Suppression periods of rivalry are accompanied by a general loss in visual sensitivity. Thus, a probe target superimposed on a stimulus engaged in rivalry is more difficult to detect when that probe is presented while the rival target is suppressed, compared to detection performance when the same probe is presented during rival target dominance (Wales and Fox, 1970; Fukuda, 1981; O'Shea and Crassini, 1981; Smith et al, 1982).
Use the animation sequence below to experience this effect for yourself. The "probe" consists of a small circular patch of grating that briefly appears in the upper left-hand portion of the grating whose bars are oriented diagonally clockwise -- the upper figure (one frame from the animation) shows the location of the probe. When you play the animation, the probe fades "on" and then fades "off" quickly. Initiate a few probe presentations when the rival target upon which the probe appears is dominant, noticing how it can barely be detected; if you have trouble seeing the probe, try looking directly at the location where it appears, not at the central fixation mark. Next initiate presentations when that grating is completely suppressed (meaning that the diagonal counterclockwise grating is dominant exclusively). Notice how the probe is now impossible to see. Quantitative measures show this loss in visual sensitivity to be on the order of 0.3 - 0.5 log units.
Fukuda, H., 1981: Magnitude of suppression of binocular rivalry within the invisible pattern, Percept. Mot. Skills 53, 371-375.
O'Shea, R.P. and Crassini, B., 1981: The sensitivity of binocular rivalry suppression to changes in orientation assessed by reaction-time and forced-choice techniques, Perception 10, 283-293.
Smith, E.L., Levi, D.M., Harwerth, R.S. and White, J.M., 1982: Color vision is altered during the suppression phase of binocular rivalry, Science 218, 802-804.
Wales, R. and Fox, R. 1970: Increment detection thresholds during binocular rivalry suppression, Percept. Psychophys. 8, 90-94.