Examining the time course of young and older adults' mimicry of enjoyment and nonenjoyment smiles.

Electromyographic (EMG) research suggests that implicit mimicry of happy facial expressions remains intact with age. However, age-related differences in EMG responses to enjoyment and nonenjoyment smiles have not been explored. The present study assessed younger and older adults' orbicularis oculi (O.oculi; eye) and zygomaticus major (Z.major; cheek) reactions to images of individuals displaying enjoyment and nonenjoyment smiles. Both age groups mimicked displays of enjoyment smiles, and there were no age differences in O.oculi and Z.major activity to these expressions. However, compared with younger participants, older adults showed extended O.oculi activity to nonenjoyment smiles. In an explicit ratings task, older adults were also more likely than younger participants to attribute feelings of happiness to individuals displaying both nonenjoyment and enjoyment smiles. However, participants' ratings of the happiness expressed in images of enjoyment and nonenjoyment smiles were independent of their O.oculi responding to these expressions, suggesting that mimicry and emotion recognition may reflect separate processes. Potential mechanisms underlying these findings, as well as implications for social affiliation in older adulthood, are considered.