Effects of trifluoperazine, chlorpromazine, and haloperidol upon temporal information processing by schizophrenic patients.

Healthy controls, unmedicated, actively symptomatic schizophrenics, and similar patients undergoing treatment with either trifluoperazine, chlorpromazine, or haloperidol were studied with tests of temporal discrimination and measures of transmitted information shown previously to be sensitive to various kinds of brain dysfunction, including haloperidol effects in a nonpsychotic population. Variations in psychophysical method, cognitive load, discrimination complexity, and sense-mode conditions permitted representative sampling of the temporal processing. Untreated, actively psychotic patients showed no impairment of temporal processing while all three antipsychotic medications were associated with significant deficit; trifluoperazine and haloperidol produced the most deficit, with chlorpromazine in the middle between the higher potency drugs on the one hand and unmedicated patients and healthy controls on the other.