Consequences of a motor programming deficit for rehearsal and written sentence comprehension

The role of central motor processes in rehearsal was investigated by studying a brain-damaged patient with a severe articulatory impairment. Evidence is presented that his articulatory impairment is due to a disruption of motor programming rather than to peripheral muscle weakness. Despite his motor programming deficit, the patient showed normal auditory span and evidence of rehearsal for auditorily presented sequences of words. For visual presentation, span was reduced and there was no evidence of rehearsal. Also, the patient showed excellent sentence comprehension for syntactically complex sentences for both auditory and visual presentation. The results imply that central motor processes are not critical for normal short-term memory, at least for auditory presentation, and that reading comprehension does not depend on inner rehearsal.