It's heartbreaking to see a hero crossover from the land of purity and innocence to the dark side. Behavioral finance, like the Force, has both a good side and a dark side. We can use behavioral studies to at least explain why people make bad decisions if not to help them make better decisions (the good side). Unfortunately, we can use those same studies to learn how to manipulate people (the dark side).

I don't know if it's the low pay of the academic research profession or what, but it's not unusual to see a researcher known for using his work to defend the masses suddenly switch to using his work for the benefit of those intent on taking advantage of the masses. If you want to see how this happens, just read this review of Robert Cialdini's Yes! 50 Scientifically Proven Ways to Be Persuasive and contrast it to this review of Cialdini's earlier book, Influence: The Psychology of Persuasion. Cialdini's Influence, published in 1984, emphasizes how the reader can defend against behavioral trickery, while Yes! shows the reader how to use behavioral techniques to attack the unsuspecting.

In the end, the sales and marketing lessons of Cialdini aren't too far removed from the world of investing and, specifically, the 401(k) environment. For years, smart fiduciaries have followed the now decades-old studies of Shlomo Benartzi and Richard Thaler. Their research, from naïve diversification strategies to myopic loss aversion have helped 401(k) plan sponsors create investment policy statements and frame the options within their plans to help employees make better investment decisions.