While Kahneman and Tversky provided the early psychological theories that would be the foundation for behavioral finance, this field would not have evolved if it weren't for economist Richard Thaler.
During his studies, Thaler became more and more aware of the shortcomings in conventional economic theoryies as they relate to people's behaviors. After reading a draft version of Kahneman and Tversky's work on prospect theory, Thaler realized that, unlike conventional economic theory, psychological theory could account for the irrationality in behaviors.
Thaler went on to collaborate with Kahneman and Tversky, blending economics and finance with psychology to present concepts, such as mental accounting, the endowment effect and other biases.