Day 17 of 150 Logic Difficulty 8/10
Fewer than 10% solve the abstract Wason 4-card task
Quick answer
Fewer than 10% solve the abstract Wason 4-card task. Today's question (Wason selection task) asks about a finding from Wason, P. C. in 1968. The correct option is Under 10% — full explanation, primary source, and glossary cross-links below.
Today's question
In the abstract Wason 4-card selection task ("If a card has a vowel on one side, it has an even number on the other"), what fraction of university students typically solve it correctly?
Reveal the answer and explanation
Correct: A — Under 10%
Wason (1968) reported that only a small minority — roughly 5–10% across studies — choose the logically correct cards (the vowel and the odd number, testing both modus ponens and modus tollens). Performance jumps dramatically when the same logic is reframed as a social-contract task ("If drinking, must be 21"), suggesting humans engage domain-specific cheater-detection rather than abstract formal-logic machinery — a central claim of Cosmides & Tooby's evolutionary-psychology programme.
About the source
Wason, P. C. (1968). Reasoning about a rule. Quarterly Journal of Experimental Psychology, 20(3), 273–281.
Every Cognition Bible question cites a primary source — a paper, book chapter, or monograph that exists, that we can point to on Google Scholar, and whose finding the question accurately summarizes. No fabricated authority strings, no name-drops without paper-level grounding.
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