Binocular summation revisited: beyond /2

Research output: Contribution to journalArticle

View graph of relations Save citation

Open

Authors

Research units

Abstract

Our ability to detect faint images is better with two eyes than with one, but how great is this improvement? A metaanalysis of 65 studies published across more than five decades shows definitively that psychophysical binocular summation (the ratio of binocular to monocular contrast sensitivity) is significantly greater than the canonical value of Ö2. Several methodological factors were also found to affect summation estimates. Binocular summation was significantly affected by both the spatial and temporal frequency of the stimulus, and stimulus speed (the ratio of temporal to spatial frequency) systematically predicts summation levels, with slow speeds (high spatial and low temporal frequencies) producing the strongest summation. We furthermore show that empirical summation estimates are affected by the ratio of monocular sensitivities, which varies across individuals, and is abnormal in visual disorders such as amblyopia. A simple modeling framework is presented to interpret the results of summation experiments. In combination with the empirical results, this model suggests that there is no single value for binocular summation, but instead that summation ratios depend on methodological factors that influence the strength of a nonlinearity occurring early in the visual pathway, before binocular combination of signals. Best practice methodological guidelines are proposed for obtaining accurate estimates of neural summation in future studies, including those involving patient groups with impaired binocular vision.

Documents

  • Binocular summation revisited

    Rights statement: © 2018 American Psychological Association. This article may not exactly replicate the final version published in the APA journal. It is not the copy of record.

    Accepted author manuscript, 696 KB, PDF-document

Details

Original languageEnglish
JournalPsychological Bulletin
StateAccepted/In press - 15 May 2018

Bibliographic note

© 2018 American Psychological Association. This article may not exactly replicate the final version published in the APA journal. It is not the copy of record.

    Keywords

  • binocular summation, meta-analysis, psychophysics, contrast, spatiotemporal frequency

Links

Employable Graduates; Exploitable Research

Copy the text from this field...