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Abstract:
In our previous work, we used a four-item divided
visual-field variant of the attentional blink paradigm to
demonstrate that under limited circumstances, the cerebral
hemispheres can consolidate visual items in parallel. Subjects
identified two target letters that appeared among numeric
distractor items. We hypothesized that the limited benefits of
parallel processing to performance was due to the difficulty of
consolidating letters among highly perceptually similar objects
such as numbers. In the current studies, we systematically
decreased the difficulty of discriminating letters from the
surrounding distractor items. Our first study used distractors
discriminated from letters with moderate difficulty, while our
second used distractor items discriminated from letters with little
difficulty. When we compared the results from the three studies, we
found that the attentional blink decreased as the perceptual
similarity of the letters and distractor items decreased. We also
found that when distractors were of moderate demand, targets
directed to opposite hemispheres were better identified than were
target items directed to the same hemisphere. When distractors of
low demand were used, however, the Attentional Blink was not
modulated as a function of the distribution of target items between
the hemispheres. These studies demonstrate that the benefits of
parallel processing to visual attention vary with attentional
demand.
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