Effects of biases on thinking and decision-making

This study investigates how social media influencer (SMI) characteristics — specifically expertise and follower count — shape teenagers’ perceptions of trust and their purchase intentions in the beauty and health industries. Drawing on psychological theories of decision-making such as Dual Process Theory and Authority Bias, the paper explores how adolescents evaluate influencer content on platforms like Instagram. It aims to uncover whether teenagers are more persuaded by an influencer’s popularity or by their perceived expertise, and how these cues influence their willingness to buy products or trust online reviews.

Using a quantitative and qualitative approach, the research employed a Google Forms questionnaire that exposed participants aged 13–19 to simulated Instagram-style posts varying in follower count and expertise level. Respondents rated each post on purchase intention and review trustworthiness. Statistical and correlational analyses were then used to identify the relative influence of each variable.

Findings revealed that influencer expertise was the strongest predictor of trust and purchase intention, while follower count and product type (beauty vs. health) had limited impact. Teenagers showed a tendency to rely on cognitive shortcuts — guided more by perceived authority and relatability than by critical evaluation — suggesting that their decisions are primarily driven by System 1 (intuitive) thinking rather than System 2 (analytical) reasoning. The paper concludes by emphasizing the ethical importance of media literacy education and responsible influencer marketing, given adolescents’ psychological susceptibility to credibility cues and social proof.