The term Stimulus Properties of Drugs refers to a particular approach for studying the drugs used to treat mental illnesses and the substances which produce drug dependence (addiction). The Drug Discrimination method has become one of the most widely used ways to study the psychological effects that these drugs bring about; it also helps in the identification of the particular chemicals in the brain upon which the drugs act to bring about the psychological effects (such as changes in behavior and mood). It plays an important role in the development of new drugs for use in psychiatry and in the search for new treatments for problems of drug dependence.

In the course of everyday living and learning, environmental stimuli act as rewards that motivate behaviour (e.g. food, sex and money) and as cues that direct behaviour (traffic lights, body language). Psychoactive drugs can also influence behaviour by acting as stimuli in a manner much like the rewarding and cuing events mentioned above. When drugs serve as rewards and motivate new behaviour, drug-taking develops and can lead to drug abuse and dependence. When drugs serve as cues (called discriminative stimuli in behavioural psychology), people learn to identify their characteristic effects in the body, such as changes in mood and emotion. The drug discrimination method is a way for training people or experimental animals to recognise these drug effects and to measure them in a precise, reliable and quantitative manner. It plays an important role in the science of psychopharmacology and is used in many academic departments of pharmacology, psychology and neuroscience, and in the pharmaceutical industry. SSPD encourages the development and application of these methods by holding scientific meetings at which experts in the field can pool their knowledge and discuss the latest research findings.