Comparison for younger and older adults: Stimulus temporal asynchrony modulates audiovisual integration

Recent research has shown that the magnitudes of responses to multisensory information are highly dependent on the stimulus structure. The temporal proximity of multiple signal inputs is a critical determinant for cross-modal integration. Here, we investigated the influence that temporal asynchrony has on audiovisual integration in both younger and older adults using event-related potentials (ERP). Our results showed that in the simultaneous audiovisual condition, except for the earliest integration (80–110 ms), which occurred in the occipital region for older adults was absent for younger adults, early integration was similar for the younger and older groups. Additionally, late integration was delayed in older adults (280–300 ms) compared to younger adults (210–240 ms). In audition‑leading vision conditions, the earliest integration (80–110 ms) was absent in younger adults but did occur in older adults. Additionally, after increasing the temporal disparity from 50 ms to 100 ms, late integration was delayed in both younger (from 230 to 290 ms to 280–300 ms) and older (from 210 to 240 ms to 280–300 ms) adults. In the audition-lagging vision conditions, integration only occurred in the A100V condition for younger adults and in the A50V condition for older adults. The current results suggested that the audiovisual temporal integration pattern differed between the audition‑leading and audition-lagging vision conditions and further revealed the varying effect of temporal asynchrony on audiovisual integration in younger and older adults.