The mystery of the missing long-term harm from incentives.

[3d post in a series; start with the first post here]

I’ve been talking about research on incentives, and how a temporary incentive might undermine intrinsic motivation. In the last post, we heard from educational policy advocate Alfie Kohn on his prediction that paying kids to do schoolwork would backfire, particularly when the incentive ended.

Perhaps the most comprehensive experiments to test these ideas in a real-world setting were done by Roland Fryer, as reported in his 2011 paper. He describes his research on education in the video below (fascinating throughout, but the student incentives discussion runs from around 17:00-24:00):

Overall, his results suggest little effect, positive or negative, of paying schoolchildren for their performance (e.g., for getting high test scores). However, he also conducted two large-scale randomized in-school trials that instead tested rewards for their efforts, for the underlying behaviors that could foster success in school. In Dallas, second-graders randomly assigned to the treatment condition were paid $2 for each book they read and passed a quiz on.  In Washington D.C., sixth through eighth graders in the treatment condition were paid for other educational inputs, including attendance, school behavior and handing in homework.

Paying kids to read books yielded a significant improvement in the Dallas students’ reading comprehension, a marginal improvement in their language scores and a positive but insignificant effect on vocabulary scores. In Washington D.C., the incentives yielded a marginal improvement in reading and a non-significant improvement in math.

The key question is what happened when the incentive program ended?  The psychological theories we’ve been discussing would predict that the kids would be worse off. Having lost their own motivation to engage in the behaviors and no longer having the external tangible incentive, motivation would be reduced, harming outcomes.  Instead, Fryer found that the positive effects were reduced by half and were no longer statistically significant after the reward ended.

To put it another way, the benefits do seem to fade when the incentive ends, but there is no evidence that the outcomes are worse than if the incentive had not been offered in the first place. This is not an isolated finding.  Three other studies with older students (high school: Jackson 2010, college: Angrist et al 2009 and Garbarino & Slonim, 2005) actually find (some) positive effects of education incentives that significantly persisted after the incentive has ended.

In his dissertation, Indranil Goswami reviewed 18 field studies across a variety of domains (including education, smoking cessation, weight loss, gym attendance, medical adherence and work productivity).  These studies all measured people’s total behavior in a period after the incentive had ended and found either no long-term effect or a modest positive effect. Not a single study found that people had worse outcomes when an incentive was offered and then ended, than if the incentive had never happened.

So where was the long-term harm that the predicted loss of intrinsic motivation from the incentive would have caused?


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