The introduction of chlorpromazine and reserpine as therapeutic agents has given great impetus to the field of psychopharmacology. The subsequent rapid development of other new drugs has increased the need for improved techniques of assessing drug effects and for investigations of the mechanisms of their action. The diverse and complex actions of these agents has, in addition, resulted in new terminologies and concepts. "Tranquilizer," "psychic normalizer," "ataractic," "neuroleptic," and "psychic energizer" are among the new terms introduced. These new terms have become very popular; many have even