What methods are used to measure sensory behaviours in ASD?

The majority of research that has been conducted on the sensory symptoms in individuals with ASD has been conducted using parent report measures. In the large majority of cases this has been conducted with the Sensory Profile (Dunn, 1999) or the Short Sensory Profile (McIntosh, Miller,

98 Shyu, & Dunn, 1999; Tomchek & Dunn, 2007). The Sensory Profile was designed in order to measure the reactions of both children with and without disabilities to frequently occurring sensory input. The full Sensory Profile consists of 125 parent report items which are rated on how frequently the sensory response is seen in their child. It covers eight modalities (Auditory, Visual, Activity level, Taste/smell, Body position, Movement, Touch & Social/emotional) as well as the four “quadrants” proposed by (Dunn (1997), 1999)) and colleagues (Dunn et al., 2002). These quadrants are based on an individual’s neurological threshold and the individual’s response to sensory input: passive

responses to sensory input are categorised as either “low registration” if the individual’s

neurological threshold is high or “sensory sensitivity” if their threshold is low. Active responses in individuals with a high threshold are classed as “sensory seeking” and active responses in individuals with a low threshold are termed “sensory avoidance.” In addition, a number of other parent-report instruments have also been used in the sensory literature such as the Sensory Experiences

Questionnaire (Baranek et al., 2006), the Sensory Sensitivity Questionnaire-Revised (Talay-Ongan & Wood, 2000), the Sensory Profile Checklist-Revised (Bogdashina, 2003) and the Sensory Processing Measure (Glennon, Miller-Kuhaneck, Henry, Parham, & Ecker, 2007).

All of these instruments utilise parent’s report of individuals’ sensory functioning. This has two inherent limitations. Firstly, the majority of research findings are based on research with

children and this can severely impact on the implications of these findings for individuals across their lifespan. Secondly, a limitation of parent report data is that it only measures a caregiver’s

interpretation of an individuals’ behaviour and parent/caregiver report has also been found to be discrepant with self-report in other behaviour domains such as emotional and behavioural problems (Achenbach, McConaughy, & Howell, 1987). This is particularly relevant to the consideration of sensory behaviours and how individuals interpret sensory information as this is an extremely personal level and also parents often attach reasons behind their child’s behaviour that may be more social than sensory i.e. does not like being in crowds, when instead it may be the noises which are affecting the individuals behaviour. Autobiographical accounts overcome these limitations such as Temple Grandin “the nerve endings on my skin were supersensitive. Stimuli that were

insignificant to most people were like Chinese water torture” (Grandin & Scarino, 1996). However, although these accounts are rich in detail they are less useful for research because they stem from the individual’s subjective account and only from that individuals’ perspective and therefore cannot be generalised to other individuals with ASD, in addition, these accounts tend to be from high functioning individuals which again limits their applicability to individuals with intellectual disability or non-verbal individuals.

99 Self-report questionnaires are another way of measuring individual’s sensory behaviours in ASD. Again the Sensory Profile is the most widely used; the Sensory Profile has been adjusted from parent to self-report for use with adults or adolescents (Adult and Adolescent Sensory Profile, AASP; Brown & Dunn, 2002). Crane, Goddard, and Pring (2009) used the AASP and found 94.4% of

individuals with ASD had an extreme sensory behaviour on at least one domain but also found a large amount of variability across the ASD group. This contrasts with many findings using parent reports that suggest that sensory behaviour abate with age (see Section 4.1.3.3 below). This indicates that individuals with ASD may learn to use coping strategies to deal with sensory input even though they are still affected by sensory problems and this may lead parent or caregiver reports to be inaccurate as they can only report what is observable (Robertson, 2012).

The only other questionnaire available for capturing sensory behaviours in a self-report format, at the time of study design, was the Highly Sensitive Persons Scale (HSP; Aron & Aron, 1997). Although research has found the measure to be reliable and have good levels of internal consistency (Aron & Aron, 1997; Liss, Mailloux, & Erchull, 2008) the behaviours asked about in this scale vary widely from behaviours that are relevant to ASD e.g. “I am bothered by intense stimuli, like loud noises or chaotic scenes” to others which are unlikely to be relevant to sensory behaviours in ASD such as “a rich, complex inner life” and this scale has not been validated in the ASD population. Both of the existing self-report questionnaires have two main limitations. Firstly neither were designed to measure sensory behaviours that are present specifically in autism. In addition, both questionnaires contain items that overlap with behaviours used in the diagnosis of autism such as “I like to go to places that have bright lights and that are colourful” or “I touch others when I am talking (for example, I put my hand on their should or shake their hands)” in the AASP and “I make it a high priority to arrange my life to avoid upsetting or overwhelming situations” in the HSP, which limits the conclusions that can be made when either tool is compared to the “core” or diagnostically relevant features of ASD as the correlations may be inflated by both measures containing similar items rather than a relation between distinct behaviours. However, the majority of research in this area has used Dunn’s model of Sensory modulation problems and the Sensory Profile, Short Sensory Profile or AASP.

Since I carried out the study design that is reported in Study 2 (below), another sensory behaviour self-report tool has been designed. Robertson and Simmons (2013) developed the Glasgow Sensory Profile. This questionnaire allows measurement of proprioceptive, vestibular, taste and smell modalities separately, which are combined as “taste/smell” and “movement” in the AASP as well as measures of visual, auditory and touch sensitivity. This questionnaire is less dependent on the quadrants proposed by Dunn that may not be relevant to individuals with ASD. Robertson and

100 Simmons (2013) found scores on this measure were significantly related to individual’s scores of the Autism Spectrum Quotient, designed to measure autistic traits in the typical population but did not specifically recruit individuals with ASD into the study.