De Bruijn, G. J., Visscher, I., & Mollen, S. (2015), Effects of previous fruit intake, descriptive majority norms, and message framing on fruit intake intentions and behaviors in Dutch adults across a 1-week period. Journal of Nutrition Education and Behavior, 47(3), 234-241. doi:10.1016/j.jneb.2015.02.001.

Objective: To test the effects of descriptive norm and message framing on fruit intake (intentions) in Dutch adults.
Design: Randomized pretest-posttest study using a 2 × 2 design.
Setting: Internet-based.
Participants: Dutch adults recruited via leaflets and announcements on intranet and Internet and who provided immediate intention (n = 294) and 1-week follow-up intention and fruit intake data (n = 177).
Intervention: Messages combining information on intake of others (low vs high intake) with information about positive or negative outcomes of (in)sufficient fruit intake.MAIN Outcome Measures: Fruit intake intentions and fruit intake.
Analyses: Analyses of covariance.
Results: Those already consuming sufficient fruit and receiving negative information about insufficient fruit intake increased their motivation to consume sufficient fruit immediately (P = .03), but not at 1-week follow-up. Those who read positive information about sufficient fruit intake reported higher fruit consumption than those who read negative information about insufficient fruit intake (P = .03). This was stronger in those already consuming sufficient fruit. There were no effects of descriptive norm information (P > .19).
Conclusion and Implications: Information about outcomes was more persuasive than descriptive majority norm information. Effects were generally stronger in those already consuming sufficient fruit.

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