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Abstract:
Past research has shown that specific-exemplar shape
recognition and metric spatial-relations encoding rely on
subsystems that operate more efficiently in the right cerebral
hemisphere than in the left. In contrast, abstract-category shape
recognition and categorical spatial-relations encoding rely on
subsystems that operate more efficiently in the left cerebral
hemisphere than in the right. How does the lateralization of one
neural subsystem relate with the lateralizations of other neural
subsystems? In a divided-visual-field experiment, we examined
performance in specific and abstract shape recognition and in
metric and categorical spatial-relations encoding, in the same set
of participants. Results demonstrated that asymmetries within
individual participants often do not reflect the population-level
asymmetries, and that the lateralizations of different subsystems
may be statistically independent of one another. These findings
suggest that lateralizations of shape-recognition and
spatial-relations subsystems are not due to a common asymmetry in
early visual processing (e.g., in spatial-frequency filters), and
that complementary (e.g., metric vs. categorical) processes are not
consistently lateralized to opposite hemispheres. Lateralizations
of neural subsystems may be based instead on learning that is
unique to individual participants but yields reliable
population-level asymmetries.
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