Bimanual coordination involving homologous and heterologous joint combinations: when lower stability is associated with higher flexibility.

Variability in behavior is often put in an unfavorable light as a marker of lack of skill. Here, we provide evidence that increased variability during preferred patterns of coordination is associated with higher flexibility in adopting new patterns. Twelve right-handed subjects performed cyclical bimanual flexion and extension patterns with four homologous and six heterologous joint combinations involving shoulder, elbow, wrist, and finger movements. Preferred (isofrequency) as well as less preferred (multifrequency) coordination patterns were studied. The findings revealed less accurate and less stable 1:1 coordination patterns during heterologous as compared to homologous limb segment combinations. Conversely, coordination patterns with a 2:1 frequency ratio were performed more accurately and more consistently during heterologous as compared to homologous conditions. Accordingly, a lower degree of coupling between effectors during performance of preferred coordination patterns was associated with more successful performance of less familiar patterns. This suggests that variability may promote the creative exploration of new performance modes. Copyright 2003 Elsevier B.V.