Center-surround inhibition and facilitation during binocular rivalry

Abstract

Predominance of a given stimulus during binocular rivalry can be modulated by stimulation within the area surrounding rival targets. Here we show that center-surround interactions implicated in other aspects of motion perception modulate dominance of moving targets during binocular rivalry. Dependent on stimulus contrast, the stimulus strength of a rival target can be modulated by either center-surround inhibition or by center-surround facilitation. Central rival targets moving in opposite directions were surrounded by motion in the same direction as one of the two. At high contrast, the target moving in the direction opposite to the surround was more dominant. At low contrast, however, the effect reversed; the target moving in the same direction was more dominant. Is dominance of the opposite direction at high contrast the result of same direction inhibition or opposite direction facilitation? To learn the answer, observers dichoptically viewed a moving target and a stationary target surrounded by motion in the same or opposite direction as the moving target. Surround motion in the opposite direction of the moving target did not modulate dominance of the targets, but the presence of surround motion in the same direction as the moving target substantially increased dominance of the stationary target, making it twice as dominant as the moving target. Evidently at high contrast, surround motion in the same direction as a moving target increased suppression of that target through center-surround inhibition of the same direction. The results are consistent with recent observations of surround suppression at high contrast and surround facilitation at low contrast (Tadin et al., Nature, 2003). Our study highlights the capacity of stimulation within regions surrounding rival targets to influence local binocular rivalry, in a manner implying that center-surround interactions modulate the stimulus strength of rival targets.

Footnotes

 supported by EY 07760