Real world decision-making requires simultaneously determining what we are observing in our environment (perceptual decision-making; PDM) and what the stimuli and actions are worth (reward-based decision-making; RDM). There is evidence of a bi-directional relationship between reward and perceptual information in guiding choice, with some studies suggesting that individuals optimally combine the two. Uncertainty in both reward expectations and perception have been shown to alter choice behavior, however few studies have manipulated both variables simultaneously. Given the distinct theoretical and computational foundations of PDM and RDM, it has also been assumed that the underlying behavioral and neural substrates of perceptual and reward-based choice are separable. However, there is evidence that task structure and subjective value/uncertainty more generally contribute to activity in large-scale networks of the brain, rather than domain specific features (perceptual salience/reward). Variability in task structures and methods of manipulating and modeling sensory and reward uncertainty, make it hard to draw definitive conclusions across these perspectives with currently available data. The current study used behavioral and fMRI techniques to investigate the neurobehavioral substrates of decision-making under simultaneous perceptual and reward uncertainty in a sample of healthy adult volunteers. The primary objectives of this project were to test: a) how simultaneous manipulations in sensory and reward uncertainty influence choice, b) whether task structure alters the influence of sensory and reward information on choice behavior, and c) whether activity in underlying neural substrates reflect domain-specific or domain-general processes. Results showed that choices were best predicted by a combined model of perceptual salience and reward, with an overall bias towards perceptual salience information. Choice percentage was not impacted by task structure, however choices were better predicted by individual features (salience and reward) when they were manipulated stably, than dynamically. Activity in the brain showed greater overlap between dynamic task conditions when compared to both salience and reward conditions. There was also greater overlap between stable task conditions when compared to reward but not salience conditions. Preliminary evidence suggests that activity in decision-relevant regions of the brain varied by uncertainty and value rather than salience and reward per se. / Doctor of Philosophy / Real world decision-making requires knowing what things in our environment are and knowing what they are worth. Uncertainty about what different options are, can affect the actions we take and the outcomes we expect. Uncertainty about the outcome of our choices or actions can also influence how attend to or consider certain options when making choices. We also know that context can affect our behavior. For example, when our environment changes frequently, choices that might have been good in the past, may not necessarily be the best course of action in the future. This can add further confusion about what to do. Across several mental health conditions, we see that problems arise when individuals need to take actions based on incomplete, uncertain, or frequently changing information.
Real world decision-making requires knowing what things in our environment are and knowing what they are worth. Uncertainty about what different options are, can affect the actions we take and the outcomes we expect. Uncertainty about the outcome of our choices or actions can also influence how we attend to or consider options when making choices. We also know that context can affect our behavior. For example, when our environment changes frequently, choices that might have been good in the past, may not necessarily be the best course of action in the future. This can add further confusion about what to do. Across several mental health conditions, we see that problems arise when individuals need to take actions based on incomplete, uncertain, or frequently changing information.
The first goal of this study was to better understand what healthy individuals do when they are faced with different levels of uncertainty around about what different options are (through changes in visual clarity), and what they are worth (through changes in probability of reward). A second goal was to see whether how the frequency at which choice clarity and outcomes change, effects the kinds of choices people make. Third, the study used a measure of brain activity, to determine what the brain is doing which participants make these complex decisions. Results showed that people's choices were best predicted by considering both clarity of the options and their outcome. Having certainty about the identity of the choices was more important than the value of those choices. Also, information about clarity and value of options were more likely to be considered when they were stable, versus when they were changing frequently. Decision-relevant regions of the brain seemed to respond most to overall information about uncertainty and stability of options rather than their clarity or outcome value per se. Future research should test these findings in a larger sample, further explore individual differences in how people respond to various types of uncertainty and determine how knowledge of these individual differences can inform personalized treatment for individuals with related mental health challenges.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/107755 |
| Date | 18 January 2022 |
| Creators | Ghane-Ezabadi, Merage |
| Contributors | Psychology, Richey, John A., Japee, Shruti, Casas, Brooks, Chiu, Pearl H. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Dissertation, Text |
| Format | ETD, application/pdf, application/pdf, application/pdf, application/pdf, application/pdf |
| Rights | Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International, http://creativecommons.org/licenses/by-nc-sa/4.0/ |
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