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Abstract:
In the present study, we found a similar pattern of
bihemispheric processing for auditory stimuli as was previously
observed by Banich and Karol (1992) in the visual modality. These
studies investigated whether redundancy of different aspects of
information influences bihemispheric processing. More specifically,
we examined how bihemispheric processing was affected by an item's
identity as compared to the response it engenders. To do so, we
presented a target number simultaneously to each ear (e.g., 1-1).
After a 100 msec interstimulus interval, a pair of probe items was
dichotically presented. On unilateral trials, the pair was composed
of a number and an animal name (e.g., 3-fox). On bilateral trials,
two numbers were presented simultaneously, one to each ear.
Participants decided whether either of the two probe numbers
matched the target in terms of numeric category (i.e., odd or
even). On bilateral trials, we varied the manner in which the
information presented was redundant. On some trials the items were
identical and led to the same decision (e.g., 3-3); on others, the
items were different but still led to the same decision (e.g.,
3-5), and on still others, the items were different and also led to
a different decision (e.g., 3-4). Facilitation in performance
compared to a unilateral baseline was observed when the items
presented to each ear were identical, but not when they were
dissimilar. By extending Banich and Karol's results (1992) to the
auditory modality, we demonstrate that bihemispheric processing is
not strongly modulated by the type of sensory channel used.
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