I am convinced that if an investor has a basic understanding of psychology they will be better investors. The following is a number of the best psychology resources that I have read recently.
Stanford Prison Experiment: "A Simulation Study of the Psychology of Imprisonment Conducted at Stanford University: What happens when you put good people in an evil place? Does humanity win over evil, or does evil triumph? These are some of the questions we posed in this dramatic simulation of prison life conducted in the summer of 1971 at Stanford University."
Born Suckers: The greatest Wall Street danger of all: you. by By Henry Blodget
"Human beings, it turns out, are wired to make dumb investing mistakes. What's more, we are wired not to learn from them, but to make them again and again. If there is consolation, it is that it's not our fault. We are born suckers."
Influence: The Psychology of Persuasion by Robert B. Cialdini
Psychology of Intelligence Analysis
THE PSYCHOLOGY OF HUMAN MISJUDGMENT by Charlie Munger
The Expert Mind
"Studies of the mental processes of chess grandmasters have revealed clues to how people become experts in other fields as well."