DIFFERENTIAL HEMISPHERE PROCESSING OF INFORMATION IN SCHIZOPHRENIA

Ten paranoid and 10 nonparanoid schizophrenics, 10 nonschizophrenic psychiatric controls, and 10 normal controls were presented with two types of dot enumeration task, structured and unstructured dot arrays, tachistoscopically. The tasks were designed to elicit left and right hemisphere functioning through automatic and controlled information-processing strategies. The findings indicated that the two tasks failed to separate information-processing strategies as intended. The display size effects were found to be significant in both tasks for all the groups. In the case of the structured task, paranoids and nonparanoids both performed significantly more accurately in the right as compared with the left hemisphere. Unlike the other three groups, the nonparanoid group was found to process the dots in both tasks using an automatic strategy but this was so only in the left hemisphere. In the right, they performed like other groups. The findings thus point to a left hemisphere deficit in the nonparanoids.