Attentional distribution of task paramters to the two hands during bimanual performance of right- and left-handers.

The author tested 12 left-handers and 12 right-handers on a bimanual circling task to examine how attention (either visual or nonvisual) to the task of 1 hand affects within-hand task parameters and whether the effects of attention manipulations are similar in left- and right-handers. The novel prediction that the attended task would be produced larger than the unattended task was confirmed in both handedness groups. The magnitude of the effect on circle size was more pronounced under visual than under nonvisual attention manipulations. The primary effects of attention were similar in the 2 handedness groups, although left-handers demonstrated some evidence of stronger parameter coupling between hands than right-handers did.