The effects of visual adaptation upon spatial and temporal resolution.
Item
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Title
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The effects of visual adaptation upon spatial and temporal resolution.
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Identifier
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AAI9510679
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identifier
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9510679
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Creator
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Lange, Gudrun.
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Contributor
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Adviser: Thomas E. Frumkes
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Date
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1994
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Language
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English
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Publisher
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City University of New York.
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Subject
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Psychology, Experimental | Psychology, Psychobiology | Biology, Neuroscience
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Abstract
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Light adapting rods increase cone-mediated visibility of either rapid flicker (Flicker effect) or fine spatial gratings (Grating effect). This study determined whether these effects reflect the action of one or several. Monocular and interocular contrast sensitivities of normal observers were measured using test gratings modulated sinusoidally in both temporal and spatial domains. In general, a {dollar}1\sp\circ\times1\sp\circ{dollar} sided test display of 10 cd/m{dollar}\sp2{dollar} average luminance presented to the same eye as a {dollar}20.8\sp\circ\times15\sp\circ{dollar}, 0.03 cd/m{dollar}\sp2{dollar} adapting field. However, the influences of size, shape, luminance, and retinal position of both test and background field as well as monocular versus interocular viewing were examined.;Rod-stimulating adapting fields enhanced sensitivity to low spatial frequencies ({dollar}{dollar}12 hz) and to high spatial frequencies ({dollar}>{dollar}12 cpd) flickered slowly ({dollar}<{dollar}2 hz), but exerted negligible influence upon intermediate spatial and temporal frequency combinations (4-8 hz and 4-8 cpd). Although both effects can involve rod-cone interaction, the Grating effect can additionally reflect rod-rod interaction while the Flicker effect can involve cone-cone interaction. Both effects decreased as test display size increased and increased with parafoveal displacement; the gradient of these influences is much steeper for the Flicker than the Grating effect. Monocular and interocular adaptation produce near-identical influences upon grating visibility, while interocular backgrounds have an insignificant influence upon flicker visibility. Collectively, these findings indicate that Grating and Flicker effects are mediated by different mechanisms.;The influence of adaptation upon visibility of different sized gratings was more intensively studied to indicate practical significance. The present results show that the influence of display size upon visibility of high spatial frequency gratings reflects a "global" influence of light-adaptation rather than any effect of display size per se.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
