Keynes drew upon psychology in developing his economic theories, and researchers in behavioral finance have integrated psychology into the study of how investors make financial decisions. Another group of researchers, experimental economists, tested some remarks of Keynes on the psychology of economic actors in specifically designed experiments. Some research in these fields, however, has been misguided because of an inadequate understanding of Keynes's original insights. Researchers in these fields can benefit from comments by Post Keynesian economists. At the same time, they have a lot to offer Post Keynesians in developing a Post Keynesian theory of finance.