AbstractAuditory rhythmic training has been shown to enhance motor performance (e.g., walking: Thaut et al., 1996). The current study recruited healthy individuals to examine the effect of unimodal (i.e., auditory or visual cues) vs. bimodal cues on the spatiotemporal adaptations of a sequential upper-limb reaching task with varying movement amplitudes. This was done because congruent bimodal information facilitates perception relative to unimodal information (Ernst & Bülthoff, 2004). Participants performed reversal movement sequences that involved 6, 12, and 18 cm amplitudes and were asked to maintain the same movement duration for all amplitudes. Before each trial in the sensory-cued conditions, the rhythm was specified with four auditory beeps, visual flashes, or audiovisual cues. The sequences were also performed without these pre-trial cues (i.e., no-cue conditions). Movement time error (MTE) corresponded to the difference between the participant's sub-movement times and the prescribed rhythm. Within the sensory- cued and no-cue conditions, small amplitude movements yielded the largest MTEs. Critically and as hypothesized, the sensory-cued audiovisual condition yielded lower MTEs relative to the auditory and visual conditions, although this was limited to the small amplitude movements. Interestingly, these lower MTEs for the small movement amplitude were also observed in the no- cue condition following the audiovisual condition vs. those following the auditory-cued conditions. Follow-up analyses involving linear de-trending confirmed that the benefits of bimodal cueing were specific to the sensory training and not a performance improvement over time. Thus, combining auditory with visual cues can enhance rhythmic training, which could also be useful in rehabilitation settings.
Acknowledgments: University of Toronto, Ontario Research Fund, Canadian Foundation for Innovation, National Sciences and Engineering Research Council