Abstract:

Auditory dominance refers to that auditory information competes for preferential access to consciousness in multisensory integration. Sound-induced flash illusion is an auditory dominance phenomenon in multisensory integration, which is the perception of brief visual stimuli could be qualitatively altered by concurrent brief sounds. It has been well documented that sound-induced flash illusion reflects cross-modal interactions at a perceptual level, and the illusion is too robust to change in many stimulus parameters. It remains unknown how modal-based attention influences the multisensory integration. Prior studies mostly asked participants to focus on the visual modal and ignore the auditory modal, however, in present study, we not only manipulated the modal-based attention (selective attention vs. divided attention) to ask the participants to focus their attention either on the visual modal or the auditory modal, but also manipulated task difficulty (high vs. low) to investigate how the cognitive control influences the sound-induced flash illusion. The present study was a 2 (modal-based attention: selective attention vs. divided attention) × 2 (flash number: 1 vs. 2) × 3 (sound number: 0 vs. 1 vs. 2) factorial design in the two experiments, the factor of modal-based attention was manipulated by block. In experiment 1, asking the participants to judge the number of flashes first, then judge the number of sounds. In experiment 2, we increased the task difficulty, asking the participants to judge the numbers of flashes first, then judge whether the number of flash and sound were consistent. In present study, we mainly focused on the fission illusion (when a single brief visual flash is accompanied by two auditory bleeps and perceived incorrectly as two flashes) and the fusion illusion (where a double flash is accompanied by a single bleep and perceived incorrectly as a single flash). From the results of accuracy (ACC), showing that fission illusion was larger than fusion illusion, and when the participants were initiative to pay attention to the auditory modal, resulting to enlarge the fission illusion, while it did not influence the fusion illusion. From the results of reaction times (RTs), regardless of the participants were focused attention on auditory stimuli passively or paid attention to auditory stimuli initiatively, fission illusion was stable, and was not affected by the attentional resources. However, the fusion illusion was not reflected in the reaction times. Together with the experiment 1and 2, we also suggested that the task difficulty could not influence the sound-induced flash illusion. The results indicated that regardless of the single modal-based attention or the cross modal-based attention, compared with the fusion illusion, the fission illusion was larger, and was more affected by the distribution of attentional resources. In addition, we also indicated that task difficulty could influence the sound-induced flash illusion.

Key words: multisensory integration, auditory dominance, fission and fusion illusion, selective and divided attention, task difficulty