Effect of transient versus sustained activation on interocular suppression.

Switches in perceptual dominance resulting from either binocular rivalry or flash suppression likely involve some mechanism of interocular suppression, although it is unclear from past research whether different mechanisms are involved in the two cases. Using monocular, centrally fixated sinusoidal gratings surrounded by contiguous annuli of rivalrous gratings, suppression of the entire central grating was possible using either technique. However, the magnitude of the suppression was unaffected by the presence of an ipsilateral surround for flash suppression, yet, for binocular rivalry, suppression no longer occurred when the surrounds were fusible. Nevertheless, computational modeling demonstrates that the differences between the techniques may be attributable to the sustained versus transient stimulation of the contralateral surround, with the magnitude of the suppression proportional to the activation of the contralateral surround. Consistent with this, suppression extends over a greater distance at the onset of the contralateral surround than during sustained rivalry. Therefore, it is likely that perceptual dominance in both binocular rivalry and flash suppression is based on the same mechanism of interocular suppression.