The web is awash with freely offered user generated content, with people seemingly all too happy to contribute photos, videos, Wikipedia articles, blogs and so on, never once expecting financial compensation for their efforts.

So what motivates them to do so?  New research by a couple of economists attempts to shed light on the issue.

Abstract

The literature on the private provision of public goods suggests an inverse relationship between incentives to contribute and group size. We find, however, that after an exogenous reduction of group size at Chinese Wikipedia, the nonblocked contributors decrease their contributions by 42.8% on average. We attribute the cause to social effects: Contributors receive social benefits that increase with both the amount of their contributions and group size, and the shrinking group size weakens these social benefits. Consistent with our explanation, we find that the more contributors value social benefits, the more they reduce their contributions after the block.

Popularity breeds popularity

So essentially what they found is that people are much more likely to contribute content if there is a strong chance that a lot of people will consume it.  This contrasts with traditional economic theory that suggests that the larger the group, the greater number of ‘free riders’ exploiting the system.

So there you go.  If you want lots of people contributing content to your website, make sure they are given lots of attention.