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    Explaining High Conjunction Fallacy Rates: The Probability Theory Plus Noise Account

    Costello, Fintan and Watts, Paul (2017) Explaining High Conjunction Fallacy Rates: The Probability Theory Plus Noise Account. Journal of Behavioral Decision Making, 30 (2). pp. 304-321. ISSN 0894-3257

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    The conjunction fallacy occurs when people judge the conjunctive probability P(A ∧ B) to be greater than a constituent probability P(A), contrary to the norms of probability theory. This fallacy is a reliable, consistent and systematic part of people's probability judgements, attested in many studies over at least 40 years. For some events, these fallacies occur very frequently in people's judgements (at rates of 80% or more), while for other events, the fallacies are very rare (occurring at rates of 10% or less). This wide range of fallacy rates presents a challenge for current theories of the conjunction fallacy. We show how this wide range of observed fallacy rates can be explained by a simple model where people reason according to probability theory but are subject to random noise in the reasoning process.

    Item Type: Article
    Keywords: conjunction fallacy; probability estimation; rationality; biases;
    Academic Unit: Faculty of Science and Engineering > Theoretical Physics
    Item ID: 11798
    Identification Number:
    Depositing User: Paul Watts
    Date Deposited: 21 Nov 2019 16:27
    Journal or Publication Title: Journal of Behavioral Decision Making
    Publisher: Wiley
    Refereed: Yes
    Use Licence: This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here

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