The behavioral consequences of the administration of.a drug depend upon a number of factors in addition to the properties of the drug. The reinforcement characteristics of the testing situation, the nature of the subjects and the type of psychological tests used are among such factors.
Experiments in animals have demonstrated that drug effects may depend on the schedules of reinforcement used (Wh~LE~ 1957; DEWS and Mons~ 1961 ; Cook and KE~,L]~En 1963). In human subjects the simultaneous investigation of drug and reiniforcement effects has received scant attention. I-Iowever, what research that has been done suggests that drug effects in man may also be modified by the conditions of reinforcement. Normal persons who are paid to serve as subjects are usually assumed to be positively motivated to perform in the testing situation, even though a reinforcement procedure may not have been included in the experimental design. Hospitalized psychiatric patients, however, are not usually rewarded for serving as subjects in drug experiments, and whether they perceive the testing situation as positive or aversive is not known. Therefore, one primary purpose of the present experiment was to investigate the effect of positive reinforcement on the performance of chronic schizophrenic patients on a variety of tests under no-drug conditions as well as after the administration of chlorpromazine and secobarbital.