The effect of cerebral dominance on time sharing between speaking and tapping by preschool children.

48 kindergartners tapped as fast as they could with either the right index finger or the left, either alone or while reciting or repeating verbal material. The secondary tasks diminished tapping rate on both sides, but disproportionately on the right. This result was predicted by a model that postulates greater interference between concurrent activities when both are programmed by the same cerebral hemisphere. Children appear to be more vulnerable to this type of interference than adults. This attribute of immature motor development can be used as an indicator of cerebral lateralization of function in children.