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    Why the Conjunction Effect Is Rarely a Fallacy: How Learning Influences Uncertainty and the Conjunction Rule

    Maguire, Phil and Moser, Philippe and Maguire, Rebecca and Keane, Mark T. (2018) Why the Conjunction Effect Is Rarely a Fallacy: How Learning Influences Uncertainty and the Conjunction Rule. Frontiers in Psychology, 9 (1011). ISSN 1664-1078

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    In this article we explore the relationship between learning and the conjunction fallacy. The interpretation of the conjunction effect as a fallacy assumes that all observers share the same knowledge, and that nobody has access to privileged information. Such situations are actually quite rare in everyday life. Building on an existing model of surprise, we prove formally that in the more typical scenarios, where observers are alert to the possibility of learning from event outcomes, the conjunction rule does not apply. Scenarios which have been engineered to produce the so-called conjunction “fallacy” (e.g., Tverksy and Kahneman, 1983) often imply subjective uncertainty and hence the possibility of learning. In Experiment 1 we demonstrate that when these scenarios are rephrased so as to eliminate subjective uncertainty, the effect is mitigated. In Experiment 2 we demonstrate that when subjective uncertainty is reduced by allowing participants to learn about the mechanism behind a conjunction-inducing scenario, the conjunction effect again diminishes. We conclude that the conjunction effect arises due to the unnaturalness of interpreting verbal descriptions in terms of a situation in which all observers share the same knowledge. Instead, when people hear descriptions of real world situations, they are likely to assume that learning is possible, and that subjective rather than objective uncertainty applies.

    Item Type: Article
    Additional Information: Citation: Maguire P, Moser P, Maguire R and Keane MT (2018) Why the Conjunction Effect Is Rarely a Fallacy: How Learning Influences Uncertainty and the Conjunction Rule. Front. Psychol. 9:1011. doi: 10.3389/fpsyg.2018.01011 Copyright © 2018 Maguire, Moser, Maguire and Keane. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
    Keywords: conjunction fallacy; learning; probability theory; informativeness; randomness deficiency; surprise; subjective uncertainty; subjective likelihood;
    Academic Unit: Faculty of Science and Engineering > Computer Science
    Faculty of Science and Engineering > Psychology
    Item ID: 10338
    Identification Number:
    Depositing User: Phil Maguire
    Date Deposited: 18 Dec 2018 14:45
    Journal or Publication Title: Frontiers in Psychology
    Publisher: Frontiers Media
    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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