Learning a new bimanual coordination pattern: interlimb interactions, attentional focus, and transfer

Because bimanual coordinative stability is governed by interlimb coupling, we examined how learning a new pattern (90°) was reflected in changes in the underlying interlimb interactions. Three interlimb interaction sources were distinguished: integrated timing of feedforward control signals, error corrections based on perceived relative phase, and phase entrainment by contralateral afference. By comparing 4 tasks that involve these interactions to a different extent, changes in the stabilizing contributions of these coupling sources could be studied. Furthermore, we studied how the learning process and changes in the underlying interactions were influenced by attentional focus (internal vs. external), and we examined retention of the learned pattern and transfer to the mirror-symmetrical pattern (270°). Results showed that stability and accuracy of the new pattern increased significantly with learning, due to improved integrated timing and error correction. Integrated timing improved first, possibly providing a reference frame for the error corrections that subsequently became more effective. Despite some qualitative differences in the learning process, neither performance of the learned pattern nor the underlying interlimb interactions was influenced by attentional focus. Whereas the learned pattern improved directly after practice, transfer followed later, suggesting that a more general representation was formed at a slower rate after practice.