How Social Media Influencers Drive Purchase Intentions: A Stimulus-Organism-Response Analysis of Vietnamese Consumers’ Psychological Responses

Purpose: This study investigates how exposure to social media influencers affects Vietnamese consumers' purchase intentions through key psychological mediators within the Stimulus-Organism-Response (S-O-R) framework.Design/methodology/approach: Data were collected via a structured survey from 406 Vietnamese social media users and analyzed using Partial Least Squares Structural Equation Modeling (PLS-SEM).The model tested the mediating roles of desire to mimic, materialism, fear of missing out (FOMO), and social comparison.Findings: All proposed hypotheses were supported.Influencer exposure significantly influences purchase intention directly ( = 0.400) and indirectly through psychological mediators.FOMO mediates the relationship between social comparison and materialism ( = 0.027), while materialism partially mediates the effect of desire to mimic on purchase intention ( = 0.050).Practical implications: Marketers should design FOMO-driven and lifestyle-centric influencer content to stimulate consumer engagement and drive purchase behavior.The findings suggest that both direct imitation and materialistic aspirations underlie consumer responses to influencer content.Originality/value: This is among the first studies to integrate the S-O-R framework into influencer marketing research in Vietnam.It uncovers novel mediation pathways and contributes to cross-cultural understanding of digital consumer psychology.