Early Life Stress Affects Human Decision Making by Increasing Expectations of Volatility.

People learn most effectively when they can flexibly modify strategies to accommodate environmental changes. Here, we explore how chronic early life stress influences the ways individuals weight and prioritize new information when making decisions. To do so, we examined the choices of 11-16-year-old children in a reward learning task. Children varied on their level of stress exposure. We used a Bayesian computational learning model to assess whether differences in children's decision making were driven by difference in their expectations about the task environment. Children with high stress exposure switched their responses rather than maintaining choices that had previously been effective for them when making decisions about rewards. This switching was driven by children with high stress exposure expecting environments to be more volatile. These findings offer insight into how early life experiences can shape the subsequent parameters of human learning. SUMMARY: How experience shapes an individual's ability to flexibly adjust learning strategies when making decisions is not well understood. Using behavioral tasks combined with a novel computational model, we find exposure to high stress environments biases children towards learning strategies optimal to unpredictable environments. Stress in childhood shapes the development of learning parameters in ways that have implications for decision making.