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Appreciation for Independence: Does Adaptation to Stochastic Dependence Imply Thinking According to Stochastic Principles?
(Kognitionsgruppen)
(Kognitionsgruppen)
(Kognitionsgruppen)
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Do people think of their environments in probabilistic concepts like “dependent” or “independent” events? Research has shown that people can learn from feedback to make accurate joint probability judgments in both cases, but it is unclear whether this implies an understanding of the task structure with respect to dependence. In this article, we report two experiments that investigate if accuracy in joint probability judgment tasks implies understanding the presence or absence of dependencies between the events in the task. Experiment 1 involved a symbolic task with stated numerical risks, whereas Experiment 2 compared this format with judgments from experience where the participants learned the joint probabilities from direct (binary) experience of the events occurring or not. The results demonstrate that participants rapidly learned to make accurate judgments of the joint probability both when events where dependent and independent, and computational modeling suggests that they draw on a variety of strategies ranging from analytic multiplication informed by probability theory, over heuristic weighted additive or weighted minimum models, to sampled proportions or exemplar memory. Despite successfully learning to accurately assess the joint probabilities, there were no indications that the participants successfully discovered whether the events were dependent or not. This suggests that rather than spontaneously thinking of the world in probabilistic terms, participants draw on generic cognitive resources with little or no conceptual overlap with notions of probability theory.

Keywords [en]
Joint probability judgment, judgment from experience, task understanding
National Category
Psychology
Research subject
Psychology; Psychology
Identifiers
URN: urn:nbn:se:uu:diva-380098OAI: oai:DiVA.org:uu-380098DiVA, id: diva2:1298581
Available from: 2019-03-24 Created: 2019-03-24 Last updated: 2019-03-24
In thesis
1. The Cognitive Basis of Joint Probability Judgments: Processes, Ecology, and Adaption
Open this publication in new window or tab >>The Cognitive Basis of Joint Probability Judgments: Processes, Ecology, and Adaption
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

When navigating an uncertain world, it is often necessary to judge the probability of a conjunction of events, that is, their joint probability. The subject of this thesis is how people infer joint probabilities from probabilities of individual events. Study I explored such joint probability judgment tasks in conditions with independent events and conditions with systematic risk that could be inferred through feedback. Results indicated that participants tended to approach the tasks using additive combinations of the individual probabilities, but switch to multiplication (or, to a lesser extent, exemplar memory) when events were independent and additive strategies therefore were less accurate. Consequently, participants were initially more accurate in the task with high systematic risk, despite that task being more complex from the perspective of probability theory. Study II simulated the performance of models of joint probability judgment in tasks based both on computer generated data and real-world data-sets, to evaluate which cognitive processes are accurate in which ecological contexts. Models used in Study I and other models inspired by current research were explored. The results confirmed that, by virtue of their robustness, additive models are reasonable general purpose algorithms, although when one is familiar with the task it is preferable to switch to other strategies more specifically adapted to the task. After Study I found that people adapt strategy choice according to dependence between events and Study II confirmed that these adaptions are justified in terms of accuracy, Study III investigated whether adapting to stochastic dependence implied thinking according to stochastic principles. Results indicated that this was not the case, but that participants instead worked according to the weak assumption that events were independent, regardless of the actual state of the world. In conclusion, this thesis demonstrates that people generally do not combine individual probabilities into joint probability judgments in ways consistent with the basic principles of probability theory or think of the task in such terms, but neither does there appear to be much reason to do so. Rather, simpler heuristics can often approximate equally or more accurate judgments.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2019. p. 60
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Social Sciences, ISSN 1652-9030 ; 166
Keywords
Judgment and decision-making, Joint probability judgment, Probability theory, Ecological rationality
National Category
Psychology
Research subject
Psychology
Identifiers
urn:nbn:se:uu:diva-380099 (URN)978-91-513-0608-7 (ISBN)
Public defence
2019-05-20, Humanistiska teatern, Engelska parken, Thunbergsv. 3H, Uppsala, 10:15 (English)
Opponent
Supervisors
Available from: 2019-04-26 Created: 2019-03-24 Last updated: 2019-06-18

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