Provocative messages targeting childhood obesity are a central means to increase problem awareness. But what happens when different online media platforms take up the campaign, comment, re-contextualize, and evaluate it? Relating to preliminary findings of persuasion research, we postulate that source credibility perceptions vary across types of online media platforms and contextualization of the message. Individual characteristics, in particular weight-related factors, are assumed to influence message effects. A 3 (media type: blog, online news, Facebook) × 2 (reinforcement versus impairment context) experimental design with students (N = 749) aged between 13 and 18 years was conducted. Results show an interaction between media type and argumentation for affective self-perceptions of weight. Self-relevance varies based on different source credibility perceptions. Overall, campaign re-contextualization of provocative messages may result in negative persuasion effects and needs to be considered in campaign development. 
Source does matter: Contextual effects on online media-embedded health campaigns against childhood obesity