03/22/2010 05:12 am ET Updated May 25, 2011

Happiness = Giving/Getting

Dunn and her colleagues found that the higher the percentage of their windfall workers spent on others, the happier they were, an effect that still existed when statistically controlling for relevant variables such prior happiness, income amount, and bonus size. What's more, the data revealed that how the employees spent their money was a better predictor of their happiness than the size of the bonus itself.

For more, see this article by Noah Goldstein over on Bob Cialdini's website.