Date of Award

1990

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Psychology

First Advisor

William D. Gouvier

Abstract

Hemispatial neglect is a visual-perceptual disorder characterized by a conscious and otherwise alert individual's failure to respond to a meaningful stimulus presented to the side opposite a right hemisphere brain lesion. In recent years researchers have demonstrated the existence of a neglect phenomenon in normal subjects which appears as the opposite of that experienced by brain injured subjects. This phenomenon is referred to as "pseudoneglect" and is demonstrated by horizontal line bisection to the left of true center. Researchers have suggested that pseudoneglect may be explained by preferential right hemisphere processing for visuospatial stimulation. The purpose of this study was to determine how the demonstration of pseudoneglect correlates with a valid measure of right hemisphere processing efficiency and contrasts with a valid measure of left hemisphere processing efficiency. In addition, a test-retest condition was included to determine the stability of pseudoneglect over time. The tasks used to demonstrate pseudoneglect were a paper and pencil line bisection task consisting of long (100 mm.) and short (20 mm.) horizontal lines, and a computer version of this same task used for comparison. Subjects were 30 male and 30 female right handed undergraduate students reporting no evidence of brain injury or visual problems. The relationships between right and left hemisphere processing efficiency and pseudoneglect defined by three different operational criteria were examined. The results of this study failed to support the theory that pseudoneglect is related to preferential right hemisphere processing for visual-spatial stimuli. Only the long lines of the paper and pencil bisection task were modestly reliable as measures of pseudoneglect which was exhibited by some, but not all of the subjects. An unexpected finding was that males appear to score higher on measures of right hemisphere activation and exhibit more pseudoneglect than females, but there was no evidence that these effects were significantly correlated. The results of this study were interpreted as suggesting that males are more asymmetrically organized than females, both sexes may employ verbal processing strategies resulting in left rather than right hemisphere activation on the visouspatial tasks used here, and that the line bisection measures employed have generally poor reliability.

Pages

125

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