Online action-to-perception transfer: only percept-dependent action affects perception

Perception self-evidently affects action, but under which conditions does action in turn influence perception? To answer this question we ask observers to view an ambiguous stimulus that is alternatingly perceived as rotating clockwise or counterclockwise. When observers report the perceived direction by rotating a manipulandum, opposing directions between report and percept ('incongruent') destabilize the percept, whereas equal directions ('congruent') stabilize it. In contrast, when observers report their percept by key presses while performing a predefined movement, we find no effect of congruency. Consequently, our findings suggest that only percept-dependent action directly influences perceptual experience.