A picture says more than a thousand words: Using consumer neuroscience to study Instagram users' responses to influencer advertising

Companies are increasingly relying on influencer marketing as a relevant pillar of their marketing communication strategy. It is therefore of vital importance to practitioners to understand better under what conditions a larger number of followers can trigger more positive responses in consumers than a smaller number and vice versa. Through a laboratory study, the authors recorded simultaneously eye‐tracking and electroencephalogram data from 109 participants to test the research question with a 2 (type of influencer: micro vs. meso) × 2 (argument quality: weak vs. strong) between‐subject design using mediated moderated linear regression analysis. The results highlight that the photo of the influencer using the product attracts more attention (i.e., fixation percentage) in the weak (vs. strong) argument quality only for micro‐ and not for meso‐influencers. Moreover, we found a statistically significant index of moderated mediation through the level of attention, which suggests that the percentage of fixations on the photo mediates the joint effect of influencer type and argument quality on behavioral activation system (BAS). Specifically, we found that when the advertising post presents weak argument quality the enhanced attention to the photo of the micro‐influencer leads to an increase in the BAS, with possible implications on advertising effectiveness and online message design. Our findings offer important theoretical and practical contributions to the influencer marketing domain by showing how the different verbal and visual elements of influencer posts affect Instagram users' responses to such posts.