The influence of concurrent task difficulty on manual performance

Subjects successively pressed two switches while performing a running-memory-span task of either words or random shapes. In short-span conditions manual performance was differentially affected by the nature of the memory task material. In longer-span conditions no differential effects were found over the right- and left-hands. These results were accounted for by an attentional model of cerebral lateralization that incorporated consideration of the neural mechanisms subserving cerebral motor functions