The participant in the experiment was a child that Watson and Rayner called "Albert B." but is known popularly today as Little Albert. When Little Albert was 9 months old, Watson and Rayner exposed him to a series of stimuli including a white rat, a rabbit, a monkey, masks, and burning newspapers and observed the boy's reactions.
The boy initially showed no fear of any of the objects he was shown.
The next time Albert was exposed to the rat, Watson made a loud noise by hitting a metal pipe with a hammer. Naturally, the child began to cry after hearing the loud noise. After repeatedly pairing the white rat with the loud noise, Albert began to expect a frightening noise whenever he saw the white rate. Soon, Albert began to cry simply after seeing the rat.