[The vigilance paradigm in schizophrenia research - studies on the Continuous Performance Test (CPT)]

Deficits in vigilance/sustained attention of schizophrenic subjects have been a main topic of neuropsychological schizophrenia research for many years. The degraded stimulus Continuous Performance Test (ds-CPT) is the standard paradigm for measuring vigilance. Measurement of vigilance requires the observation of the course of perceptual sensitivity over time. The present review shows that from a theoretical point of view it is possible to show vigilance deficits (as a decrease of sensitivity) with the ds-CPT if certain conditions are given. However, only in a few schizophrenia studies the course of sensitivity over time was evaluated, while in most studies merely the level of sensitivity was analysed. Results presented in this review suggest that level and course of sensitivity are largely independent variables. Vigilance can be operationalised adequately only when considering the course of sensitivity over time. Therefore there still is a considerable need for research on the meaning of vigilance deficits for manifestation, course and treatment of schizophrenia.