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The Role of Strategy in Decision-Making under Risk: An fMRI Investigation
Date of Award
Doctor of Philosophy (PhD)
When making decisions involving risk, people often deviate markedly from the predictions of normative choice models, and show a systematic tendency to minimize risk rather than maximizing expected value (EV). This bias is widely attributed to a tendency to assign greater emotional weight to negative prospects relative to positive prospects. However, it remains unclear to what extent such emotional responses are controllable and subject to strategic modulation. In this study, participants were scanned with fMRI while engaging in a standard gambling paradigm involving repeated choice between two probabilistic rewards (e.g., 70% of 400 vs. 30% of 1000). I experimentally manipulated the manner in which rewards were computed as well as the nature of the feedback participants received. Results provided strong evidence that strategy choice is a critical determinant of decision-making under risk. Behaviorally, participants consistently maximized EV under some reward schedules while exhibiting robust risk aversion under others. These differences persisted even when participants received no feedback about the outcome of their choices and stimuli were perceptually identical in all conditions. FMRI analyses identified qualitatively different patterns of activation associated with different decision-making strategies. Specifically, EV maximization strategies were associated with increased activation in frontoparietal regions implicated in numerical computation and visuospatial manipulation, whereas probability-maximizing heuristics were associated with increased activation in dorsal ACC and anterior insula when participants made risky choices. Collectively, these results suggest that risk aversion is a strategy-dependent phenomenon that can often be eliminated with little difficulty given appropriate environmental cues.
Chair and Committee
Ian Dobbins, Leonard Green, Steven Petersen, Rebecca Treiman, Camillo Padoa-Schioppa
Yarkoni, Tal, "The Role of Strategy in Decision-Making under Risk: An fMRI Investigation" (2009). Arts & Sciences Electronic Theses and Dissertations. 320.