Dichoptic temporal frequency differences do not lead to binocular rivalry

The influence of temporal modulation on binocular rivalry was examined in two ways. First, an uncontoured field viewed by one eye had its luminance sinusoidally modulated at 4 Hz (full-field flicker). The other eye viewed a similar field that flickered at different temporal frequencies ranging from 5 to 16 Hz. Second, orthogonal sinusoidal dichoptic gratings were phase shifted so as to duplicate the range of temporal-frequency disparities presented with full-field flicker. Three subjects recorded exclusive visibility of the rival fields over 60-sec trials. Full-field flicker produced very few reports of rivalry, and was described as resembling “visual beats” or as an intermediate flicker rate. Usual amounts of rivalry were reported between orthogonal sine-wave gratings; the field flickering at low rates dominated less. These results were essentially confirmed in a second experiment, designed to minimize individual differences in response criteria by requiring subjects to respond to disappearances of small, dichoptic, nonrival markers superimposed on the rival fields. The markers disappeared in concert with episodes of rivalry suppression of the gratings, although disappearances were slightly briefer than supression durations. Disappearances of markers on full-field flicker were rare, extremely brief, and could be attributed to Troxler’s fading rather than rivalry. The absence of rivalry between temporally disparate full-field flicker suggests that rival interactions within transient mechanisms are minimal.