Visual information processing in positive, mixed, and negative schizophrenic syndromes

The purpose of this study was to determine whether schizophrenics with positive, mixed, and negative syndromes are distinguished in terms of visual stimulus registration thresholds and efficiency of information processing. Forty-five schizophrenic inpatients were classified accordingly into groups of 15 each and compared with one another and with 15 normal control subjects on a visual backward masking task. Repeated-measures analysis of variance revealed that all three schizophrenic groups were less efficient information processors than were normal subjects. Relative to the positive group, the negative group displayed significantly longer registration thresholds, fewer correct target stimulus detections, and longer time intervals to achieve their first significant improvement in performance and to first exceed chance response levels. The three syndrome groups were not significantly different in their rates of improvement over trials. Secondary correlational analyses showed that the information-processing measures were unrelated to a variety of demographic, psychiatric, and cognitive developmental variables, although shorter recognition thresholds and shorter unmasking interval scores were associated with faster psychomotor rates. Complex interrelationships were uncovered between the information-processing measures, positive and negative symptomatology, and general psychopathology. The results were interpreted as supporting the validity of the positive-negative distinction for explaining some of the heterogeneity in schizophrenia.