Visual and auditory information shed light on savings mechanisms

Successful completion of natural motor actions relies on feedback information delivered through different modalities, including vision and audition. The nervous system weights these sensory inflows according to the context and they contribute to the calibration and maintenance of internal models. Surprisingly, the influence of auditory feedback on the control of fine motor actions has only been scarcely investigated alone or together with visual feedback. Here, we tested how 46 participants learned a reaching task when they were provided with either visual, auditory or both feedback about terminal error. In the VA condition, participant received visual (V) feedback during learning and auditory (A) feedback during relearning. The AV group received the opposite treatment. A third group received visual and auditory feedback in both learning periods. Our experimental design allowed us to assess how learning with one modality transferred to relearning in another modality. We found that adaptation was high in the visual modality both during learning and relearning. It was absent in the learning period under the auditory modality but present in the relearning period (learning period was with visual feedback). An additional experiment suggests that transfer of adaptation between visual and auditory modalities occurs through a memory of the learned reaching direction that acts as an attractor for the reaching direction, and not via error-based mechanisms or an explicit strategy. This memory of the learned reaching direction allowed the participants to learn a task that they could not learn otherwise independently of any memory of errors or explicit strategy.