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Abstract:
Attention can be directed to spatial locations and to
objects. Less is known about whether spatial attention is directed
differentially to elementary features of objects. We investigated
this question in a right brain damaged subject EG by testing his
ability to detect whether targets changed in color, shape or
disappeared in right and left hemispace. Normal control subjects
were equally accurate in detecting these changes in both
hemispheres. They also reacted faster to changes in color and shape
than to the disappearance of the target. EG detected each of the
changes in his right visual field with similar accuracy (range 96%
to 98%). By contrast, in his left visual field he was less likely
to detect changes in color (66%) than shape (88%) or disappearance
(89%) of targets (Chi sq. (2) = 12.09, p<. 005). These results
cannot be accounted for by a general deficit of attention or
vigilance to the left, but suggest that spatial attention to
individual visual features (color in this case) can be
disproportionately impaired.
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