Age-related changes in audiovisual simultaneity perception and their relationship with working memory.

OBJECTIVE Perceiving simultaneity of a visual and an auditory signal is critical for humans to integrate these multisensory inputs effectively and respond properly. We examined age-related changes in audiovisual simultaneity perception, and the relationships between this perception and working memory performances with aging. METHODS Audiovisual simultaneity perception of young, middle-aged, and older adults was measured using a simultaneity judgment (SJ) task, in which a flash and a beep were presented at one of 11 stimulus onset asynchronies (SOAs). Participants judged whether these two stimuli were perceived simultaneously. Precision of simultaneity perception, the SOA corresponding to the peak probability of subjective simultaneity (PSS), and response errors at each SOA were estimated using model fitting. The precision and PSS are associated with multisensory perception per se whereas the response error reflects executive ability when performing the SJ task. Visual working memory of the same middle-aged and older adults was measured using the Cambridge Neuropsychological Test Automated Battery (CANTAB) beforehand. RESULTS Compared to young adults' performances, middle-aged and older adults showed a decreased precision, a shift of PSS toward the visual-leading SOAs, and increased response errors at the visual-leading SOAs. Among these changes, only the increased response errors correlated with worse spatial recognition memory in middle-aged and older adults. DISCUSSION Age-related decrements in audiovisual simultaneity perception start from middle age and are manifested in both perceptual and executive parameters. Furthermore, higher-order executive ability is plausibly a common cause for age-related degenerations in the audiovisual simultaneity perception and visual working memory.