Atypical autonomic nervous system complexity accompanies social cognition task performance in ASD

•Autonomic nervous system (ANS) function is important in ASD.•Existing analytical techniques are limited in their ability to model and complexity.•We introduced a new method for ANS quantification in ASD using multi-scale entropy.•Results revealed a decrease for short term patterns and an increase in long term pattern in ASD.•Results are consistent with parasympathetic differences in ASD as well as decreasing couple between ANS components.