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Abstract:
Our goal was to assess age differences in perceptual priming
and skill acquisition, and to determine whether they are mediated
by cerebral shrinkage and decline in cognitive resources. Two
independent samples of healthy adults (N=97 and 68, age 18-77 and
22-80) were asked to identify common objects on line drawings,
which were degraded by deletion of segments and presented in a
descending order of fragmentation, stopping at correct recognition
(identification threshold, IT). After the training set, another set
was presented; the old pictures were interspersed with the new. The
repeated pictures IT residualized on the IT for the training
pictures indexed repetition priming; the IT for new pictures
residualized on the training IT measured skill acquisition. Volumes
of brain structures relevant to picture identification, perceptual
learning and priming (caudate nucleus, prefrontal cortex, visual
cortex, hippocampus) were obtained from MRI. The cognitive
resources were indexed by working memory. The results revealed
significant age-related increases in identification threshold and
attenuation of priming in both samples. Older age was associated
with smaller gains in skill but that trend reached significance
only in the larger sample. In both samples, visual cortex was the
only brain region associated with perceptual priming and skill
acquisition, although it was weakly related to age. No relations
among priming, skill learning and cognitive resources were
observed.
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