Comprehending a word: the influence of speed and redundancy on auditory comprehension in aphasia.

To assess the contribution of various factors to comprehension of a target word, an auditory comprehension test was devised and administered to a series of aphasic patients. Patients were required to select from an array that picture which corresponded to a spoken target word. Each patient heard the target word under five conditions: (1) target spoken alone; (2) target embedded in a neutral (low redundancy) sentence enunciated at a normal rate of speaking; (3) target in a neutral sentence enunciated at a slow rate of speaking; (4) target embedded in a sentence containing semantic support (high redundancy); (5) target embedded in a sentence containing a semantically-deceptive element. Semantic redundancy and rate of presentation made contributions to comprehensibility. Semantic confusions were prevalent among all aphasics but, contrary to earlier reports, posterior patients were especially prone to acoustic confusions. Except for conduction aphasics, patients were more likely to confuse words which began with the same sounds than words which ended with the same sounds. Patients with adequate comprehension at the start of the testing displayed a uniform tendency to improve on the conditions administered later, while those with impaired comprehension at the start usually did not.