The effect of visual guidance and hemispace on lateralized vocal-manual interference

When right-handers speak while performing manually, their right-hand performance declines disproportionately to their left. The present study shows that this is true for a sequentially homogeneous activity--repetitive single finger tapping; does not depend on the hemispace location of the performing hand; is not abolished by viewing the performing hand; and is not an artifact of trade-off with rate of concurrent speech production. These findings contradict some suggested models for such effects.