In all tested complex tasks, as the amount of information increases, the user's confidence increases, but their accuracy quickly deteriorates.
"In fact, simplicity or singleness of approach is a greatly underestimated factor of market success."
This book, written in 1982, is surprisingly well conceived and laid out. But when he makes probability calculation errors, you start to question the validity of the statistics he's done (7 choose 6 =? 1 on page 99; there are 2 kinds of stocks, good and bad, so your odds of picking a good stock =? 1/2 on page 109).
This book actually just needs a good financially-inclined editor and updating for a new second edition. It does a great job for a 1982 text on behavioral economics and its impact on finance, and analyses of various methods of choosing companies to invest in.
"When the dependence on physical reality is low, the dependence on social reality is correspondingly high."