In an experiment out of Harvard Business School by Michael Norton and Elizabeth Dunn, people were randomly approached and given either $5 or $20 to spend by the end of the day. Half were instructed to spend the money on themselves (personal spending) and half to spend the money on someone else (prosocial spending).
That evening, people who had been assigned to spend the money on someone else reported happier moods over the course of the day than did those people assigned to spend the money on themselves. The amount of money the participants received had no bearing on their happiness. See a TEDx Talk by Michael Norton below.
