The recent addition of Instagram feature, ad labels for sponsored posts, enables users to explicitly identify sponsored posts, increasing the level of transparency of posts (O’Brien, 2017). In sponsored posts in social media, followers are aware the marketing efforts that go on behind the user generated contents and message threads. Thus, the impact of postings on the followers’ behavioral response may vary depending on the levels of trust that followers have with the brand sponsored Instagram posts. In that regards, retailers implementing Instagram platform have faced creating more persuasive postings that can build the posting credibility and generate positive responses toward the brand. Grounded upon the Elaboration Likelihood Model (ELM) (Petty & Cacioppo, 1986), this study attempted to identify determinants of persuasive postings that build the message credibility of brand sponsored Instagram posts and positive responses toward the brand and to examine how the levels of trust followers have with the brand sponsored Instagram moderate the persuasion process when followers elaborate the postings. Data was collected via online survey and a total of 263 responses were determined to be usable in this study. Structural equation modeling was used to test the study hypotheses. The study results showed that post popularity and the argument quality of the post were determinants of the persuasive posting, increasing message credibility and yielding positive response towards the sponsored brand. Interestingly, post attractiveness was not a persuasive post characteristic. The results implied that post popularity and argument quality of post increased Instagram post credibility. These characteristics of posts have persuasive power to increase the post credibility, leading to a positive response toward the sponsored brand. Consumers’ levels of trust on the Instagram post sponsored brand moderated the persuasive process. The result supported that consumers with a low level of trust on the Instagram post sponsored brand carefully read a wide range of information and pay more attention to argument quality of posts, which consisted of the post content and other followers’ input regarding the product. Through the lens of Elaboration Likelihood Model, this study suggests that retailers should pay particular attention on the argument quality of a post and post popularity. The argument quality of a post is the influential factor determining persuasive and credible posts, further leveraging post credibility for consumers with a low level of trust on the sponsored post.

• Lindsey Tanoff(University of North Texas, USA)
• Kiseol Yang(University of North Texas, USA)