Date of Award

Spring 2008

Project Type

Dissertation

Program or Major

Psychology

Degree Name

Doctor of Philosophy

First Advisor

William Wren Stine

Abstract

When one views a square-wave grating and changes the average luminance or contrast of the monocular images relative to each other, at least three perceptual phenomena occur. These are the Venetian blind effect, or a perceived rotation of the bars around individual vertical axes; binocular luster, or a perceived shimmering; and binocular rivalry, or an alternating perception between the views of the two eyes. In this paper, it is shown that increasing the dichoptic luminance modulation leads to these three phenomena in sequence, while increasing dichoptic contrast modulation generally only leads to perceived rotation.

It is also shown that average luminance and contrast are not the deciding factors in when the three perceptual phenomena occur. Perception of luster and rivalry occur when the light bars in the grating dichoptically straddle the background luminance, with little impact of the dark bars, as demonstrated when light bars or dark bars are presented in isolation. Also when presented in isolation, perceived rotation ceases when the bars dichoptically straddle the background luminance. The deciding factor is shown not to be the adaptation level of the participant and instead to be this relation of the monocular images to the background.

The patterns for perceived rotation versus binocular luster and binocular rivalry suggest separate mechanisms in the visual system. Possible mechanisms are suggested, and experimental manipulations are proposed that would discriminate between them.

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