Ward Edwards was the founder of behavioral decision theory. Working at the University of Michigan and later USC, he introduced Bayesian probability and subjective expected utility to psychologists, created the experimental paradigms that launched decision research, and trained researchers who developed prospect theory and other landmark contributions.
Bayesian Decision Making in Psychology
Posterior odds = Likelihood ratio x Prior odds
Edwards' 1954 paper introduced expected utility theory and subjective probability to psychology, arguing that normative models serve as benchmarks for evaluating human judgment. His bookbag-and-poker-chip experiments revealed conservatism: people update beliefs in the correct direction but insufficiently, extracting only about half the information Bayes' theorem prescribes.
Edwards' 1954 and 1961 review papers defined a new field by synthesizing subjective probability, utility theory, and empirical findings on human judgment. These directly inspired Tversky, Kahneman, Slovic, and Lichtenstein.
Applied Decision Analysis
Edwards developed SMART (Simple Multi-Attribute Rating Technique) for practical multi-attribute decisions and championed Bayesian methods in clinical, military, and policy settings, bridging normative theory and practical application.
Legacy and Impact
Edwards' insistence that normative models are necessary as benchmarks -- not because people follow them, but because deviations are informative -- established the methodological template that decision research follows to this day.