Aims and outline of the thesis

The overall aim of the thesis is to examine the sensory issues present in those with a diagnosis of ASD, as well as in individuals who exhibit higher-than-typical levels of autistic traits. The direct measurement data for sensory sensitivities in ASD are extremely variable, across all the sensory domains. As a result of the hyper-sensitive responses exhibited by many individuals with ASD, experimenters have concentrated on measuring absolute detection thresholds in a variety of sensory domains, with the majority of studies finding no differences (Bennetto et al., 2007; Bertone et al., 2005; Güçlü et al., 2007; Jones et al., 2009; Pellicano et al., 2005; Tavassoli & Baron-Cohen, 2012a). It would appear that the sensory issues experienced by many with ASD could be far more complex than

lowered thresholds; it may be the way that the brain deals with the stimuli that is of greater importance. Therefore, the work presented in this thesis concentrates on the sensory experiences that those with ASD (and the broader phenotype) have. It is hoped that by elucidating the common triggers, coping mechanisms and impact of sensory stimuli, that a) improved experimental paradigms for assessing sensory atypicalities in ASD and b) an environmental intervention to help increase accessibility could be developed. As there is increasing evidence for the role of an endophenotype in ASD, the sensory issues of those with elevated autistic traits will also be reported. Overviews of the other chapters in the thesis are provided below.

In Chapter 2, I report the results of a questionnaire-based study assessing atypical sensory experiences in those with varying levels of autistic traits. The sensory questionnaire was constructed and developed by us, and used alongside a standard questionnaire for

determining autistic traits (Baron-Cohen et al., 2001). The purpose of the study was to determine whether there was a relationship between number of autistic traits (measured by the AQ; Baron-Cohen et al., 2001) and sensory sensitivities (measured by the GSQ;

Robertson & Simmons, 2012). Both hyper- and hypo-sensitivities were assessed over seven modalities (vision, audition, gustation, olfaction, touch, vestibular processing and proprioception). After the preliminary data analysis, a principal components analysis was performed in order to reduce the number of questions in GSQ. Data from the development of the GSQ, as well as from the experiment proper are presented in Chapter 2. The results are discussed in relation to the literature on self- and parent-report data on sensory

sensitivities in ASD.

In Chapter 3, I report the results of responses to four open questions about sensory issues from a broad population, with participants (n=212) also completing the AQ. These data were analysed using mixed methods. Two themes were drawn from these data using thematic analysis and frequency comparisons were made across sub-groups. Data are presented in Chapter 3 and the results are critiqued in comparison to relevant studies.

The aim of the research described in Chapter 4 was to investigate the sensory experiences of children with a diagnosis of autism. This involved conducting two separate studies: a focus group with caregivers of those with autism and small group interactive interviews with children who had autism. Nine participants took part in the caregiver focus group.

Caregivers provided negative and positive examples of interaction with sensory stimuli and described the impact that this could have on their child, as well as themselves.

Furthermore, children with a diagnosis of autism (n=10) participated in one of three group interviews, where they were asked questions in a short semi-structured interview format.

They also took part in interactive ‘experiments’ designed to elicit descriptions of tactile, auditory and olfactory stimuli. The data from these studies are discussed, in relation to both self-report and direct measurement literature, in Chapter 4.

The purpose of the study described in Chapter 5 was to elucidate information about the nature and impact of sensory issues directly from those with a diagnosis of ASD. This involved conducting a focus group study with a group of adults working for a local

company that employs those with a diagnosis of ASD. Thematic analysis showed that there

were four main themes, and that negative affect could impact on the response to sensory stimuli. Both positive and negative interactions with sensory stimuli were reported.

In Chapter 6, the results from a group discussion of older adults are reported. The purpose of this study was to determine the effect that naturally-occurring sensory changes in older adults could have, on both the individuals themselves and their relatives. Three themes were drawn from these data, showing that sensory issues were a problem concomitant with normal ageing. Data are presented in Chapter 6 and the results are critiqued in comparison to our findings from the ASD population as well as relevant studies.

The aim of the study reported in Chapter 7 was to determine whether there were any significant differences in the olfactory thresholds, discrimination abilities and

identification skills of those with high and low levels of autistic traits. Participants in the general population were administered the AQ and the Sniffin’ Sticks Extended Test (n=106), with a sub-group also being given the GSQ developed in Chapter 2 (n=62).

These data are presented in Chapter 7, with results discussed in light of recent evidence of increased intra-participant variability in ASD (Gowen & Hamilton, 2012; Milne, 2011;

Simmons et al., 2009).

The purpose of the pilot study described in Chapter 8 was to develop a freely available and systematic method of assessing an environment, highlighting any difficulties, and

ameliorating associated problems. In order to do this, we worked in conjunction with a local company employing those with ASD, as well as determining the most problematic causes of sensory discomfort from the studies described in Chapters 3-5. Data of a) how the sensory audit was developed and b) the results of the pilot sensory audit are reported in Chapter 8, along with potential practical applications of the Sensory Audit and ideas for future development.

In Chapter 9, the results of all the studies are summarised and compared to each other and the literature. In addition, the data are discussed in relation to a) the potential mechanisms underlying sensory issues, b) the implications of atypical sensory processing for caregivers and c) the relationship between atypical sensory processing and the broader phenotype. In addition, the practical applications of the work discussed in this thesis and the potential future directions of research in this field are discussed.

Chapter 2 The Relationship between sensory issues