Classic research Edward Deci (1971): the undermining effect of rewards on intrinsic motivation

If you had to point out one starting point in the development of self-determination theory, it should probably be Edward Deci's classic research into intrinsic motivation. He published that study in 1971, and it was the first major publication in a large series of publications that would follow from Ed Deci and Richard Ryan and an ever-expanding network of researchers. Here you can read a brief description of that study.

1960s: Intrinsic motivation became popular

In the 1960s, the concept of intrinsic motivation became well established, partly through the book The Human side of enterprise by Douglas McGregor (1960). In short, intrinsic motivation implies the following. An activity is intrinsically motivated when the activity is seen as its own goal (and extrinsic when the activity serves to achieve another separate goal). In practical terms, this means that you are doing the activity because you like it or find it interesting and not because you want to achieve anything specific with it.

Many people recognized the importance of intrinsic motivation and believed that incentives should be given to people to motivate them for work for which they were intrinsically motivated. In 1971, Ed Deci wanted to investigate whether this was an effective strategy. He was curious about what would happen when people were rewarded for doing something they find interesting such as a sport or a hobby (Deci, 1971; 1975).

Deci's research: rewards can undermine intrinsic motivation

Deci conducted a study in three steps. In the first step, he let students solve so-called SOMA cubes. In this part of the study, the students indicated that they really liked the puzzles. In the second part of the study, he let one part of the students just do the puzzles. He told another part of the group that for every puzzle they solved, they would receive a financial reward of a few dollars.

The Free choice period

The third part of the study consisted of a so-called free choice period. Such a free choice period has become an important technique in the investigation of intrinsic motivation. It includes the following. During the research, the researcher leaves the research room with an excuse so that the participants are left alone. He says they can choose for themselves what they would like to do. For example, they could continue with the activity (in this case the SOMA puzzles) or do something else. 

While the researcher is away, the participants assume that they are not being observed, nor do they expect to be judged or rewarded. So if they continue with the activity, they are doing it out of interest or enjoyment. The amount of time they spend on the task during this free-choice period is therefore an indication of their intrinsic motivation.

The undermining effect

What Deci found was that the students who had been rewarded for doing the puzzles during the second part, continued to do the puzzles to a lesser extent during the third part than the students who were not rewarded. Also noteworthy: Deci saw that the students who were paid to do the puzzles performed less well. Rewards had undermined their intrinsic motivation and performance.

Shift from IPLOC to EPLOC

What this research showed is something that has been proven many times in research by now. By giving the reward, the students' attention shifted from their intrinsic reason (their interest) of doing the puzzles to an extrinsic reason (the reward). Their perception of what they were doing shifted from “I do this because I find it interesting” to “I do this because I get rewarded for it, not because I find it interesting”. 

Within self-determination theory, this shift is called a shift from an internal perceived locus of causality (IPLOC) to an external perceived locus of causality (EPLOC). As soon as the external reason disappeared (during the free-choice period), the reason for doing the activity disappeared and they stopped.

Other factors that can influence intrinsic motivation

A lot of follow-up research has since been done that has shown that certain things can reduce intrinsic motivation such as:
  1. the use of threats (Deci & Cascio, 1972)
  2. deadlines (Amabile et al., 1976)
  3. assessments (Amabile, 1979)
  4. internal competition (Deci et al., 1981)
  5. supervision (Lepper & Greene, 1975)
At the same time, other things actually promote intrinsic motivation such as:
  1. giving freedom of choice (Zuckerman et al. 1978)
  2. feeling competent (Dysvyk et al., 2013)
  3. receiving behavioral positive feedback (Henderlong & Lepper, 2002)
  4. acknowledging emotions (Koestner et al., 1984).

Not all rewards undermine intrinsic motivation

Incidentally, unexpected rewards, such as a bonus for good performance which is not agreed to in advance, will generally not undermine intrinsic motivation. Rewards undermine intrinsic motivation only if the rewarded person knows that the reward will be there and experiences it as the reason why he does the task (Deci et al., 1999).