Date of Award


Degree Type


Degree Name

Doctor of Philosophy in Psychology


Behavioral Science



First Advisor

Lyn Stein


Objective: Twenty-first birthdays are associated with extreme levels of heavy drinking and alcohol-related harm. However, few 21st birthday preventive interventions have been tested, and even fewer have been supported as effective. The current study was designed to 1) test a text-message intervention to reduce 21st birthday estimated Blood Alcohol Content (eBAC) and alcohol problems, and 2) examine potential mediators and moderators.

Method: College students (n=200; 69% female, 87.5% White/Caucasian) with an upcoming 21st birthday completed a baseline assessment and were randomized to a text-message intervention or an assessment-only control condition. Participants in the intervention group were sent, and were asked to reply to, a text-message the day before and day of their planned 21st birthday celebration focusing on 21st birthday specific personalized normative feedback (PNF) and protective behavioral strategies (PBS), respectively. All participants were sent a follow-up assessment the day after their birthday celebration (92.9% retention rate).

Results: Among participants in the intervention group, 95.8% responded to text-message 1, and 95.8% responded to text-message 2. Regression analyses did not reveal an overall treatment effect for eBAC or alcohol problems. However, there were indirect effects with perceived norms as the mediator and eBAC (-.175 [SE=.060]; 95% CI [-.292, -.080]) and alcohol problems (-.124[SE=.044]; 95% CI [-.245, -.057]) as the outcome such that the intervention was associated with lower perceived norms, which was, in turn, related to less alcohol involvement.

Conclusions: Although no main effect of treatment was observed, this study provides further evidence that changing perceived norms is a promising strategy for preventive interventions with event-level alcohol use.



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