18 Experiments That Crossed Every Line, Ranked By Cruelty

Psychologists John B. Watson and Rosalie Rayner wanted to prove emotions could be learned through conditioning. Their study involved a baby known as “Little Albert,” who was exposed to a white rat paired with a frightening noise. The child eventually developed fear toward the animal and similar objects. The experiment became famous in psychology, but it also highlighted serious issues surrounding consent and the treatment of children in research.