The purpose of this study is to investigate whether autistic children show more aversive response to social stimuli than non-autistic children. The heart rate (HR) responses of six autistic and six mental retarded children were compared under the two conditions which varyed in novelty of social stimuli.
The results were as follows. (1) In the mental retarded group, the deceleration of their HRs was greater under the high novelty condition than the low novelty condition, while the HR changes of autistic group showed no difference between each condition. (2) The HR responses of the autistic children could be distinguished into three types: accelerated type, deccelerated type, low reactive type. (3) The accelerated type showed most serious impairment of the social interaction (e. g. He always avoids other persons.). The deccelerated type showed least impairment of the social interaction which was similar to mental retarded children's. The low reactive type showed moderate impairment of the social interaction.