Atypical signatures of motor variability found in an individual with ASD

Abstract

We provide objective metrics of sequential movements and study a young adolescent with Autism Spectrum Disorders (ASD) in relation to novice typical controls (TC) as they learned to perform beginners' martial–arts routines. We studied segments staged to hit an opponent simultaneously performed with supplemental segments. In TC instructed changes in speed had profound differential effects on the intended vs. supplemental segments that were absent in the ASD case. Moreover, the frequency-distribution of velocity and acceleration maxima in TC was well fitted by a Gamma distribution but in the ASD case the fit was exponential yielding uncannily precise motions with atypically low-range of spatio-temporal variability.

Keywords:

• ASD case study
• Goal-directed movements
• Supplemental movements
• motor variability
• Log-normal distribution
• Exponential distribution

Acknowledgments

We thank Uri Yarmush, our Psychology undergraduate martial arts expert who performed, instructed and supervised the routines in these motor experiments. We thank Amy Hansdford and the personnel at the Douglass Developmental Disability Center at Rutgers University for the clinical evaluations. We thank Prof. Jorge V. José for technical guidance on Statistical Mechanics and Dr. Robert W. Isenhower for useful comments. This work was funded by the NSF Cyber-Enabled Discovery and Innovation Type I (Idea) grant # 0941587 to EBT ‘A novel quantitative framework to study lack of social interactions in Autism Spectrum Disorders’ and by the New Jersey Governor's Council for Medical Research and Treatment of Autism grant # 10–403–SCH–E–0 ‘Perceptual Motor Anticipation in ASD’.