It sounds almost too simple to be impressive. A test with only three questions claims to reveal whether you think more carefully than most people. No long exam. No complicated formulas. Just three short problems.
Yet research suggests that fewer than 20 percent of people answer all three correctly.
This tiny but powerful quiz is called the Cognitive Reflection Test, often shortened to CRT. It was designed in 2005 by psychologist Shane Frederick, who later worked at the Yale School of Management. The test was originally developed to study how people make decisions and why they sometimes fall for thinking traps.
Over the years, this three question IQ style test has resurfaced again and again, especially online. A recent TikTok video explaining the questions gathered millions of views. People continue debating the answers, confidently defending their first instincts.
That first instinct is exactly what the test is designed to challenge.
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What Is the Cognitive Reflection Test?
The Cognitive Reflection Test is not about memorized knowledge. It does not require advanced math skills. Instead, it measures something more subtle. It looks at whether a person can pause, question their first impulse, and think a little deeper.
Each question has an answer that feels obvious at first glance. In fact, the “obvious” answer pops into most people’s minds almost instantly. The catch is that the obvious answer is wrong.
To get the correct solution, you have to slow down and carefully work through the logic.
In Shane Frederick’s original study, the test was given to more than 3,000 participants, many of whom were students from highly respected universities including MIT, Princeton, and Harvard. Even in that group, only about 17 percent answered all three questions correctly.
Later studies produced mixed results. Some research found even lower success rates, while others reported higher percentages depending on the group being tested. Still, the pattern remains consistent. Most people answer at least one question incorrectly.
Let us see why.
Question One: The Bat and Ball Problem
A bat and a ball together cost $1.10.
The bat costs $1.00 more than the ball.
How much does the ball cost?
Most people immediately say ten cents.
It feels right. If the ball costs ten cents and the bat costs one dollar more, that seems to match the total of $1.10.
But look closer.
If the ball costs ten cents, then the bat would cost $1.10. That would make the total $1.20, not $1.10.
The correct answer is five cents.
Here is why.
If the ball costs $0.05, then the bat costs exactly $1.05, which is one dollar more. Together, $1.05 plus $0.05 equals $1.10.
The trick lies in that phrase “one dollar more than the ball.” Many people mentally separate the one dollar from the ten cents and stop thinking. The test works because it nudges your brain toward a quick calculation that feels complete.
But intelligence in this case is not about speed. It is about checking your thinking.
Question Two: The Machine and Widget Problem
If it takes five machines five minutes to make five widgets, how long would it take 100 machines to make 100 widgets?
The most common answer is 100 minutes.
Again, it feels logical. More machines, more products, more time.
But that reasoning overlooks a key detail.
If five machines make five widgets in five minutes, that means each machine makes one widget in five minutes. The production rate does not change when you increase the number of machines. Each machine still takes five minutes to produce one widget.
So if you have 100 machines, and each machine produces one widget in five minutes, then 100 machines will produce 100 widgets in five minutes.
The correct answer is five minutes.
The mistake here comes from scaling the numbers without examining the relationship between time and output. Many people instinctively multiply everything without asking whether multiplication is necessary.
The Cognitive Reflection Test challenges that habit.
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Question Three: The Lily Pad Problem
In a lake, a patch of lily pads doubles in size every day.
If it takes 48 days for the patch to cover the entire lake, how long does it take to cover half the lake?
The answer that most people give is 24 days.
That would make sense if the growth were steady and linear. If something increases evenly over time, half the total time would equal half the growth.
But the question states that the patch doubles every day. That means the growth is exponential.
If the lake is fully covered on day 48, then it must have been half covered on day 47. One day later, it doubled to fill the entire lake.
The correct answer is 47 days.
This question reveals how easily the human brain defaults to simple division. Halving the time feels natural, but it ignores the pattern of doubling.
Why So Many People Get It Wrong
The Cognitive Reflection Test highlights an important difference between two kinds of thinking.
One kind is fast, automatic, and intuitive. It helps you react quickly and navigate everyday life. The other is slower, more deliberate, and analytical. It requires effort and attention.
The three questions are designed to tempt you into using the fast system. They sound simple, so your brain assumes the answer must also be simple.
Research shows that people who answer all three questions correctly tend to pause longer before responding. They resist the first idea that pops into their head. That reflective pause makes a difference.
This does not mean that someone who misses a question lacks intelligence. It simply suggests that they relied on intuition rather than reflection in that moment.
In fact, the CRT has been linked to decision making skills. Studies have found that people who score higher are less likely to fall for common reasoning errors and more likely to evaluate evidence carefully.
How This Relates to IQ and Standardized Tests
The CRT is sometimes described as the world’s shortest IQ test. That label is catchy but somewhat misleading.
Traditional IQ tests measure a broad range of abilities including verbal skills, memory, spatial reasoning, and pattern recognition. The CRT focuses narrowly on cognitive reflection, which is the ability to override an incorrect gut response and engage in deeper reasoning.
Interestingly, research has found that CRT scores correlate with performance on standardized exams such as the SAT. Both require careful reading and logical thinking.
However, three questions alone cannot define overall intelligence. They can only reveal how someone approaches certain types of problems.
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What This Test Really Teaches
The most important lesson of the Cognitive Reflection Test is not about being smarter than 80 percent of the population.
It is about the value of slowing down.
In daily life, quick thinking is useful. But there are moments when fast answers lead to costly mistakes. Financial decisions, career choices, and even simple misunderstandings can benefit from an extra moment of reflection.
The CRT reminds us that the first answer is not always the best one.
Taking a breath. Checking the math. Rereading the question. These small habits can improve not only test performance but everyday reasoning.
So, were you able to solve all three correctly?
If you did, you demonstrated strong cognitive reflection skills. If you did not, you are in good company. Most people fall for at least one trap.
Either way, the real takeaway is this. Intelligence is not just about knowing facts. It is also about knowing when to question your own thinking.
And sometimes, the smartest move is simply to pause before you answer.
Featured image: Freepik.
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