Audiovisual integration facilitates age-related perceptual decision making.

Objectives: Aging populations commonly experience a decline in sensory functions, which negatively affects perceptual decision making. The decline in sensory functions has been shown to be partially compensated by audiovisual integration. Although audiovisual integration may have a positive effect on perception, it remains unclear whether the perceptual improvements observed in older adults during perceptual decision making are better explained by the early or late integration hypothesis.

Methods: An audiovisual categorization task was used to explore responses to unisensory and audiovisual stimuli in young and older adults. Behavioral drift-diffusion model (DDM) and electroencephalography (EEG) were applied to characterize differences in cognitive and neural dynamics across groups.

Results: The DDM showed that older adults exhibited higher drift rates and shorter nondecision times for audiovisual stimuli than for visual or auditory stimuli alone. The EEG results showed that during the early sensory encoding stage (150-300 ms), older adults exhibited greater audiovisual integration in beta band than younger adults. In the late decision-formation stage (500-700 ms), older adults exhibited greater audiovisual integration in beta band and greater audiovisual integration in the anterior frontal electrodes than younger adults.

Discussion: These findings highlight the crucial role of audiovisual integration in both the early and late stages of perceptual decision making in older adults. The results suggest that enhanced audiovisual integration in older adults compared with younger adults may serve as a specific mechanism to mitigate the negative effects of aging on perceptual decision making.