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Abstract:
The right hemisphere mediates aspects of both arousal and
attention (Heilman, 1995). In addition, Levy et al. (1990) suggest
that cerebral arousal is allocated adaptively based on hemispheric
specialization and/or task demands. One goal of the present study
was to determine if exposure to prior left visual field/right
hemisphere (LVF/RH) compared to right visual field/left hemisphere
(RVF/LH) stimuli enhanced performance on a right hemisphere
(vigilance) task. Sixty-eight normal adults (34 males, 34 females,
age range 18 to 80 years) pressed a key in response to the onset of
an asterisk presented to either the LVF/RH or RVF/LH. The delay
interval between the onset of a fixation cross and the onset of the
asterisk varied, with analyses performed for delay intervals of 3
s, 6-9 s, 12 s, 15-18 s. Reaction times decreased more rapidly on
LVF/RH trials than on RVF/LH trials for delay intervals ranging
from 3 to 12 s. Beyond the 12 s delay interval, reaction time
decreases continued for RVF/LH but not LVF/RH trials. Prior
stimulation/arousal of the right hemisphere increased hemispheric
asymmetries, enhancing overall reaction time performance on the
vigilance task. In other words, on trials preceded by a stimulus to
the LVF/RH, the visual field by delay interval interaction was
quite robust. On trials preceded by a stimulus to the RVF/LH, this
interaction was absent. Results of the present study thus provide
additional support for right hemisphere superiority of aspects of
arousal and attention.
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