When a different stimulus is presented to each eye, the perceived image spontaneously and stochastically alternates between the two stimuli (binocular rivalry). The dynamics of perceptual bistability can be modeled by a system consisting of two potential energy minima, corresponding to the two predominantly perceived images, with internal stochastic noise (e.g., spontaneous neural discharge) generating the spontaneous perceptual shifts. We investigated the properties of this model by examining how the binocular rivalry responded to an external periodic signal. The relative strengths (contrast) of the left-eye and right-eye stimuli were oscillated at various frequencies and amplitudes, while observers continuously reported dynamic alternations between the two perceived images. Distributions of dominance phase durations were obtained for various driving frequencies and for the non-driven control. Synchronization of binocular rivalry was indexed by an increase (relative to the non-driven control) in the "resonant" component of the dominance phase durations matching the half-period of the driving oscillation (i.e. matching the driving frequency). We found evidence of stochastic resonance in that the proportion of the resonant component within each dominance-phase distribution was maximal when the driving frequency was near the mean alternation frequency in the non-driven control (Kramer's rate). By analyzing the dependence of the dominance-phase distribution on the driving frequency and amplitude, we inferred the relationship between the depth of the two potential minima and the intensity of the internal noise for the double-well potential model.
ASJC Scopus subject areas
- Sensory Systems