Have you ever thought about how quickly you decide whether to trust something you read online? Before you even finish the first paragraph, your eyes have likely scanned the author’s name, the headshot, the credentials quietly signaling who is speaking. Most people think they judge health information based on facts. At least, we assume we read the evidence, weigh the arguments, and then decide what to believe. But in reality, the decision often begins earlier than that. It relies on shortcuts, which Psychologists call heuristics, mental strategies that help us make quick decisions when information is overwhelming. In this case, it could be a professional title, a university affiliation, or even a simple label like “doctor” that can activate stored assumptions about expertise and authority. In seconds, trust can begin to take shape, often before we are consciously aware of it.
This dynamic was explored in a recent study on HPV vaccination messaging in the journal Health Literacy and Communication, which examined whether attention to source credentials shapes how people judge the credibility of health information before they consciously realize it.
The Experiment
To test how quickly trust forms, the researcher, Laura Crosswell, Director of the Center for Advanced Media Studies and Associate Professor of Health Communication at the University of Nevada, Reno, designed a controlled experiment using blog posts about HPV and the HPV vaccine. Each post contained the exact same health information. The only difference was the author’s identity.
In one version, the post was written by a doctor. In another, by a blogger. In the third, by an actress. Participants were randomly assigned to read one of the three versions. The goal was simple but precise: determine whether changing the source label alone would shift how credible the message appeared.
According to Crosswell, much of the existing research suggests that in today’s digital environment, audiences often gravitate toward relatable voices rather than traditional experts.
“A lot of the literature says that today we are turning to online sources and bloggers more so than physicians,” Crosswell said. “We tend to trust our peers. Because of this, I assumed that bloggers would hold a lot more credibility.”
By keeping the HPV information constant and altering only the source credentials, the study isolated a simple but powerful question: when the facts remain the same, does who appears to be speaking change how the message is judged?
To capture what participants were paying attention to, the research team used eye-tracking technology to measure where readers looked and how long they fixated on source credentials. Afterward, participants completed surveys assessing how trustworthy, believable, and credible they found the blog post, as well as whether they would consider following vaccination recommendations, which helped compare what people explicitly reported with their visual behavior. The idea was to observe those subtle moments when attention to source credentials might quietly shape trust, even before readers consciously reflect on the message.
Did It Work?
Participants rated the doctor as significantly more trustworthy than both the blogger and the actress. Despite assumptions that online audiences gravitate toward relatable voices, traditional medical credentials carried the most credibility in this experiment.
“They still saw the physician credentials and rated those messages as much more trustworthy,” Crosswell said.
The pattern became even more nuanced when the researchers examined visual attention. Nearly all participants glanced at the source credentials at least once. But attention did not function the same across conditions. Greater fixation strengthened trust when the source was a doctor. The same fixation reduced trust when the source was an actress. In other words, attention amplified existing impressions rather than automatically boosting credibility.
Crosswell admitted the outcome was not what she initially expected. “I was surprised a little bit,” she said.
The study also found that when participants perceived the message as more believable, they were more likely to report intentions to consider HPV vaccination. Trust, even when formed subtly, carried behavioral implications.
Why It Matters
The findings suggest that credibility online is not just about capturing attention, but about what that attention lands on. In this study, participants who perceived the message as more believable were also more likely to report intentions to consider HPV vaccination. Trust, even measured subtly through gaze and self-reports, had consequences for how people said they might act.
At the same time, the study found that fixation on credentials did not directly increase perceptions of the blog’s overall content credibility. That distinction is important. Credentials shaped trust in the source, and message believability was linked to vaccination intention, but credibility was not automatically transferred simply because readers looked longer at the author information. In practice, this means health communicators cannot rely on attention alone. Expertise cues matter, but the message itself must still be clear, evidence-based, and strong enough to stand on its own.
What Does This Mean For Science and Health Communicators
For science and health communicators, this means credibility cannot be treated as an afterthought. Who delivers the message shapes how the message is received, even before audiences consciously evaluate the content. In this study, participants who viewed the doctor as the source reported significantly higher trust than those who viewed the blogger or actress, even though the information was identical. The findings suggest that expertise cues do not simply decorate a message; they frame it. When credentials clearly signal authority, attention to them can reinforce trust. When they do not, that same attention can heighten doubt. For communicators working in crowded digital spaces, the implication is clear: the source is not separate from the science. It is part of how the science is judged.
Bottom Line
Credibility matters a lot in communicating complex scientific ideas. In online spaces where audiences are flooded with competing voices, trust often forms before the evidence is fully processed. This study shows that source credentials still play a measurable role in shaping that trust. When expertise is clearly signaled, attention can reinforce confidence in the message. When it is not, attention can amplify skepticism. For science and health communicators, the straightforward takeaway is that accurate information is necessary but not sufficient. How expertise is presented can determine whether that information is accepted, questioned, or dismissed.
Abdulmalik Adetola is a master’s student in the Media Innovation and Journalism program at UNR and a graduate assistant for the Hitchcock Project. He is a passionate advocate for health literacy and digital communication, dedicated to promoting accurate and accessible health information in the modern age.
