Vote-buying and reciprocity

"While vote-buying is common, little is known about how politicians determine who to target. We argue that vote-buying can be sustained by an internalized norm of reciprocity. Receiving money engenders feelings of obligation. Combining survey data on vote-buying with an experiment-based measure of reciprocity, we show that politicians target reciprocal individuals. Overall, our findings highlight the importance of social preferences in determining political behavior"--National Bureau of Economic Research web site.