Spatio-temporal localization of the face inversion effect: an event-related potentials study

Event-related potentials (ERPs) from 58 electrodes at standard EEG sites were recorded while 14 subjects performed a delayed-matching task on normal and inverted faces. A large and single difference between normal and inverted face processing was observed at occipito-temporal sites about 160 ms following stimulus onset, mainly in the right hemisphere (RH). Although the topographies indicate that similar areas are involved at this latency in processing the two types of stimuli, the electrophysiological activity, which corresponds to the previously described N170, was larger and delayed for inverted as compared to normal face processing. These results complement and specify, at a neural level, previous behavioral and divided visual field studies which have suggested that the loss of configural face information by inversion may slow down and increase the difficulty of face processing, particularly in the RH.