Synesthetic congruency modulates the temporal ventriloquism effect

People sometimes find it easier to judge the temporal order in which two visual stimuli have been presented if one tone is presented before the first visual stimulus and a second tone is presented after the second visual stimulus. This enhancement of people's visual temporal sensitivity has been attributed to the temporal ventriloquism of the visual stimuli toward the temporally proximate sounds, resulting in an expansion of the perceived interval between the two visual events. In the present study, we demonstrate that the synesthetic congruency between the auditory and visual stimuli (in particular, between the relative pitch of the sounds and the relative size of the visual stimuli) can modulate the magnitude of this multisensory integration effect: The auditory capture of vision is larger for pairs of auditory and visual stimuli that are synesthetically congruent than for pairs of stimuli that are synesthetically incongruent, as reflected by participants' increased sensitivity in discriminating the temporal order of the visual stimuli. These results provide the first evidence that multisensory temporal integration can be affected by the synesthetic congruency between the auditory and visual stimuli that happen to be presented.