The time-course of face processing: evidence from studies on the N170 face-sensitive component

Rossion, B.
University of Louvain, Belgium

Electrophysiological recordings on the human scalp have shown that the processing of faces and other objects start to differ reliably between about 130 and 170 ms following stimulus onset: faces elicit a larger occipito-temporal N170 than other object categories. Here I will review evidence from a number of electrophysiological studies showing that the N170 reflects much more than the simple occurrence of a face-specific detection system, and can be used as a tool to clarify the time-course of face and object processing stages. EEG analysis suggests that the N170 is the only scalp electrophysiological response that differs between the perception of faces and objects (but also among object categories), thus probably carrying information about several object and face categorization stages. In agreement with this proposal, it will be argued that (1) multiple cortical sources contribute to elicit the N170, with perhaps little contribution from face-sensitive areas in the middle fusiform gyrus; (2) faces and non-face objects in a domain of expertise compete for the same visual processes reflected by the N170 during object categorization; (3) both the detection of a face (vs. non-face object categories) and the individual recognition of faces occur at this level.