Are emotion impairments unique to, universal, or specific in autism spectrum disorder? A comprehensive review

There is widespread belief that individuals with autism spectrum disorders (ASDs) are "emotionally detached" from others. This comprehensive review examines the empirical evidence for this assumption, addressing three critical questions: (1) Are emotion-processing impairments universal in ASD? (2) Are they specific, or can they be explained by deficits in other domains? (3) Is the emotion processing profile seen in ASD unique to these conditions? Upon review of the literature (over 200 studies), we conclude that: (1) emotion-processing impairments might not be universal in ASD, as suggested by variability across participants and across emotion-processing tasks; (2) emotion-processing impairments might not be specific to ASD, as domain-general processes appear to account for some of these impairments; and (3) the specific pattern of emotion-processing strengths and weaknesses observed in ASD, involving difficulties with processing social versus non-social, and complex versus simple emotional information (with impairments more consistently reported on implicit than explicit emotion-processing tasks), appears to be unique to ASD. The emotion-processing profile observed in ASD might be best understood as resulting from heterogeneous vulnerabilities in different components of an "emotional communication system" that, in typical development, emerges from the interplay between domain-general cognitive, social and affective processes.