The Wason selection task (or four-card problem) is a logic puzzle devised by Peter Cathcart Wason in 1966.[1][2][3] It is one of the most famous tasks in the study of deductive reasoning.[4] An example of the puzzle is:
You are shown a set of four cards placed on a table, each of which has a number on one side and a color on the other. The visible faces of the cards show 3, 8, blue and red. Which card(s) must you turn over in order to test that if a card shows an even number on one face, then its opposite face is blue?
A response that identifies a card that need not be inverted, or that fails to identify a card that needs to be inverted, is incorrect. The original task dealt with numbers (even, odd) and letters (vowels, consonants).
The test is of special interest because people have a hard time solving it in most scenarios but can usually solve it correctly in certain contexts. In particular, researchers have found that the puzzle is readily solved when the imagined context is policing a social rule.
- ^ Wason, P. C. (1968). "Reasoning about a rule". Quarterly Journal of Experimental Psychology. 20 (3): 273–281. doi:10.1080/14640746808400161. PMID 5683766. S2CID 1212273.
- ^ Wason, P. C. (1966). "Reasoning". In Foss, B. M. (ed.). New horizons in psychology. Vol. 1. Harmondsworth: Penguin. LCCN 66005291.
- ^ Wason, P. C.; Shapiro, Diana (1971). "Natural and contrived experience in a reasoning problem". Quarterly Journal of Experimental Psychology. 23: 63–71. doi:10.1080/00335557143000068. S2CID 7903333.
- ^ Manktelow, K. I. (1999). Reasoning and Thinking. Psychology Press. p. 8. ISBN 978-0-86377-708-0.
The Wason selection task has often been claimed to be the single most investigated experimental paradigm in the psychology of reasoning.