Abstract
Binocular rivalry results in perceptual alternations with conflicting images in each eye. Stimulus rivalry allows a similar percept despite repeated swapping of the images in each eye (Logothetis et al, 1996, Blake, 2001). Recent studies have further characterized the parameters required for rivalry, and proposed an integrated framework that may suggest a similar mechanism for both types of rivalry (Van Boxtel et al, 2008). However, a direct comparison of binocular and stimulus rivalry has not been reported with manipulation of interocular grouping. We tested subjects with matched stimuli in both rivalry conditions. The stimuli were sinusoidal gratings (left & right oblique orientations) at 1.4 cpd, and 3.8 degree size. Luminance contrast was 70% or 100%. For binocular rivalry, images were presented dichoptically (with polarizers) with short blank periods, stimulus flicker at 5.6 Hz. For stimulus rivalry, the stimuli were identical except that the images shown to each eye were swapped at 5.6 Hz. Another similar condition created stimulus ‘quilts,’ by presenting half of one grating to one eye and the other half to the other eye, to increase the demands on interocular grouping. Subjects performed a rivalry report task. We find that alternation rates do not differ for the binocular and stimulus rivalry conditions, for both intact and quilted stimuli, suggesting a common mechanism at the binocular stage for both conditions (average alternation periods were 1.4, 1.6, 2.2, and 2.2 sec respectively for binoc/intact, stim/intact, binoc/quilt, and stim/quilt). This result holds with flicker rates slow enough to defeat monocular masking. Alternation rates are modestly slower for both the quilted conditions. This is consistent with greater grouping demands and possibly a greater network contribution from higher visual areas. Future fMRI work could test hypotheses regarding the neural sites of binocular versus stimulus rivalry, monocular or binocular masking, and interocular grouping.
Meeting abstract presented at VSS 2012