Over the years, many theories have been proposed to account for the ab
errant behavior of drug dependent individuals. Heyman posits that the
existing theories of drug dependence are inadequate to explain the com
plex processes inherent in human drug-taking. He proposes that incongr
uous behaviors that comprise addiction, such as continued drug use in
spite of adverse consequences, can be explained by application of the
matching law approach. While the matching law theory of addiction expl
ains certain aspects of human behavior, its application to the area of
addiction must be subjected to experimental verification.