This research project was designed to investigate the nature of the speech disorders consequent upon lesions of the basal ganglia. For many years it was assumed that the speech disorders associated with basal ganglia damage were no more than a manifestation of underlying rigidity. However, experience has shown that surgery which successfully ameliorates the rigidity in no way lessens the speech disturbance of patients with Parkinson's disease. Indeed, in some studies, there are reports of speech disturbances being induced by the operation. From the literature, it seems that there is a strong case for the assumption that the speech disturbances are due not to rigidity, but to akinesia. This project was designed to test this hypothesis.