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Abstract:
This event-related potential (ERP) study was designed to
examine the neurophysiological correlates of age and gender
perception on faces. The experiment included four conditions. In
one condition, young and old female faces were delivered in
separate runs, preventing any age and gender categorization. In a
second condition where the age was irrelevant for the task, faces
of both young and old women were randomly intermixed in the same
run, thus possibly inducing incidental age categorization. In the
third and fourth conditions, faces were intentionally categorized
according to their age and their gender, respectively. We found
that neither age nor gender processing had effect on the N170
occipito-temporal component, supposed to reflect on the scalp the
structural encoding of faces. Later effects, starting from about
200 ms, were observed over occipito-parietal regions for the
intentional conditions ; they lasted longer (up to around 400 ms)
for age than for gender processing. These results bring
electrophysiological support to Bruce and Young's model (1986),
that assumes the existence of separate modules for face perception
: one designed to the structural encoding of facial features, the
other, acting sequentially, supposed to process the age, gender, or
race in faces. Additional early ERP differences were found at
central sites around 40-90 ms and 140-190 ms. These findings
suggest that higher aspects of visual processing, possibly related
to categorization processes between wide stimulus classes, may be
achieved very rapidly.
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