he idea that we compensate for insecurity or low self-esteem with our checkbook is so widely accepted that it's a cultural cliché: Why else would we consider a middle-aged man in a Ferrari to be a midlife crisis on wheels?

Now there is empirical evidence of the link between self-doubt and materialism.

Robert Arkin, Ph.D., of Ohio State University, found that undergraduate students who identified themselves as chronic self-doubters were far more likely to agree with statements such as "I like to own things that impress people," and "The things I own say a lot about how well I'm doing in life." A second study found that increasing a sense of self-doubt heightened the materialistic tendencies of subjects already prone to insecurity.

"Self-doubt is very unpleasant, so people cope by investing themselves in something. Materialism is one such investment," says Arkin. The results, published in Psychology and Marketing, also link materialism to a sense of anomie or uncertainty about one's place in society (as opposed to doubt about one's own abilities or identity). In both cases, the Ferrari is a poor buffer: Arkin points out that psychological tests repeatedly link a materialistic worldview to lower levels of life satisfaction.