Some psychology experiments make you marvel at human curiosity. Others make you want to invent a time machine and shout, “Please don’t do this!”
The Monster Study, conducted in 1939, falls firmly in the second category.
The goal was simple enough: figure out whether stuttering is something you’re born with or something you can learn. The method? Take a group of orphans and try to give some of them speech problems by criticizing their every word.
Spoiler: it didn’t go well.
The Monster Study is remembered not for its scientific brilliance but for its ethical failures. It’s a case study in how easily “research” can cross into cruelty when compassion is left out of the equation.
And yet, it also left us with lessons about the power of labels, the importance of supportive environments, and the absolute necessity of ethical safeguards in science.
Background and Context
The experiment was the brainchild of Wendell Johnson, a well-known speech pathologist at the University of Iowa. Johnson himself had struggled with stuttering, which gave him a personal stake in understanding the condition.
At the time, theories about stuttering were divided into two camps:
- Biological theories: Stuttering was thought to be caused by some kind of neurological or genetic defect.
- Environmental theories: Others argued it was learned, reinforced by the way parents and teachers reacted to normal speech slip-ups.
Johnson leaned heavily toward the environmental side.
He suspected that stuttering wasn’t about faulty vocal cords or brain wiring, but about how children were treated when they spoke. If a child was constantly told their speech was “wrong,” Johnson believed, they might actually begin to stutter.
To test this, Johnson enlisted his graduate student, Mary Tudor (not to be confused with the 16th-century English queen also known as “Bloody Mary”), to carry out the study. They chose the Soldiers and Sailors Orphans’ Home in Davenport, Iowa, as their testing ground.
Why orphans, you ask?
Sadly, because they were “available” and unlikely to have parents who would object.
Are your ethical alarm bells already ringing?
Good. They should be.
The Experiment Itself
The study involved 22 children, ages 5 to 15. Half of them already stuttered; the other half did not. Tudor divided them into groups and gave them very different kinds of feedback:
- Positive feedback group: These children were praised for their speech, even if it wasn’t perfect. They were told things like, “You’re speaking beautifully,” and “You don’t have any speech problems.” In other words, they got the motivational-poster treatment.
- Negative feedback group: These children were criticized for their speech, even when it was perfectly normal. They were told things like, “You’re beginning to stutter,” “You must stop this,” and “You have a serious problem with your speech.” Imagine being told you’re failing a test you didn’t even know you were taking.
The researchers wanted to see if this negative feedback could create stuttering in children who had previously spoken fluently.
The outcome? The children didn’t suddenly develop full-blown stutters, but they did become more self-conscious, hesitant, and anxious about speaking. Some withdrew socially, avoided talking in class, or developed noticeable speech problems.
The damage wasn’t just temporary, either, by the way. Reports suggest that some participants carried the emotional scars of this study for years.
Impact on Psychology
The Monster Study didn’t revolutionize speech therapy the way its authors might have hoped. Instead, it became a cautionary tale with an unacceptable human cost.
Scientifically, the Monster Study offered partial support for Johnson’s theory: negative reactions to normal speech can indeed make children more anxious and hesitant, which may reinforce stuttering.
In a sense, the study showed the power of labeling, where if you tell a child often enough that they have a problem, they might start acting like they do.
But the way this knowledge was obtained overshadowed the findings.
The study didn’t become a celebrated breakthrough; it became a whispered embarrassment in the field of speech pathology. Johnson himself never published the results in a major journal, perhaps recognizing how controversial it was. The data remained tucked away in university archives for decades.
Perhaps ironically, modern speech therapy has embraced the opposite of what the negative-feedback group experienced. Today, therapists emphasize positive reinforcement, patience, and creating low-pressure speaking environments.
In other words: don’t tell children they’re broken. Instead, encourage them to keep talking.
Connections to Broader Theories
The Monster Study ties into several broader psychological concepts:
- Labeling theory: A concept later popularized in sociology, labeling theory suggests that being labeled in a certain way can shape identity and behavior. If you call a child a stutterer, they may start to see themselves that way.
- Self-fulfilling prophecy: Closely related, this is the idea that expectations can create the very outcomes they predict. Tell a child they’re destined to fail, and they might just live down to that expectation.
- Behaviorism: Like many experiments of the time, the study was rooted in the idea that environment and reinforcement shape behavior. The Monster Study was essentially an extreme (and unethical) test of this principle.
So while the study itself was ethically indefensible with no excuses for its methods, the concepts it brushed against do remain central to psychology today.
Ethical Considerations
This is where the Monster Study earns its monstrous nickname. By today’s standards, it violated nearly every ethical principle imaginable:
- No informed consent: The children didn’t know they were part of an experiment, and their guardians weren’t properly informed.
- Exploitation of a vulnerable population: These were orphans with children with no parents to advocate for them. Choosing them as subjects was not just opportunistic; it was downright predatory.
- Harm without benefit: The children in the negative-feedback group suffered real psychological harm, with no therapeutic benefit.
- No debriefing or follow-up care: The researchers didn’t attempt to undo the damage or provide support afterward.
The ethical fallout was so severe that Johnson’s colleagues quietly buried the study.
It wasn’t widely known until the early 2000s, when it resurfaced in the press. Survivors of the study came forward, describing lasting harm, and in 2001, the state of Iowa issued a formal apology and, in 2007, a financial settlement.
Replication and Critiques
The Monster Study has never been replicated, and for good reason. But its basic premise has been supported by more ethical research.
Studies have shown that parental reactions to children’s speech do matter.
Children who are pressured or criticized for normal disfluencies are more likely to develop persistent stuttering. Conversely, children who are encouraged and supported tend to outgrow normal speech bumps.
Critics argue that Johnson could have tested his theory in far less harmful ways. For example, he could have studied families naturally prone to criticism versus those who were more supportive, rather than manufacturing trauma in orphans.
The fact that he didn’t speaks volumes about the blind spots in psychology at the time and just how far the field has come in recognizing the importance of ethics.
Modern Relevance
Today, the Monster Study is taught not as a triumph of discovery but as a cautionary tale. It shows up in research ethics courses alongside other infamous studies, reminding students that scientific curiosity must never outweigh human dignity.
For speech therapy, the study underscores the importance of positive reinforcement and supportive environments. Therapists now know that encouraging fluency, reducing pressure, and avoiding negative labels are key to helping children who stutter.
For psychology as a whole, it’s a sobering case study in how ambition and curiosity can quickly cross the line into harm if not checked by ethical safeguards.
And for the rest of us, it’s a sobering reminder that just because you can run an experiment doesn’t mean you should.
The Monster Study may have been buried for decades, but its legacy lives on not as a proud achievement but as a warning.
Tomato Takeaway
The Monster Study set out to answer an important question about stuttering, but it did so in a way that harmed some of the most vulnerable children imaginable.
It showed the power of labeling and suggestion, but at a cost that no scientific insight can justify. Today, it stands as a reminder that science without compassion can become cruelty.
Which takes us to today’s Tomato Takeaway…
Do you think researchers should still study controversial questions if the potential knowledge is valuable, or should ethics always come first?
Share your thoughts in the comments, and let’s take the conversation further.
Fueled by coffee and curiosity, Jeff is a veteran blogger with an MBA and a lifelong passion for psychology. Currently finishing an MS in Industrial-Organizational Psychology (and eyeing that PhD), he’s on a mission to make science-backed psychology fun, clear, and accessible for everyone. When he’s not busting myths or brewing up new articles, you’ll probably find him at the D&D table or hunting for his next great cup of coffee.