Impaired timing of audiovisual events in the elderly.

Perceptual binding of multisensory events occurs within a limited time span known as the temporal binding window. Failure to correctly identify whether multisensory events occur simultaneously, what their temporal order is, or whether they should be causally bound can lead to inaccurate representations of the physical world, poor decision-making, and dangerous behavior. It has been shown that the ability to discriminate simultaneity, temporal order, and causal relationships among stimuli can become increasingly difficult as we age. In the present study, we assessed the relationship between these three attributes of temporally processing multisensory information in both younger and older adults. Performance on three tasks (temporal order judgment: TOJ, simultaneity judgment: SJ, and stream/bounce illusion) was compared using a large sample within-subjects design consisting of younger and older adults to determine aging effects as well as relationships between the three tasks. Older adults had more difficulty (larger temporal binding window) discriminating temporal order and perceived collision than younger adults. Simultaneity judgments in younger and older adults were indistinguishable. Positive correlations between TOJ and SJ as well as SJ and stream/bounce tasks were found in younger adults, which identify common (SJ) and distinct (TOJ, stream/bounce) neural mechanisms that sub-serve temporal processing of audiovisual information that is lost in older adults. We conclude that older adults have an extended temporal binding window for TOJ and stream/bounce tasks, but the temporal binding window in SJ is preserved, suggesting that age-related changes in multisensory integration are task specific and not a general trait of aging.