Abstract
We examine the impact of glucose in a choice task that can distinguish Bayesian from lower-level reinforcement heuristic choice. Drawing from a dual systems framework, we hypothesize that glucose administration will increase response times and improve Bayesian accuracy because it should shift decision making toward the more deliberate system 2 and away from the more automatic system 1 decision process. We study 113 subjects randomly assigned to either a glucose or placebo drink condition, who make choices in incentivized easy and difficult Bayesian task trials. Our results indicate a significant robust effect of glucose on response times. Glucose administration has a main effect of increasing response time, as predicted, and it also facilitates faster response times across trials. We do not find a direct impact of glucose administration on Bayesian accuracy, but we do estimate an impact of response times on accuracy that differs by task difficulty. This suggests an indirect impact of glucose on decision outcomes via its impact on response times.