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Computational and cognitive mechanisms of exploration heuristics

Dubois, Magda; (2022) Computational and cognitive mechanisms of exploration heuristics. Doctoral thesis (Ph.D), UCL (University College London). Green open access

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Abstract

Should I leave or stay in academia? Many decisions we make require arbitrating between novelty and the benefits of familiar options. This is called the exploration-exploitation trade-off. Solving this trade-off is not trivial, but approximations (called ‘exploration strategies’) exist. Humans are known to rely on different exploration strategies, varying in performance and computational requirements. More complex strategies perform well, but are computationally expensive (e.g., require to compute expected values). Cheaper strategies, i.e., heuristics, require less cognitive resources but can lead to sub-optimal performance. The simplest heuristic strategy is to ignore prior knowledge, such as expected values, and to choose entirely randomly. In effect, this is like rolling a dice to choose between different choice options. Such ‘value-free random’ exploration strategy may not always lead to optimal performance but allows to spare cognitive resources. In this thesis, I investigate the mechanisms of exploration heuristics in human decision making. I developed a cognitive task allowing to dissociate between different strategies for exploration. In my first study, I demonstrate that humans supplement complex strategies with exploration heuristics and, using a pharmacological manipulation, that value-free random exploration is specifically modulated by the neurotransmitter noradrenaline. Exploration heuristics are of particular interest when access to cognitive resources is limited and prior knowledge uncertain, such as in development and mental health disorders. In a cross-sectional developmental study, I demonstrate that value-free random exploration is used more at a younger age. Additionally, in a large-sample online study, I show that it is specifically associated to impulsivity. Together, this indicates that value-free random exploration is useful in certain contexts (e.g., childhood) but that high levels of it can be detrimental. Overall, this thesis attempts to better understand the process of exploration in humans, and opens the way for understanding the mechanisms of arbitration between complex and simple strategies for decision making.

Type: Thesis (Doctoral)
Qualification: Ph.D
Title: Computational and cognitive mechanisms of exploration heuristics
Open access status: An open access version is available from UCL Discovery
Language: English
Additional information: Copyright © The Author 2022. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request.
UCL classification: UCL
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences > UCL Queen Square Institute of Neurology
URI: https://discovery.ucl.ac.uk/id/eprint/10158939
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