Research employing the patient as his own control while systematically introducing and reversing the treatment conditions can be a useful strategy in the investigation of drug-environment-behavior interactions. Reliable observations can be carried out on clinically significant behaviors. In the current article, autistic withdrawal, interpersonal eye contact, and delusional speech in psychotics were the behaviors targeted for intervention with phenothiazine drugs. The phenothiazine was shown to be the primary causal variable for altering social withdrawal, contributory for increases in eye contact, and irrelevant in the control of delusional speech.