The psychological trick behind why personality tests like Myers-Briggs always ‘work’ |
If there’s one thing individuals and Fortune 500 companies have in common, it’s the inability to resist a personality test. Employers have long used tests like the Myers-Briggs Type Indicator or the Enneagram to understand their employees better and build more compatible teams. And people in general seem strangely addicted to quizzes that categorize them by personality type.
It’s long been known that most personality tests aren’t scientifically sound, but that doesn’t stop people from taking them. Part of the reason is that those tests tell us something about ourselves as individuals while also making us feel like we’re part of a group identity. They seem to help us understand ourselves and one another better, and thus appear to “work.”
However, as researcher Madelyn Leembruggen explained on SciShow, most personality profiles simply play into a psychological trick we humans easily fall into.
The Barnum effect and how it works
“Personality tests and profiles take advantage of a weird psychological tendency that also benefits everything from horoscopes to fortune tellers to Buzzfeed quizzes,” Leembruggen said. It’s called the Barnum effect.
“The Barnum effect was named after P.T. Barnum, the iconic and problematic showman known for his ability to captivate, and often manipulate, an audience,” she explained. “The Barnum effect is the phenomenon where if you give someone a personality test, they’re pretty likely to believe that the results are true and accurate, regardless of how hard the profile-maker actually tried. There’s something about taking the test itself that makes an audience more likely to believe the end result.”
Personality tests became popular after WWI, when someone developed an assessment to determine which soldiers might be prone to PTSD. In the decades that followed, personality profiles appeared in popular magazines and psychologists’ offices alike. But researcher and college professor Bertram Forer felt skeptical about their accuracy. He basically said the results weren’t any more specific than saying that a person has opposable thumbs.
Professor Forer’s 1949 personality test experiment
In 1949, he conducted an experiment to test his hypothesis. He gave his Intro to Psychology students a personality questionnaire. Then, he told them he’d analyze the results and create a unique personality profile for each student. When they got their results, they rated them for accuracy. Only one student rated their results below a 4 out of 5, indicating nearly all students felt their results reflected their personality. However, Forer had duped them. He had actually given every student the exact same analysis.
“Forer made a list of general, vaguely flattering, and universally relatable statements,” Leembruggen explained. “So, why did everyone believe that their list was so perfectly tailored to them? Well, that’s the Barnum effect.”
Essentially, most personality descriptors in personality profiles are fairly relatable to most people. And when you combine any sense of the trait being positive, most people will see themselves in it.
The SciShow video gives these statements as examples:
“You have an analytical mind, though you also might space out at times.”
“You pride yourself as an independent thinker, and don’t accept other people’s statements without good proof.”
“You love variety and tend to rebel against too many restrictions and limitations.”
“You don’t always reveal all of yourself to others.”
“You have a great desire for other people to like and admire you.”
Most people see themselves in some, if not all, of those statements because they’re vague enough to feel true.
However, 1949 was a long time ago. Haven’t psychologists gotten better at creating real personality profiles?
How accurate is the Myers-Brigg Type Indicator, though?
One of the most popular personality tests of the past 50 years is the Myers-Briggs Type Indicator, or MBTI. This test splits people into 16 personality categories based on combinations of eight traits or preferences: Introversion/Extroversion, Sensing/Intuition, Thinking/Feeling, and Perceiving/Judging. Your “type” would be a combination of four letters, like INTP or ESFJ, with a corresponding description of that personality.
Many people have taken an MBTI test at work, but is it really accurate?
“When researchers want to see how well a certain assessment tool, test, or survey actually works, one thing they’ll do is have the same people take the same test multiple times,” Leembruggen said. “If they get the same score each time, we’d say that tool has good test-retest reliability. And in studies of MBTI where participants took the assessment multiple times, up to half or even more test takers received a different result for at least one of the four letters.”
Accurate or not, people love their Myers-Briggs. However, psychologists prefer a more recent personality indicator known as the Big Five Personality Trait model.
12 Things Everyone Should Know About Personality1. Most psychologists agree that most personality variation can be captured with just a handful of higher-order traits. The most popular approach posits five traits, often known as the Big 5.[Link at end of thread.] pic.twitter.com/lciTNcZOGo— Steve Stewart-Williams (@SteveStuWill) November 25, 2025
12 Things Everyone Should Know About Personality1. Most psychologists agree that most personality variation can be captured with just a handful of higher-order traits. The most popular approach posits five traits, often known as the Big 5.[Link at end of thread.] pic.twitter.com/lciTNcZOGo— Steve Stewart-Williams (@SteveStuWill) November 25, 2025
What is the Big Five Personality Trait model?
In the Big Five, people rank as low, medium, or high in five personality dimensions: extroversion, neuroticism, openness, conscientiousness, and agreeableness. (A more recent test known as HEXACO includes honesty-humility as a trait.)
“These tests, and newer variations that include subcategories of these five, do seem to show better test-retest reliability,” Leembruggen shared. “One major reason that newer tests based on the Big Five are more reliable is that they’re based on accumulating data from multiple long-term studies from the 1990s onwards. And they’re rooted in the principle that, if a personality trait exists in humans, languages will adopt words to describe it.”
However, she notes, most research only includes people from WEIRD countries: Western, Educated, Industrialized, Rich, and Democratic. That reality alone makes it hard to extrapolate universal personality traits or types.
The way personality tests are designed is inherently flawed
Finally, the nature of personality tests with multiple-choice answers, most of which only offer two options, is flawed.
“When you have to answer every question from a list of predetermined options, it’s called a forced-choice measure,” Leembruggen explained. “These tests are easy to administer and to grade, but the downside is that they’re really rigid and can flatten nuance, including how people’s personality traits can change due to the passage of time and other variables. We’ve all stared at a multiple-choice question and wished there was an option to check ‘other.’ So trying to make a questionnaire-style test that can accurately gauge anybody’s personality might be kind of impossible.”
That certainly won’t stop a lot of people from taking those tests, though. Accurate or not, there’s something about them that draws us in. Maybe it’s just fun to self-analyze. Maybe we yearn to know ourselves better, and those tests offer a structured and largely harmless way to do that—or at least to feel like we’re doing it.
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While a bottle of bubbles might seem out of place in a hospital setting, you might be surprised to learn that, for thousands of children around the world born with cleft lip and palate, they can be a helpful tool in comprehensive cleft care. Lilia, who was born with cleft lip and palate in 2020, is one of the many patients who received this care.
As a toddler, Lilia underwent two surgeries to treat cleft lip and palate with Operation Smile’s surgical program in Puebla, Mexico. Because of Operation Smile’s comprehensive care, it wasn’t long before her personality transformed: Lilia went from a quiet and withdrawn toddler to an exuberant, curious explorer, babbling, expressing herself with a variety of sounds, and engaging with others like any child her age.
Lilia is now a healthy five-year-old, with the same cheerful attitude and boundless energy. Her progress is the result of care at every level, from surgery to speech therapy to ongoing support at home—but it’s also evidence that small, sustained interventions throughout it all can make a meaningful difference.
Cleft Conditions: A Global Problem
Since 1982, Operation Smile has provided cleft lip and cleft palate surgeries to more than 500,000 patients worldwide with the help of generous volunteers and donors. Cleft conditions are congenital conditions, meaning they are present at birth. With cleft lip and palate, the lip or the roof of the mouth do not form fully during fetal development. Cleft conditions put children at risk for malnutrition and poor weight gain, since their facial structure can make feeding challenging. But cleft conditions can have an enormous social impact as well: Common difficulties with speech can leave kids socially isolated and unable to meet the same developmental milestones as their peers.
Surgery is a vital step in treating cleft conditions, but it’s also just one part of a much larger solution. Organizations like Operation Smile emphasize the importance of multi-disciplinary teams that provide comprehensive, long-term care to patients across many years. This approach, which includes oral care, speech therapy, nutritional support, and psychosocial care, not only aids in physical recovery from surgery but also helps children develop the skills and confidence to eat easily, speak clearly, and engage in everyday life. This ensures that each patient receives the full range of support they need to thrive.
A Playful (and Powerful) Solution
Throughout a patient’s care, simple tools like bubbles can play a meaningful role from start to finish.
Immediately before surgery, children are often in a new and unfamiliar environment far from home, some of them experiencing a hospital setting for the first time. When care providers or loved ones blow bubbles, it’s a simple yet effective technique: Not only are the children soothed and distracted, the bubbles also help create a sense of joy and playfulness that eases their anxiety.
In speech therapy, bubbles can take on an even more important role. Blowing bubbles requires controlled airflow, as well as the ability to form a rounded “O” shape with the lips, which are skills that children with cleft conditions may struggle to develop. Practicing these skills with bubbles allows children to gently strengthen their facial muscles, improve breath control, and support the motor skills needed for speech development. Beyond that, blowing bubbles can help kids connect with their parents or providers in a way that’s playful, comforting, and accessible even for very young patients.
Finally, bubbles often follow patients with cleft conditions home in the “smile bags” that each patient receives when the surgical procedure is finished. Smile bags, which help continue speech therapy outside of the hospital setting, can contain language enrichment booklets, a mirror, oxygen tubing, and bubbles. While regular practice with motor skills can help with physical recovery, small acts of play help as well, giving kids space to simply enjoy themselves and join in on what peers are able to do.
Bubbles at Home and Beyond
Today, because of Operation Smile’s dedication to comprehensive cleft care, Lilia is now able to make friends and speak clearly, all things that could have been difficult or impossible before. Instead of a childhood defined by limitation, Lilia—and others around the world—can look forward to a childhood filled with joy, learning, discovery, friends, and new possibilities.
CTA: Lilia’s life was changed for the better with the care she received through Operation Smile. Find out how you can make an impact in other children’s lives by visiting operationsmile.org today.
If you’re not one, you probably know one: conscientious people are never late, they’re organized, and their word is their bond. They do things the “right” way. They like things in order. And they have a strong, nearly unbreakable sense of right and wrong.
They’re often good people. Very good. It’s hard to imagine there could be a downside to this personality type. But new research indicates there’s a little more to it than meets the eye.
New research reveals the costs of being too “good”
A recent study out of the University of Galway aimed to find out how personality traits affect the way we experience emotions.
Researchers began by measuring participants using a Five-Factor Model, which breaks personality into five key dimensions: Openness to Experience, Extraversion, Agreeableness, Neuroticism, and Conscientiousness.
Then they exposed the volunteers to several video clips which were each designed to elicit a specific emotion: anger, disgust, fear, joy, sadness, and surprise.
Interestingly, the clip the team chose to elicit joy was none other than the famous diner scene from When Harry Met Sally: a comedy classic.
People who scored high in conscientiousness were among the only group to react negatively to finding the scene funny or enjoyable. It did not trigger nearly as much joy in this group as it did for the others.
The research team theorized that, with such a powerful correlation, it was relatively safe to say that extremely orderly, structured, and conscientious people may have a lower capacity for experiencing spontaneous joy.
But there’s still a powerful upside to being conscientious
Here’s the tradeoff: while highly conscientious people laughed less and felt less joyful during the comedy scene, they also reacted less powerfully to the scene that primarily stimulated sadness.
What scene was that? The Lion King, of course. You know the one.
The findings suggest that, perhaps, living a structured and highly-orderly life can protect against negative emotions—even at the cost of some of the good ones.
Think about it. Imagine a person who never misses a deadline, forgets to pay a bill, or runs a red light. They’re never in trouble. People don’t get angry at them. They don’t wind up on probation at work or, worse, in jail.
“How people structure their environment may be a key shield from experiencing sadness, which may represent a significant motivator for people high in orderliness if they are sensitive to this emotion,” the researchers wrote.
If that doesn’t sound like a worthwhile tradeoff, another recent study builds on these findings and explores even more of the upside to living a conscientious life.
“Good” people excel at finding meaning and satisfaction in their work
Psychology Today reveals details of another recent study where, again, the Big Five personality dimensions were used to sort people into buckets.
Researchers out of KU Leuven found that highly conscientious people were among those most likely experience a “flow state.”
Flow is a mental state where you become completely immersed in your work, to the point that you don’t even notice the passage of time. It’s sometimes known as being “in the zone,” a state of effortless momentum, and generally people find it to be an enjoyable and deeply meaningful feeling.
“The characteristics of Conscientious individuals are essential for maintaining focus, managing challenges, and regulating efforts toward meaningful tasks,” the study’s authors write.
Psychology Today sums up the cutting-edge research: “Being dutiful,........