Do rewards change behavior?

Introduction: Researchers tested whether a classroom point system would increase homework completion.

Participants: 102 sixth-grade students (52 girls and 50 boys) in four classes at one middle school in Ohio took part with parental consent and student assent.

Method: Two of the four classes were randomly selected to use a point system for 8 weeks; the other two classes continued as usual. In the point-system classes, students earned 1 point for each completed homework assignment and could trade 10 points for 15 minutes of free time or a small school-supply prize. Researchers recorded the percentage of homework assignments completed for 4 weeks before the program, during the 8-week program, and for 4 weeks after the points stopped.

Results and Discussion: During the program, the point-system classes completed significantly more homework than the comparison classes (see the table). After the points stopped, their completion rate fell but stayed above its level before the program.

Introduction: Researchers studied whether rewarding children for an activity they already enjoy changes how often they choose it later.

Participants: 72 children aged 3 to 5 at two preschools on a university campus who, during two weeks of observation, spent at least 10% of their free-play time drawing. Parents gave consent.

Method: Children were randomly assigned to one of three conditions. In the expected-reward condition, children were told they would get a 'Good Artist' certificate with a gold star if they drew pictures, and then received it. In the unexpected-reward condition, children drew pictures and then received the same certificate as a surprise. In the no-reward condition, children drew pictures and received nothing. Two weeks later, observers who did not know each child's condition recorded the percentage of free-play time each child spent drawing.

Results and Discussion: Only the expected-reward group showed a significant drop in the time it spent drawing.

Introduction: Researchers tested whether the pattern in which rewards are given affects how long a new exercise habit lasts once the rewards stop.

Participants: 180 adults aged 25 to 60 (60% women) who exercised less than once a week signed up for a 12-week study through a fitness app.

Method: During weeks 1 to 6, participants earned app points, which could be exchanged for gift cards, for logging a 30-minute workout confirmed by a fitness tracker. Participants were randomly assigned to one of two groups. The every-workout group earned points after every logged workout. The unpredictable group earned points after a randomly chosen one-third of workouts, on average, and received three times as many points each time, so both groups could earn the same total. During weeks 7 to 12, no points were given. The app recorded the number of workouts per week.

Results and Discussion: Before the study, participants averaged 0.6 workouts per week. During weeks 1 to 6, both groups worked out about equally often (3.1 versus 2.9 workouts per week). During weeks 7 to 12, the every-workout group averaged 1.2 workouts per week, while the unpredictable group averaged 2.3.