Cognitive Reflection Test (CRT): A Test of Only Three Questions

This CRT test contains only three questions. It was developed by a professor from Yale University and the Massachusetts Institute of Technology (MIT). It's a test of ingenuity and deduction in which reflection is key. This means not saying the first thing that comes to mind.
Cognitive Reflection Test (CRT): A Test of Only Three Questions
Valeria Sabater

Written and verified by the psychologist Valeria Sabater.

Last update: 26 June, 2023

Do you let yourself be carried away by your intuition? Or, are you defined by a more reflective and analytical approach? Both competencies are positive and useful in different circumstances.

Sometimes, the demands of the environment are so sudden and unexpected that you need to respond quickly and you do it via hunches and what’s known as instinct. However, at other times, you encounter more complex challenges. This is when you must stop, at least for a moment, and think. Interestingly, as a rule, it’s quite difficult to process reality from a more reflective filter.

The Nobel Prize winner, Daniel Kahneman, claims that thinking slowly and thinking well isn’t too common today. That’s because our minds have become too used to a world nourished by stimuli that continually change and move extremely fast. Indeed, today’s world of technology, social media, and digital intoxication doesn’t exactly benefit our cognitive processes.

In 2005, in view of this reality, psychologist Shane Frederick created a test to measure our capacity for reflection and analysis. With this resource, he demonstrated that many of us reason and analyze information impulsively. But, acting on intuition isn’t always the best response. Try this test and you’ll be able to check if you belong to the small section of the population that employs more logical thinking.

If our capacity for analysis and reflection is high, we can reduce impulsiveness and the risk of giving wrong answers to life’s problems.

Person doing the Cognitive Reflection Test
On starting the cognitive reflection test, it’s common to be carried away by our intuition. If so, we’ll tend to make errors.

The cognitive reflection test (CRT)

The cognitive reflection test is often defined as the shortest of the psychometric instruments. It consists of only three questions. Its objective isn’t to give an IQ score. After all, intelligence, as we well know, consists of different processes, elements, and strategies. However, its ultimate goal is to allow us to provide answers to specific problems.

The cognitive reflection test (CRT) is an instrument designed to measure people’s ability to reflect, as well as their effort to selectively follow the imperative of impulses. In an article published by Professor Shane Frederick on this tool in 2005, he defined it as an ideal resource for assessing whether we’re capable of resisting the tendency to entrust almost everything to our own intuition.

Does this mean that listening to the inner voice that orchestrates your intuition and your hunches is counterproductive? The answer is no, but there are nuances that the famous psychologist Daniel Kahneman clarifies. “If we already have experience in a field and we know the regularities that orchestrate it, we can respond quickly by letting ourselves be guided by intuition ”.

However, we can’t trust the intuitive mind if we’re dealing with irregular and complex matters and we lack previous experience in this particular area. In effect, the uncertain world in which we find ourselves today requires moments of reflection. This test allows us to assess that competence.

The cognitive reflection test uses numerous mental heuristics. It attempts to assess and analyze every idea that occurs to us.

The three questions

The original test developed by Dr. Frederick contains, as we mentioned earlier, only three questions. To resolve them, we suggest calmly reading the information given and reflecting on what they’re really asking.

1. The bat and ball question

A bat and a ball cost $1.10 in total. Knowing that the bat costs $1 more than the ball, how much does the ball cost?

2. The machine question

If five machines take five minutes to make five objects, how long would it take one hundred machines to make one hundred objects?

3. The water lily question

In a lake, there’s a group of water lilies. Every day, the patch doubles in size. It takes 48 days to cover the entire lake. How long would it take to cover only HALF?

Boy with glasses thinking about Cognitive Reflection Test
Only 17 percent of people answer the three questions in the cognitive reflection test correctly

Reasoned answers to questions

Before answering the questions on the cognitive reflection test, it’s interesting to know that, as Professor Shane Frederick points out, 83 percent of people usually fail it. Indeed, in their tests applied to a community of students of different educational levels, only 17 percent answered the three questions correctly.

Now, check and see if you’re one of them.

Answer to question 1

5 cents (0.05)

  • If the price of the ball is X, the price of the bat is X+1. This leads to the following equation: X + X + 1 = 1.10.
  • If you clear the value of X: 2X + 1 = 1.10 / 2X = 0.10 (Remember that when passing the 1 from one side to the other, it changes value, going from positive to negative) / X = 0.05 ( The 2 becomes dividing).

Answer to question 2

Five minutes

Consider that one machine takes five minutes to make an object. Therefore, each of the hundred machines will also take five minutes to make an object. This leads to the deduction that, after five minutes, there’ll be one hundred objects.

Answer to question 3

47 days

Try to visualize the following reasoning: every day, the group of water lilies doubles in size. So, when you count backward, the group of lily pads is reduced by half. Therefore, on day 47, the lake will be half full.

Is the test really valid to measure cognitive reflection?

Once you’ve analyzed the answers to the cognitive reflection test, they’ll probably seem obvious. However, to arrive at these solutions, you must apply various analytical processes. This isn’t always easy. At least not for the vast majority. At this point, the question is: is the test valid and effective in assessing cognitive reflection?

The answer is yes. A study conducted by the Center for Economic Psychology and Decision Sciences of Kozminski University (Poland) evidenced its validity. It claimed the test is an extremely useful resource to check for good analytical or deliberative reasoning, the kind that allows us to control impulses or quick and intuitive thinking.

All cited sources were thoroughly reviewed by our team to ensure their quality, reliability, currency, and validity. The bibliography of this article was considered reliable and of academic or scientific accuracy.

  • Bialek M, Pennycook G. The cognitive reflection test is robust to multiple exposures. Behav Res Methods. 2018 Oct;50(5):1953-1959. doi: 10.3758/s13428-017-0963-x. PMID: 28849403.
  • Frederick, Shane. 2005. “Cognitive Reflection and Decision Making.” Journal of Economic Perspectives19 (4): 25-42.DOI: 10.1257/089533005775196732
  • Sinayev A, Peters E. Cognitive reflection vs. calculation in decision making. Front Psychol. 2015 May 7;6:532. doi: 10.3389/fpsyg.2015.00532. PMID: 25999877; PMCID: PMC4423343.

This text is provided for informational purposes only and does not replace consultation with a professional. If in doubt, consult your specialist.