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Acta Ophthalmol Scand. 2001 Aug;79(4):422-5.

The influence of level and polarity of figure-ground contrast on vision.

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1
Optometric Research, Higham Ferrers, Northamptonshire, United Kingdom.

Abstract

PURPOSE:

To document the effect upon human foveal vision of changes in the level and polarity of figure-ground contrast under photopic controlled test conditions, with particular emphasis on performance at low contrast levels.

METHODS:

Using a forced-choice psychophysical paradigm, threshold acuity estimates were derived at 9 discrete levels over a near-3 octave contrast range for Landolt ring-type stimuli of either positive or negative polarity. Data were obtained under binocular conditions from 10 young adults, each wearing their optimum low myopic spectacle correction.

RESULTS:

Visual acuity declined linearly with reducing stimulus contrast, the deterioration increasing substantially at <10% figure-ground contrast regardless of stimulus polarity. Performance was slightly (but not statistically significantly) better for positive contrast stimuli.

CONCLUSION:

Irrespective of contrast polarity, a reduction in stimulus figure-ground contrast <10% produces an accelerated decrement in photopic foveal vision compared to the performance at levels >10%. Some clinical and practical implications of this outcome are considered with regard to the examination of patients with normal and compromised visual function.

PMID:
11453867
[Indexed for MEDLINE]
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