Links Between Temporal Acuity and Multisensory Integration Across Life Span

The temporal relationship between individual pieces of information from the different sensory modalities is one of the stronger cues to integrate such information into a unified perceptual gestalt, conveying numerous perceptual and behavioral advantages. Temporal acuity, however, varies greatly over the life span. It has previously been hypothesized that changes in temporal acuity in both development and healthy aging may thus play a key role in integrative abilities. This study tested the temporal acuity of 138 individuals ranging in age from 5 to 80. Temporal acuity and multisensory integration abilities were tested both within and across modalities (audition and vision) with simultaneity judgment and temporal order judgment tasks. We observed that temporal acuity, both within and across modalities, improved throughout development into adulthood and subsequently declined with healthy aging, as did the ability to integrate multisensory speech information. Of importance, throughout development, temporal acuity of simple stimuli (i.e., flashes and beeps) predicted individuals' abilities to integrate more complex speech information. However, in the aging population, although temporal acuity declined with healthy aging and was accompanied by declines in integrative abilities, temporal acuity was not able to predict integration at the individual level. Together, these results suggest that the impact of temporal acuity on multisensory integration varies throughout the life span. Although the maturation of temporal acuity drives the rise of multisensory integrative abilities during development, it is unable to account for changes in integrative abilities in healthy aging. The differential relationships between age, temporal acuity, and multisensory integration suggest an important role for experience in these processes. Public Significance Statement How individuals combine information across the senses, known as multisensory integration, greatly influences how they perceive the world around them. One driving factor in multisensory integration is the relative timing of this information-when individuals sense auditory and visual information at the same time, it is a strong indicator that they should perceive these two inputs as a single object or event. This study shows that throughout development, from childhood, through adolescence, and into adulthood, individuals' ability to perceive the timing of sensory inputs accurately drives their multisensory integrative abilities. Contrasting that, as they age and their ability to perceive the timing of sensory inputs declines, this does not lead to a decrease in their ability to combine sensory information across modalities. Taken together, this suggests that the impact of temporal perception on multisensory integration changes across the life span.