Abstract
The sound-induced flash illusion (SiFI) is a classical auditory-dominated multisensory integration phenomenon in which the observer misperceives the number of visual flashes due to the simultaneous presentation of a different number of auditory beeps. Although the SiFI has been documented to correlate with perceptual sensitivity, to date there is no consensus as to how it corresponds to sensitivity with aging. The present study was based on the SiFI paradigm (Shams et al., 2000), adding repeated auditory stimuli prior to the appearance of audiovisual stimuli to investigate the effects of repetition suppression (RS) on the SiFI with aging. The repeated auditory stimuli consisted of one or two of the same auditory stimuli presented twice in succession, which were then followed by the audiovisual stimuli. By comparing the illusions in old and young adults, we aimed to explore the influence of aging on the RS of auditory stimuli on the SiFI. The results showed that both age groups showed SiFI effects, however, the RS performance of the two age groups had different effects on the fusion and fission illusions. The illusion effect in old adults was weaker than in young adults. Specifically, RS only affected fission illusions in the old adults but both fission and fusion illusions in young adults. Thus, the present study indicated that the decreased perceptual sensitivity based on auditory RS could weaken the SiFI effect in multisensory integration and that old adults are more susceptible to RS, showing that old adults perceived the SiFI effect weakly under auditory RS.
Highlights
Our bodies receive all kinds of information simultaneously, and most of this information arrives in multisensory modalities
There were no significant differences between illusion type and the number of repeated stimuli, F(1,51) = 1.12, p = 0.29, η2 = 0.02, and there were no significant differences among illusion type, number of repeated auditory stimuli and participant group, F < 1
Since there were significant differences in multisensory processing between the old and young adults, we further investigated the potential interaction between illusion type and number of repeated auditory stimuli for the two groups of participants
Summary
Our bodies receive all kinds of information simultaneously, and most of this information arrives in multisensory modalities. The first type are multisensory illusion effects, which involve merging of information across senses; in some cases, one sensory modality within the multisensory information competes for preferential access to the consciousness, which means that this modality dominates the others to receive preferential processing during multisensory competition and eventually dominates the awareness and behavior of the observer (Stein and Meredith, 1993; Driver and Noesselt, 2008; Koelewijn et al, 2010; Talsma et al, 2010; Spence, 2011; Chen and Zhou, 2013; Huang et al, 2015). People will misperceive the number of visual flashes due to the simultaneous presentation of the different numbers of auditory beeps. This effect can be divided into fission and fusion illusions (Shams et al, 2000, 2002; Andersen et al, 2004). The fission illusion occurs when two flashes are perceived if a single flash is accompanied by two auditory stimuli (Shams et al, 2000, 2002); the fusion illusion occurs when one flash is perceived if two flashes are accompanied by one auditory stimulus (Andersen et al, 2004)
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