Source Credibility

The concept of source credibility has been studied for a long time. Hovland and Weiss (1951) already showed that information from highly credible sources was trusted more than information from sources with low credibility. However, this difference faded with time; information from both source types was trusted equally after a few weeks.

Considering source credibility can be considered heuristic processing in credibility evaluation (Chaiken & Maheswaran, 1994). An important determinant for this behavior is task importance (i.e., the necessity for correct information). When task importance is low, users often perform a heuristic evaluation, thus focusing on the source of information. A systematic evaluation will only be performed when task importance is higher.

Eastin (2001) investigated the relationship between source expertise and knowledge of the content. Source expertise can be considered a more specific form of source credibility, since the key components of credibility are trustworthiness and expertise (Hovland, Janis, & Kelley, 1982; Fogg & Tseng, 1999). An interaction between source expertise and knowledge of content was hypothesized; Eastin (2001) expected that users with more knowledge would attribute less value to source credibility, as they are able to focus more on the actual content of the information. However, no significant interaction was found in an online experiment. The lack of differences found between sources of varying expertise was attributed to the overall high level of trust in online information.

1.3 Domain Expertise

As stated, Eastin (2011) did not find an effect of knowledge of content (or level of domain expertise) on the use of source credibility in credibility evaluation. However, domain expertise has been demonstrated to influence trust in information in various ways. Lucassen and Schraagen (2011b) showed that domain experts are influenced by arguably the most important aspect of credibility, namely factual accuracy. In contrast, domain novices do not notice factual errors in information. Hence, it could be argued that domain

experts are better calibrated to the accuracy of information. This notion is supported by Kelton et al. (2008), who argued that the general propensity to trust is less influential on trust in a particular piece of information when the user has knowledge on the topic at hand. Moreover, Fogg and Tseng (1999) showed that users of automation evaluate computer products more stringently when they are familiar with the content. As a result, perceived credibility will be lower with familiar users.

Chesney (2006) asked several domain experts to rate the credibility of Wikipedia articles on topics inside and outside their own domain. Information in their own domain was perceived more credible (albeit only at the 10% significance level) as information outside their domain. Based on this difference, Chesney concluded that Wikipedia is highly accurate.

1.4 Wikipedia

Now that the potential influence of the source of information on perceived credibility is established, the influence of Wikipedia as an information source should be considered. This has yielded ambiguous results. In an online experiment by Lucassen and Schraagen (2011b), about 30 percent of the participants noted the source of the information (Wikipedia) as a motivation for their level of trust. However, for about half of these participants, the source was a reason to trust the information, whereas the other half did not trust the information for the same reason.

Kubiszewski, Noordewier, and Costanza (2011) systematically manipulated the source of information by presenting the same information in the form of a page on Encyclopædia Britannica, Wikipedia, or Encyclopedia of Earth to their participants. They found that information presented on Encyclopædia Britannica was perceived as having significantly more credibility than on the other two sources. A similar effect was found by Flanagin and Metzger (2011). However, they also demonstrated that while information presented on Wikipedia was perceived as less credible (regardless of the content), information actually from Wikipedia was perceived as more credible (regardless of the source presented). This clearly demonstrates the distinction between the active and passive strategies in the 3S-model by Lucassen and Schraagen (2011b); when actively evaluating the information itself the perceived credibility is different than when passively relying on earlier experiences with the source of information.

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1.5 Hypotheses

It is thus hard to predict whether the availability of source cues indicating that information comes from Wikipedia actually increases or diminishes the credibility of the information. However, compared to a condition without any cues about the source of the presented information, we expect that trust will be higher. When the source of information is known, users have more cues to base their trust on (cf. 3S-model, Lucassen & Schraagen, 2011b), which is likely to make them more confident of the credibility of information. This leads to the first hypothesis:

H1: Information is trusted more when the source (Wikipedia) is known.

In line with the hypothesized interaction between source credibility and knowledge of content (Eastin, 2001), we expect that the availability of source cues is less important for people who are familiar with the topic at hand. Such familiar users are able to directly evaluate semantic features of the information (Lucassen & Schraagen, 2011b), which makes them less dependent on source cues. This leads to the second hypothesis:

H2: Users who are familiar with the topic at hand are less influenced by source cues than unfamiliar users.

A second influence of source cues on credibility evaluation can also be expected. Considering the source of information as an indicator of credibility is highly heuristic behavior (Chaiken & Maheswaran, 1994). As the motivation to evaluate credibility is often limited (Metzger, 2007), the availability of this heuristic may lead users to skip other, more effortful evaluation methods altogether (i.e., evaluating the actual information itself). This possibility was also acknowledged by Lucassen and Schraagen (2011b), who described the ‘source heuristic’ as a biasing influence on trust. When the availability of source cues indeed leads users away from a more systematic evaluation, the actual quality of the information is likely to have less influence on trust, as the cues which indicate the quality level are not considered. This leads to the final hypothesis:

H3: The influence of information quality on trust is diminished by the availability of source cues.

2. Method

2.1 Participants

A total of 43 university students participated in the experiment for course credit. Two of these students had to be removed from the analysis due to incomplete data. The average age of the remaining 41 students was 20.6 years (SD = 2.1). The participants were either Dutch (N = 29) or German (N = 12). The questionnaires in the experiment were in Dutch, whereas the stimulus articles were obtained from the English Wikipedia. All participants were familiar with reading texts in these two languages. Hence, the participants reported no major language problems after taking part in the experiment.