The Wason Selection Task Explained (Try It First)
The Wason selection task is a four-card logic puzzle that asks which cards you must turn over to test an "if-then" rule. Explained simply: the right answer is to flip the cards that could break the rule, not the ones that could confirm it, and most people miss this. It was created by psychologist Peter Wason in the 1960s and is still one of the most famous tests of human reasoning.
If "if-then" puzzles like this one trip you up, IQ Tester can check whether logic chains are one of your weak spots and give you a daily drill for them: Find my weak spots.
Try the four-card puzzle first
Don't scroll yet. Give this a real try.
Four cards sit on a table. Each card has a letter on one side and a number on the other. You can see:
| Card 1 | Card 2 | Card 3 | Card 4 |
|---|---|---|---|
| E | K | 4 | 7 |
The rule: "If a card has a vowel on one side, then it has an even number on the other side."
Which cards do you need to turn over to find out whether the rule is true or false? Flip as few as possible, but don't miss any that matter.
Write your answer down. Seriously. Commit to it before you read on, because the whole point of the puzzle is catching what your brain does on the first pass.
The Wason selection task answer
The answer is E and 7.
Card by card
- E (flip it). E is a vowel. If the back is odd, the rule is broken. You have to check.
- K (leave it). K is a consonant. The rule says nothing about consonants. Any number on the back is fine.
- 4 (leave it). This is the one almost everyone picks. But the rule doesn't say "even numbers must have vowels." A consonant behind the 4 breaks nothing.
- 7 (flip it). If there's a vowel on the back of the 7, then a vowel sits with an odd number. That breaks the rule. You have to check.
The solution rests on one idea: a rule "if P then Q" can only be broken by a case where P is true and Q is false. So you check the P card (E) and the not-Q card (7).
Why most people get the Wason selection task wrong
The most common wrong answers are "E and 4" or "just E." Across many studies since Wason's, only a small minority of people pick E and 7 on this abstract version. That includes university students and people who are good at math. So if you got it wrong, you're in very normal company.
Confirmation bias
The 4 card feels important because it matches the rule's words. Your brain goes looking for examples that fit the rule instead of cases that could disprove it. This pull toward confirming evidence is often called confirmation bias, and the Wason task is one of the classic ways to show it.
Matching
Another explanation is simple matching. The rule mentions "vowel" and "even number," so people pick the cards showing a vowel and an even number. It's a shortcut, not reasoning.
Reversing the rule
Picking 4 also suggests people quietly flip the rule into "if even, then vowel." That's a different rule. "If it's raining, I carry an umbrella" doesn't mean every umbrella day is a rain day.
The drinking-age version (wason selection task alcohol)
Here's the twist that made this puzzle famous. Researchers later rewrote it with a social rule, and far more people solved it.
You're checking IDs at a party. The rule: "If a person is drinking alcohol, they must be over 21." Each card shows what a person is drinking on one side and their age on the other.
| Card 1 | Card 2 | Card 3 | Card 4 |
|---|---|---|---|
| Beer | Soda | 25 | 16 |
Which do you check? Most people see it instantly: Beer and 16. The beer drinker might be underage, and the 16-year-old might be drinking. The soda drinker and the 25-year-old can't break the rule.
It's the exact same logic as E and 7. Beer is P, 16 is not-Q.
Why the story helps
Psychologists still debate why. Some argue people reason well about social rules and cheating. Others say familiar situations just make it obvious what a violation looks like. Either way, the lesson is useful: the logic hasn't changed, only how easy it is to picture breaking the rule.
What the Wason card test says about logic
Three takeaways that matter outside the puzzle.
- Test rules by trying to break them. To check "if I study the night before, I do well," look for times you studied and did badly, not just the good days.
- Watch the direction. "If P then Q" is not "if Q then P." Ads, arguments and rumors often rely on you flipping it.
- Abstract logic is harder than stories. When a problem feels impossible, turn it into a real situation with people and rules. Then turn it back.
If you like this kind of puzzle, syllogisms train the same muscle. Try our syllogism questions with answers, or read the full plan for how to improve deductive reasoning.
Training yourself to test the rule
You don't fix this bias by reading about it once. You fix it by practising the check until it's a habit.
A 3-question checklist for any if-then rule
- What is P and what is Q? Name them out loud. "P is vowel. Q is even."
- What would break the rule? Always "P and not Q." Say it: "a vowel with an odd number."
- Which cases could hide that? Only the P cards and the not-Q cards.
Make your own Wason selection task examples
Build new versions and try them on a friend:
- "If a student is in the band, they stay after school on Tuesday." Cards: Band, Soccer, Stays, Goes home.
- "If a shape is red, it's a circle." Cards: Red, Blue, Circle, Square.
- "If a game is rated M, the player must be 17 or older." Cards: Rated M, Rated E, 19, 14.
(Answers: Band and Goes home. Red and Square. Rated M and 14.)
The tricky part of training alone is that you can't see your own blind spot, you just feel sure. IQ Tester's 16-question check shows whether logic chains, rushing or putting reasoning into words is where you slip, and drills like "Name the rule out loud" build exactly the habit this puzzle tests. Find my weak spots
Put the Wason selection task explained into daily practice
Knowing the answer to one puzzle is a start. In about two minutes, IQ Tester gives you a reasoning tier, names your weak spots out of seven, and then serves one tip and one 10-minute drill a day, weighted toward them, across pattern, number, verbal and logic problems.
FAQ
What is the correct answer to the Wason selection task?
In the classic version with E, K, 4 and 7, the answer is E and 7. Those are the only cards that could reveal a vowel paired with an odd number, which is the one thing that breaks the rule.
Why is the Wason selection task so hard?
People tend to look for cards that confirm the rule rather than cards that could disprove it. They also match the words in the rule or quietly reverse it. The abstract letters and numbers give no real-world clue about what cheating looks like.
Is the Wason selection task about confirmation bias?
It's often used to show confirmation bias, because people pick the confirming 4 card over the disconfirming 7 card. Researchers also point to matching and rule reversal as causes.
Can I take a Wason selection task test online?
Yes, several psychology sites and university demos let you try the four-card problem online. You can also make your own versions with index cards using the examples above.
Does being good at the Wason task mean a high IQ?
Not by itself. It's one puzzle that tests a specific habit: checking for what breaks a rule. That habit can be trained with practice.