Abstract
Previous research has found age-related differences in the sound-induced flash illusion. However, only a single study with younger adults has examined the effects of flashes on the perceived number of beeps (Andersen, Tiippana, & Sams, 2004). The current study examined this reversal of the illusion at multiple visual and auditory intensities in older and younger individuals. Twelve younger (M=22, SD=2.2) and twelve older (M=76, SD=7.1) individuals participated in the study. On the first day, 70%, 82% and 94% detection thresholds for a single visual flash and for a single auditory beep were determined with QUEST using a two-interval forced choice procedure. On the second day, participants were presented 1-2 beeps (3.5 kHz sine wave tones), paired with 0-2 flashes of a uniform white disc, 5° visual angle below fixation, presented on a grey background. Beeps were presented at the three threshold intensities, and were paired with 0-2 visual flashes that were also presented at the three threshold intensity levels. Participants reported the number of beeps perceived on each trial while ignoring the flashes. Results indicate that the illusion, while small, was consistently present and significant at all intensity levels. Older adults showed a greater effect of the illusion for both fusion (two beeps perceived as one when paired with one flash) and fission trials (one beep perceived as two when paired with two flashes). The effects of beep and flash intensity were found to be nearly equal for the age groups for fusion trials. However, the effects of intensity for older and younger participants was found to significantly differ for fission trials. The importance of these findings to aging, multisensory integration, and the sound-induced flash illusion will be presented.
Meeting abstract presented at VSS 2015