This morning NPR reported on an experiment by French traffic cops
Instead of scanning the road for bad drivers, traffic police in one town south of Paris, are looking for drivers who are obeying the rules of the road. They’re pulling over good drivers at random, and handing them gas vouchers worth more than $60.
People respond to incentives but they respond more to disincentives or negative incentives. According to Prospect Theory the satisfaction from a gain of $60 gas voucher is not as intense as the pain from losing $60 (or more) to traffic tickets. Besides, I am not sure who would enjoy being pulled over even if it is for being presented with a gift for obeying traffic rules.
When it comes to changing behaviors sticks are better nudges than carrots.
Here is another study on the effect of Stick vs. Carrot reported in today’s WSJ that validates the power of sticks over carrots:
Our main findings are that reemployment bonuses don’t seem to have worked, while benefit sanctions increased the job finding rate significantly,” the economists write.