A Look Back at Psychology's Most Unethical Experiments

The pursuit of knowledge is a noble endeavor, a cornerstone of modern science that has unraveled many mysteries of the world and the human mind. Scientists today operate within a strict framework of safety procedures and ethical codes, ever mindful of the risks involved. But this was not always the case. In the past, the lines were often blurred, and the quest for understanding led to experiments that were not just ethically questionable, but truly cruel, leaving permanent scars on their participants. We must look back at these dark chapters, not to sensationalize them, but to understand the price that was paid for the ethical lessons we hold dear today.

Creating Fear: The Case of Little Albert

In late 1919, John B. Watson, the founder of behaviorism, set out to prove a chilling hypothesis: that an emotional response like fear is not innate, but learned through conditioning. His subject was a nine-month-old infant, known to history only as "Little Albert." Initially, Albert was a trusting child, showing no fear of the objects presented to him—a white rat, a rabbit, cotton wool, and even a Santa Claus mask.

The experiment began when Albert was allowed to play with the white rat. But as soon as the baby reached for the animal, Watson would strike a steel bar with a hammer behind the child’s head, creating a terrifyingly loud noise. After several repetitions, the infant’s curiosity turned to terror. He began to cry and desperately avoid the rat. This conditioned fear soon generalized to other furry objects; Albert became distressed at the sight of the rabbit and even a fur coat. Watson had proven his theory, but at a terrible cost. He had intended to reverse the conditioning, but Albert was moved from the hospital before this could happen. His ultimate fate remains a mystery. Some reports suggest he died at age six from hydrocephalus, while others claim he lived a long life, albeit with a profound and unexplained aversion to animals.

The Voices We Silenced: The Monster Study

The shadow of unethical experimentation on children looms again over a study from the late 1930s. At the University of Iowa, Dr. Wendell Johnson and his graduate student Mary Tudor embarked on an experiment to understand the effects of psychological pressure on speech development. They selected 22 children from an orphanage and labeled it "The Monster Study" for its cruel methods. They selected 22 children from an orphanage in Davenport.

The children were divided into two groups. The first group received positive reinforcement; they were praised for their fluency and clear speech. The second group, however, was subjected to relentless negative reinforcement. For every minor imperfection in their speech, these children were belittled and told they were stutterers. The results were devastating. Children in the experimental group, many of whom had no prior speech issues, developed significant stutters and a deep-seated fear of speaking. They suffered from anxiety and psychological problems that would follow them for the rest of their lives. Because the subjects were orphans, there was no one to intervene, no parent to put a stop to the cruelty being inflicted in the name of research.

The Nature of Love and Despair: Harlow's Monkeys

What is the nature of love? What creates the powerful bond between a mother and her child? In the 1950s, American psychologist Harry Harlow sought to answer these questions through a series of experiments on rhesus monkeys that were as innovative as they were shocking. Harlow separated infant monkeys from their mothers just hours after birth and placed them in isolation with two surrogate "mothers." One was a cold, wire-frame figure that provided milk from an attached bottle. The other was covered in soft terry cloth but offered no food.

The infant monkeys’ behavior was unequivocal. Though they went to the wire mother for nourishment, they spent the vast majority of their time clinging desperately to the soft, cloth mother, seeking a comfort that food alone could not provide. Harlow’s work proved that contact and tactile comfort are critical components of attachment and psychological development. Yet, this proof came from observing infant monkeys trembling with fear and crying after being deprived of their real mothers.

Harlow’s work also delved into depression. He constructed a device he called the "pit of despair"—an inverted, steep-sided steel pyramid from which escape was impossible. Monkeys placed inside would initially struggle to climb out, but would soon give up, succumbing to a state of utter hopelessness. When finally removed, these animals were severely disturbed, displaying behaviors akin to profound psychosis from which they never recovered.

Learning to Be Helpless

In 1967, psychologist Martin Seligman stumbled upon a phenomenon he would name "learned helplessness"—a state where a person or animal ceases to try to escape a negative situation because the past has taught them that they have no control. His experiment involved dogs placed in a chamber where the floor could deliver painful, though not physically harmful, electric shocks.

One group of dogs could press a panel with their nose to stop the shocks. A second group was yoked to the first; they received shocks for the same duration but had no control over stopping them. A third group received no shocks at all. Later, all the dogs were moved to a new enclosure with a low barrier they could easily jump over to escape to a shock-free area. The dogs from the first and third groups quickly learned to leap over the barrier to safety. But the dogs from the second group, who had learned that their actions had no effect, simply lay down and whimpered, enduring the shocks without any attempt to escape their fate.

The Power of Authority: The Milgram Experiment

How far would you go in obeying an order from an authority figure, even if it meant harming another person? This unsettling question was at the heart of one of history's most controversial experiments, conducted by Stanley Milgram in 1963. Participants were told they were taking part in a study on memory and learning. Each was assigned the role of "teacher," while an actor played the "learner."

The teacher was instructed to administer an electric shock to the learner for every incorrect answer, increasing the voltage by 15 volts with each mistake, up to a potentially lethal 450 volts. The shock generator was fake, and the learner was an actor who would grunt, shout, and eventually fall silent as the voltage escalated. If the teacher hesitated, a stern experimenter in a lab coat would urge them to continue. The results were chilling: a staggering majority of participants obeyed the authority figure and continued to administer shocks up to the maximum level, despite the apparent agony of the learner. The study exposed a dark facet of human nature but also sparked intense debate about the psychological distress inflicted upon the participants, who believed their actions were causing real, severe pain.

The Prison We Build Ourselves

Perhaps no experiment is more famous for its depiction of how easily good people can do terrible things than the 1971 Stanford Prison Experiment. Led by psychologist Philip Zimbardo, the study aimed to understand the causes of conflict and abuse in prisons. Healthy, psychologically normal college students were recruited and randomly assigned the role of either "prisoner" or "guard" in a simulated prison environment.

The guards were given uniforms, billy clubs, and broad authority, short of using physical violence. The prisoners were "arrested," deloused, and given numbers to replace their names, stripping them of their identity. The experiment, planned for two weeks, had to be terminated after only six days. The situation had spiraled out of control. The guards quickly embraced their roles with a sadistic zeal, humiliating the prisoners by forcing them to do push-ups, depriving them of sleep and washing facilities, and making them clean toilets with their bare hands. A prisoner rebellion on the second day was harshly suppressed. The study demonstrated how powerfully situations and social roles can influence behavior, turning ordinary students into tormentors. While the experiment's methodology has since been criticized—arguing that participants were biased or coached—its brutal outcome remains a powerful and cautionary tale.

The legacy of these experiments is a dual one. They provided profound, and often terrifying, insights into fear, obedience, despair, and cruelty. But more importantly, their ethical failings forced the world of psychology to confront its own demons. The creation of strict ethical codes, first established by the American Psychological Association in 1953 and refined over decades, was the direct result of this dark history. These rules now protect human and animal subjects around the globe, ensuring that the pursuit of knowledge never again comes at the cost of our humanity.

References

• Milgram, S. (1963). Behavioral Study of Obedience. Journal of Abnormal and Social Psychology, 67(4), 371–378.

  This is the original paper published by Stanley Milgram detailing his famous experiment on obedience to authority. It describes the experimental setup, the procedure where "teachers" administered what they believed were real electric shocks, and the startling quantitative results showing how many participants proceeded to the maximum voltage. It provides a firsthand account of the research that raised profound questions about individual conscience and authority.

• Harlow, H. F. (1958). The nature of love. American Psychologist, 13(12), 673–685.

  In this seminal article, Harry Harlow presents his findings from the experiments with rhesus monkeys and surrogate mothers. He challenges the prevailing belief that the infant-mother bond is based solely on the fulfillment of physiological needs like hunger. The paper details how infant monkeys overwhelmingly preferred the cloth surrogate for comfort over the wire surrogate that provided food, establishing the critical importance of contact comfort in the development of attachment.

• Haney, C., Banks, W. C., & Zimbardo, P. G. (1973). A study of prisoners and guards in a simulated prison. Naval Research Review, 30(4), 4-17.

  This publication provides a detailed report of the Stanford Prison Experiment, co-authored by Philip Zimbardo himself. It outlines the methodology, including the random assignment of participants to roles of "guard" and "prisoner," and chronicles the rapid psychological changes observed in both groups. It discusses the pathological nature of the guard's behavior and the passive, helpless response of the prisoners, arguing that the simulated situation, rather than individual personality, was the primary cause of the observed behaviors.