Writing in the Journal of Personality and Social Psychology in 1975, Len Sushinsky and I suggested that the so-called undermining of material rewards on intrinsic motivation was just a distraction effect of novel rewards. Now 35 years later, I would like to suggest we were right.
The evidence for undermining is almost entirely limited to the study of novel rewards. In other words, the participants in studies on intrinsic-extrinsic motivation receive only one trial of reward. One. Not even two, just one. The researchers then assume that the effects of novel rewards can be projected to long term uses of reward, such as grades in schools or pay for industrial workers. But is that assumption true? Are there students who only get one grade in their life? Are their workers who get only one paycheck in their life? No, there aren't. So I ask, "Are the effects of novel rewards the same as the effects of rewards used for a long period of time?"
Suppose that we were to conduct research on drugs, say, major tranquilizer medications. In our studies we give just one pill. That's it -- just one pill. Then we draw conclusions about the long terms effects of the drug. If we were to operate like that, we would conclude that long-term use of tranquilizers is safe. We would be mistaken, however, because long-term use can cause the very serious side effect of tardive dyskensia that isn't caused by a single pill never repeated.
Scientists don't assume that the effects of a single trial of a treatment can be projected out to the long term. Many social psychologists make this assumption, but scientists don't. Since the literature demonstrating undermining is almost entirely (95 percent or more) based on single trial reward studies, we really have to conclude that this literature is inadequate and cannot say anything about real-world, long terms rewards such as grades and pay.
Novel rewards are distracting. Think of your first pay check or a child's first report card. The excitement and reactions of the "first" fade over time. When a novel reward is given for performance of an activity, the reward can have a minor undermining effect because of distraction. Of course, distraction is less likely as the novelty wears off.
Edward Deci responded to my criticism by suggesting that I need to present evidence that distraction can cause undermining. I would dispute this; I think researchers need to study long term effects before they can draw conclusions about the long term. In any event, there are two published studies showing that distraction from novel rewards can cause undermining: One by Len Sushinshy and me, and the other by Pitman. Both of these studies appear in articles Deci has cited, so he should know that there are replicated data on distraction, and researchers should have controlled for this possibility in their studies.
