Spontaneous facial mimicry in response to dynamic facial expressions

Based on previous neuroscientific evidence indicating activation of the mirror neuron system in response to dynamic actions, we hypothesized that facial mimicry would occur while subjects viewed dynamic facial expressions. To test this hypothesis, dynamic/static facial expressions of anger/happiness were presented to 18 subjects. The subjects´ facial actions were unobtrusively videotaped and blindly coded. In dynamic presentations, brow lowering, a prototypical action in angry expressions, occurred more frequently in response to angry expressions than to happy expressions. The pulling of lip corners, a prototypical action in happy expressions, occurred more frequently in response to happy expressions than to angry expressions in dynamic presentations. The mean latency of these actions was less than 900ms after the onset of dynamic changes in facial expression. These results indicate that dynamic facial expressions elicit spontaneous and rapid facial mimicry, which functions both as a form of intra-individual processing and as inter-individual communication