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Abstract:
Humans are better at discriminating faces of their own
ethnies than faces of another ethnies, the so-called 'other race
effect'. However, recent behavioral evidence suggest that subjects
are quicker at detecting other-race faces than own-race faces. To
track the spatio-temporal correlates of these observations, 64
channel ERPs were recorded in 12 caucasian face subjects presented
with upright and upside-down pictures of asian, african, and
caucasian faces. Stimuli were randomly presented for 500 ms (ISI
between 1000-1500 ms) and subjects had to determine the orientation
of the face. All stimuli gave rise to a clear N170
occipito-temporal component, which was delayed and increased for
inverted faces, regardless of the race of the faces. Two-by-two
subtraction analyses revealed an early (130 ms) occipito-temporal
difference between own-race faces and other-race faces. This
apparent amplitude difference was caused by an earlier P1 and N170
to other race faces. No difference was found between african and
asian faces. The effect was not observed when faces were presented
upside-down, and is thus unrelated to basic visual differences
between distinct race face stimuli. These observations complement a
previous study on upright caucasian and asian faces, showing that
detection of other race faces occurs very early in the human brain,
in bilateral occipito-temporal regions.
Supported by Belgium National Fund for Scientific Research
(FNRS)
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