While watching a movie, a TV show, or a play, I may True False become so involved that I may forget about myself and my surroundings and experience the story as if it were real and as if I were taking part in it. If I stare at a picture and then look away from it, I can True False sometimes "see" an image of the picture almost as if I were still looking at it. Sometimes I feel as if my mind could envelop the True False whole world. I like to watch cloud shapes change in the sky. True False If I wish I can imagine (or daydream) some things so True False vividly that they hold my attention as a good movie or story does. I think I really know what some people mean when True False they talk about mystical experiences. I sometimes "step outside" my usual self and True False experience an entirely different state of being. Textures -- such as wool, sand, wood -- sometimes True False remind me of colours or music. Sometimes I experience things as if they were doubly True False real. When I listen to music I can get so caught up in it that I True False don't notice anything else. If I wish I can imagine that my body is so heavy that I True False could not move it if I wanted to. I can often somehow sense the presence of another True False person before I actually see or hear her/him. The crackle and flames of a wood fire stimulate my True False imagination It is sometimes possible for me to be completely True False immersed in nature or in art and to feel as if my whole state of consciousness has somehow been temporarily altered. Different colors have distinctive and special meanings True False for me. I am able to wander off into my thoughts while doing a True False routine task and actually forget that I am doing the task, and then find a few minutes later that I have completed it. I can sometimes recollect certain past experiences in True False my life with such clarity and vividness that it is like living them again or almost so.

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Things that might seem meaningless to others often True False make sense to me. While acting in a play I think I could really feel the True False emotions of the character and "become" her/him for the time being, forgetting both myself and the audience. My thoughts often don't occur as words but as visual True False images. I often take delight in small things (like the five-pointed True False star shape that appears when you cut an apple across the core or the colours in soap bubbles). When listening to organ music or other powerful music True False I sometimes feel as if I am being lifted into the air. Sometimes I can change noise into music by the way I True False listen to it. Some of my most vivid memories are called up True False by scents and smells. Some music reminds me of pictures or changing colour True False patterns. I often know what someone is going to say before he True False or she says it. I often have "physical memories"; for example, after I True False have been swimming I may still feel as if I am in the water. The sound of a voice can be so fascinating to me that I True False can just go on listening to it. At times I somehow feel the presence of someone who True False is not physically there. Sometimes thoughts and images come to me without True False the slightest effort on my part. I find that different odours have different colours. True False I can be deeply moved by a sunset. True False

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Appendix L: Dissociative Experiences Scale

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Appendix M: Relaxation and absorption pilot scores

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Pilot 1

Absorption Relaxation Absorption Relaxation Time 1 Time 1 Time 2 Time 2 1. 20 70 50 80 Absorption 2. 65 80 32 80 Absorption 3. 30 40 10 20 Absorption

Absorption Relaxation Absorption Relaxation Time 1 Time 1 Time 2 Time 2 1. 40 30 80 60 Relaxation 2. 11 11 11 11 Relaxation 3. 75 65 90 85 Relaxation

Pilot 2

Absorption Relaxation Absorption Relaxation Time 1 Time 1 Time 2 Time 2 1. 65 50 100 70 Absorption 2. 35 35 84 63 Absorption 3. 50 60 80 70 Absorption

Absorption Relaxation Absorption Relaxation Time 1 Time 1 Time 2 Time 2 1. 40 50 70 65 Relaxation 2. 60 60 75 65 Relaxation 3. 57 50 65 75 Relaxation

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Appendix N: Participant Information Sheet

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Participant Information Sheet (PIS)

The effect of relaxation on auditory perception.

You are being invited to take part in a research study as part of a student project. Before you decide it is important for you to understand why the research is being done and what it will involve. Please take time to read the following information carefully and discuss it with others if you wish. Feel free to email the researchers if there is anything that is not clear or if you would like more information. Please take the time to decide whether or not you wish to take part.

What is the purpose of the study?

The purpose of this study is to understand more about the voices we hear and what effect different states can have on the frequency of voices that we experience. We are particularly interested in voices that people hear when no-one is actually speaking to them. We hope that the research will give us a better understanding of how to help people who hear voices and are upset by them.

Why have I been invited to take part in this study?

You have been invited to take part because you have expressed an interest in this study. We need 66 people to take part in the study overall.

Do I have to take part?

No, you do not have to take part in the study if you do not want to. Taking part in the research is voluntary; this means it is completely up to you to decide whether or not to join the study. Your decision to participate in this study will not be connected with your involvement with the University of Manchester either now or in the future. If you decide to take part and sign the consent form but change your mind later, you are free to withdraw at any point during the study without giving a reason and without any consequence to your current or future time at the University of Manchester.

What will participation involve?

The initial phase of the study will involve taking part in a screening process where you will be asked to complete a consent form and short online questionnaire. The online questionnaire includes questions such as ‘I hear people call my name and find that nobody has done so’.

If you score within a certain range on the questionnaire you will be eligible to take part in the study. You will then you will be invited to book a slot to take part in the study at the University of Manchester and will be asked to complete a second consent form. 137

You will be asked to attend the University of Manchester on one occasion, lasting up to 60 minutes. Participants will be asked to listen to a series of recordings and to record how many voices are on each recording. During the study, the researcher will also ask the participant to follow a set of relaxation instructions. Participants will be asked to complete two short questionnaires. An example of the questions asked on the questionnaires are ‘Some people sometimes have the experience of feeling that other people, objects, and the world around them are not real’ and ‘When I listen to music I can get so caught up in it that I don't notice anything else’.

Although the questionnaires and recordings are unlikely to cause discomfort or distress, there is a small chance that they will be slightly upsetting for some people. If you think that you are likely to be upset listening to recordings of voices or being asked questions such as the ones above then please do not take part in the study.

If you wish to, you can provide us with your email address in case you would like to receive a summary of our findings.

What is the duration of the research?

The screening questionnaire should take no longer than 5 minutes to complete. Participating in the study at the University of Manchester should take no longer than 60 minutes.

What are the possible disadvantages and risks of taking part?

There is a small chance that you will find some of the questionnaire items slightly distressing. There are some examples of the questions provided above. Having looked at these, please decide whether you would feel ok to answer similar questions and if you think you would be unduly distressed please do not take part in the study.

What are the possible benefits of taking part?

Some people can enjoy completing questionnaires or tasks in research. Every participant who completes the screening questionnaire will be entered into a prize draw to win one of three £20 gift cards. Every participant who goes on to participate in the study will receive a financial reimbursement of £5 or 4 research participation credits for psychology students, in line with their preference. They will also be entered into a prize draw to win a £20 shopping voucher.

Will my taking part in the study be kept confidential? What will be done to ensure confidentiality?

Your confidentiality will be maintained throughout. All electronic and paper-based data will be stored securely at the University of Manchester on dedicated university servers, on the researcher’s laptop in an encrypted file and in secure locked filing cabinets at the University of Manchester. Participant data will not be linked with participant names and each participant will be identified through a unique code.

What will happen if I do not want to carry on with the study?

You can withdraw at any point up until your participation in the study has ended, without giving a reason and without any adverse consequence to yourself. No further data will be collected from the moment you withdraw and any data we have already collected will be

138 destroyed. It will not be possible for you to withdraw your data after you have participated in the study, as all data will be fully anonymised after each data collection session.

What if I have any questions?

If you have any questions or you have a concern about any aspect of the study, please do not hesitate to contact me on the following email address [email protected] What will happen to the results of the research study?

We hope to publish the research in a peer-reviewed academic journal and possibly present them at academic conferences. The results will also form part of a student Doctoral thesis.

Who has reviewed the study?

The study has been reviewed by The University of Manchester Research Sub-Committee and by the University Ethics Committee.

What if there is a problem?

It is unlikely that anything would go wrong but if there is a problem, you may contact me in the first instance ([email protected]) or my supervisor Dr Richard Brown ([email protected]). Any complaint you have about the study will be resolved with you promptly and information will be provided by phone or in writing about how the complaint has been addressed.

If myself or my supervisor are unable to resolve your concern and you remain unhappy, or if you do not want to contact either of us directly, please contact a University Research Practice and Governance Co-ordinator on 01612757583 / 01612758093 or by email to [email protected]

The University of Manchester is providing insurance cover for this research. In the event that something does go wrong as a result of taking part in this research, you may have grounds for claiming compensation.

What if I feel distressed as a result of taking part?

If you feel that you have suffered any distress as a result of taking part in this study, you can contact the University of Manchester Counselling Service on 0161 275 2864, or visit them in person at:

University of Manchester Counselling Service 5th Floor, Crawford House Precinct Centre Booth Street East Manchester M13 9QS

You are able to contact the Samaritans 24hrs a day on 0161 236 8000. Alternatively, you can visit the Samaritans to speak to someone at the following address and times:

Address: 72-74, Oxford Street, Manchester, M1 5NH 139

Opening times: Monday to Friday between the hours of 08:30-20:30

The Hearing Voices Network is also contactable for further support on 0114 271 8210 or you can access further information and support they provide in Manchester via their website: www.hearing-voices.org

Further information

If you have any questions or require any additional information please do not hesitate to contact me at [email protected]

You can also contact Dr Richard Brown if you have any concerns ([email protected]).

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Appendix O: Consent Form – Screening

141

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Appendix P: Consent Form – Main Study

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Appendix Q: Demographic Information

145

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Appendix R: Manipulation Scripts

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Absorption script

To begin with, I’d just like you to close your eyes. Now… relax, make yourself entirely comfortable. Concentrate on my voice. I want you to relax completely. Relax completely. Relax every muscle of your body. Relax the muscles of your legs. Relax the muscles in your arms. Make yourself, perfectly comfortable. Let yourself be limp. Relax more and more…relax more and more. Relax completely…Relax completely…Relax completely. Your legs feel heavy. Heavy and limp. Your arms are heavy, heavy, heavy as led. Your whole body feels heavy, heavy. You feel relaxed, relaxed, very relaxed. You feel relaxed, very relaxed. Your breathing is slow and regular, slow and regular. And as time goes by, you find yourself becoming more and more and more relaxed. Completely relaxed. Just enjoy those good relaxed feelings for a moment.

In a minute we’d like you to repeat the voice hearing task. When you did the task earlier, you did it ‘cold’, that is, without any special preparation. However, many people find that they’re able to hear more voices when they’re really absorbed in the task… allow yourself to become completely absorbed right now… all other thoughts are just slipping away… you’re losing yourself in what you’re doing… you’re becoming more and more absorbed… you’re no longer thinking about anything… more and more absorbed… completely absorbed… completely absorbed…

The voice hearing task is going to begin in a minute and you’ll remain completely absorbed throughout. Completely absorbed.

Now, when you are ready, open your eyes and look at the question on the screen.

Relaxation script

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In a minute we’d like you to repeat the voice hearing task. When you did the task earlier, you did it ‘cold’, that is, without any special preparation. However, many people find that they’re able to hear more voices when they’re really relaxed in the task... allow yourself to relax even more right now… your body and mind are so relaxed… you’re completely relaxed in what you’re doing… you’re becoming more and more relaxed… you’re no longer feeling any tension… more and more relaxed… completely relaxed… completely relaxed…

The voice hearing task is going to begin in a minute and you’ll remain completely relaxed throughout. Completely relaxed.

Now, when you are ready, open your eyes and look at the question on the screen.

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Appendix S: Statistical SPSS Output

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Mean RHS, TAS, DES scores between groups

Descriptive Statistics

Condition N Minimum Maximum Mean Std. Deviation absorption Total_DES 36 5 61 25.14 14.382 Total_TAS 36 10 31 19.44 5.459 Valid N (listwise) 36 relaxation Total_DES 37 5 62 25.62 12.866 Total_TAS 37 6 32 19.57 5.970 Valid N (listwise) 37

Descriptive Statistics

Condition N Minimum Maximum Mean Std. Deviation absorption RHS 36 8 15 9.58 1.779 Valid N (listwise) 36 relaxation RHS 37 7 14 9.95 1.731 Valid N (listwise) 37

Was the absorption manipulation successful: 2 x2 Repeated ANOVA

Multivariate Testsa

Hypothesis Partial Eta Effect Value F df Error df Sig. Squared time Pillai's Trace .334 35.637b 1.000 71.000 .000 .334

Wilks' Lambda .666 35.637b 1.000 71.000 .000 .334

Hotelling's .502 35.637b 1.000 71.000 .000 .334 Trace

Roy's Largest .502 35.637b 1.000 71.000 .000 .334 Root time * Pillai's Trace .001 .060b 1.000 71.000 .808 .001

Condition Wilks' Lambda .999 .060b 1.000 71.000 .808 .001

Hotelling's .001 .060b 1.000 71.000 .808 .001 Trace

Roy's Largest .001 .060b 1.000 71.000 .808 .001 Root a. Design: Intercept + Condition Within Subjects Design: time

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3. Condition * time

Tests of Within-Subjects Contrasts Measure: MEASURE_1 Type III Sum of Mean Partial Eta Condition Source time Squares df Square F Sig. Squared absorption time Linear 20.903 1 20.903 26.802 .000 .434

Error(time) Linear 27.296 35 .780 relaxation time Linear 18.242 1 18.242 12.970 .001 .265 Error(time) Linear 50.633 36 1.406

Was the relaxation manipulation successful: 2 x2 Repeated ANOVA

Multivariate Testsa

Hypothesis Partial Eta Effect Value F df Error df Sig. Squared

time Pillai's Trace .707 170.936b 1.000 71.000 .000 .707

Wilks' Lambda .293 170.936b 1.000 71.000 .000 .707

Hotelling's 2.408 170.936b 1.000 71.000 .000 .707 Trace

Roy's Largest 2.408 170.936b 1.000 71.000 .000 .707 Root time * Pillai's Trace .003 .205b 1.000 71.000 .652 .003

Condition Wilks' Lambda .997 .205b 1.000 71.000 .652 .003

Hotelling's .003 .205b 1.000 71.000 .652 .003 Trace

Roy's Largest .003 .205b 1.000 71.000 .652 .003 Root

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Tests of Within-Subjects Contrasts Measure: MEASURE_1 Type III Sum of Mean Partial Eta Condition Source time Squares df Square F Sig. Squared absorption time Linear 107.308 1 107.308 82.039 .000 .701

Error Linear 45.780 35 1.308 (time) relaxation time Linear 96.017 1 96.017 89.466 .000 .713 Error Linear 38.636 36 1.073 (time)

Median absorption and relaxation ratings

Statistics

Absorption 1 - Absorption 2 - after T1, after script, Relaxation Relaxation Condition before script before T2 1 2 absorption N Valid 36 36 36 36 Missing 0 0 0 0 Median 75.00 87.50 67.50 90.00 Range 66 48 90 50 Percentiles 25 70.00 76.25 50.00 76.50 50 75.00 87.50 67.50 90.00

75 90.00 94.50 78.75 94.50 relaxation N Valid 37 37 37 37 Missing 0 0 0 0 Median 75.00 85.00 70.00 90.00 Range 59 51 88 41 Percentiles 25 64.00 73.00 60.00 82.50 50 75.00 85.00 70.00 90.00 75 85.00 95.00 80.00 93.50

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Did change in state absorption correlate with trait absorption: Spearman’s Correlation Correlations

Condition abs_change Total_TAS Spearman's rho absorption abs_change Correlation Coefficient 1.000 .219 Sig. (2-tailed) . .199 N 36 36 Total_TAS Correlation Coefficient .219 1.000

Sig. (2-tailed) .199 . N 36 36 relaxation abs_change Correlation Coefficient 1.000 -.112 Sig. (2-tailed) . .510 N 37 37 Total_TAS Correlation Coefficient -.112 1.000 Sig. (2-tailed) .510 . N 37 37

Test of Hypothesis 1: ANCOVA

Tests of Between-Subjects Effects Dependent Variable: FA_T2_sr Type III Sum of Mean Partial Eta Source Squares df Square F Sig. Squared

Corrected Model 36.491a 2 18.246 32.733 .000 .483 Intercept 6.386 1 6.386 11.456 .001 .141 FA_T1_sr 32.076 1 32.076 57.544 .000 .451 Condition .283 1 .283 .509 .478 .007 Error 39.019 70 .557 Total 731.000 73 Corrected Total 75.510 72 a. R Squared = .483 (Adjusted R Squared = .468)

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Tests of Between-Subjects Effects Dependent Variable: Hit_T2_sr Type III Sum of Mean Partial Eta Source Squares df Square F Sig. Squared

Corrected Model 17.312a 2 8.656 14.359 .000 .291 Intercept 9.906 1 9.906 16.433 .000 .190 Hit_T1_sr 13.228 1 13.228 21.943 .000 .239 Condition 4.081 1 4.081 6.770 .011 .088 Error 42.197 70 .603 Total 424.000 73 Corrected Total 59.509 72 a. R Squared = .291 (Adjusted R Squared = .271)

Difference in false alarms from time 1 to time 2: Wilcoxon signed ranks Ranks

Condition N Mean Rank Sum of Ranks absorption FA T2 - FA T1 Negative Ranks 16a 17.41 278.50 Positive Ranks 20b 19.38 387.50 Ties 0c Total 36 relaxation FA T2 - FA T1 Negative Ranks 14a 17.89 250.50 Positive Ranks 20b 17.23 344.50 Ties 3c Total 37 a. FA T2 < FA T1 b. FA T2 > FA T1 c. FA T2 = FA T1 Test Statisticsa Condition FA T2 - FA T1 absorption Z -.858b Asymp. Sig. (2-tailed) .391 relaxation Z -.807b Asymp. Sig. (2-tailed) .420 a. Wilcoxon Signed Ranks Test b. Based on negative ranks. c. FA T2 = FA T1

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Median false alarm and hit rate at time 1 and 2 in absorption and relaxation conditions

Statistics

Condition Hits T1 Hits T2 FA T1 FA T2 absorption N Valid 36 36 36 36 Missing 0 0 0 0 Median 5.00 7.50 10.00 9.00

Range 16 18 29 34 Percentiles 25 2.25 3.00 6.00 8.00 50 5.00 7.50 10.00 9.00 75 7.00 9.75 13.75 15.00 relaxation N Valid 37 37 37 37 Missing 0 0 0 0 Median 6.00 4.00 6.00 7.00 Range 11 13 20 23 Percentiles 25 3.00 2.00 4.50 4.50

50 6.00 4.00 6.00 7.00 75 7.00 6.00 10.00 11.50

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Test of Hypothesis 2: Spearman’s correlation

Correlations

abs_change FA_change Spearman's rho abs_change Correlation Coefficient 1.000 -.032 Sig. (2-tailed) . .791 N 73 73 FA_change Correlation Coefficient -.032 1.000 Sig. (2-tailed) .791 .

N 73 73

Are the DES and TAS correlated to false alarm average? Pearson’s Correlation Correlations

FA_average_lo g Total_DES_sqr Total_TAS FA_average_log Pearson Correlation 1 .226 .064 Sig. (2-tailed) .055 .591 N 73 73 73 Total_DES_sqr Pearson Correlation .226 1 .520** Sig. (2-tailed) .055 .000 N 73 73 73 Total_TAS Pearson Correlation .064 .520** 1 Sig. (2-tailed) .591 .000 N 73 73 73 **. Correlation is significant at the 0.01 level (2-tailed).

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