Date of Award

Summer 8-17-2014

Degree Type

Thesis

Degree Name

MS Experimental Psychology

Department

Psychology

Advisor

Kelly Goedert, PhD

Committee Member

Marianne Lloyd, PhD

Committee Member

Peii Chen, PhD

Keywords

spatial bias, hemifield, line bisection, eye patch

Abstract

Healthy individuals do not perceive the left and right sides of space equally, showing a leftward spatial bias on visuospatial tasks. This bias may be more attributed to a perceptual-attentional (PA) component than a motor-intentional (MI) component. While monocular eye patching alters this spatial bias via modification of PA but not MI, hemifield eye patches that occluded the left or right half of the visual field have been shown to be more effective at modifying spatial bias, but only in patients with spatial neglect. Furthermore, it is unclear whether hemifield patching affects PA, MI, or both. The goal of the current study was to determine whether hemifield patches would alter the spatial bias of healthy participants via modification of PA. Healthy participants bisected lines on a computer monitor, before, during, and after wearing hemifield patches under both normal and reversed viewing conditions, allowing for the calculation of PA and MI components of spatial bias. All participants bisected lines to the left of true center without the patches on. Hemifield patching that blocked out the right side of visual input, but not the left, shifted bisections rightward, and affected the PA but not MI component. Left hemifield patches did not alter bisection scores. The effects of right hemifield patching did not persist after the patches were removed. These results suggest that hemifield patches may only serve to offset naturally occurring biases but not enhance them. Such effects appear driven by purely perceptual mechanisms.

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