[Disorders of early information processing and vigilance as vulnerability markers for schizophrenia]

Disordered processes of scanning iconic memory and vigilance deficits are well-known phenomena in schizophrenics. The "Span of Apprehension" and the "Continuous Performance Test" are among the most important research techniques assessing these impairments and are considered possible neuropsychological vulnerability markers of schizophrenia. Numerous studies compared schizophrenics with psychiatric control groups on these tasks to determine the specificity of the performance deficits which represents a central criterion for vulnerability markers. The review of the empirical results suggests a non-specificity of the performance of schizophrenics on the "Span of Apprehension" and the degraded stimulus version of the Continuous Performance Test. These findings are critically discussed with reference to the technical and methodological characteristics of the studies. Furthermore, studies are presented which examined the relationship of vigilance performance on the Continuous Performance Test and rate of detecting on "Span of Apprehension" and psychopathological symptoms with the aim to evaluate the marker qualities of these research techniques for schizophrenic symptoms. According to the available data a partial symptomatic specificity can be attributed to the "Span of Apprehension".