Behaviourism as a movement in psychology appeared in 1913 when John Broadus Watson published the classic article 'Psychology as the behaviourist views it'.
Watson believed that all individual differences in behaviour were due to different experiences of learning. He famously said:
Watson proposed that the process of classical conditioning (based on Pavlov’s observations) was able to explain all aspects of human psychology.
Everything from speech to emotional responses were simply patterns of stimulus and response. Watson denied completely the existence of the mind or consciousness.
Watson and Rayner (1920) Little AlbertIvan Pavlov showed that classical conditioning applied to animals. Did it also apply to humans? In a famous (though ethically dubious) experiment Watson and Rayner (1920) showed that it did "Little Albert" was a 9-month-old infant who was tested on his reactions to various stimuli. He was shown a white rat, a rabbit, a monkey and various masks. Albert described as "on the whole stolid and unemotional" showed no fear of any of these stimuli. However what did startle him and cause him to be afraid was if a hammer was struck against a steel bar behind his head. The sudden loud noise would cause "little Albert to burst into tears.
When "Little Albert" was just over 11 months old the white rat was presented and seconds later the hammer was struck against the steel bar. This was done 7 times over the next 7 weeks and each time "little Albert" burst into tears. By now "little Albert only had to see the rat and he immediately showed every sign of fear. He would cry (whether or not the hammer was hit against the steel bar) and he would attempt to crawl away. Watson and Raynor had shown that classical conditioning could be used to create a phobia. A phobia is an irrational fear, i.e. a fear that is out of proportion to the danger. Over the next few weeks and months "Little Albert" was observed and 10 days after conditioning his fear of the rat was much less marked. This dying out of a learned response is called extinction. However even after a full month it was still evident.