Money is the prime incentive in economic models. Recent evidence makes it clear that people are also greatly concerned about how their incomes compare with those of others, suggesting that rank may be a strong motivator as well. Three experiments in Vietnam assessed whether students in real-world learning environments were concerned with their performance rankings. The results showed that concern with rank, even when rankings were not publicly revealed, strongly motivated performance on academic tests. Moreover, rank was able to outweigh money as a motivator.
Tran, Anh, and Richard Zeckhauser. "Rank as an Incentive." HKS Faculty Research Working Paper Series RWP09-019, July 2009.