Exploration of Interocular Suppression Using Perceptual Reverse Correlation and Computational Modeling

Abstract

Binocular rivalry is often studied with participants making perceptual reports about which of two overlapping incongruent images presented to different eyes, such as rivalrous gratings, are visible at any particular moment in time. However, the rivalrous gratings being judged are also directly activating the neural mechanisms involved in the perceptual decision process, i.e. interocular suppression. Taking advantage of the spatially extended nature of interocular suppression with a continuation of a combined psychophysical and computational modeling study (Nichols & Wilson, 2009), the current study temporally modulated the presence of surround annuli while participants made judgments on the visibility of static circular gratings that were presented to either one eye (monocular) or both eyes with different orientations (rivalrous). A perceptual reverse correlation technique was used with moving gratings in the surround annuli changing direction every second while also randomly changing with regard to which eye or eyes they were presented to. Key qualitative findings were replicated, e.g. the presence of an annulus in the eye contralateral to a monocular center grating is necessary for the suppression of the grating but removal of the annulus is not necessary for the reappearance of the grating. New qualitative findings included how the presence of an ipsilateral annulus is similarly influential for the return to perceptual dominance for both monocular and rivalrous center gratings. New quantitative measurements included the relative necessity and sufficiency of different annulus conditions for interocular suppression. Implementation of the model with fluctuations in the input strength of the surround components that inhibit the center components to match the experimental design revealed many qualitative similarities to the data but also some qualitative and quantitative differences. Future tuning of the model to establish greater consistency with the psychophysical data can shed light on the role of contralateral and ipsilateral surrounds in interocular suppression. Meeting abstract presented at VSS 2017