Aging Impairs Audiovisual Facilitation of Object Motion Within Self-Motion

The presence of a moving sound has been shown to facilitate the detection of an independently moving visual target embedded among an array of identical moving objects simulating forward self-motion (Calabro et al., Proc. R. Soc. B, 2011). Given that the perception of object motion within self-motion declines with aging, we investigated whether older adults can also benefit from the presence of a congruent dynamic sound when detecting object motion within self-motion. Visual stimuli consisted of nine identical spheres randomly distributed inside a virtual rectangular prism. For 1 s, all the spheres expanded outward simulating forward observer translation at a constant speed. One of the spheres (the target) had independent motion either approaching or moving away from the observer at three different speeds. In the visual condition, stimuli contained no sound. In the audiovisual condition, the visual stimulus was accompanied by a broadband noise sound co-localized with the target, whose loudness increased or decreased congruent with the target's direction. Participants reported which of the spheres had independent motion. Younger participants showed higher target detection accuracy in the audiovisual compared to the visual condition at the slowest speed level. Older participants showed overall poorer target detection accuracy than the younger participants, but the presence of the sound had no effect on older participants' target detection accuracy at either speed level. These results indicate that aging may impair cross-modal integration in some contexts. Potential reasons for the absence of auditory facilitation in older adults are discussed.