Electrophysiological correlates of perceiving and evaluating static and dynamic facial emotional expressions.

Recent evidence suggests that dynamic facial expressions of emotion unfolding over time are better recognized than static images. However, the mechanisms underlying this facilitation are unclear. Here, participants performed expression categorizations for faces displaying happy, angry, or neutral emotions either in a static image or dynamically evolving within 150 ms. Performance replicated facilitation of emotion evaluation for happy expressions in dynamic over static displays. An initial emotion effect in event-related brain potentials evidenced in the early posterior negativity (EPN) was both enhanced and prolonged when participants evaluated dynamic in comparison to static facial expressions. Following the common interpretation of the EPN, this finding suggests that the facilitation for dynamic expressions is related to enhanced activation in visual areas starting as early as 200 ms after stimulus onset, presumably due to shifts of visual attention. Enhancement due to dynamic display was also found for the late positive complex (LPC), indicating a more elaborative processing of emotional expressions under this condition at subsequent stages.