Poster F136, Tuesday, March 28, 8:00 – 10:00 am, Pacific Concourse
Ventromedial Prefrontal Cortex (VMPFC) Tracks Subjective Expectancy in a Gambler's Fallacy Task
Kimberly Morris1, Sean O'Bryan1, Evan Livesey2, Darell Worthy3, Tyler Davis1; 1Texas Tech University, 2University of Sydney, 3Texas A&M University
The gambler’s fallacy describes the tendency to expect an opposite outcome (e.g., tails) after a long run of another outcome (heads). Previous behavioral studies have been able to produce Gambler’s fallacy behavior in the laboratory; such that when two outcomes, outcome A, and outcome B (OA, OB) occur equally frequently, participants rate OB as more likely to occur as the run of OA increases. One outstanding question is whether this fallacious conscious expectancy taps the same Ventromedial Prefrontal Cortex (VMPFC) systems associated with choice confidence in value-based decision making and category learning. Our hypothesis was that the VMPFC would track conscious expectancies, even when they are at odds with the actual stimulus probabilities. To test this question, participants were given a categorization task were they were first asked to predict the next stimuli (face or house), and then asked to rate the likelihood of their response on a 1-7 scale. Behaviorally we found evidence of a Gambler’s fallacy where participants increased their expectations of face stimuli as the number of houses presented increased (and vice versa). This increase in expectancy was accompanied by an increase in VMPFC activation, consistent with the hypothesis that the VMPFC would track subjective confidence even when it is at odds with the objective probabilities in the task. These results bolster results from previous studies suggesting that VMPFC function may have a role in problem gambling.
Topic Area: THINKING: Decision making