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Abstract:
This study investigated developmental changes in the nature
and magnitude of hemispheric specialization for global and local
spatial processes. Previous research with normal and neurologically
impaired populations has suggested that integrative (global)
processes are best performed by the right hemisphere, whereas
segmentation (local) processes are a left-lateralized function.
Children 7 to 14 years of age were presented hierarchical stimuli
to the left, right or central visual field and asked to identify
shapes at the global or local level. Previous studies using this
task found that adults exhibit a large RVF advantage for local
level processing and a mild LVF advantage for global level
processing. Our results indicate several developmental trends.
First, children experienced a significant amount of interference
when information from the unattended level conflicted with that of
the attended level; an effect that decreased between 7 and 14 years
of age. Additionally, in the youngest subjects, the amount of
interference generated from the global level was greater than that
from the local level, suggesting a global attentional bias in
school aged children that diminishes with age. Lateralization of
the two spatial analytic functions also appears subject to
developmental change. Specifically, there is an increase in the RVF
advantage for local processing and a decrease in the LVF bias for
global processing, such that by age 14 children's lateralization
profiles are approaching those of adults.
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