Barbara Mellers does research on judgment and decision making. For years, she explored models of when and why we violate principles of rationality. She has investigated what underlies our perceptions of fairness, why our emotions influence choices, and how seemingly unimportant variables, such as the context around a stimulus and the phrasing of a question, can shape judgments and choice. Currently, she investigates methods for improving the accuracy of human forecasts. By examining hundreds of questions and millions of forecasts, she and her colleagues have discovered how to make human forecasts surprisingly more accurate. The secret lies in using relatively simple behavioral and statistical interventions. Mellers also studies nudges, choice environments, and behavioral interventions that result in better decisions.