The Effects of Social Media Influencer Expertise and Follower Count on Teenage Purchase Decision-making in Influencer Marketing

Social media influencers (SMIs) use various strategies to distinguish their marketing content from traditional advertising, grow their digital reach and create authentic relationships with audiences and brands. This study investigates how SMIs' expertise and follower count shape teenagers' purchase intention and perceptions of trustworthiness of social media reviews of products in the beauty and health industries. Results indicate that influencer expertise is the strongest determinant of trust, suggesting that teenagers perceive influencers with relevant expertise as more credible sources of information. In contrast, follower count and product category had limited influence, indicating that online popularity alone does not significantly drive purchase behaviour. Frequent social media users tended to express greater trust in influencers overall, implying that regular exposure to online content may heighten susceptibility to bias. Together, these results suggest that teenagers' purchase decisions are guided by heuristics in System 1 thinking rather than System 2 processing, valuing perceived authority over critical evaluation.