Rewards and intrinsic motivation

Introduction

Self-determination theory predicts that an expected reward for doing an activity a person already enjoys can lower their intrinsic motivation once the reward stops (the overjustification effect). The researchers tested this prediction with a puzzle game that most teenagers find enjoyable.

Participants

96 students, ages 15 to 18 (52 girls, 44 boys), from three public high schools in suburban Minnesota. All students had rated the puzzle game as enjoyable (5 or higher on a 7-point scale) in a screening session. Parents gave written permission and each student gave assent. Students were told they could stop at any time without losing anything. The study was approved by a university institutional review board.

Method

Students were randomly assigned to two groups of 48. In the first session, the reward group was told before starting that they would earn $1 for every puzzle they solved; the no-reward group was not offered any reward. Both groups played for 20 minutes. One week later, each student came back alone and was told the researcher needed 10 minutes to set up. During those 10 minutes the student could do anything in the room: play the puzzle game, read magazines or use their phone. Free-choice play was the number of seconds, out of 600, the student spent playing the puzzle game, recorded by a hidden timer. After the session, students were told about the timer and the purpose of the study, and given the chance to have their data removed.

Results

In the first session, the two groups solved a similar number of puzzles. In the free-choice period one week later, the reward group spent a mean of 182 seconds playing the game and the no-reward group a mean of 311 seconds. The difference was statistically significant ($p < .05$).

Discussion

The researchers concluded that the expected reward reduced students' later free-choice interest in an activity they had enjoyed, as self-determination theory predicts. They noted that the study used one game and one kind of reward.

Invented study for practice.