Nonlinearities in the binocular combination of luminance and contrast


We studied the rules by which visual responses to luminous targets are combined across the two eyes. Previous work has found very different forms of binocular combination for targets defined by increments and by decrements of luminance, with decrement data implying a severe nonlinearity before binocular combination. We ask whether this difference is due to the luminance of the target, the luminance of the background, or the sign of the luminance excursion. We estimated the pre-binocular nonlinearity (power exponent) by fitting a computational model to ocular equibrightness matches. The severity of the nonlinearity had a monotonic dependence on the signed difference between target and background luminance. For dual targets, in which there was both a luminance increment and a luminance decrement (e.g. contrast), perception was governed largely by the decrement. The asymmetry in the nonlinearities derived from the subjective matching data made a clear prediction for visual performance: there should be more binocular summation for detecting luminance increments than for detecting luminance decrements. This prediction was confirmed by the results of a subsequent experiment. We discuss the relation between these results and luminance nonlinearities such as a logarithmic transform, as well as the involvement of contemporary model architectures of binocular vision.

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Divisions: College of Health & Life Sciences > School of Optometry > Optometry
College of Health & Life Sciences > Clinical and Systems Neuroscience
College of Health & Life Sciences > School of Optometry > Centre for Vision and Hearing Research
Additional Information: NOTICE: this is the author’s version of a work that was accepted for publication in Vision research. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Baker, Daniel; Wallis, Stuart; Georgeson, Mark A and Meese, Timothy S (2012). Nonlinearities in the binocular combination of luminance and contrast. Vision research, 56 (1), pp. 1-9. DOI:
Uncontrolled Keywords: binocular vision,luminance,contrast,matching,binocular summation,Ophthalmology,Sensory Systems
Publication ISSN: 1878-5646
Last Modified: 05 Jun 2024 07:09
Date Deposited: 09 Feb 2012 11:22
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Related URLs: http://www.scop ... tnerID=8YFLogxK (Scopus URL)
PURE Output Type: Article
Published Date: 2012-03-01
Authors: Baker, Daniel
Wallis, Stuart (ORCID Profile 0000-0002-3588-055X)
Georgeson, Mark A (ORCID Profile 0000-0002-8173-9522)
Meese, Timothy S (ORCID Profile 0000-0003-3744-4679)


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