Familiarity facilitates the corticocortical processing of face perception

The visual evoked potentials elicited by mosaic pictures were used to elucidate the initial step of face perception. Three different mosaic levels (subthreshold, threshold, suprathreshold) for familiar and unfamiliar faces and objects were randomly presented for 250 ms. The latencies of occipital N1 and posterior-temporal N2 were shortened by decreasing the mosaic levels of faces but not for object. The N2 amplitude significantly increased at threshold and suprathreshold levels for familiar and unfamiliar faces. The latency difference between N1 and N2 at threshold level for a familiar face was significantly shortened compared with that for an unfamiliar face. Our findings suggest the initial step of face perception is already set in the primary visual cortex, and familiarity can facilitate the corticocortical processing of face information.