Reasoning
Wason Selection Task
Also called: Wason card selection task, four-card problem, deontic selection task, conditional reasoning task
Measure how people test an if-then rule: participants choose which of four cards to turn over, on abstract, everyday and permission rules written for this test.
7-10 minUntimed
Free to start: 10 free participants per account, then $0.99 per participant for academic research, or any yearly plan. Preview any test free after you sign up.
- Papers, 2021 to 2025
- 22
- Evidence grade
- D
- Registered clinical studies
- 0
What it measures
Measures how people test an if-then rule. On each of 12 problems, participants choose which of four cards to turn over to check a rule: 4 abstract rules about letters and numbers, 4 everyday rules and 4 permission rules. The main score counts the problems answered with the logically correct cards. The problems are written in each of the eight languages.
Constructs
- Conditional reasoning
- Hypothesis testing
- Deductive reasoning
- Reasoning about permissions
Research uses
- Reasoning and decision-making research
- Dual-process and individual-differences research
- Content effects in reasoning
- Within-study group comparison
How the paradigm works
The Wason selection task measures how people test an if-then rule. Four cards each have two sides, and only one side of each is showing. A rule says that if a card has P on one side, it has Q on the other, and the participant chooses the cards that must be turned over to test it. Only the P card and the not-Q card could break the rule, so they are the logically correct choice. Few people choose them when the rule is abstract: most choose the P card alone, or the P and Q cards, the two the rule names (Wason 1968; Evans and Lynch 1973). People do much better when the rule is a permission and the question is whether anyone is breaking it (Griggs and Cox 1982; Cheng and Holyoak 1985). Across 228 published experiments, P and not-Q made up 19% of the four common selections with abstract rules, 29% with everyday rules and 64% with deontic rules, while P and Q made up 39%, 37% and 19% (Ragni, Kola and Johnson-Laird 2017).
More about the paradigm
This test has 12 problems written for it, 4 of each kind. Abstract rules name a letter and a number, on cards with a letter on one side and a number on the other. Everyday rules are about everyday things, such as jars and the color of their lids, and both kinds ask whether the rule is true or false. Permission rules say what a person must have to do something, such as a first-class ticket to sit in first class, and ask whether anyone is breaking the rule. The other two cards show another letter, number, color or place, never a negation of the rule's words. Every session sees the same problems, in its own language. The session's seed orders them, with no more than 2 of one kind in a row, and places the cards so that each card is in each position once per kind. Participants click or tap the cards they choose and press Done. One practice problem, about which cards have a color on their hidden side, has feedback; the test has none and no time limit.
The main score counts the problems answered with exactly the P and not-Q cards. Each kind of rule has its own count, and the everyday and permission effects give how much more often those rules were answered correctly than abstract rules, in percentage points. Matching selections (P and Q), the P card alone and how often the Q and not-Q cards were chosen describe the errors. Solving abstract problems went with higher cognitive ability, while two well-known permission problems did not (Stanovich and West 1998). Scores support research and do not diagnose.
Scores
- Correct Selectionscount
- Problems answered with exactly the P and not-Q cards, the only cards that could break the rule, out of 12.
- Higher means more logically correct answers
- Abstract Rules Correctcount
- Abstract rules about letters and numbers answered with exactly the P and not-Q cards, out of 4.
- Higher means more correct answers on abstract rules, which few people answer correctly
- Everyday Rules Correctcount
- Everyday rules, asked as true or false, answered with exactly the P and not-Q cards, out of 4.
- Higher means more correct answers on everyday rules
- Permission Rules Correctcount
- Permission rules, asked as whether anyone is breaking them, answered with exactly the P and not-Q cards, out of 4.
- Higher means more correct answers on permission rules, which most people answer correctly
- Everyday Rule Effect%
- Percent correct on everyday rules minus percent correct on abstract rules, in percentage points.
- Positive means everyday content helped
- Permission Rule Effect%
- Percent correct on permission rules minus percent correct on abstract rules, in percentage points.
- Positive means permission rules helped, the usual content effect
- Matching Selectionscount
- Problems answered with exactly the P and Q cards, the two cards the rule names.
- Higher means more answers that match the rule's words
- P Card Alonecount
- Problems answered with the P card alone.
- A common answer on abstract rules
- Q Card Chosen%
- Percent of problems on which the Q card was among the cards chosen. That card cannot break the rule.
- Higher means the Q card was chosen more often
- Not-Q Card Chosen%
- Percent of problems on which the not-Q card was among the cards chosen. That card could break the rule.
- Higher means the not-Q card was chosen more often
- Median Decision Timems
- Median time from a problem's screen to Done, over answers at or after 100 ms.
- Describes pace; the test has no time limit
- Answers Under 100 mscount
- Answers given less than 100 ms after the screen appeared. They still count as answers.
- Expected to be 0
- Problems Answeredcount
- Problems answered in the scored run.
- 12 in a full session
Use and evidence
22 papers from 2021 to 2025 name this task in their title or abstract, down 27% compared with 2016 to 2020. That ranks it 326 of 395 test families in our census. See the counts for every test.
Show the numbers
| Year | Papers |
|---|---|
| 2025 | 5 |
| 2024 | 6 |
| 2023 | 1 |
| 2022 | 7 |
| 2021 | 3 |
| 2020 | 7 |
| 2019 | 4 |
| 2018 | 8 |
| 2017 | 7 |
| 2016 | 4 |
| 2015 | 10 |
| 2014 | 5 |
| 2013 | 15 |
| 2012 | 2 |
| 2011 | 7 |
| 2010 | 4 |
| 2009 | 4 |
| 2008 | 9 |
| 2007 | 9 |
| 2006 | 5 |
| 2005 | 6 |
| 2004 | 12 |
| 2003 | 1 |
| 2002 | 5 |
| 2001 | 9 |
| 2000 | 6 |
Use grade E
Fewer than 30 papers from 2021 to 2025.
Evidence grade D
Little published measurement evidence found.
- Papers on test-retest reliability
- 0
- Papers on reliability or validity
- 16
- Registered clinical studies using it as an outcome
- 0
How the grades work
Use: A is 1,000 or more papers from 2021 to 2025, B 300 to 999, C 100 to 299, D 30 to 99 and E fewer than 30. Evidence: A means at least 25 papers report its test-retest reliability and at least 25 registered clinical studies use it as an outcome; B, at least 8 test-retest papers, and either 5 registered clinical studies or 150 reliability or validity papers; C, at least 2 test-retest papers, 30 reliability or validity papers or 3 registered clinical studies; D, little published measurement evidence found. The counts measure use. They include every paper that names the task in its title or abstract. Grades describe the published research on this task, not ConductCognition's version of it.
Source: ConductCognition test census 0.14.0, counted 31 October 2026 from OpenAlex and ClinicalTrials.gov.
Task design
The trial sequence as the test runs in ConductCognition.
- Problems
- 12 written for this test, 4 of each kind: abstract rules about letters and numbers, everyday rules and permission rules. They are shown in the session's language.
- Cards
- Four cards per problem, P, not-P, Q and not-Q, each with one side showing. The not-P and not-Q cards show another letter, number, color or place, never a negation of the rule's words.
- Abstract
- Cards with a letter on one side and a number on the other, and a rule that names one letter and one number. The question asks whether the rule is true or false.
- Everyday
- A rule about everyday things, such as jars and the color of their lids, asked the same way.
- Permission
- A rule that says what a person must have to do something, such as a first-class ticket to sit in first class, and the question whether anyone is breaking it.
- Choice
- Click or tap one or more cards, then Done, with no time limit and no feedback. The order, with no more than 2 problems of one kind in a row, and the card positions come from the session's seed; each card is in each position once per kind.
- Practice
- 1 problem about which cards have a color on their hidden side, followed by its answer. It has no rule to test.
- Scores
- Problems answered with exactly the P and not-Q cards, overall and for each kind; the everyday and permission effects against abstract rules; matching selections (P and Q); and how often the Q and not-Q cards were chosen.
The rules and cards follow the classic task but were written for this test; no published problem, such as the drinking-age rule, is used. The scores support research and do not diagnose.
Quality checks
Each session is marked valid, needs review or invalid, with the reason, before you see its scores.
Scored rows: the scored run's answers to the 12 problems, each a set of one to four cards. A choice has no chance level, so accuracy is not judged against chance. The same screen positions chosen on 90% of the problems invalidates. A run with fewer than half its problems answered is invalid and any other shortfall is flagged. Answers under 200 ms on at least half the problems invalidate.
Why these rules
There is no correct option to compare with chance, so accuracy is not judged against chance. Most people choose the wrong cards on abstract rules, so a low score is the result the test measures, not a sign of careless answering. Every card is in every position once per kind of rule, so choosing the same positions on nearly every problem cannot follow the rules or the cards. An answer under 200 ms is faster than a simple visual reaction, so it cannot reflect the item. Following response-time effort screening for untimed tests (Wise and Kong 2005), the session is invalid only when at least half the answers are that fast.
Running this test
Settings you can change
This test runs with fixed settings.
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Devices and languages
- Untimed test: runs on desktops, laptops, tablets and phones. Participant devices
- Languages: English, Spanish, French, German, Italian, Portuguese (Brazil), Chinese (Simplified) and Japanese.
- Available on: Every plan, including the free plan.
- Recruiting online? See the setup guides for Prolific, Sona Systems, CloudResearch Connect and Qualtrics.
Cite and describe
Participants completed the Wason Selection Task in a web browser (ConductCognition task version 1.0.0, scoring version 1.0.0; Wason, 1968; Griggs & Cox, 1982; Cheng & Holyoak, 1985). The main score was correct selections (problems answered with exactly the P and not-Q cards, the only cards that could break the rule, out of 12).
ConductCognition versions: task version 1.0.0, scoring version 1.0.0. Every export records the versions each session used, for a methods section.
- Wason, P. C. (1968). Reasoning about a rule. Quarterly Journal of Experimental Psychology, 20(3), 273-281. https://doi.org/10.1080/14640746808400161
- Evans, J. St. B. T., & Lynch, J. S. (1973). Matching bias in the selection task. British Journal of Psychology, 64(3), 391-397. https://doi.org/10.1111/j.2044-8295.1973.tb01365.xChoosing the cards that the rule names.
- Wason, P. C., & Shapiro, D. (1971). Natural and contrived experience in a reasoning problem. Quarterly Journal of Experimental Psychology, 23(1), 63-71. https://doi.org/10.1080/00335557143000068Everyday rules against abstract rules.
- Griggs, R. A., & Cox, J. R. (1982). The elusive thematic-materials effect in Wason's selection task. British Journal of Psychology, 73(3), 407-420. https://doi.org/10.1111/j.2044-8295.1982.tb01823.xRules about what people must do, checked for anyone breaking them.
- Cheng, P. W., & Holyoak, K. J. (1985). Pragmatic reasoning schemas. Cognitive Psychology, 17(4), 391-416. https://doi.org/10.1016/0010-0285(85)90014-3Permission rules.
- Stanovich, K. E., & West, R. F. (1998). Cognitive ability and variation in selection task performance. Thinking & Reasoning, 4(3), 193-230. https://doi.org/10.1080/135467898394139Abstract and permission problems as measures of individual differences.
- Ragni, M., Kola, I., & Johnson-Laird, P. N. (2018). On selecting evidence to test hypotheses: A theory of selection tasks. Psychological Bulletin, 144(8), 779-796. https://doi.org/10.1037/bul0000146Choices across 228 experiments with abstract, everyday and deontic rules.
Source papers
- Ragni M, Kola I, Johnson-Laird PN (2017). The Wason selection task: A meta-analysis. Proceedings of the 39th Annual Meeting of the Cognitive Science Society, 980-985.Paradigm source, Adults
Questions
How long does the Wason Selection Task take?
About 7 to 10 minutes, as listed in the test library.
What device does a participant need?
Untimed test: runs on desktops, laptops, tablets and phones. The browser must be Chrome, Edge, Firefox or Safari.
What scores does it produce?
Correct Selections, Abstract Rules Correct, Everyday Rules Correct, Permission Rules Correct, Everyday Rule Effect, Permission Rule Effect, Matching Selections, P Card Alone, Q Card Chosen, Not-Q Card Chosen, Median Decision Time, Answers Under 100 ms and Problems Answered. Each session is also marked valid, needs review or invalid, with the reason.
How widely is the Wason Selection Task used in research?
22 papers from 2021 to 2025 name it in their title or abstract, down 27% compared with 2016 to 2020. That ranks it 326 of 395 test families in the ConductCognition test census (use grade E). Source: ConductCognition test census 0.14.0, counted 31 October 2026 from OpenAlex and ClinicalTrials.gov.
How much reliability evidence does the Wason Selection Task have?
In the published research, 0 papers report its test-retest reliability and 0 registered clinical studies use it as an outcome (evidence grade D in the ConductCognition test census).
Which languages can participants use?
Participants can take this test in English, Spanish, French, German, Italian, Portuguese (Brazil), Chinese (Simplified) and Japanese, with its words in the same language. English is on every plan, and the other languages come with yearly plans. Have a native speaker read the machine-translated text before launch.
Is this a clinical test?
No. ConductCognition is for research use only. It runs, scores and exports the test; clinical interpretation is outside the platform.
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