Robertson, Ashley E. (2012) Sensory Experiences of Individuals with Autism Spectrum Disorder and Autistic Traits: a Mixed Methods Approach
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Robertson, Ashley E. (2012) Sensory experiences of individuals with Autism Spectrum Disorder and autistic traits: a mixed methods approach. PhD thesis http://theses.gla.ac.uk/3769/ Copyright and moral rights for this thesis are retained by the author A copy can be downloaded for personal non-commercial research or study, without prior permission or charge This thesis cannot be reproduced or quoted extensively from without first obtaining permission in writing from the Author The content must not be changed in any way or sold commercially in any format or medium without the formal permission of the Author When referring to this work, full bibliographic details including the author, title, awarding institution and date of the thesis must be given. Glasgow Theses Service http://theses.gla.ac.uk/ [email protected] Sensory experiences of individuals with Autism Spectrum Disorder and autistic traits: a mixed methods approach Ashley E. Robertson M.Sc., M.A. (Hons.) Submitted in fulfilment of the requirements of the degree of Doctor of Philosophy School of Psychology College of Science and Engineering University of Glasgow November 2012 For mum, dad, Cameron, Greig and Kyle In memory of my papa, Frank 2 Abstract Abstract There has been a recent increase in research into sensory sensitivity in Autism Spectrum Disorders (ASDs), which has prompted the inclusion of sensory issues as an explicit criterion in the impending revision of diagnostic guidelines (DSM-5: American Psychiatric Association, 2010). However, one of the most interesting aspects of research in this field is that a clear disparity exists between the results of self- or parent-report studies and behavioural studies. The former class of studies shows that those with ASD report clear, consistent differences in their sensory experiences (Baranek et al., 2006; Crane et al., 2009; Leekam et al., 2007), whereas the findings in the behavioural field are complex to interpret, with all but a few areas of sensory processing (e.g. visual search: Joliffe & Baron-Cohen, 1997; Shah & Frith, 1983, 1993) demonstrating consistent consensus (e.g. Dudova et al., 2011; Tavassoli et al., 2012a). The thesis presented here aims to explore the nature of sensory sensitivities in those with ASD and the broader autism phenotype (BAP) further using a combination of qualitative and quantitative research designs. In addition, an approach was developed (the Sensory Audit: Chapter 8) which can be used to objectively assess an environment for sensory stressors. Chapters 2 and 3 report the development of a sensory questionnaire (GSQ: Robertson & Simmons, 2012), which was administered to those with varying AQ scores, as measured by the Autism Spectrum Quotient (AQ: Baron-Cohen et al., 2001). There were both quantitative (Chapter 2) and qualitative (Chapter 3) features of the questionnaire. In the quantitative component, seven modalities were assessed (vision, audition, gustation, olfaction, touch, vestibular processing and proprioception), taking into account both hyper- and hypo-sensitivity to stimuli. We found that there was a strong, positive relationship between sensory sensitivity and AQ score, with medium scorers (who would be unlikely to be diagnosed with ASD) reporting significantly more difficulties with sensory stimuli than low scorers. For Chapter 3, we found that those with high levels of autistic traits (i.e. may be likely to have a diagnosis of ASD) tended to report using different coping techniques from medium and low scorers (e.g. avoiding situations and using sensory soothing rather than non-sensory soothing). The results from these studies suggest that sensory issues may be prevalent throughout the population and that the differences observed in Chapter 2 are mirrored in the themes extracted for each group in Chapter 3. The second set of studies (Chapters 4-6) report data from three focus groups (caregivers of those with autism, adults with ASD and an elderly control group), as well as from 3 Abstract interactive group interviews with children who have autism. Although similar themes (e.g. control, consequences of problematic stimuli and positive effects of sensory stimuli) arose in all four studies, there were different types of information gathered from the groups. For those with ASD (Chapter 4 and Chapter 5), the discussion mainly centred around how sensory stimuli made them feel, and the implications of this for them. For the caregivers (Chapter 4) and the elderly group (who mainly discussed their relatives’ experiences) (Chapter 6), the themes reflected their own experiences, concentrating on the implications of adverse reactions to sensory stimuli (for both themselves and their loved ones). The data from these studies provide insight into living with someone who has sensory issues, for both those with a diagnosis of ASD and their caregivers, as well as the relatives of elderly individuals suffering from vision and hearing loss. Chapter 7 reports a study into the relationship between olfactory processing and the broader autism phenotype (as measured by the AQ). Participants completed the AQ as well as the Sniffin’ Sticks Extended Test. A subset of the sample (n=62) also completed the Glasgow Sensory Questionnaire (GSQ) that was developed as part of Chapter 2. As expected, there were no significant differences in the Threshold, Discrimination or Identification performance of those with high and low AQ scores. However, there was significantly greater intra-participant variability in the Threshold scores for the top 15% of scorers on the AQ. Furthermore, a similar relationship to that reported in Chapter 2 between sensory score and autistic traits was observed. These results indicate that there may be other differences in various aspects of performance in those with ASD that are not being targeted by current behavioural paradigms (which may explain the disparity between reported sensory differences and those observed using direct measurement). Finally, the last study reported is that of the development of a pilot Sensory Audit. This was an effort to apply the information gained from our previous research in a practical, useful way for individuals with ASD. Details of the development of the Sensory Audit, as well as the results of the pilot study are reported in Chapter 8. By making this freely available, we hope to help companies ensure that their working environments do not contain any undue stressors that could increase stress for those with sensory issues in their workforce. The results are discussed in light of three overarching themes of the thesis as a whole. Firstly, the potential mechanisms underlying sensory responsiveness in ASD, with the suggestion that emotional states may be an important avenue to consider in future research. 4 Abstract Secondly, the impact of atypical sensory processing on caregivers, with particular attention paid to the compensation of these issues by caregivers, and the social implications of challenging behaviour instigated by unpleasant sensory stimuli. Thirdly, the data are discussed in light of the relationship between sensory processing and the broader autism phenotype (as measured using the AQ). The greater levels of intra-participant variability in the olfactory task (Chapter 7) are highlighted, as is the elevated sensory responsiveness of those with moderate levels of autistic traits reported in Chapters 2 and 3. The final section of the discussion deals with the limitations of the thesis, potential practical applications of the research and future directions. 5 Contents Table of Contents Contents Page Title page 1 Dedication 2 Abstract 3 Table of contents 6 List of tables 11 List of figures 12 List of publications and presentations from the thesis 14 Acknowledgements 15 Declaration 17 List of abbreviations 18 Chapter 1 – Introduction 21 1.1 Issues in ASD research 21 1.2 General sensory processing in ASD 24 1.2.1 Self-report 24 1.2.2 Parent report 26 1.3 Domain-specific Sensory Processing in ASD 27 1.3.1 Vision 27 1.3.1.1 Spatial vision 27 1.3.1.2 Colour vision 29 1.3.1.3 Motion perception 31 1.3.1.4 Visual search 33 1.3.1.5 Summary of visual processing in ASD 36 1.3.2 Audition 36 1.3.2.1 Auditory processing: pure tones 36 1.3.2.2 Auditory processing: complex tones 39 1.3.2.3 Auditory processing: speech 41 1.3.2.4 Summary of auditory processing in ASD 43 1.3.3 Touch 44 1.3.3.1 Summary of tactile processing in ASD 47 1.3.4 Smell 47 1.3.4.1 Summary of touch processing in ASD 49 1.3.5 Taste 49 1.3.5.1 Summary of taste processing in ASD 51 1.3.6 Vestibular 51 1.3.6.1 Summary of vestibular processing in ASD 53 1.3.7 Proprioception 53 1.3.7.1 Summary of proprioceptive processing in ASD 54 1.3.8 Summary of sensory processing 54 1.4 The Broader Autism Phenotype (BAP) 55 1.4.1 General 55 1.4.2 Sensory processing and the BAP 59 1.4.2.1 First-degree relatives 60 1.4.2.2 General population 62 1.4.2.3 Summary of the Broader Autism Phenotype 64 6 Contents 1.5 Theories of ASD 65 1.5.1 Cognitive 66 1.5.1.1 Theory of Mind/Extreme Male Brain Theory 66 1.5.1.2 (Weak) Central Coherence Theory 67 1.5.1.3 Executive Dysfunction Theory 68 1.5.2 Neural 69 1.5.2.1 Enhanced Perceptual Functioning Theory 69 1.5.2.2 Neural noise hypothesis 70 1.6 Aims and outline of thesis 71 Chapter 2 – Relationship between sensory issues and autistic traits 74 2.1 Introduction 74 2.2 Methods 76 2.2.1 Participants and recruitment 76 2.2.2 Materials 78 2.2.3 Missing data and comprehension difficulties 80 2.2.4 Data analysis 80 2.3 Results 80 2.3.1 Descriptive statistics 80 2.3.2 Relationship