Free Cognitive Bias quiz: 40 trivia questions and answers — your brain's favourite traps. Easy to hard, with explained answers. No sign-up.

Why do we pick the full restaurant? Why does a crossed-out price make us give in? This quiz explores cognitive biases, the mental shortcuts that fool us every day, through real-life situations and the famous experiments that revealed them. A great way to sharpen your critical thinking… and to be a little wary of yourself.

Did you know?

During World War II, statistician Abraham Wald advised armouring the areas of returning planes that showed no damage: the others had never come back.
In 1913, at the Monte Carlo casino, black reportedly came up 26 times in a row at roulette, ruining players convinced that red was 'due'.
In Stanley Milgram's experiments (1963), about two out of three participants obeyed all the way to the maximum electric shock, which was in fact fake.
The Dunning-Kruger effect, described in 1999, holds that beginners overestimate their level, while experts tend to underestimate theirs.

This quiz currently has 40 questions, ranging from easy to hard, available in French, English and Spanish when the Spanish translation is available.

Cognitive Bias quiz: trivia questions and answers

Warm up before the quiz with these 8 trivia questions and their explained answers: click a question to reveal the answer.

Easy questions

At roulette, red has come up 6 times in a row. Believing that black is now 'due' is an example of…

Answer: Gambler's fallacy. Roulette has no memory: on each spin, the odds stay the same. At the Monte Carlo casino in 1913, black reportedly came up 26 times in a row, and many players went broke betting on red.

After a widely reported plane crash, many people fear flying more than driving, even though driving is far more dangerous. Which bias is at play?

Answer: Availability bias. We judge risk by the examples that come easily to mind. One spectacular crash sticks far more than the thousands of road accidents that rarely make the headlines.

At dice, some players throw harder when they want a high number. Which bias are they showing?

Answer: Illusion of control. We believe we can influence events that are pure chance. Psychologist Ellen Langer also showed that people value a lottery ticket more if they picked it themselves.

'I passed the exam thanks to my hard work; I failed because the questions were unfair.' Which bias?

Answer: Self-serving bias. We take credit for successes and blame failures on circumstances. It protects self-esteem… but sometimes stops us learning from our mistakes.

Hard questions

During World War II, statistician Abraham Wald advised armouring the areas of returning planes that showed NO bullet holes. Which bias was he avoiding?

Answer: Survivorship bias. Planes hit in those areas… never came back. Looking only at the 'survivors' skews the conclusion, just like studying only the companies that succeeded.

In countries where you must explicitly opt out of organ donation, there are far more donors than where you must sign up. What explains this?

Answer: Default effect (status quo bias). Most people don't change the default option. A 2003 study showed dramatic gaps between neighbouring countries, due solely to the box ticked in advance.

In 1951, Solomon Asch showed that volunteers gave a clearly wrong answer about the length of lines. Why?

Answer: To conform to the group. The other participants were stooges who all gave the same wrong answer. About a third of the volunteers' answers went along with this collective error.

In a famous study, a stand offering 24 jams drew crowds but sold less than a stand offering only 6. Which phenomenon is at play?

Answer: Choice overload. Too many options can paralyse decision-making. This 2000 study became a classic, although later research has qualified how strong the effect is.

32 more questions are waiting for you in the quiz!

Cognitive Biases Quiz

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Cognitive Bias quiz: trivia questions and answers

Easy questions

Hard questions

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