The Role of Memory in Value-Based Decisions

Our decisions reflect who we are and shape who we become. The field of decision-making and learning has revealed how past outcomes guide our future choices by updating value representations. However, we often make choices among options we never experienced before, and therefore their value is not immediately accessible. How do we navigate these choices? This dissertation posits that such decisions rely on memory mechanisms that facilitate generalization and inferential reasoning. Through a combination of behavioral experiments, computational modeling and neuroimaging measures, I explore the diverse ways in which memory mechanisms influence value-based decisions between options for which value is unknown. In Chapter One, I investigate how individuals assign value to unchosen alternatives and propose that memory creates an associative link between choice options, with consequences for later updating of value. Through a series of five experiments, I demonstrate an inverse relationship between the valuation of unchosen options and the direct learning about chosen options, and show that this inverse inference of value is related to memory of the decision itself. In Chapter Two, I manipulate the associative link between choice options using a well-established memory manipulation technique and observe a reduction in the inverse inference of unchosen options. This provides further evidence for the causal role of associative memory in the inferential effect. Additionally, I introduce a novel policy-gradient model incorporating memory components that offers the best explanation for observed behaviors. Lastly, in Chapter Three, I present behavioral and neuroimaging evidence supporting the influence of conceptual knowledge in value-based decisions involving entirely new choice options. I show that people use existing category knowledge to group similar items together, enabling value extraction at a category level and generalization to novel items. Overall, this dissertation underscores the fundamental role of memory in shaping the construction and use of value to guide choice. It emphasizes the adaptive and flexible nature of memory, showing how it combines past experiences to guide future actions

Replication of Mudrik & Koch, 2013

The study aims at replicating Mudrik & Koch (2013), which reported unconscious semantic integration between an object and the scene in which it appears. These findings challenged the widely accepted claim that consciousness is needed for information integration, especially one that pertains to high-level semantic relations between objects and the scenes in which they appear

Working memory has better fidelity than long-term memory: The fidelity constraint is not a general property of memory after all

Here we present data files and analyses codes to reproduce the results of our study. (1) Data_files_per_experiment folder includes all individual and summary data files for Experiments 1-3, as well as Matlab and R scripts for our main analyses. (2) Bayesian_hierarchical_modeling folder includes our Stan implementation to the Bayesian version of the two-parameter model of Zhang and Luck (2008) (3) Hue_transformation folder includes scripts for unifying the hue of images. (4) Simulations folder includes a simulation for recovery of parameters using MLE