Experience-based risk taking is primarily shaped by prior learning rather than by decision-making

The tendency to embrace or avoid risk varies across and within individuals, with significant consequences for economic behavior and mental health. Such variations can partially be explained by differences in the relative weights given to potential gains and losses. Applying this insight to real-life decisions, however, is complicated because such decisions are often based on prior learning experiences. Here, we ask which cognitive process-decision-making or learning-determines the weighting of gains or losses? Over 28 days, 100 participants engaged in a longitudinal decision task wherein choices were based on prior learning. Computational modeling of participants' choices revealed that changes in risk-taking are primarily explained by changes in how learning, not decisions, weight gains and losses. Moreover, inferred changes in learning manifested in participants' neural and physiological learning signals in response to outcomes. We conclude that in experience-based decisions, learning plays a primary role in governing risk-taking behavior.