Evidence Accumulation in Rumination: the Role of Uncertainty in Information-Seeking Behavior

Abstract

Rumination is a common symptom of depression involving repetitive, self-focused thoughts of negative valence. Past studies have hypothesized that the repeated sampling of events during rumination may function to achieve certainty about the consequences of potential future actions. Here, we test the predictions of a computational model of this theory with an online information-seeking task. Using a modified version of the ‘beads task’ (Phillips & Edwards, 1966), we investigated whether increased information seeking (i.e., increased draws-to-decision) is associated with the severity of rumination symptoms, as determined by responses to a battery of self-report questionnaires. In our task, participants (n = 73) had to choose between two actions (each of which led to either reward or loss) or sample more information (which may increase knowledge of which choice would lead to reward). We hypothesized that increasing perceptual overlap between the distributions (i.e., making it unclear if the stimulus was from the distribution that would require action 1 or the distribution that would require action 2) would increase draws-to-decision to resolve the ambiguity of the current distribution. We further predicted more draws-to-decision in individuals who are high-trait ruminators. Our model-based analysis demonstrated a relationship between depression score and decision threshold. We found that participants with higher depression scores exhibit less of a difference between medium and low uncertainty condition decision thresholds. This result suggests that more depressed participants required a higher degree of certainty before making a choice, possibly due to perceiving the samples as more ambiguous.