Abstract

The present study was conducted to investigate attention deficit of schizophrenic patients on Continuous Performance Tests(CPT). Specifically, the effects of task difficulty and the chronicity of patients on the performance of CPT were evaluated. 20 psychiatric inpatients diagnosed as schizophrenia and 20 normal controls matched for age and years in education were tested on two types of CPT, Hanguel CPT and Playing card CPT. Each CPT task was given under both distracter and nondistractor condition. Signal detection analysis was performed on the hit and false alarm rates, yielding sensitivity and response criterion index. The results indicated that sensitivity on the playing card CPT with higher information loading was lower than on the Hanguel CPT. The patients with more than 5years since the first admission date(chronic group) showed little difference in their CPT performance as a function of task difficulty, while the patients with less than 5 years since the first admission date(acute group) showed a significantly poorer performance on the more difficult CPT. There was little difference in response criterion index as a function of chronicity, suggesting that cognitive impairments rather than motivational deficit characterize chronic schizophrenic patients. The results imply that within schizophrenic patients group, different types of information processing deficit are evident depending on the chronicity and that the task difficulty variable which has been paid little attention in the literature is an important factor to consider in future research.