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Moses illusion

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A cognitive illusion induced by a question such as: ‘How many animals of each kind did Moses take on the Ark?’ A substantial proportion of people (roughly 50 per cent) answer ‘two’ rather than ‘none’, and feel confident about their answer, even when they are given unlimited time to think about it, in spite of the fact that they know that it was Noah and not Moses who took animals on to the Ark. The illusion depends primarily on the semantic similarity between the names Noah and Moses and possibly also on their phonological similarity (two syllables, similar stress patterns, the same vowel in the stressed syllable, and so on). It is not explained by the respondent mishearing the question, because people make Moses mistakes even after correctly reading the question aloud, nor is it explained by the misdirection created by the words ‘how many’, because the illusion persists, though it is slightly reduced, when respondents are asked to respond ‘True’ or ‘False’ to the statement: ‘Moses took two animals of each kind on the Ark’. The illusion was first reported in an article by the US psychologists Thomas D(avid) Erickson (born 1956) and Mark E(dward) Mattson (born 1957) in the Journal of Verbal Learning and Verbal Behavior in 1981. Compare yolk phenomenon. [Named after Moses, the Hebrew prophet who, according to the Old Testament, led the Israelites out of Egypt to the Promised Land and handed down laws revealed to him by God]

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