Repetitive behaviors are one of the three core symptoms of Autism Spectrum Disorder (ASD). Given the prevalence of repetitive behaviors, their diverse manifestations, and their potential to create profound functional impairment, the dearth of research on repetitive behaviors in ASD is surprising. Researchers tend to describe repetitive behaviors as maladaptive and occurring without reason (MacDonald et al., 2007; Matson & Dempsey, 2008). In contrast, many individuals with ASD describe repetitive behaviors as a way of coping with sensory processing (Yack, Sutton & Aquilla, 2003).
Sensory behaviors are well-associated clinical features of ASD. These behaviors are more common in individuals with ASD than those with intellectual disability (Baranek et al., 2007; Rogers, Hepburn & Wehner, 2004). A recent study found that 88% of children with ASD have difficulties with sensory processing (Minshew & Hobson, 2008). Sensory behaviors may be related to patterns of repetitive behaviors in some individuals with ASD; however, empirical investigation into this relationship has been minimal. Separately, the presence of repetitive behaviors and the presence of sensory behaviors have been found to be inversely related to mental age in children with ASD (Baranek et al. 2007; Bishop, Richler, & Lord, 2006).
The current study was designed to extend the research on repetitive behaviors and sensory behaviors – particularly Boyd et al. (2009 & 2010), and Gabriels et al. (2008) – by quantitatively investigating their relationship while (a) employing a reliable measure of repetitive behaviors, the Repetitive Behavior Scale-Revised (RBS-R), (b) employing a reliable measure of sensory behaviors, the Sensory Profile, (c) analyzing the subdomains of each measure, and (d) co-varying a consistent measure of cognitive ability.
Data was collected from 35 children with ASD aged 3 to 11 years (M = 6.4 years, SD = 2.2 years; 29 males). Diagnostic status was confirmed by the Autism Diagnostic Observation Schedule – two children were excluded from analysis for not meeting the cut-off. Cognitive ability was measured using the Differential Abilities Scales. Our primary analysis examined correlations between repetitive behaviors, sensory behaviors, and autism severity as measured by the RBS-R, Sensory Profile, and Social Communication Questionnaire, respectively. Overlapping items between the three tests were removed.
A positive correlation was found between sensory behaviors and repetitive behaviors, r(31) = .70, p < .001, after partialling out mental age. No significant correlations were found between these factors and autism severity. A correlation matrix was computed for the five RBS-R factors and six Sensory Profile processing domains. After correcting for multiple comparisons, this analysis revealed that reports of the factors stereotyped behavior and ritualistic/sameness behavior had the strongest correlations with sensory behaviors in this sample, over the factors self-injurious behavior, compulsive behavior, and restricted interests.
This study found a significant relationship between parent-reports of sensory processing difficulties and repetitive behaviors in children with ASD, controlling for the effects of mental age: More frequent sensory behaviors related to more frequent and severe RBs. This study also suggests that ritualistic/sameness behavior and stereotyped behavior may have the strongest relationship with sensory behaviors.
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