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Abstract:
Abstract: We previously found that when processing demands
are low the processing of target information presented to one
hemisphere can be relatively insulated from task-irrelevant
information presented to the opposite hemisphere (Passarotti and
Banich, 1998;1999). Here we examined whether this effect is limited
to a division of target and task-irrelevant information across the
hemispheres, or whether similar suppression of task-irrelevant
information occurs when it is directed to the same hemisphere as
the target. In addition, we investigated whether these effects
varied as a function of processing load. Two hierarchical letters
(e.g., a global "S" composed of small "Hs") were presented, either
one in each visual field (across-field trials) or both to the same
visual field (within-field trials). Participants indicated the
identity (e.g., H or S) at a pre-assigned level (i.e., global or
local) of the target letter, which was cued by an asterisk. Under
low processing demands the global and local aspects of the target
were the same and therefore there was little interference between
them. But under higher processing demands they differed, which
created some interference. Our results confirmed that previous
findings are specifically due to the relative insulation of
irrelevant information across the hemispheres, because there was
little suppression of task-irrelevant information for within-field
trials, no matter whether processing demands were high or
low.
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