Do You Like What You Like Because You Like What I Like?

An experiment:

• Have a large group of people rate songs they’ve never heard before. Each person listens and rates privately so no one knows what others have done. If a person likes a song, he or she can download it. Call this group the “independent group.”
• Now have another large group of people do the same thing with the same songs, except members of this group can see how popular the songs are with others. Call it the “social-influence” group.
• Split the social-influence group into eight subgroups (“worlds”). Every world has the same songs, but a song’s popularity is counted only within that world. Thus, the social-influence group is split into eight parallel popularity contests.

The 4/15/2007 New York Times Magazine had a piece by Duncan Watts, professor of sociology at Columbia University, about this experiment. It was conducted via the Web with more than 14,000 participants. Professor Watts’ summary of the expectations and results follows.

First, if people know what they like regardless of what they think other people like, the most successful songs should draw about the same amount of the total market share in both the independent and social-influence conditions—that is, hits shouldn’t be any bigger just because the people downloading them know what other people downloaded. And second, the very same songs—the “best” ones—should become hits in all [eight] social-influence worlds.

What we found, however, was exactly the opposite. In all the social-influence worlds, the most popular songs were much more popular (and the least popular songs were less popular) than in the independent condition. At the same time, however, the particular songs that became hits were different in different worlds....

So does a listener’s own independent reaction to a song count for anything? In fact, intrinsic “quality,” which we measured in terms of a song’s popularity in the independent condition, did help to explain success in the social-influence condition. When we added up downloads across all eight social-influence worlds, “good” songs had higher market share, on average, than “bad” ones. But the impact of a listener’s own reactions is easily overwhelmed by his or her reactions to others. The song “Lockdown,” by 52metro, for example, ranked 26th out of 48 in quality; yet it was the No. 1 song in one social-influence world, and 40th in another. Overall, a song in the Top 5 in terms of quality had only a 50 percent chance of finishing in the Top 5 of success.

And why did this happen?

[W]hen people tend to like what other people like, differences in popularity are subject to what is called “cumulative advantage,” or the “rich get richer” effect. This means that if one object happens to be slightly more popular than another at just the right point, it will tend to become more popular still. As a result, even tiny, random fluctuations can blow up, generating potentially enormous long-run differences among even indistinguishable competitors—a phenomenon that is similar in some ways to the famous “butterfly effect” from chaos theory. Thus, if history were to be somehow rerun many times, seemingly identical universes with the same set of competitors and the same overall market tastes would quickly generate different winners: Madonna would have been popular in this world, but in some other version of history, she would be a nobody, and someone we have never heard of would be in her place.

I’ve quoted at length because I think it’s an ingenious and compelling experiment, well explained by Professor Watts. Although we all intuitively know the bandwagon effect, this experiment quantifies its importance in judging unfamiliar music. In this context, the results suggest we—the notorious average “we”—are quick to let what’s popular tell us what’s good.