Behavioral “properties” of drugs

Abstract

False conclusions about scientific studies can arise from faulty design or conduct of a study. False conclusions can also arise from the misapplication of terms to the results of a study. Thus, scientists should pay close attention to their verbal behavior. In this letter we argue that scientists have been incorrectly using the term "p rope r ty" to refer to the demonstration of behavioral effects of drugs. Drugs are typically referred to as possessing "reinforcing property(ies)" and "discriminative (stimulus) property(ies)". For example, in the last 2 years of Psychopharmacology 75% (21/28) of the articles in these areas used some derivation of the term property. The definitions given by the Oxford Old English Dictionary (Murray 1933, pp 1471-1472) for the term property indicate the term refers to an inherent, immutable attribute that is owned by a thing. Scientific data do not support the position that behavioral effects and discrimination are inherent attributes owned by drugs. In fact, perhaps the most important finding in the field of behavioral pharmacology is that the behavioral effects o f drugs are malleable and depend on several factors (Thompson and Dews 1977-1984). For example, studies have shown that with concurrent schedules, the same dose of a drug can simultaneously serve as a reinforcer and as an aversive stimulus (Spealman 1979). Studies have also shown that non-pharmacologic factors such as training can influence discriminative effects of drugs (Overton 1984). It is difficult to believe that a behavioral effect of a drug is an intrinsic property of a drug when that effect appears or disappears across conditions. We believe the inappropriate use of the term properties arises principally from two sources. First, scientists endeavor to discover order out of seeming disorder. Accordingly, behavioral scientists have developed classifications o f drugs based on their behavioral effects. With these classifications, the term property came into use to describe the effects that certain drugs had in common (e.g., antidepressants). However, unlike molecular structure in chemical classifications or leaf structure in botanical classifications, behavioral functions are not immutable characteristics. Second, recent advances in the study of neurotransmitters and CNS receptors have increased the belief in a one-to-one relationship