Audio-visual correspondence: 3D-presentation increases bouncing reports and illusory crescents

Establishing object correspondence often requires perceptual inferences, especially when motion paths are ambiguous or intersect. For example, when two disks move toward each other, fully overlap, and then move apart, observers may perceive either a bouncing or a streaming event. Introducing a tone at the moment of overlap increases the likelihood of a bouncing interpretation (auditory-induced bouncing impression) and simultaneously creates the illusion of reduced overlap between the disks (auditory-induced illusory crescent). One theoretical explanation for this misperception is perceptual correction: full overlaps are unlikely in naturalistic bouncing events, whereas partial overlaps are more plausible, such as when one object approaches diagonally in depth (the motion path interpretation hypothesis). To test this, we rendered the moving objects in 3D to clarify the dimensionality of the motion paths, aiming to reduce ambiguity and, in turn, perceptual corrections. Contrary to expectations, we observed an increase in illusory crescent perceptions, along with a higher proportion of bouncing responses. These results challenge the motion path interpretation hypothesis and prompt consideration of alternative explanations for auditory-induced illusory crescents.