Incentives and Unintended Consequences: Spillover Effects in Food Choice

Little is known about how peers influence the impact of incentives. We study how peers’ actions and incentives can lead to peer spillover effects. Using a field experiment on snack choice in the school lunchroom (choice of grapes versus cookies), we randomize who receives incentives, the fraction of peers incentivized, and whether or not it can be observed that peers’ choices are incentivized. We show that, while peers’ actions of picking grapes have a positive spillover effect on children’s take-up of grapes, seeing that peers are incentivized to pick grapes has a negative spillover effect on take-up. When incentivized choices are public, incentivizing all children to pick grapes, relative to incentivizing none, has no statistically significant effect on take-up, as the negative spillover offsets the positive impacts of incentives. (JEL C93, D12, I21, J13)