title: Decision speed and bias after unilateral stroke.
abstract: Nonverbal visual memory together with speed and bias in response decisions were evaluated in two experiments comparing patients with a left-hemisphere stroke lesion to those with a right-hemisphere stroke lesion. In the first experiment, the decision times of vocal recognition responses from aphasic (left stroke) patients did not correlate with their verbal scores on the Porch Index of Communicative Ability, taken as an estimate of severity of their language impairment. Thus, impairment of verbal processing was not reflected in speed of response. In the second experiment, 19 left and 19 right-stroke patients were compared with 19 volunteers on a recurrent recognition task of complex nonverbal art designs using measures of discriminability and decision bias derived from Theory of Signal Detection. Right stroke patients had lowest recognition scores but adopted normal decision criteria, whereas left stroke patients employed high negative decision bias (i.e., made few false as well as few correct recognitions). Both stroke groups responded significantly slower than controls; the right stroke patients, however, had markedly fewer long-latency decisions than left stroke patients. Compared with controls, only the speed and bias of decision making were deficient in left stroke patients independent of their verbal deficit; their recognition ability was relatively preserved.
mesh_terms: D001037:Aphasia / Q000523:psychology; D001925:Brain Damage, Chronic / Q000523:psychology; D002561:Cerebrovascular Disorders / Q000523:psychology*; D003657:Decision Making; D004292:Dominance, Cerebral; D006801:Humans; D002542:Intracranial Embolism and Thrombosis / Q000523:psychology; D011939:Mental Recall; D008875:Middle Aged; D009483:Neuropsychological Tests; D010364:Pattern Recognition, Visual; D011930:Reaction Time