
Studies indicate that spending money on others is one of the best ways to increase your own happiness. I don't have references handy, but check out the book "Happy Money: The Science of Smarter Spending." That is loaded with references to studies that support that claim.
The claim I made is broad, so it's not based on one experiment, but on numerous factors that point in the same direction. We are social creatures, and feeling like we are a part of a greater whole makes people happier. In the recent book Happy Money, the authors, two Ph.D. researchers in the area, describe experiments that indicate that spending money on others promotes happiness. Of the three components of Self-Determination Theory, one is "Relatedness", feeling connected with and caring others (contributing to a bigger whole). I'm happy to share more.
