Differential effects of attention and contrast on transition appearance during binocular rivalry.

Binocular rivalry occurs when each eye sees a different image, causing conscious perception to alternate between them even though the physical stimuli remain constant. Contrast and attention have been shown to influence these alternations similarly, suggesting attention boosts effective stimulus contrast. This study examined brief transition periods between clear percepts, which are less understood. Observers reported four common transition types while contrast or exogenous attention was manipulated. Contrast and attention similarly affected overall rivalry dynamics, but their effects on transition appearance differed. This indicates attention's effect is not merely enhancing stimulus strength, a distinction revealed only when analyzing transition types.

Study at a glance

Abstract

Binocular rivalry occurs when two eyes are presented with two conflicting stimuli. Although the physical stimulation stays the same, the conscious percept changes over time. This property makes it a unique paradigm in both vision science and consciousness research. Two key parameters, contrast and attention, were repeatedly shown to affect binocular rivalry dynamics in a similar manner. This was taken as evidence that attention acts by enhancing effective stimulus contrast. Brief transition periods between the two clear percepts have so far been much less investigated. In a previous study we demonstrated that transition periods can appear in different forms depending on the stimulus type and the observer. In the current study, we investigated how attention and contrast affect transition appearance. Observers viewed binocular rivalry and reported their perception of the four most common transition types by a button press while either the stimulus contrast or the locus of exogenous attention was manipulated. We show that contrast and attention similarly affect the overall binocular rivalry dynamics, but their effects on the appearance of transitions differ. These results suggest that the effect of attention is different from a simple enhancement of stimulus strength, which becomes evident only when different transition types are considered.