A behavioral analysis of incentive prompts for motivating seat belt use.

The seat belt usage of drivers was observed at the entrance to two campus parking lots during morning arrival times. After 11 days of baseline, fliers which prompted seat belt wearing were handed to drivers of incoming vehicles. At one parking lot all fliers offered a chance to win a prize (noncontingent rewards); while at the second lot only those fliers given to seat belt wearers included a chance to win a prize (contingent rewards). After 24 consecutive observation days, these interventions were removed for 14 days of withdrawal. The recording of vehicle license plates enabled an analysis of belt usage per individual over repeated exposures to the experimental conditions. At the lot with the contingent reward intervention, mean belt usage was 26.3% during baseline, 45.7% during treatment, and 37.9% during withdrawal. At the noncontingent reward lot, the mean percentage of belt wearing was 22.2% during baseline, 24.1% during treatment, and 21.8% during withdrawal. The analysis of repeated exposures per individual verified that only contingent rewards influenced substantial increases in belt wearing, and showed that most of the influence occurred after the initial incentive prompt.