It's been the refrain of behavioral economists and, in my case at least, my wise husband for years: Spend your money on experiences, not things. A vacation or a meal with friends will enrich your life; new shoes will quickly lose their charm.

That's true, but it's not the whole story, argue psychologists Darwin A. Guevarra and Ryan T. Howell in a new paper in the Journal of Consumer Psychology. Not all goods, they say, should be lumped together.

Here's the problem, as Guevarra and Howell see it: In many studies, participants are asked to think about material items as purchases made "in order to have," in contrast with experiences—purchases made "in order to do." This, they say, neglects a category of goods: those made in order to have experiences, such as electronics, musical instruments, and sports and outdoors gear. Do such "experiential goods," as Guevarra and Howell call them, leave our well-being unimproved, as is the case with most goods, or do they contribute positively to our happiness?

In a series of experiments, Guevarra and Howell find that the latter is the case: experiential goods made people happier, just like the experiences themselves.

This might seem like a pedantic distinction, just a breaking down of two categories of purchases (goods and experiences) into three (pure goods, experiences, and the goods that enable you to have those experiences). But there is more to it: Understanding why some things make people happy and others don't reveals a little bit about the mechanics of human happiness and how to cultivate it.