Dissertation/Thesis Abstract

The Role of Uncertainty and Priority in Visual Working Memory
by Yoo, Aspen H., Ph.D., New York University, 2019, 159; 22615590
Abstract (Summary)

Visual working memory, the process involved in actively maintaining visual information over a short period of time, is essential for numerous everyday behaviors. A substantial amount of research has gone into characterizing the exact nature of one of the defining characteristics of visual working memory, its seemingly-counterintuitive limited capacity. Typically, these studies involve testing the memory for the value of a feature of some number of stimuli (e.g., the orientation of one of four oriented stimuli).

However, more recent studies have shown that visual working memory holds more than just a point estimate of a stimulus feature, implying that the previous methods investigating visual working memory limits are underestimating the capacity and flexibility of this process. In my dissertation, I use psychophysical, computational, and neuroimaging methods to investigate how people maintain and use two additional pieces of information: an item's uncertainty, or the knowledge of the noise associated with its memory, and its priority, or behavioral relevance.

In the first two chapters, I investigate how priority is maintained and used in working memory. In the first chapter, I investigate how we allocate our working memory resource across items with different priorities. I show that people allocate resources consistent with a loss-minimizing strategy. In the second chapter, I ask how priority is maintained in the brain during a delay. I find that, in visual areas, priority is maintained through the amount of delay-period activity of the same neural populations maintaining each item’s location.

In the third chapter, I investigate uncertainty in working memory, showing that people maintain an accurate representation of item-specific uncertainty over a delay and use it optimally when deciding if a stimulus has changed in orientation.

In the final chapter, I investigate both priority and uncertainty, replicating and extending findings from previous chapters. First, I show that people allocate resource in a way consistent with a loss-minimizing strategy, even when incentivized to use a different strategy. Second, I show that people maintain an item-specific representation of uncertainty, which isn’t affected by priority information. Finally, I show that people use item-specific uncertainty optimally when placing a wager about the accuracy of their memory.

Together, my studies demonstrate different ways in which working memory maintains and uses information that is helpful with interacting effectively with our environment.

Indexing (document details)
Advisor: Ma, Wei Ji
Commitee: Curtis, Clayton, Landy, Michael, Savin, Cristina, Wolpert, Daniel
School: New York University
Department: Psychology
School Location: United States -- New York
Source: DAI-B 81/5(E), Dissertation Abstracts International
Subjects: Experimental psychology, Psychology, Neurosciences
Keywords: Bayesian, fMRI, Psychophysics, Visual working memory
Publication Number: 22615590
ISBN: 9781392839676
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