From Scarcity and Social Interaction to Impulse Buying: The Mediating Roles of FOMO and Flow in TikTok Live-Stream Fast-Fashion Purchases

Live-stream commerce combines time scarcity, real-time social interaction and entertainment in a highly immersive purchase environment. Drawing on the Stimulus-Organism-Response (S-O-R) framework, this study examines how limited-time discounts (LTD), interpersonal interaction (IPI) and entertainment (ENT) influence impulse buying (IB) through fear of missing out (FOMO) and flow experience (FLOW) in TikTok fast-fashion livestreams. A cross-sectional survey of 212 students in Tu Liem, Hanoi was conducted using convenience sampling and seven-point Likert scales. The data were analyzed with SPSS 26 and a two-stage PLS-SEM procedure in SmartPLS 4 because interpersonal interaction was modeled as a second-order construct combining viewer-streamer and viewer-viewer interaction. Measurement quality was satisfactory after removal of one entertainment item: composite reliabilities ranged from 0.880 to 0.927 and AVE values from 0.707 to 0.785. The structural model explains 52.9% of FOMO, 56.5% of FLOW and 56.8% of impulse buying. LTD increases FOMO (beta=0.451), IPI increases both FOMO (beta=0.348) and FLOW (beta=0.380), and ENT increases FLOW (beta=0.434). FOMO (beta=0.451) and FLOW (beta=0.353) both increase impulse buying. All four hypothesized indirect effects are significant, whereas viewing frequency is not. The findings clarify two distinct psychological routes through which livestream stimuli translate into unplanned purchasing and support a responsible-design perspective on scarcity and immersive commerce.