Media and Communication Ph.D. Dissertations


Assessing Source Credibility On Social Media–––An Electronic Word-Of-Mouth Communication Perspective

Date of Award


Document Type


Degree Name

Doctor of Philosophy (Ph.D.)


Media and Communication

First Advisor

Louisa Ha (Advisor)

Second Advisor

Gi Woong Yun (Committee Member)

Third Advisor

Michael Horning (Committee Member)

Fourth Advisor

Mary Benedict (Committee Member)


Twitter has become an important news medium in recent years. The 140-character length limit of Twitter posts not only facilitates rapid expansion and success of fast news in the battle for attention, but also accelerates information diffusion on social media forums. However, given the rapid and uncontrollable spread of information on Twitter, an authoritative and credible information source in this environment is particularly important. Hoaxes on Twitter can have severe consequences. For example, a Twitter hoax in April, 2013 claimed that President Obama was injured in an explosion at the White House, which resulted in a 150 points Dow Jones Industrial Average fall, evaporating a $136 billion market value in minutes (Chozick & Perlroth, 2013). Even though people soon learned that the fake tweet was posted by hackers through the Associated Press (AP) account and the domestic market rebounded, it caused panic in the global markets and some investors lost money. Another hoax news was put up in May, 2013. Five-time NBA champ, Kobe Bryant, was said to retire in the fake news posted by a hoax Twitter account pretending to be Yahoo’s well-known sports writer Adrian Wojnarowski. No market plunge occurred this time. But people did believe that Bryant was going to end his career after 17 seasons. The rumor ended only with Bryant’s rebuttal tweet, “Really?? Me. Retire?? Soon, but not yet! Vino still has work to do.” Fake news on Twitter exerts great influence on us whether we are aware of it or not. In effect, it is the sources that play a vital role in the process of information dissemination because only when people believe the sources will they accept and spread the information provided by such sources.

Then again, why people believe these social media sources to be credible and spread these rumors like they are real news? Now, what if a real sports writer, or AP or ESPN reporter publicized Bryant’s retirement instead of, say, a makeup artist or a mechanical engineering scientist? Whose words sound more credible? Again, if we are talking about makeup and beauty, does a post by a makeup artist make it more authoritative and credible to you? The platform provided by interactive technology does accelerate information diffusion and then increase communication effect, but most of the time, communication effect on social media is more hinged on “hubs”—individuals more connected and visible in the networks (Barabasi, 2002). Thus, the credibility of these hub-sources is more critical to both academia and practitioners in marketing.

According to Barabasi (2002), cyberspace is a networked world, which consists of a few highly connected hubs and numerous connectors. Hubs have more links and outreach connections than connectors. Although both hubs and connectors can have their views published online, what matters is whose posts have more chances of being read, or who has a more influential communication effect? In the case of social media, public figures with a huge number of followers/fans are hubs in the virtual social network. They are amplifiers that contribute to effective communication by reaching out to lots of people in just a few seconds. However, public visibility cannot guarantee effective communication; people still need to make judgments on information based on source credibility. In regards to different kinds of information/news, people hold different expectations from different “hubs.” Compared with any popular individual Twitter account, the AP has more credibility when it comes to distributing political news. That’s why the fake news posted by a hacker via the AP Twitter handle caused such a furor.

To put it in a nutshell, although numerous research has been done on persuasion and effective communication, there are new features and attributes of communication in the context of social media. On the one hand, social media facilitates communication in scale and speed; on the other hand, the technology makes online communication more complicated. Within the multiple source layers in online communication, it is harder to estimate information and source credibility than the traditional direct and visible criteria of face-to-face communication. However, technology affordances such as followers and blue verified badges, do provide some cues for people to make judgments on source credibility. Therefore, the researcher would like to investigate how people’s evaluation criterion of source credibility changes, and which factors influence people’s perceived source credibility in the context of social media.