Children's representations of facial expression and identity: identity-contingent expression aftereffects.

This investigation used adaptation aftereffects to examine developmental changes in the perception of facial expressions. Previous studies have shown that adults' perceptions of ambiguous facial expressions are biased following adaptation to intense expressions. These expression aftereffects are strong when the adapting and probe expressions share the same facial identity but are mitigated when they are posed by different identities. We extended these findings by comparing expression aftereffects and categorical boundaries in adults versus 5- to 9-year-olds (n=20/group). Children displayed adult-like aftereffects and categorical boundaries for happy/sad by 7 years of age and for fear/anger by 9 years of age. These findings suggest that both children and adults perceive expressions according to malleable dimensions in which representations of facial expression are partially integrated with facial identity.