The two main types of behaviourism, only one of which – logical behaviourism – is a philosophical theory. The other theory – psychological behaviourism – grew out of the theories of American psychologists J. B. Watson and B. F. Skinner. Psychological behaviourism attempts to predict and control human behaviour by studying the stimuli needed to produce certain responses.

Perhaps the most famous example of a behaviourist experiment is the one conducted by the Russian scientist I. P. Pavlov (1849 - 1936). In the experiment, Pavlov fed some dogs whilst simultaneously ringing a bell. Eventually, Pavlov discovered, the dogs came to associate the bell ringing with being fed and began to salivate. In this way, one stimulus (the food) could be replaced with another which otherwise had no connection with it (the bell) in order to produce the same reaction (salivation).

Psychological behaviourism is therefore mainly concerned with accounting for human behaviour in terms of stimulus and response. However, it is also interested in the methods involved in conditioning and predicting the outcome of stimuli. From this point of view, although it has something to say about the relation of mind and body, it is not really its main concern.