Katie Milkman is a professor at the Wharton School of the University of Pennsylvania. Her research finds that when groups work together on a project, a number of factors collude to form the planning fallacy. Overconfidence makes us feel better about ourselves and we're often rewarded for it. We put off doing things we know we should do in favor of what's instantly gratifying. Information overload is thought to decrease US productivity by $1 trillion a year.