Embodied neural responses to others' suffering.

To investigate whether and how facial mimicry in observers affects their empathic neural responses to others' pain expressions, we recorded event-related potentials (ERPs) from Chinese adults while viewing pain and neutral expressions of Asian and Caucasian faces. Facial mimicry was manipulated by allowing participants to freely move their facial muscles (the relaxed condition) or asking them to hold a pen horizontally using both teeth and lips to prevent facial muscle movement and facial mimicry (the blocked condition). We found that the frontal N1 at 100-120 ms was enlarged by pain vs. neutral expressions. The N1 modulation by facial expressions was significantly reduced in the blocked compared to relaxed conditions and this effect was observed for Asian but not Caucasian faces. The findings suggest that facial mimicry plays a causal role in the early empathic neural response and the embodied empathic neural responses are constrained by the racial intergroup relationship.