Behaviourism, a movement in psychology that advocates the use of strict experimental procedures to study observable behaviour (or responses) in relation to the environment (or stimuli). The behaviouristic view of psychology has its roots in the writings on associationism of British philosophers. It also arose out of the American school of psychology known as functionalism and the Darwinian theory of evolution, both of which emphasize the way that individuals adapt and adjust to the environment.


Behaviourism was first developed in the early 20th century by the American psychologist John B. Watson. The dominant view of that time was that psychology is the study of inner experiences or feelings by subjective, introspective methods. Watson did not deny the existence of inner experiences, but he insisted that these experiences could not be studied because they were not observable. He was greatly influenced by the pioneering investigations of the Russian physiologists Ivan P. Pavlov and Vladimir M. Bekhterev on the conditioning of animals (classical conditioning).

Watson proposed to make the study of psychology scientific by using only objective procedures such as laboratory experiments designed to establish statistically significant results. The behaviouristic view led him to formulate a stimulus-response theory of psychology. In this theory, all complex forms of behaviour—emotions, habits, and such—are seen as composed of simple muscular and glandular elements that can be observed and measured. He claimed that emotional reactions are learned in much the same way as other skills.

Watson’s stimulus-response theory resulted in a tremendous increase in research activity on learning in animals and in humans, from infancy to early adulthood.

Between 1920 and midcentury, behaviourism dominated psychology in the United States and also had wide international influence. By the 1950s, the new behavioural movement had produced a mass of data on learning that led such American experimental psychologists as Edward C. Tolman, Clark L. Hull, and B. F. Skinner to formulate their own theories of learning and behaviour based on laboratory experiments instead of introspective observations.


Skinner’s position, known as radical (or basic) behaviourism, is similar to Watson’s view that psychology is the study of the observable behaviour of individuals interacting with their environment. Skinner, however, disagrees with Watson’s position that inner processes, such as feelings, should be excluded from the study. He maintains that these inner processes should be studied by the usual scientific methods, with particular emphasis on controlled experiments using individual animals and humans. His research with animals, focusing on the kind of learning—known as operant conditioning—that occurs as a consequence of stimuli, demonstrates that complex behaviour such as language and problem-solving can be studied scientifically. He postulated a type of psychological conditioning known as reinforcement.


Since 1950, behavioural psychologists have produced an impressive amount of basic research directed at understanding how various forms of behaviour are developed and maintained. These studies have included the role of (1) the interactions preceding behaviour, such as the attention span and perceptual processes; (2) changes in behaviour itself, such as the formation of skills; (3) interactions following behaviour, such as the effects of incentives or rewards and punishments; and (4) conditions prevailing over all the events, such as prolonged emotional stress and deprivations of the essentials of life.

Some of these studies were conducted with humans in rooms especially equipped with observational devices and also in natural settings, as in school or at home. Other studies used animals, particularly rats and pigeons, as subjects, in standard laboratory settings. Most studies with animals required simple responses. For example, the animal was trained to press a lever or peck a disc in order to receive something of value, such as food, or to avoid painful stimulation, such as a slight electric shock.

At the same time, psychologists have undertaken studies using behavioural principles on practical problems. This work has yielded a set of therapies known as behaviour modification, or applied behaviour analysis. Applied behavioural research has been carried out in three main areas.

The first focuses on the techniques of psychological treatment for troubled adults and children with behaviour disorders. This area is known as behaviour therapy. The second centres on improving teaching and training methods. Some studies have explored the teaching processes used in the educational system from pre-school to college; others have focused on training in business and industry and in the armed forces, where methods of programmed instruction have been developed. Many studies have dealt with the problems of improving teaching and training methods for handicapped children at home, in school, or in institutions. The third area of applied research is concerned with the long- and short-term effects of drugs on behaviour. In these studies, drugs usually are administered to animals in various dosages and combinations. Changes are then observed in the way in which these animals perform repetitive tasks, such as pressing a lever.


The initial influence of behaviourism on psychology was to minimize the introspective study of the mental processes, emotions, and feelings and to substitute the study of the objective behaviour of individuals in relation to their environment by means of experimental methods. This orientation suggested a way to relate human and animal research and to bring psychology into lines with the natural sciences, such as physics, chemistry, and biology.


Present-day behaviourism has extended its influence on psychology in three ways. It has replaced the mechanical concept of stimuli and responses with a functional concept that emphasizes the meaningfulness of stimulating conditions to the individual. It has introduced a research method for the experimental study of a single individual. Finally, it has demonstrated that behavioural concepts and principles can be applied to many practical problems.