A new psychology study helps explain why some stars burn bright, long, long after their talent has faded – if it ever was there to begin with.

Simply put, says Nathanael Fast of Stanford University in California, people need something to talk about. The human desire to find common ground in conversation pushes us to discuss already popular people, he says.

Many economists have argued that in the market of popular culture, quality marks the difference between popularity and obscurity. For instance, a 1991 study by William Hamlen Jr of the University at Buffalo, New York,found that an objective measure of vocal harmony predicted album sales, with Barbara Streisand coming out on top in both measures.

Volunteers who were baseball fans themselves tended to pick an obscure player if they thought they were emailing an expert. Yet the same fans tended to converse about prominent players when they didn't know anything about their correspondent.