To tweet or to retweet? That is the question for health professionals on twitter.

Guided by the MAIN model ( Sundar, 2008 ), this study explored the effects of three interface cues conveying source attributes on credibility of health messages in Twitter: authority cue (whether a source is an expert or not), bandwagon cue (the number of followers that a source has-large vs. small), and source proximity cue (distance of messages from its original source-tweet vs. retweet). A significant three-way interaction effect on perceived credibility of health content was found, such that when a professional source with many followers tweets, participants tend to perceive the content to be more credible than when a layperson source with many followers tweets. For retweets, however, the exact opposite pattern was found. Results also show that for tweets, content credibility was significantly associated with the perceived expertise of proximal source, whereas for retweets, it was associated with the perceived trustworthiness of proximal source. Theoretical and practical implications are discussed.