Monetary Incentive Interventions Can Enhance Psychological Factors Related to Fruit and Vegetable Consumption
Incentive interventions have gained popularity to motivate health behavior change, but some psychological theorists caution that they may have deleterious effects on factors that potentiate behavior maintenance. Importantly, no empirical study has tested whether incentives indeed have iatrogenic effects on key psychological constructs associated with health behavior change and maintenance.
The study aims to explore the effects of monetary incentives on theoretically informed psychological constructs and fruit and vegetable consumption.
Individuals reporting insufficient fruit and vegetable consumption were randomly assigned to receive either daily monetary incentives, delayed monetary incentives, or no incentives for their fruit and vegetable consumption during a 3-week intervention period. Behavior engagement and psychological factors were measured at baseline, at the end of the intervention, and 2 weeks following the cessation of the intervention.
Participants in the daily incentive condition demonstrated the greatest increase in self-reported consumption during the intervention and at the follow-up. Moreover, increases in consumption during the intervention period were associated with increases in attitudes and self-efficacy, which, in turn, predicted behavior maintenance at follow-up. Intrinsic motivation to consume fruits and vegetables increased over time across the entire sample but did not differ between groups.
Monetary incentives can alter health behavior engagement without decreasing intrinsic motivation or other relevant cognitive and motivational constructs. Further, although incentives may serve as a vehicle to initiate behavior change, increased experience with the behavior may then lead to enhancements in key psychological constructs that serve as mechanisms to potentiate behavior maintenance following the cessation of incentives.
Trial Registration Number
The trial was registered with the ClinicalTrials.gov database (NCT02594319) https://www.clinicaltrials.gov/ct2/show/NCT02594319.
KeywordsIncentives Fruits and vegetables Eating behavior Motivation Self-efficacy
This research was funded by a National Science Foundation Graduate Research Fellowship awarded to Casey K. Gardiner. Data were collected and managed in REDCap (NIH/NCRR Colorado CTSI Grant UL1 TR001082). The authors wish to acknowledge Layne Perkins and Dominique Pataroque for their assistance with data collection.
Compliance with Ethical Standards
Conflicts of Interest
Authors Casey K. Gardiner and Angela D. Bryan declare that they have no conflict of interest. All procedures, including the informed consent process, were conducted in accordance with the ethical standards of the responsible committee on human experimentation (institutional and national) and with the Helsinki Declaration of 1975, as revised in 2000.
This research was funded by a National Science Foundation Graduate Research Fellowship awarded to Casey K. Gardiner.
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