The Monster Study was a 1939 speech experiment conducted on 22 orphan children at the University of Iowa, designed to test whether stuttering could be caused by negative reinforcement. Led by speech pathologist Wendell Johnson and carried out by his graduate student Mary Tudor, the study deliberately told normally fluent children that their speech was defective, then tracked whether the criticism alone could produce stuttering-like behavior. It did. The experiment was hidden from the public for over six decades, and its eventual exposure led to a formal apology from the university and a legal settlement for the survivors.
Why It Was Called the Monster Study
The name didn’t come from Johnson or Tudor. It came from Johnson’s peers at the University of Iowa, who were horrified when they learned what the experiment involved. Experimenting on orphan children, particularly by deliberately trying to induce a speech disorder, struck other researchers as monstrous even by the standards of 1939. The nickname stuck, and it became the only name most people know the study by today.
What the Researchers Were Trying to Prove
Wendell Johnson was himself a person who stuttered. He had spent his career developing what became known as the diagnosogenic theory of stuttering: the idea that stuttering isn’t something a child is born with, but something that develops when adults label normal childhood speech hesitations as a problem. In Johnson’s view, it was the diagnosis itself that created the disorder. A parent or teacher who anxiously corrected a child’s speech could, according to this theory, turn ordinary disfluency into a lasting stutter.
To test this, Johnson needed to take children who spoke normally and subject them to exactly that kind of negative labeling, then see if stuttering emerged. In the fall of 1938, he recruited Mary Tudor, a 22-year-old graduate student in clinical psychology, to carry out the experiment at the Iowa Soldiers’ Orphans’ Home in Davenport.
How the Experiment Worked
Tudor selected 22 children from the orphanage, ranging in age from 5 to 15. Some already stuttered; others spoke fluently. She divided them into two groups of 11. One group received positive speech therapy. They were praised for their fluency, encouraged to speak, and told their speech was fine. The other group received the opposite treatment: they were told they were stutterers, that their speech was poor, and that they should stop speaking until they could do so correctly.
The children in the negative group were belittled and corrected regardless of how they actually spoke. Even the children who had no speech problems at all were told they were beginning to stutter. Tudor visited the orphanage regularly over several months, reinforcing these messages each time.
What Happened to the Children
The results were disturbing. The normally fluent children who had been labeled as stutterers began exhibiting behaviors that looked remarkably like actual stuttering. They started whispering, shuffling their feet, gulping before trying to speak, and clamping their mouths shut. Some became reluctant to speak at all. They hadn’t developed a neurological speech disorder, but they had internalized the anxiety and self-consciousness that comes with being told something is wrong with you, and it changed the way they communicated.
The children who received positive reinforcement, by contrast, showed no such deterioration. And the children who already stuttered before the experiment were not helped by the negative treatment; their speech problems persisted or worsened.
Tudor herself recognized the harm during the study. She returned to the orphanage after the experiment ended and attempted to undo the damage by reassuring the children that their speech was normal. It didn’t work. The psychological effects had already taken root.
Why the Study Was Hidden for 60 Years
Johnson never published the results. Tudor’s thesis was filed at the University of Iowa, but Johnson made no effort to publicize the findings, and the study remained buried in the university’s archives. The most likely reason is that Johnson understood the ethical implications. The experiment had been conducted on vulnerable children who could not consent, in an institution where no parent or guardian had meaningfully agreed to their participation. By the time Johnson became one of the most prominent speech pathologists in the country, the study was a liability.
The timing mattered too. By the early 1940s, news of Nazi medical experiments was reaching the public, and any research that involved deliberately harming children would have drawn immediate comparison. Johnson built a distinguished career on other work, and the Monster Study stayed in the shadows.
It wasn’t until 2001, when a San Jose Mercury News investigation uncovered the details, that the public learned what had happened in Davenport. The story drew national attention and forced the University of Iowa to respond.
The University’s Apology
Following the newspaper exposé, the University of Iowa issued a formal apology in 2001, describing the experiment as “regrettable.” David J. Skorton, then vice president for research at the university, acknowledged the harm directly: “In no way does his excellent reputation and other good work change the fact that this was a regrettable study.” The university pointed to modern research ethics policies and institutional review boards as safeguards that now prevent experiments of this nature.
The word “regrettable” struck some critics as too mild for an experiment that had caused lifelong harm to children in state care. But it marked the first time the institution formally acknowledged what had happened.
The Lawsuit and Settlement
Six of the surviving participants from the negative reinforcement group, now elderly, filed a lawsuit against the State of Iowa. On August 17, 2007, seven of the orphan children (or their estates) were awarded a total of $925,000 for lifelong psychological and emotional scars caused by six months of torment during the experiment. The settlement acknowledged what the survivors had lived with for decades: anxiety around speaking, social withdrawal, and lasting shame rooted in an experiment they never agreed to.
What the Study Means for Stuttering Science
Johnson’s diagnosogenic theory was influential for decades. The idea that parental anxiety about a child’s speech could cause stuttering shaped how speech therapists counseled families through the mid-20th century. Parents were often told to ignore disfluency entirely, for fear that drawing attention to it would make it permanent.
Modern research has largely moved past this framework. Stuttering is now understood to have a strong genetic and neurological basis. Brain imaging studies show structural and functional differences in the speech-processing areas of people who stutter, and the condition runs in families at rates that can’t be explained by environmental labeling alone. The Monster Study did demonstrate that negative reinforcement can create speech anxiety and avoidance behaviors in children, but that’s different from causing stuttering as a neurological condition.
The study’s most lasting contribution may be to research ethics rather than speech science. It stands alongside other infamous mid-century experiments as a case study in what happens when researchers prioritize a hypothesis over the welfare of their subjects, particularly when those subjects are children without advocates.