4. The Little Albert Experiment
In 1920, psychologists John B. Watson and Rosalie Rayner conducted an experiment on a 9-month-old infant, known as “Little Albert,” at Johns Hopkins University. They conditioned him to fear white rats by pairing the presence of the rats with loud, frightening noises. This experiment demonstrated that emotional responses could be conditioned in humans. However, it raised significant ethical concerns regarding consent and the potential for psychological harm, as the infant was neither informed nor protected from distress. (apa.org)