Those seeking a definition of “behaviour therapy” or “behaviour modification” may experience some frustration when textbooks and journals are consulted. At one stage it was generally agreed that behaviour therapy involves the application of the principles and knowledge of modern learning theory to maladaptive human behaviour (Eysenck, 1959). However, this definition has been challenged. It has been suggested that behaviour therapy should not be restricted to learning theory but encompass experimental psychology and related disciplines such as physiology and neurophysiology (Yates, 1971). Still others suggest that ties to learning theory and experimental psychology are tenuous and should be discarded (Lazarus, 1971). With the advent of several conceptual variations — applied behaviour analysis, the neobehaviouristic stimulus-response model, multimodal behaviour therapy, social learning theory and cognitive-behaviour modification — attempts to define behaviour therapy are even more difficult. However, Kazdin and Hersen (1980) suggest that the major characteristics of behaviour therapy consist of:
1. A strong commitment to empirical evaluation of treatment and intervention techniques;
2. A general belief that therapeutic experiences must provide opportunities to learn adaptive or prosocial behaviour;
3. Specification of treatment in operational and, hence, replicable terms;
4. Evaluation of treatment effects through multiple-response modalities, with particular emphasis on overt behaviour.