His definition of this approach was highly practical. Thus, Watson believed psychology should be a purely objective field of knowledge used to accurately predict and control human behaviour and development. Introspection and self-analysis are useless if applied to psychology and there is no difference between humans and animals. In fact, Watson neglected the concept of the conscious and unconscious as such (Littleton, Toates, & Braisby, 2002).
Formulating his views Watson relied primarily on the Ivan Pavlov's discovery of the mechanism of classical conditioning. Pavlov's studies of dog's digestion transformed the common understanding of learning and development. The scientist carried out a series of experiments in order to test his initial conclusions. He provided a sound or light signal that was immediately followed by some food placed in the dog's moth. The dog started to perceive the signal in conjunction with the food and after several repetitions the dog salivated immediately after the signal even without any food. This fact made Pavlov introduce a new psycho-physiological concept of a conditional stimulus in distinction to an unconditioned stimulus (Littleton, Toates, & Braisby, 2002: 170-171).
Although Pavlov revealed the phenomenon of classical conditioning during experimental studies, which involved animals, the key principle of this process proved valid in human behaviour too. Watson described an example of the classical conditioning in human beings. Albert, an infant with a pet rat, was not afraid of it until once Watson banged a metal plate while the boy was reaching for his pet. Subsequently, Albert started to demonstrate fear of the rat (Littleton, Toates, & Braisby, 2002: 172). Another good example of the classical conditioning in human behaviour is the bell-and-pad technique that is often used to cope with bed-wetting in children. Two perforated metal sheets connected to a low-tension battery are placed under the bed sheet. When a child moistens the bed urine short-circuits the sheets, and the battery produces a laud alarm making the child wake up. After several alarms the child is able to wake up without the alarm: the sensation of a full bladder is finally connected to the necessity of waking up (Lattal & Chase, 2003).
Skinner further elaborated on the behaviourist conception of behaviour by paying attention not only to stimuli resulting in certain patterns of behaviour, but also exploring the stimuli affecting the actor after performance. In a series of experiments involving rats and pigeons that were rewarded with food for pressing a lever in the Skinner box, the scientist observed that positive stimuli led to more frequent repetition of the act that caused them; he called such stimuli "reinforcers" (Littleton, Toates, & Braisby, 2002: 175-176). Skinner recognised situational influences as predominant factors that cause different reactions of children. The reactions largely depend upon the previous experience and genetic code of individual. Skinner also believed that analysis of specific mental states, which had been so popular in psychoanalytic