Abruptness of tone onsets, but not offsets, elicits the auditory-induced bouncing/streaming illusion

The way we perceive the movement of two intersecting discs can be influenced by auditory information. When a brief tone is played while these discs overlap, people tend to report that the discs bounce off each other instead of streaming past each other. This is known as the auditory-induced bouncing/streaming illusion. Both perceptual/attentional and decisional processes have been discussed as explanations for the bouncing/streaming illusion. In four experiments, we study how the abruptness of tone onsets and offsets affects the bouncing/streaming illusion. We found that tones with more abrupt onsets and offsets resulted in a higher proportion of bouncing impressions than those with smoother ones (Experiment 1). This effect was not due to differences in loudness between the tones (Experiment 2). Additionally, we found that the abruptness of the tone onset, rather than the offset, caused the increase in bouncing impressions (Experiment 3). This effect was observed regardless of the temporal alignment of the tones with the moment of visual overlap (onset-aligned vs. centered vs. offset-aligned; Experiment 4). In sum, our results revealed evidence in favor of a chain of perceptual as well as decisional processes contributing to the reported bouncing/streaming impressions, and we discuss how both might interact during the resolution of the ambiguous bouncing/streaming display. (PsycInfo Database Record (c) 2025 APA, all rights reserved).