Separate mechanisms for the structural encoding of faces and the processing of age or gender

In our previous study based on a similar paradigm (Mouchetant-Rostaing et al., 2000a), we had found that gender processing of faces had no effect on the occipito-temporal N170 ERP component, assumed to be associated with the neurophysiological mechanisms subtending the structural encoding of facial features (Bentin et al., 1996; George et al., 1996; Jeffreys, 1996).

The present experiment replicates this finding for gender and reveals similar results for age processing (the only effect being a slight delay of 3 msec on the N170 peak latency when age could be incidentally processed). The major results therefore indicate that the perceptual analysis of faces and the processing of physiognomic features related to age or gender are mostly performed by different brain mechanisms. This conclusion supports the Bruce and Young’s model (1986), which assumes the existence of two functionally distinct modules for the structural encoding of facial features and the age or gender extraction, referred to as the Structural and the Directed Visual encoding modules, respectively.