Date of Award:


Document Type:


Degree Name:

Master of Science (MS)


Nutrition, Dietetics, and Food Sciences


Heidi J. Wengreen


During college, students establish nutritional habits that may last a lifetime. Fruit and vegetable consumption often decreases during the first few years of college and the vast majority of college-­‐aged students are not meeting current recommendations. Social norms theory has been shown to be an effective method for influencing behaviors in this population. This study was designed to test whether or not providing students with normative and manipulated social norms feedback could influence fruit and vegetable intakes among college-­‐aged students as evidenced by changes in skin carotenoid levels and food frequency questionnaire reports.

Participants (n=244) were randomly assigned to a control group or given either normative feedback or manipulated social norms feedback regarding their skin carotenoid levels in comparison to their peers, with carotenoid levels being an objective measurement of fruit and vegetable intake. Those receiving manipulated feedback were given an artificially low carotenoid score implying that peer consumption was greater than their own.

Results indicated no significant within-­‐participant changes in fruit and vegetable intakes reported in the FFQ (P=.635). While there was no change in the control groups skin carotenoid levels (P=.996), there was a borderline significant increase among those receiving normative feedback (P=.066) and a significant increase among those receiving manipulated social norms feedback (P<.001). Repeated measures of analysis showed that within-­‐participant increases in carotenoid scores were dependent on group assignment (P=.033) with an effect size of η2p=.026 which according to Cohen’s guideline is a small effect size. The distribution of carotenoid scores and FFQ results were approximately normal. Comparisons between FFQ results and skin carotenoid levels found Pearson correlation coefficients of .301 (P<.001) and other positive correlations were found between skin carotenoid levels and both exercise and BMI (.111, P=.049; -­‐.253, P<.001).

The results of this study suggest that manipulated social norms feedback can increase skin carotenoid levels. The observed increases may indicate higher carotenoid containing fruit and vegetable consumption. These findings imply that social norms feedback may potentially be used as a strategy to promote and influence greater fruit and vegetable consumption among college students.



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