Dynamic perceptual changes in audiovisual simultaneity.
BACKGROUND
The timing at which sensory input reaches the level of conscious perception is an intriguing question still awaiting an answer. It is often assumed that both visual and auditory percepts have a modality specific processing delay and their difference determines perceptual temporal offset.


RESULTS
Here, we show that the perception of audiovisual simultaneity can change flexibly and fluctuates over a short period of time while subjects observe a constant stimulus. We investigated the mechanisms underlying the spontaneous alternations in this audiovisual illusion and found that attention plays a crucial role. When attention was distracted from the stimulus, the perceptual transitions disappeared. When attention was directed to a visual event, the perceived timing of an auditory event was attracted towards that event.


CONCLUSIONS
This multistable display illustrates how flexible perceived timing can be, and at the same time offers a paradigm to dissociate perceptual from stimulus-driven factors in crossmodal feature binding. Our findings suggest that the perception of crossmodal synchrony depends on perceptual binding of audiovisual stimuli as a common event.
Kanai
Ryota
R
Division of Biology, California Institute of Technology, Pasadena, California, United States of America. kanair@gmail.com
Sheth
Bhavin R
BR
Verstraten
Frans A J
FA
Shimojo
Shinsuke
S
D000222:Adaptation, Physiological; D001288:Attention; D001307:Auditory Perception; D006801:Humans; D014796:Visual Perception