Table 1.
Main findings of included papers and their effect on credibility or trust, separated by manipulated variable: number of likes, number of followers, number of retweets, source, and language.
| Outcomes/author (year) [citation] | Population group | Key significant results | |
| Number of likes | |||
|
|
Borah and Xiao (2018) [47] | Students | In the 2 studies conducted, the number of likes did not affect source credibility overall when looking at Facebook posts (study 1: P=.93; study 2: P=.09) |
|
|
Phua and Ahn (2016) [66] | Students | Brand trust was higher when likes were high on Facebook post (P<.005) or when friends’ likes were high (P<.001). Friends’ likes were more important in trust than overall total likes (P<.005). The number of likes had no direct effect on brand trust when the intensity of Facebook use was controlled for (P=.89) |
|
|
Shen et al (2019) [50] | Paid online workers | Bandwagon cues did not impact credibility when looking at images on Twitter and Facebook (P=.85) |
| Number of followers | |||
|
|
Jin and Phua (2014) [48] | Students | A higher number of Twitter followers on the celebrity’s account increased source credibility and intention to build an online friendship with the celebrity endorser for all dimensions of source credibility: physical attraction (P<.05), trustworthiness (P<.05), and competence (P<.01) |
|
|
Lee (2018) [49] | Students | The number of followers on Facebook made a statistically significant difference on the believability of the answer (P<.05), with a high number of followers increasing believability. There were no significant results for trustworthiness or accuracy |
|
|
Westerman et al (2011) [57] | Students | Trustworthiness indicated an inverted U-shaped relationship with the number of followers on Twitter (P=.02) |
| Number of retweets | |||
|
|
Lin and Spence (2018) [63] | Students | The highest level of trust (on Twitter) was when participants viewed the post with 400 retweets, followed by 40 retweets, whereas 4000 retweets had the lowest level of trust (P=.01). Participants perceived the highest levels of source competence when viewing the post with 40 retweets, followed by 400 retweets. The post with 4000 retweets had the lowest perceived competence (P=.01) |
|
|
Lin and Spence (2019) [64] | Students | There were significant differences in trust perceptions across varying retweet conditions (P=.046). People who viewed the FDA’sa Twitter page containing 4000 retweets were more likely to perceive lower organizational trust than the condition of 40 retweets (P<.05) |
|
|
Lin and Spence (2016) [65] | Students | Participants perceived lowest competence when viewing a peer’s Twitter page with no retweets (P<.001). The highest level of perceived source goodwill, trustworthiness, and competence was when participants viewed the CDCb page with no retweets (P<.001) |
| Source (expert, peer, or stranger) | |||
|
|
Borah and Xiao (2018) [47] | Students | In the 2 studies conducted on Facebook, the CDC and WebMD authors were seen as more credible than unknown authors (study 1: P<.01; study 2: P<.01) |
|
|
Lin and Spence (2018) [63] | Students | Participants viewing an FDA expert’s Twitter account were more likely to perceive higher trust (P=.01), competence (P<.001), and goodwill (P<.001) than those viewing a peer or stranger’s account |
|
|
Lin and Spence (2016) [65] | Students | Higher credibility was assigned to risk information from an expert compared with a peer and a stranger on Twitter (P<.001) |
| Language (message credibility) | |||
|
|
Borah and Xiao (2018) [47] | Students | In the 2 studies conducted, a gain-framed message was more credible than a loss-framed message on Facebook (study 1: P<.001; study 2: P<.001) |
|
|
Houston et al (2018) [51] | Paid workers | Nonopinionated tweets were perceived as more credible than opinionated tweets (P<.001) |
|
|
Yilmaz and Johnson (2016) [59] | Students | Personalized status updates on Facebook were seen as more competent and trustworthy than personalized tweets (P=.007, P=.001 respectively). Depersonalized tweets were more trustworthy than the source of depersonalized status updates on Facebook |
aFDA: Food and Drug Administration.
bCDC: Centers for Disease Control and Prevention.