Does cross-modal correspondence modulate modality-specific perceptual processing? Study using timing judgment tasks

Cross-modal correspondences refer to associations between stimulus features across sensory modalities. Previous studies have shown that cross-modal correspondences modulate reaction times for detecting and identifying stimuli in one modality when uninformative stimuli from another modality are present. However, it is unclear whether such modulation reflects changes in modality-specific perceptual processing. We used two psychophysical timing judgment tasks to examine the effects of audiovisual correspondences on visual perceptual processing. In Experiment 1, we conducted a temporal order judgment (TOJ) task that asked participants to judge which of two visual stimuli presented with various stimulus onset asynchronies (SOAs) appeared first. In Experiment 2, we conducted a simultaneous judgment (SJ) task that asked participants to report whether the two visual stimuli were simultaneous or successive. We also presented an unrelated auditory stimulus, simultaneously or preceding the first visual stimulus, and manipulated the congruency between audiovisual stimuli. Experiment 1 indicated that the points of subjective simultaneity (PSSs) between the two visual stimuli estimated in the TOJ task shifted according to the audiovisual correspondence between the auditory pitch and visual features of vertical location and size. However, these audiovisual correspondences did not affect PSS estimated using the SJ task in Experiment 2. The different results of the two tasks can be explained through the response bias triggered by audiovisual correspondence that only the TOJ task included. We concluded that audiovisual correspondence would not modulate visual perceptual timing and that changes in modality-specific perceptual processing might not trigger the congruency effects reported in previous studies.