Binocular functional architecture for detection of contrast-modulated gratings


Combination of signals from the two eyes is the gateway to stereo vision. To gain insight into binocular signal processing, we studied binocular summation for luminance-modulated gratings (L or LM) and contrast-modulated gratings (CM). We measured 2AFC detection thresholds for a signal grating (0.75 c/deg, 216msec) shown to one eye, both eyes, or both eyes out-of-phase. For LM and CM, the carrier noise was in both eyes, even when the signal was monocular. Mean binocular thresholds for luminance gratings (L) were 5.4dB better than monocular thresholds - close to perfect linear summation (6dB). For LM and CM the binocular advantage was again 5-6dB, even when the carrier noise was uncorrelated, anti-correlated, or at orthogonal orientations in the two eyes. Binocular combination for CM probably arises from summation of envelope responses, and not from summation of these conflicting carrier patterns. Antiphase signals produced no binocular advantage, but thresholds were about 1-3dB higher than monocular ones. This is not consistent with simple linear summation, which should give complete cancellation and unmeasurably high thresholds. We propose a three-channel model in which noisy monocular responses to the envelope are binocularly combined in a contrast-weighted sum, but also remain separately available to perception via a max operator. Vision selects the largest of the three responses. With in-phase gratings the binocular channel dominates, but antiphase gratings cancel in the binocular channel and the monocular channels mediate detection. The small antiphase disadvantage might be explained by a subtle influence of background responses on binocular and monocular detection.

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Divisions: College of Health & Life Sciences
Additional Information: © 2016, Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International Funding: BBSRC grant (BB/H00159/X1); and EPSRC (EP/F026269/1). To access the research data underlying this publication, please see
Uncontrolled Keywords: binocular summation,gratings,luminance modulation,contrast modulation,second-order filters,Ophthalmology,Sensory Systems
Publication ISSN: 1878-5646
Last Modified: 08 Jan 2024 08:15
Date Deposited: 27 Oct 2016 10:55
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Related URLs: http://www.scop ... tnerID=8YFLogxK (Scopus URL)
PURE Output Type: Article
Published Date: 2016-11
Published Online Date: 2016-10-14
Accepted Date: 2016-09-12
Submitted Date: 2016-01-23
Authors: Georgeson, Mark A.
Schofield, Andrew (ORCID Profile 0000-0002-0589-4678)

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