The effects of eye and face inversion on the early stages of gaze direction perception--an ERP study.

Eye direction perception is highly important for social cognition. However, the neural mechanism underlying gaze direction perception has not been well elucidated. The present study aimed to examine the specific neural mechanism of gaze direction perception by investigating how the event related potential components, which presumably reflect the early stages of face processing, are affected by inverting eye region and face context, i.e., facial parts other than eye region. The results showed that eye region inversion significantly delayed the peak latency of the N170 component. At the same time, N170 latency was also delayed by inverting face context alone. Moreover, we observed that the P100 latency was delayed by inverting the eye region in an upright face context, but not in an inverted face context. We suggest that N170 reflects the eye-sensitive cortical response, but also the processing of other facial regions, and that the processing of eye region begins at an early stage of face processing, around 100 ms after stimulus onset.