Robertson, Ashley E.
Sensory experiences of individuals with Autism Spectrum Disorder and autistic traits: a mixed methods approach.
PhD thesis, University of Glasgow.
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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 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. 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.
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