In a world where time is precious and attention spans are short, the allure of a quick intelligence test is undeniable. Enter the Cognitive Reflection Test (CRT), often dubbed the “World’s Shortest IQ Test,” comprising just three deceptively simple questions. Despite its brevity, the CRT has confounded even the brightest minds, challenging our ability to pause and reflect before jumping to conclusions.

🧠 What Is the Cognitive Reflection Test?

Developed in 2005 by MIT professor Shane Frederick, the CRT aims to assess an individual’s capacity for reflective thinking. Unlike traditional IQ tests that measure a range of cognitive abilities, the CRT focuses on how well one can override impulsive, intuitive responses in favor of more deliberate reasoning.

The three questions are designed to be straightforward yet tricky, often leading respondents to arrive at incorrect answers due to their initial gut reactions.

🧩 The Three Questions

Here are the three questions that make up the CRT:

1. A bat and a ball together cost $1.10. The bat costs $1 more than the ball. How much does the ball cost?

2. If five machines take five minutes to make five widgets, how long would it take 100 machines to make 100 widgets?

3. In a lake, there is a patch of lily pads. Every day, the patch doubles in size. If it takes 48 days for the patch to cover the entire lake, how long would it take for the patch to cover half of the lake?

🧠 Common Mistakes

Many individuals, including those from prestigious institutions like Harvard, Yale, and MIT, have struggled with these questions. In fact, studies have shown that only about 17% of participants answer all three questions correctly.

The most common incorrect answers are:

10 cents for the first question

100 minutes for the second question

24 days for the third question

These responses often stem from intuitive thinking, highlighting the importance of reflective reasoning.

✅ The Correct Answers

Let’s break down each question and its correct answer:

1. How much does the ball cost?

Correct Answer: 5 cents

Explanation: If the ball costs x dollars, then the bat costs x + $1. Together, they total $1.10. So, x + (x + $1) = $1.10. Solving for x gives x = $0.05. Therefore, the ball costs 5 cents, and the bat costs $1.05.

2. How long would it take 100 machines to make 100 widgets?

Correct Answer: 5 minutes

Explanation: If five machines take five minutes to make five widgets, then each machine takes five minutes to make one widget. Therefore, 100 machines would take five minutes to make 100 widgets, as each machine works simultaneously.

3. How long would it take for the patch to cover half of the lake?

Correct Answer: 47 days

Explanation: If the patch doubles in size every day and covers the entire lake on day 48, it must have covered half the lake on day 47. This is because on day 48, the patch doubles to cover the full lake.

🧠 Why Do So Many People Get It Wrong?

The CRT tests our ability to suppress intuitive but incorrect responses in favor of more deliberate reasoning. The initial, impulsive answers often feel right, but they overlook the nuances of the problems. This phenomenon underscores the importance of reflective thinking in problem-solving.

📊 The Significance of the CRT

While the CRT is not a comprehensive measure of intelligence, it provides insight into how individuals approach problems. The ability to pause and reflect before answering can lead to more accurate solutions, highlighting the value of critical thinking skills.

🧩 Try the Test Yourself

Before you read on, take a moment to answer the three questions yourself. Remember, the goal is to think carefully and resist the urge to go with your first instinct.

🧠 Final Thoughts

The Cognitive Reflection Test serves as a reminder that intelligence is not just about quick thinking but also about the ability to pause, reflect, and reason carefully. In a world that often values speed over accuracy, taking the time to think critically can lead to better outcomes.

Whether you’re sharing this test with friends or using it as a personal challenge, remember that the journey to the correct answer is just as important as the answer itself.