Differential development of audio-visual integration for saccadic eye movements and manual responses

摘要

The developmental time course of human audio-visual integration is currently unclear. In a simple task eliciting reflexive orienting, infants as young as 8a??10 months show reaction time advantages for combined vs. single visual-auditory cues that exceed purely statistical facilitation (Neil et al, Dev Sci 2006). On the other hand, most children do not show similar multisensory advantages until after 7 years when tested with a manual button-pressing task (Barutchu et al, Dev Sci 2009). We propose that these differences may reflect differential development of reflexive orienting, dependent on the superior colliculus, and sensory decisiona??a??making, dependent on cortical integration of sensory evidence. To test this our aim is to compare the development of multisensory orienting and button-pressing for the same audio-visual stimuli. In an initial study we recorded eye movements of children aged 4a??13 years (N = 19) in response to visual (V) flashes, auditory (A) beeps, or both (AV), presented at 20?° eccentricity. Subjects first fixated a central cross that disappeared 1300a??2300 ms before the stimulus onset in order to avoid cue competition. Overall, mean AV saccadic latencies were significantly shorter than either A or V, and the group as a whole showed a trend towards AV latencies shorter than those predicted by statistical facilitation (Miller, Cog Sci 1982). These results indicate that unlike in button-pressing tasks, children aged 4 years and above can show reaction time advantages consistent with cue integration when tested with a simple saccadic orienting task. We propose that this capacity depends on early-developing subcortical multisensory processing (Wallace & Stein, J Neurosci 1997).