Neuropsychological models of stuttering--II. Interhemispheric interference.

The performance of male adult stutterers and fluent speakers was compared on repetitive sequential finger tapping and index finger tapping with one hand while carrying out concurrent paced tasks with the other hand. For the theoretically meaningful condition of right-hand sequential tapping and left-hand concurrent task performance, there was more interference on the tapping task among stutterers than fluent speakers. The data were interpreted as being consistent with a neuropsychological model of stuttering that includes as an element enhanced left-hemisphere vulnerability to interference by concurrent right-hemisphere activity.