The depth and selectivity of suppression in binocular rivalry

Abstract

Binocular rivalry occurs when the two eyes are presented with incompatible stimuli and the perceived image alternates between the two stimuli. The aim of this study was to find out whether the periodic perceptual loss of a monocular stimulus during binocular rivalry is mirrored by a comparable loss of contrast sensitivity. We presented brief test stimuli to one eye while its conditioning stimulus was dominant or suppressed. The test stimuli were varied widely across four stimulus domainsnamely, the relative stimulation of medium-and long-wavelength-sensitive cones, duration, spatial frequency, and grating orientation. The result in each case was the same. Suppression depended slightly or not at all on the type of test stimulus, and contrast sensitivity during suppression was around 64% of that during dominance. The effect of suppression on sensitivity is therefore very weak, relative to its effect on the perceived image. Furthermore, suppression was largely independent of the similarity between the conditioning and the test stimuli, indicating that our results are better explained by eye suppression than by stimulus suppression. A model is presented to account for the small, monocular sensitivity loss during suppression: It assumes that test detection precedes conditioning stimulus perception in the visual pathway.

Conditions required for binocular rivalry suppression

“…The coefficients, along with their 95% confidence intervals, were d 1 0.394 0.058 and d 2 0.008 0.047. The first coefficient indicates that eye suppression produces a sensitivity loss of about 0.4 log units, consistent with previous findings (Blake & Camisa, 1979;Nguyen, Freeman, & Alais, 2003;Nguyen et al, 2001). Although the sensitivity loss due to eye suppression is significantly different from zero ( p 10 10 ), the confidence interval for d 2 includes zero, consistent with an absence of feature suppression.…”

“…We have approached this question by predicting the sensitivity changes expected when eye and feature suppression act alone and then fitting these predictions to the observations. Second, although previous studies have produced clear evidence in favor of eye suppression (Blake & Fox, 1974b;Blake et al, 1980;Chen & He, 2004;Nguyen et al, 2001), there is reason to believe that the experimental designs used may have led to an underestimation for feature suppression. Because the stimuli in those studies were orthogonal gratings, subjects could have made their decisions about which monocular stimulus was dominant from the perceived orientation at a single visual field location.…”

“…First, the depth of binocular rivalry suppression can be measured by dividing visual sensitivity in the suppressed state by that during dominance (Blake & Camisa, 1979;Nguyen et al, 2001). Is it therefore possible to measure the depths of both eye suppression and feature suppression in the same experiment and to compare those…”

Can binocular rivalry reveal neural correlates of consciousness?

“…For several reasons, we doubt whether this condition is sufficient for that purpose. First, neural events associated with suppression of a stimulus are certainly not equivalent to those associated with complete, intermittent removal of that stimulus-during suppression phases, evidence for traces of residual neural activity associated with the suppressed stimulus can found within early stages of visual processing as well as in higher tier visual areas [33][34][35][36][37]. At best, therefore, a rivalry mimic condition can reveal the upper limit on the extent to which rivalry suppression might squelch visual responses.…”

Global Mapping of the Whole-Brain Network Underlining Binocular Rivalry

“…Based on this theory, both layers would contribute to the perceptual alternation phenomenon, even though their properties are very different (Blake and Logothetis, 2002;Nguyen et al, 2001;Ooi and He, 2003;Tong et al, 2006).…”