Dissociation of Smooth-Pursuit and Saccadic Eye Tracking in Remitted Schizophrenics

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Abstract
• Twenty-four schizophrenic outpatients in remission were compared with 21 medical outpatient controls on tasks designed to evaluate smooth pursuit of different frequency sinusoidal targets, saccadic eye tracking, and performance on psychomotor analogues of these tasks that require eye-hand coordination. The schizophrenics demonstrated impaired performance on all the smooth-pursuit and psychomotor tracking tasks. However, the oculomotor reaction times of schizophrenics during the saccadic eye-tracking tasks were equal to those of controls. This dissociation of smooth-pursuit and saccadic performance indicates that smooth-pursuit dysfunction cannot be attributed to a lack of motivation, simple inattention, or oculomotor control mechanisms for which the pursuit and saccadic systems share a common anatomy. The saccadic eye-tracking task is quite similar to a variable-foreperiod simple reaction-time task. That schizophrenics produce normal response latencies on this task raises important questions about the nature of the reaction-time deficit in schizophrenia.