Purdue University Graduate School
Li_Xin_Lim_PhD_dissertation -revised and formatted.pdf (2.28 MB)

The interaction of working memory and Uncertainty (mis)estimation in context-dependent outcome estimation

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posted on 2023-11-13, 19:17 authored by Li Xin LimLi Xin Lim

In the context of reinforcement learning, extensive research has shown how reinforcement learning was facilitated by the estimation of uncertainty to improve the ability to make decisions. However, the constraints imposed by the limited observation of the process of forming environment representation have seldom been a subject of discussion. Thus, the study intended to demonstrate that when incorporating a limited memory into uncertainty estimation, individuals potentially misestimate outcomes and environmental statistics. The study included a computational model that included the process of active working memory and lateral inhibition in working memory (WM) to describe how the relevant information was chosen and stored to form estimations of uncertainty in forming outcome expectations. The active working memory maintained relevant information not just by the recent memory, but also with utility. With the relevant information stored in WM, the model was able to estimate expected uncertainty and perceived volatility and detect contextual changes or dynamics in the outcome structure. Two experiments to investigate limitations in information availability and uncertainty estimation were carried out. The first experiment investigated the impact of cognitive loading on the reliance on memories to form outcome estimation. The findings revealed that introducing cognitive loading diminished the reliance on memory for uncertainty estimations and lowered the expected uncertainty, leading to an increased perception of environmental volatility. The second experiment investigated the ability to detect changes in outcome noise under different conditions of outcome exposure. The study found differences in the mechanisms used for detecting environmental changes in various conditions. Through the experiments and model fitting, the study showed that the misestimation of uncertainties was reliant on individual experiences and relevant information stored in WM under a limited capacity.


Degree Type

  • Doctor of Philosophy


  • Psychological Sciences

Campus location

  • West Lafayette

Advisor/Supervisor/Committee Chair

Sébastien Hélie

Additional Committee Member 2

Anne Sereno

Additional Committee Member 3

Stephen Broomell

Additional Committee Member 4

Yu-Chin Chiu