Hemispheric asymmetries in motor function: I. Left-hemisphere specialization for memory but not performance

Patients with unilateral brain lesions of vascular origin were administered tests designed to determine if left-hemisphere specialization in manual-sequence tasks involves memory for these sequences, or performance of them, or both. Patients with left-sided lesions were worse than patients with right-sided lesions on two tasks requiring the recall of hand positions. Whereas patients with left-sided lesions showed a trend towards being worse on speeded performance of an already learned manual sequence, in both groups on this task there were a large number of failures to remember the sequence. When memory demands were better controlled by providing a model during the speeded performance task, there were no group differences. It is proposed that there is left-hemisphere specialization for memory but not performance of such motor tasks.