Continuous tracking of audiovisual motion.

Multisensory processing is important for studying and understanding typical and atypical development; however, traditional paradigms involve numerous conditions and trials, making sessions long and tedious. A technique referred to as "continuous-tracking" has been introduced which can assess perceptual thresholds in a shorter time. We tested this technique in an audiovisual context by asking participants to track 1-minute audiovisual stimuli moving in a random walk. The stimuli could be visual, auditory, or audiovisual. In the last case, we had a congruent and incongruent condition with a spatiotemporal shift between the two stimuli, so either vision or audition led the walk by a given time. We further modulated the reliability of the visual stimulus to shift the weight toward the audio. We found a straightforward visual dominance regarding motion perception in audiovisual contexts. Regardless of its state, visual information interferes with auditory perception. Moreover, the continuous tracking yielded a new measurement of motion perception, the lag, giving information on the delay between visual and auditory information processing. Indeed, we observed that the tracking of auditory motion lagged relative to visual motion.