The experiment showed how classical conditioning could be used to explain STIMULUS GENERALIZATION.
John Watson used a 9 months old baby to show that a subject can be conditioned to fear an object which he did not fear before. Albert was a baby who does not fear anything: cat, rat, rabbit, flurry objects, etc, but he does not like loud noise. Albert was allowed to play with white rat, which he did not show any fear for. But during the course of the experiment, anytime the baby touch the rat, Watson used bell to make loud noise. Because of this, the baby become afraid of the rat and started running away from it. To show stimulus generalization, the baby also started running away from all other objects [cat, rabbit, flurry objects, etc] which he did not fear before. Thus the fear he developed for the rat was extended to other objects.
