Binocular summation, binocular fusion and the transition to diplopia

Mark Georgeson, Stuart Wallis

Research output: Contribution to journalMeeting abstract

Abstract

The visual system combines spatial signals from the two eyes to achieve single vision. But if binocular disparity is too large, this perceptual fusion gives way to diplopia. We studied and modelled the processes underlying fusion and the transition to diplopia. The likely basis for fusion is linear summation of inputs onto binocular cortical cells. Previous studies of perceived position, contrast matching and contrast discrimination imply the computation of a dynamicallyweighted sum, where the weights vary with relative contrast. For gratings, perceived contrast was almost constant across all disparities, and this can be modelled by allowing the ocular weights to increase with disparity (Zhou, Georgeson & Hess, 2014). However, when a single Gaussian-blurred edge was shown to each eye perceived blur was invariant with disparity (Georgeson & Wallis, ECVP 2012) – not consistent with linear summation (which predicts that perceived blur increases with disparity). This blur constancy is consistent with a multiplicative form of combination (the contrast-weighted geometric mean) but that is hard to reconcile with the evidence favouring linear combination. We describe a 2-stage spatial filtering model with linear binocular combination and suggest that nonlinear output transduction (eg. ‘half-squaring’) at each stage may account for the blur constancy.
Original languageEnglish
Article number4P1M117
Pages (from-to)319
Number of pages1
JournalPerception
Volume44
Issue numberSuppl.1
DOIs
Publication statusPublished - 31 Aug 2015
Event38th European Conference on Visual Perception - Liverpool, United Kingdom
Duration: 24 Aug 201627 Aug 2016

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Binoculars
Diplopia
Fusion reactions
Vision Disparity
Weights and Measures
Linear Models

Bibliographical note

ECVP 2015 Abstract: 38th European Conference on Visual Perception (ECVP) 2015 Liverpool

Cite this

Georgeson, Mark ; Wallis, Stuart. / Binocular summation, binocular fusion and the transition to diplopia. In: Perception. 2015 ; Vol. 44, No. Suppl.1. pp. 319.
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abstract = "The visual system combines spatial signals from the two eyes to achieve single vision. But if binocular disparity is too large, this perceptual fusion gives way to diplopia. We studied and modelled the processes underlying fusion and the transition to diplopia. The likely basis for fusion is linear summation of inputs onto binocular cortical cells. Previous studies of perceived position, contrast matching and contrast discrimination imply the computation of a dynamicallyweighted sum, where the weights vary with relative contrast. For gratings, perceived contrast was almost constant across all disparities, and this can be modelled by allowing the ocular weights to increase with disparity (Zhou, Georgeson & Hess, 2014). However, when a single Gaussian-blurred edge was shown to each eye perceived blur was invariant with disparity (Georgeson & Wallis, ECVP 2012) – not consistent with linear summation (which predicts that perceived blur increases with disparity). This blur constancy is consistent with a multiplicative form of combination (the contrast-weighted geometric mean) but that is hard to reconcile with the evidence favouring linear combination. We describe a 2-stage spatial filtering model with linear binocular combination and suggest that nonlinear output transduction (eg. ‘half-squaring’) at each stage may account for the blur constancy.",
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Binocular summation, binocular fusion and the transition to diplopia. / Georgeson, Mark; Wallis, Stuart.

In: Perception, Vol. 44, No. Suppl.1, 4P1M117, 31.08.2015, p. 319.

Research output: Contribution to journalMeeting abstract

TY - JOUR

T1 - Binocular summation, binocular fusion and the transition to diplopia

AU - Georgeson, Mark

AU - Wallis, Stuart

N1 - ECVP 2015 Abstract: 38th European Conference on Visual Perception (ECVP) 2015 Liverpool

PY - 2015/8/31

Y1 - 2015/8/31

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AB - The visual system combines spatial signals from the two eyes to achieve single vision. But if binocular disparity is too large, this perceptual fusion gives way to diplopia. We studied and modelled the processes underlying fusion and the transition to diplopia. The likely basis for fusion is linear summation of inputs onto binocular cortical cells. Previous studies of perceived position, contrast matching and contrast discrimination imply the computation of a dynamicallyweighted sum, where the weights vary with relative contrast. For gratings, perceived contrast was almost constant across all disparities, and this can be modelled by allowing the ocular weights to increase with disparity (Zhou, Georgeson & Hess, 2014). However, when a single Gaussian-blurred edge was shown to each eye perceived blur was invariant with disparity (Georgeson & Wallis, ECVP 2012) – not consistent with linear summation (which predicts that perceived blur increases with disparity). This blur constancy is consistent with a multiplicative form of combination (the contrast-weighted geometric mean) but that is hard to reconcile with the evidence favouring linear combination. We describe a 2-stage spatial filtering model with linear binocular combination and suggest that nonlinear output transduction (eg. ‘half-squaring’) at each stage may account for the blur constancy.

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