Smiling in influencer marketing: how smiles shape authenticity and consumer engagement

Purpose Many influencer marketing campaigns feature smiling influencers. However, whether smiling is always beneficial, and under which circumstances it might not be, remains underexplored. This paper aims to examine how an influencer’s smile (vs no smile) affects consumer engagement with influencer posts. Design/methodology/approach The authors conducted a field study and several online experiments. In the field study, they analyzed 802 influencer campaigns with a total of over 125 million consumer interactions (i.e. liking and commenting). In the experiments, participants viewed influencer posts featuring commonly promoted products such as headphones (nStudy2 = 192, nStudy4 = 231), sunglasses (nStudy3 = 304) and protein bars (nStudy5 = 236, nSupplemental = 247). Findings The authors show that a smile (vs no smile) in influencer posts can backfire. Smiling can lead to lower engagement by reducing perceived authenticity. However, this negative effect is contingent upon influencer type (micro vs macro) and sponsorship presence (sponsored vs. non-sponsored). Research limitations/implications While Instagram was the authors’ focus, smile effects may be different on other platforms. Although they focused on engagement, other marketing outcomes may exhibit different patterns. Finally, other contextual factors may influence whether smiling backfires or not. Practical implications Marketers and influencers should carefully consider the use of smiles when endorsing products on social media. While smiling may enhance engagement for micro influencers, it can have the opposite effect for macro influencers. However, for macro influencers, smiling may still boost engagement when the product recommendation is not sponsored. Originality/value In revealing a negative effect of smiling in influencer posts, along with an underlying mechanism and boundary conditions, the authors’ study advances the influencer marketing literature. The authors show that a smile can increase engagement and purchase likelihood for some influencer types and campaigns, while it can decrease it for others. Thus, they provide a nuanced picture of the importance of smiling in influencer marketing on social media.