This post is based on submission by reader Professor Daniel Bitran.
The original experiment consists of presenting various "neutral" stimuli to a child (Little Albert) which evoke no reaction from him. Then a stimulus is shown while a loud bang is sounded, and now the same stimulus evokes a fearful reaction. While the experiment moved Behaviorism forward, it is now a discussion point regarding ethics in scientific research.
In 2009, researchers pieced together census records and Watson's personal correspondence to determine that Little Albert was in fact Douglas Merritte and, despite Watson's claims to the contrary, suffered from hydrocephalus from birth (he died very young).
My original reaction to this information was that perhaps this strengthens, rather than weakens, the results of the original experiment. However, Dr. Bitran has pointed out that the study was predicated on a normal child developing a phobia—a study with a child who has other issues introduces confounding effects that are not controlled.