Stereotypical motor movements are one of the most common and least understood behaviors occurring in individuals with Autism Spectrum Disorder (ASD). When severe, engagement in these behaviors can lead to social stigmatization and complicate social interaction. Moreover, if a stereotypical motor movement becomes a dominant behavior in an individual's repertoire, it can interfere with the performance of established skills and acquisition of new skills, and may lead to self-injurious behavior.
Stereotypical motor movements are complex and thought to serve a multiplicity of functions. However, problems with traditional methods for measuring stereotypical motor movements have made it difficult to determine when and why these behaviors occur. In an effort to overcome these measurement problems, two studies, one conducted in a laboratory setting and the other in a classroom setting, were undertaken to evaluate the use of wireless accelerometers and pattern recognition software to automatically detect two of the most common, high frequency stereotypical motor movements, body rocking and hand flapping , in children with ASD.
The system developed used three small, unobtrusive wireless and wearable movement sensors placed on participants' left wrist, right wrist, and torso. Both studies employed an idiographic approach, focusing on the individual in a series of six single case studies. In addition to excellent compliance and performance with the sensors across settings, findings revealed that, on average, automated classification algorithms correctly identified approximately 90% of stereotypical motor movements observed in the laboratory and approximately 85% observed in the class.
Taken together, new algorithms for body rocking and hand flapping detection were developed that advance the state-of-the-art in stereotypical motor movement monitoring in children with ASD, for use in both laboratory and naturalistic settings. Obtaining detailed and accurate information on the occurrence, type of movement, frequency, and duration of stereotypical motor movements is critical to understanding and treating this potentially disruptive behavior. Precise recording of stereotypical motor movements will enable researchers to study what functional relations may exist between these behaviors and specific antecedents and consequences. These measures can also facilitate efficacy studies of behavioral and pharmacologic intervention intended to decrease the incidence or severity of stereotypical motor movements.
