Rivalry Suppression Research Articles

Adaptation to invisible gratings and the site of binocular rivalry suppression.

THE visual system can be described usefully as a hierarchical series of functional stages, the initial stage being physical impingement of the stimulus and the terminal stage being visual perception. Psychophysical investigations typically provide rigorous specification of the first and last stages in the sequence, but a more complete explanation clearly must include information about intermediate stages as well. At present, however, very few techniques are available for analysing inferentially the intermediate stages1. By incorporating two separate phenomena, binocular rivalry and visual aftereffects, into one paradigm, we describe here another technique for inferential analysis of the stages leading to vision. This technique indicates the sequence of stages underlying both phenomena.

Independence between binocular rivalry suppression duration and magnitude of suppression.

Independence between binocular rivalry suppression duration and magnitude of suppression.

Increment detection thresholds during binocular rivalry suppression

In two experiments, two-choice forced-choice duration thresholds for increment test flashes were estimated during phases of rivalry suppression and nonsuppression and for a nonrivalry monocular control condition. In both experiments thresholds of both eyes of each S were measured and, to maximize correct detections, feedback was given after every trial and Ss were relieved of the task of continually reporting changes in rivalry phases. Results of both experiments support the conclusion that suppression constitutes an elevation in threshold, on the order of .5 log units relative to thresholds found during nonsuppression and monocular conditions. These data, in concert with others, reinforce the general conclusion that rivalry suppression is an inhibitory state that nonselectively attenuates all classes of inputs falling within the spatial boundaries of the suppressed target.

Detection of motion during binocular rivalry suppression.

Detection of motion during binocular rivalry suppression.

Cerebral potentials evoked by pattern reversal and their suppression in visual rivalry.

SINCE the introduction of techniques to improve the signal to noise ratio1, the number of publications on human visual evoked potentials has been considerable; usually the stimulus has been a brief flash or series of flashes (flicker) on an unstructured field, but recently the interest of patterned fields has become apparent2–4. Following a suggestion by Gross et al.5 we have demonstrated the effectiveness of “pattern reversal”, without change in the total luminous flux, in evoking visual cortical responses and have applied the method to the investigation of binocular rivalry.

Forced-choice form recognition during binocular rivalry

Forced-choice form recognition thresholds were obtained for both eyes concurrently under rivalry suppression and nonsuppression and for a nonrivalry control condition. Suppression produced a significant decrement in recognition; nonsuppression and nonrivalry did not differ significantly. These data support the hypotheses that suppression represents an inhibitory state and that nonsuppression represents a state of normal visual sensitivity.