A new study suggests why sadness makes us want to buy: increased self-focus. Low moods cause us to turn inward, and as we reflect we devalue ourselves. So to enhance ourselves we buy more stuff, whether it's porcelain woodland creatures, or needlepoint woodland creatures.
The experimenters, who will present their findings this weekend at the Society for Social and Personality Psychology’s Annual Meeting, made some of their subjects watch a sappy video clip and then write a personal essay (just to amp their self-focus further). These subjects were then willing to pay three times as much for some crappy water bottle. Putting a number on what that means in the real world is tough, though: On the one hand, we don't go around writing autobiographical essays at the mall, but on the other hand we're often hit by much more grievous circumstances than having to sit in a lab and watch The Champ.
In their upcoming paper on the topic ("Misery is not Miserly" [pdf]) the researchers also offer another possible interpretation of the data (in addition to the self-enhancement theory): Maybe we just value everything else more highly in comparison to ourselves when we're down. This view fits a previous study [pdf] showing that when we're sad, we'll pay more for things but also sell things for less: Whatever the other person's got, be it Chia Pets or Benjamins, we value it more than what we have. The cash is always greener, etc.
I can see boosting the self by annexing it with possessions, but I haven't quite integrated this pay-more-when-you're-sad business with the idea of, say, manic spending sprees. I always thought people buy more crap when they're happy. I know I'm a tightwad when depressed. That's why when bookstores started selling coffee, I thought it was brilliant. But, according to the research, maybe Borders should really be installing monitors and looping Beaches.
Not that I want to encourage the compulsive shopping epidemic.