The development of interlimb coordination during bimanual finger tapping.

Normal subjects aged 7-25 years were asked to tap the index fingers of both hands: a) in four different patterns of interlimb coordination; b) at two different response frequencies; and c) both before and after the entraining metronome was turned off. The outcome variables of primary interest were the within-subject variability of interresponse intervals (IRI) as an index of timing precision; and deviations from prescribed response frequency, as an index of temporal tracking accuracy. Stability of timing precision and accuracy of temporal tracking increased significantly from 7 to 9 and from 9 to 11 years, with only minor advances thereafter. There were significant right-left performance asymmetries in all bimanual tasks; variability of IRI and deviations from prescribed rate were greater at the faster of the two response frequencies tested; and stability of IRI and accuracy of temporal tracking were greater with than without the metronome. Stability of IRI and accuracy of temporal tracking were strongly correlated in some bimanual tasks. The findings are discussed in terms of the two major theoretical perspectives on human brain-behavior relationships that have specifically addressed the issue of bimanual coordination.