Exploring the Mechanisms Underlying Reduced Emotion Contagion in Autism Spectrum Disorders

Background: Why is laughter ‘contagious’ and why might it be less contagious for people with autism spectrum disorders (ASD)? Typical adults often find certain emotional expressions contagious, particularly laughter. Observing someone laughing frequently results in the observer reciprocating laughter, even if the reason for the original laughter is unknown (Dimberg, 1982). This emotion contagion is suggested to have developed to serve a social function, bonding individuals involved in an interaction (Provine, 2005). Emotion contagion is thought to involve three processes: 1) a physiological response via the sympathetic nervous system 2) internalisation of the observed emotion in the form of a perceived change in subjective mood 3) mirroring the observed emotion by imitating the expression (laughing back).

Objectives: Recent research and numerous case reports suggest that people with ASD are less likely to demonstrate emotion contagion than typical people (Helt, Eigsti, Synder & Fein, 2010) but the reason for this reduced emotion contagion is unknown. The objective of the present research was to identify which of the three processes involved in emotion contagion is impaired in ASD by measuring physiological responses, changes in subjective mood, and time spent mirroring emotions, in adult participants with ASD compared to matched controls.

Methods: Twenty-two participants with ASD (20 males; Mean age = 22.2 years) were matched with 22 controls (20 males; Mean age = 21.1 years) on gender, age and National Adult Reading Test score. Participants viewed three naturalistic video montages of strangers laughing, yawning and crying. Physiological responses to the videos were measured using galvanic skin conductance recording throughout viewing. Internalisation of emotions was measured by comparing pre-and post-video questionnaire responses, in which participants rated their subjective moods. Mirroring was measured by video recording and subsequently coding the amount of time participants spent reciprocating the observed emotion using their facial expressions.

Results: The three processes were analysed separately using 2 (ASD, controls) x 3 (observing laughter, yawning, crying) mixed ANOVAs. Participants in the ASD group showed comparable skin conductance responses to controls while observing emotional expressions (p>.05). However, they were significantly less likely to perceive changes in their own emotions as a result of viewing emotional expressions (p<.01) and they also spent significantly less time than controls mirroring the observed emotions through their facial expressions (p<.001). This was particularly true for laughter, where the largest discrepancies between the ASD and control groups were found (p<.001).

Conclusions: Participants with ASD showed the same physiological reactions as controls to observing emotional expressions, which suggests a typically functioning sympathetic nervous system. However, they were significantly less likely to internalise or mirror these expressions, particularly laughter. Emotion contagion is thought to foster social cohesion, and sharing positive emotions may promote strong positive bonds between individuals. Consequently, this reduced emotion contagion in people with ASD, particularly noticeable for laughter, is likely to further impede social relationships, which may already be difficult.