Forty years ago, prospect theory introduced the notion that risky options are evaluated relative to their recent context, causing a significant shift in the study of risky monetary decision-making in psychology, economics, and neuroscience. Despite the central role of past experiences, it remains unclear whether, how, and how much past experiences quantitatively influence risky monetary choices moment-tomoment in a nominally learning-free setting. We analyzed a large dataset of risky monetary choices with trial-by-trial feedback to quantify how past experiences, or recent events, influence risky choice behavior and the underlying processes. We found larger recent outcomes both negatively influence subsequent risk-taking and positively influence the weight put on potential losses. Using a hierarchical Bayesian framework to fit a modified version of prospect theory, we demonstrated that the same risks will be evaluated differently given different past experiences. The computations underlying risky decision-making are fundamentally dynamic, even if the environment is not. Prospect theory is conceivably the most successful recent theory in risky decision-making 1. The theory is founded on the idea that people evaluate options relative to "the past and present context of experience" (p. 277) 1. While this central insight led to two of the most successful components of prospect theory, the reflection effect in risk aversion (diminishing marginal utility of values expressed as concavity for gains and convexity for losses) and loss aversion (overweighting losses compared to gains of the same magnitude), it is unclear how recent events quantitatively influence risky monetary decision-making, moment-to-moment. We sought to quantify how recent events (e.g. previous outcomes) influence choices by analyzing a large dataset of risky choices in the presence of feedback compiled from four studies 2-5. Laboratory and field studies have suggested that recent events shape the subjective value of risky choice options 6-9 and actions 10. The directionality and mechanism supporting these effects are unclear as some studies of risky decision-making in the presence of feedback have found that previous gains, relative to losses, lead to less risk-taking 6,10 or a mixture of less and more risk-taking 7-9,11 , discrepancies that may be related to how and when outcomes are realized, or paid 12. Theories that have sought to specify the directionality of the effect of feedback on risky choice have not described the size of the effect, its characteristics (e.g. how far it extends in time) or the precise decision processes that would be altered by feedback 13. Interpreting these previous findings is complicated by the fact that almost all of these studies included design features intended to elicit temporal context effects (e.g. explicitly-signaled contexts, displays with cumulative elements) and thus may have strengthened, or even created, dynamic context effects. While such an approach identifies an upper bound on the possible presence and ma...