Long Term Objective: This proposal is part o a program that combines clinical and basic research objectives, with the long term goal of elucidating brain-behavior relationships in aphasic patients. There is emerging evidence that perseveration is an integral component of some aphasia syndromes, and can be a major deterrent to evaluation and rehabilitation of aphasic individuals. The focus here is on the role of perseveration in the communication breakdown in aphasia and the effects of treatment on perseveration and language performance. The proposed research aims: 1) to test the two most commonly cited hypotheses regarding the underlying mechanisms responsible for recurrent perseveration in aphasia, i.e. post-activitation of semantic memory traces in short term memory versus motor memory traces; 2) to study the effects of specific treatment on aphasic perseveration; 3) to study patients' awareness of perseverative responses; and 4) to qualitatively and quantitatively chart the evolutionary course of perseveration in patients who receive specific treatment for perseveration versus those who do not receive treatment for perseveration.