The Little Albert experiment was a controlled experiment to condition a phobia in an emotionally stable child. The experiment proved that, a child can acquire a phobia with seemingly fearless objects (neutral stimulus) when those objects are associated with distinctive stimulus (loud noise) which are feared by a child.
The experiment was carried out by John B. Watson and his graduate student, Rosalie Rayner, at Johns Hopkins University. The results were first published in the February 1920 issue of the Journal of Experimental Psychology. Watson noticed that the fearful response of children to loud noises is an inborn feature.
A 9-month-old infant named Albert was given many objects like white rat, rabbit, dog, monkey, masks (with and without hair), cotton, wool to play with. Albert showed no fear of any of these items as these objects are neutral stimuli for the child. This also proved that Albert was emotionally stable.
Then the expermint entered next phase when Albert was 11-month-old. At this point, Watson and Rayner gave Albert a white rat to play with but whenever the baby touched the rat they made a loud sound behind Albert's back by striking a suspended steel bar with a hammer. Albert responded to the noise by crying and showing fear. After several such pairings (in two sessions, one week apart) of the two stimuli, Albert was presented with only the rat. Upon seeing the rat, Albert got very distressed, crying and crawling away.
Apparently, the infant associated the 'rat' with the noise. The rat, originally a neutral stimulus, had become a conditioned stimulus, and it was eliciting an emotional response similar to the distress originally given to the noise. Five days later, Watson and Rayner found that Albert developed phobias of objects which shared characteristics with the rat, including dog, a fur coat, some cotton wool and other few furry objects.
The Little Albert Experiment demonstrated that classical conditioning could be used to create a phobia. A phobia is an irrational fear, that is out of proportion to the danger. In this experiment, a previously unafraid baby was conditioned to become afraid of a rat.
Albert was about one year old at the end of the experiment, and he reportedly left the hospital shortly thereafter. Though Watson had discussed what might be done to remove the phobia, no one was sure that Albert ever went through the reversal process. Many believed that Albert's fear of furry things continued post-experimentally.