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Abstract:
Last year we showed that early visual input is necessary for
the later development of configural face processing: children who
missed that input because of binocular cataracts showed deficits in
discriminating faces that differed only in the spacing of features
but performed normally in discriminating faces that differed in the
shape of individual features (Le Grand et al., 2000). Here we
investigated the importance of the binocularity of early input by
studying 11 patients who had been treated for unilateral congenital
cataract that prevented any patterned input to one eye until the
cataract was removed and the eye fitted with a compensatory contact
lens (range of deprivation 1-6 months). We tested their face
processing abilities several years later (mean age at test = 16;
range = 9-20 years); all testing was binocular. Unlike an
age-matched control group who differentiated with equal accuracy
faces that required featural vs configural processing, unilateral
cataract patients tested to date have abnormal difficulty
discriminating faces that require configural processing
(t(10)=2.59, p<.01), but perform normally in discriminating
faces that require featural processing (t(10)=0.58, p>.10). The
results imply that binocular input during early infancy is
necessary for the normal development of expertise in face
processing and are consistent with evidence that cells in temporal
cortex have binocular receptive fields.
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