He read from "Leaves of Grass," and then asked his students the following:
◦1/2 of the students were asked if they would be willing to pay Ariely $10 for a 10-minute poetry recitation
◦1/2 of the students were asked if they would be willing to listen to a 10-minute poetry recitation if Ariely paid them $10
◦The students who were asked if they were willing to pay offered $1 for a short reading, $2 for a medium reading, and $3 for a long reading.
◦The students who were asked if they'd accept pay demanded $1.30 for a short reading, $2.70 for a medium reading, and $4.80 for a long reading.
If you try to prevent people from doing something, it creates a "forbidden fruit" effect that makes them want to do it more. If you try to reward people for doing something, it makes them think it's not worth doing by itself, and that the "reward" is what they really want.