Social Experiments in the 20th Century: The History of the World’s Most Famous and Infamous Psychological Experiments

The human psyche is one of the most complex, unpredictable, enigmatic, and therefore riveting phenomena in existence, one that psychologists have been working on deciphering since the dawn of modern science. To better understand the multifaceted intricacies of human behavior, and to unlock the secrets of the conscious mind and the subconscious, ambitious professionals in the field have conducted numerous groundbreaking – and at times, problematic – psychological experiments. The practice originated with German philosopher Wilhelm Wundt, one of the fathers of modern psychology and the creator of the world's first experimental psychology laboratory at the University of Leipzig. He sought to measure the average speed of thought processes by assigning a range of reaction time tasks to his subjects.

As the nascent, yet fast-developing scientific discipline took hold around the globe, psychological experiments simultaneously diversified. As revolutionary and eye-opening as many of these experiments were, they often danced on the fine line between ethical and unethical. There was, for instance, the now-infamous Little Albert Experiment, conducted at Johns Hopkins University in 1920, in which a nine-month-old infant was deliberately manipulated into developing an irrational fear for the purpose of studying classical conditioning, and the correlation between adult fears and childhood traumas. The Monster Study, carried out at the University of Iowa in 1939, attempted to convert orphans into stutterers, half of whom were subjected to positive reinforcements and the others to negative ones. Then, there was arguably the most notorious psychological experiment in history: the 1971 Stanford Prison Experiment, in which participants were randomly assigned the character of either prisoner or prison guard. That role-playing study quickly spiraled out of control.