BACKGROUND Despite 30 years of research, some surprisingly fundamental gaps remain in our understanding of schizophrenic input dysfunctions. METHODS In a provisional test of a 'hyperattention' hypothesis, schizophrenic patients and control subjects performed a behavioural test that was adapted from a paradigm originally developed for characterising vigilance or sustained attention in animals. On this computerised operant testing procedure, subjects discriminated between signals of various salience and non-signal presentations. Hits and correct rejections resulted in monetary rewards while misses and false alarms entailed monetary costs. RESULTS Data from in-patients with schizophrenia and age, education and gender-matched controls support hypotheses not only about hyperattentional dysfunctions in schizophrenia with respect to overall signal detectability but also in terms of resistance to the vigilance decrement that normally occurs over trials. CONCLUSIONS The theoretical importance of impairments of this sort are discussed with respect to the cognitive and perceptual consequences of hypervigilance and 'input dysfunction'.