Reduced representational momentum for subtle dynamic facial expressions in individuals with autism spectrum disorders

• The subjective perception of dynamic facial expressions was investigated in ASD.
• They perceive dynamic facial expressions to be more exaggerated than static ones.
• A between-group difference was evident when facial expressions were subtle.
• Exaggeration of emotional intensity is lower in extent in ASD than controls.
• Such reduced perception of emotional intensity might cause social impairment.

The cognitive mechanisms underlying social communication via emotional facial expressions are crucial for understanding the social impairments experienced by people with autism spectrum disorders (ASD). A recent study (Yoshikawa & Sato, 2008) found that typically developing individuals perceived the last image from a dynamic facial expression to be more emotionally exaggerated than a static facial expression; this perceptual difference is termed representational momentum (RM) for dynamic facial expressions. RM for dynamic facial expressions might be useful for detecting emotion in another's face and for predicting behavior changes. We examined RM for dynamic facial expressions using facial expression stimuli at three levels of emotional intensity (subtle, medium, and extreme) in people with ASD. We predicted that individuals with ASD would show reduced RM for dynamic facial expressions. Eleven individuals with ASD (three with Asperger's disorder and eight with pervasive developmental disorder not otherwise specified) and 11 IQ-, age- and gender-matched typically developing controls participated in this study. Participants were asked to select an image that matched the final image from dynamic and static facial expressions. Our results revealed that subjectively perceived images were more exaggerated for the dynamic than for the static presentation under all levels of intensity and in both groups. The ASD group, however, perceived a reduced degree of exaggeration for dynamic facial expressions under the subtle intensity condition. As facial expressions are often displayed subtly in daily communications, reduced RM for subtle dynamic facial expressions may prevent individuals with ASD from appropriately interacting with other people as a consequence of their difficulty detecting others’ emotions.