Effects of interocular grouping demands on binocular rivalry

Abstract

Binocular rivalry (BR) is a visual phenomenon in which perception alternates between two non-fusible images presented to each eye. Transition periods between dominant and suppressed images are marked by mixed percepts, where participants report fragments of each image being dynamically perceived. Interestingly, BR remains robust even when typical images are subdivided and presented in complementary patches to each eye, a phenomenon termed interocular grouping (IOG). The objective of the present study was to determine if increasing grouping demand in the context of BR changes the perceptual experience of rivalry. In 48 subjects with normal vision, mean dominant and mixed percept durations were recorded for classic BR and IOG conditions with increasing grouping demands from two, four, and six patches. We found that, as grouping demands increased, the duration of mixed periods increased. Indeed, durations of dominant and mixed percepts, as well as percentage of time spent in dominant or mixed state, differed significantly across conditions. However, durations of global dominant percepts remained relatively stable and saturated at about 1.5 seconds, despite the exponential increase in possible mixed combinations. Evidence shows that this saturation followed a nonlinear trend. The data also indicate that grouping across the vertical meridian is slightly more stable than for the horizontal meridian. Finally, individual differences in speed of alternation identified during BR were maintained in all interocular grouping conditions. These results provide new information about binocular visual spatial integration and will be useful for future studies of the underlying neural substrates and models of binocular vision.

Figure 1.

Example of interocular grouping stimuli adapted from literature review. (A) Reproduction of Diaz-Caneja stimuli (1928), where stimulus flicker altered interocular grouping during BR (Knapen et al., 2007). (B) Reproduction of visual stimuli presented by Sutoyo and Srinivasan (2009). (C) Reproduction of visual stimuli presented by Golubitsky et al. (2019) showing four quadrant interocular grouping (see Discussion section).

Figure 2.

Experimental design and BR stimuli with increasing interocular grouping demands. (A) Experimental design to capture behavioral responses for alternations in percepts during BR and interocular grouping. Subjects were asked to report with a two-button press-and-hold response when viewing dominant percepts. Mixed percepts were inferred from periods of no responses. Illustration is shown over the time course of the visual presentation of rivalrous images. (B) BR with dichoptic presentation of stimuli. (C) Interocular grouping with two patches divided along the vertical meridian of each classic BR image. (D) Interocular grouping with two patches divided along the horizontal meridian of each classic BR image. (E) Interocular grouping with four patches divided along the vertical and horizontal meridian of each classic BR image. (F) Interocular grouping with six patches divided along the vertical meridian of each classic BR image. (G) Interocular grouping with six patches divided along the horizontal meridian of each classic BR image.

Figure 3.

Comparison of flicker frequencies. (A–C) Mean duration values for dominant and mixed percepts and alternation rate for BR and IOG. (D–F) Mean duration values for dominant and mixed percepts and alternation rate for increasing grouping demands during IOG. Dominant percepts are plotted as mean values for red and green responses. Black lines are the median values, and the dots represent participant data.

Figure 4.

Mean duration and proportion of viewing time for BR and interocular grouping. (A) Mean durations of percepts plotted for BR and IOG conditions. Duration of percepts is plotted as the mean duration for red and green percepts. (B) Mean proportion of viewing time for red, green, and mixed percepts across BR and IOG conditions. (C) Alternation rates plotted for each condition. Error bars plotted in all three graphs are 95% confidence intervals.

Figure 5.

Correlation matrix with R values plotted of mean values for participants depicting relationship between BR and interocular grouping. (A) Mean duration (seconds) of dominant (red and green) percepts. (B) Mean duration (seconds) of mixed percepts. (C) Alternation rate (Hz). All correlations were statistically significant after FDR correction.

Figure 6.

Scatterplot depicting correlations between the alternation rate and mean duration of mixed percepts, with linear lines of best fit. (A) BR alternation rate and mean duration of dominant and mixed percepts. (B) Interocular grouping alternation rate and mean duration of dominant and mixed percepts.

Figure 7.

Transition probabilities between perceptual states during rivalry. (A) Results for BR. (B) Combined results for all conditions of interocular grouping. Lines between perceptual states are drawn to scale of the mean probability of values of transition. Arrows point toward percepts reported from the previous state.

Figure 8.

Visual model that accounts for tristable paradigm observed during BR. Schematic of competition occurring at higher level of the visual pathway, in a proposed region that received information from both monocular and binocular driven neurons. Competition in higher order visual areas results in perception of the dominant percept and feedback inhibition of suppressed percepts.