[Visual-haptic simultaneity judgments for dynamic deformation].

Simultaneity is important in cross-modal information processing. However, it is still unclear how simultaneity is perceived between different sensory modalities. Various factors such as spatial location or attention are known to affect simultaneity judgments. In the present study, we focused on the simultaneity judgments of dynamic events, and investigated what kinds of dynamic properties affect these judgments. We presented the deformation of a virtual object in vision and haptics with various stimulus onset asynchronies. Participants judged whether the deformation occurred simultaneously. We measured the effects of duration, velocity, and the amount of deformation on the visual-haptic simultaneity judgments. The results showed that the point of subjective simultaneity changed depending on the duration of deformation. For a shorter duration (400 ms), the visual deformation needed to precede the haptic one to be judged as simultaneous, while for a longer duration (800 ms, 1 200 ms), the asymmetry was diminished, suggesting that information relevant to the duration of the event was used for the vision-haptics simultaneity judgments of dynamic events.