The Sensory Profile: An Investigation of Its Relationship with Experimentally Measured Sensory Thresholds in Adults with Autism Spectrum Conditions

Background: Anecdotal reports suggest sensory differences in autism spectrum conditions (ASC) (Grandin, 2006; Chamak et al, 2008). In fact, the Sensory Profile, a questionnaire measure, finds differences in sensory processing in over 90% of children with ASC (Kientz & Dunn, 1997; Tomcheck & Dunn, 1997; Watling et al, 2001, Wiggins et al, 2009), adults with ASC (Crane et al, 2009, Kern et al 2007), and across cultures (Cheung & Siu, 2009). Scores on the Sensory Profile have been correlated with repetitive behaviours (Chen et al, 2009), stress levels (Corbett et al, 2009) and skin conductance (Brown et al, 2001). However no study to date has investigated the link between Sensory Profile scores and experimentally measured sensory thresholds.

Objectives: We aimed to test if a) adults with ASC differed in Sensory Profile scores or b) sensory thresholds, and c) to investigate whether the Sensory Profile scores show any relationship with experimentally measured sensory thresholds in vision, touch, hearing, taste, and smell.

Methods: 24 adults with ASC were matched to 30 control participants on age, sex and IQ. The Sensory Profile was administered, and scores calculated for the following subscales, both in sum and modality-specific: Low Registration, Sensation Seeking, Sensory Sensitivity and Sensation Avoiding. Sensory thresholds in vision were measured by a qualified optometrist assessing clinical visual functioning as well as experimentally tested visual acuity measured by the FrACT. Tactile spatial acuity was measured using the 'Domes gratings', and tactile sensitivity thresholds were measured using the 'Semmes Weinstein Von Frey Aesthesiometer' on both the fingertip and the arm. Hearing thresholds for low, middle and high frequencies were measured using the 'Audio-CD'. Taste thresholds were measured by the 'Taste strips' for sweet, sour, bitter, and salty tastes. Finally, the smell threshold was measured using 'Sniffin sticks'.

Results: Adults with ASC showed differences on all subscales of the Sensory Profile. They had higher scores in Low Registration (U: 82.5, p=0.002), Sensory Sensitivity (U: 87.5, p=0.003), Sensation Avoiding (U: 36, p< 0.00) and lower scores in Sensation Seeking (U: 42, p<0.00). Regarding the experimentally measured sensory thresholds, the ASC group had higher taste thresholds overall (U: 146, p=0.002), but otherwise did not differ to controls. Correlations between Sensory Profile subscales and experimentally measured sensory thresholds were surprisingly few and are reported.

Conclusions: The current experiment confirms differences in the Sensory Profile scores between adults with ASC as compared to controls. However, the few relationships between Sensory Profile subscale scores and experimentally measured sensory thresholds suggest these two methods may measure different sensory constructs.