Abstract
Social functioning is a key domain of impairment in both autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD). This review adopts the social information-processing model as the theoretical framework to compare and contrast the deficits of ASD and ADHD at each of the six steps of social information-processing. Both disorders show deficits at each step, but the nature and origins of the deficits are different. Thus, while both disorders exhibit a common outcome of social impairment, the exact pathways that each disorder traverses along the six steps of social information-processing are different. For ASD, there is a social knowledge/behaviour deficit arising from difficulties in social/emotional cue detection, encoding, and interpretation, leading to problems in joining and initiating social interaction. For ADHD, there is a performance deficit incurred by disruption arising from the ADHD symptoms of inattention and hyperactivity/impulsivity, while its acquisition capacity on social knowledge is relatively intact. The inattentive, intrusive, and impulsive behaviours of ADHD unsettle social interaction. Finally, this review proposes training targets for intervention along the six steps of the social information-processing model for ASD and ADHD, as well as areas for future research in further elucidating the social impairment of the two disorders.