Sensitivity to Social Touch in School-Age Children with Autism Spectrum Disorders

Background: Atypical sensitivity to touch has been described frequently in children with autism spectrum disorders (ASD), although these reports have been largely anecdotal.  Existing reports cover a wide array of behaviors, including undersensitivity to pain, oversensitivity to light touch, preference for deep pressure, and atypical reaction to social touch.  Most of these reports have been qualitative, however, and few studies exist with direct, quantitative measurements of sensitivity to social touch in individuals with ASD. 

Objectives: The aim of this study was to measure selective sensitivity and response to contingent social touch in school-age children with autism spectrum disorders in comparison with matched typically-developing peers.  Control conditions measured sensitivity and response to mechanical (non-social) touch. 

Methods: We designed and built a novel device for measuring haptic interaction between two individuals or between one individual and a pre-recorded signal.  The device consisted of horizontal rollers, linked remotely, that could be turned by either of two participants.  The rollers of each participant were coupled electromechanically, so that if one participant moved a roller, the other participant would feel that movement on his or her own roller; if both participants moved their rollers, the resulting motion of each roller would be proportional to the force applied to both.  The force applied by the test participant in response to varying input signals (contingent social versus non-social, mechanical manipulation) served as the dependent variable for measuring haptic sensitivity. 

Results: We compared the behavior of 20 children with ASD and of age- and IQ-matched, typically-developing controls during non-social, mechanical manipulation tasks and during haptic social interaction.  The behavior of children with ASD was distinguished by stereotyped and repetitive movements and, in a subset of the children, by the favoring of select parts of the hand and forearm during task completion. These patterns were not observed in typically-developing children.  In addition, children with ASD, in contrast to controls, showed little change in behavior between the haptic interaction condition and the non-social, mechanical manipulation condition. 

Conclusions: These results quantify altered sensitivity and response to social touch in individuals with ASD, and serve as a platform for future studies of the development of haptic intersubjectivity: how typically-developing children, beginning in infancy, are highly sensitized to recognize certain kinds of touch as social, and to react and respond in kind.  This will be an important part of understanding atypical behavioral and neural specialization in individuals with ASD.