Abstract
Previous research has examined perceptual interpretations of a classic cross-modal phenomenon – the audiovisual bounce-inducing effect (ABE) – yet the neurological underpinning of the effect remains poorly understood. This effect presents two identical objects with opposite trajectories moving uniformly in a downwards motion along diagonals. It is a bistable perception where participants make stream vs bounce perceptual judgments which can be modulated when a sound is introduced at the point of coincidence of the two objects’ trajectories (i.e., sound increases ‘bounce’ percepts). The present study investigated the neural activation underlying the ABE using electroencephalography (EEG). Two identical discs moving in downward directions were presented to observers where the discs moved at one of three motion dynamics (uniform motion, acceleration, or deceleration). Sound was presented either synchronously with the point of coincidence or was absent. Participants indicated via keypress whether they perceived the discs to be bouncing off or streaming through each other. Our results show that sound modulates our perceptual interpretations of the effect, and that these modulations can be further modulated by changing motion dynamics of the visual targets. Additionally, our findings shed light on perceptual timing in the posterior parietal regions in the ABE during the phenomenon.