The effects of increasing resource demand on vigilance performance in adults with schizophrenia or developmental...

The goal of this study was to assess whether degree of information processing load differentially affects vigilance performance in patients with schizophrenia as compared to normal controls or patients with other attentional disorders. We contrasted the performance of clinically stable outpatients with schizophrenia (n = 18), with that of normal controls (n = 17), and adults with developmental attentional/learning disorders (n = 13) on simple and demanding versions of a visual continuous performance test (CPT). Patients with schizophrenia were significantly impaired on both versions of the CPT compared to normal controls, and showed a significant decline in perceptual sensitivity and significantly more omission errors with increased processing demands. Compared to adults with developmental attentional/learning disorders, patients with schizophrenia manifested a tendency toward a decline in perceptual sensitivity. There were no significant differences between groups on a measure of response bias. The data support the hypothesis that patients with schizophrenia have insufficient information processing resources to cope with higher processing demands on effortful attention tasks. Further study comparing schizophrenic patients with patients who have other neuropsychiatric disorders, controlling for severity of illness, is required to determine the specificity of this deficit in schizophrenia.