From Certainty to Doubt: The Impact of Streamer Expression Certainty on Consumer Purchase Behavior in Live-Stream E-Commerce

This study explores the impact of streamer expression certainty on consumer purchase behavior in live-stream e-commerce and its underlying mechanisms. Based on an empirical analysis of 3842 product live-stream data from the Douyin platform and an experimental study, the results show that streamer expression certainty has a significant inverted U-shaped relationship with consumer purchase behavior. Moderate expression certainty enhances consumers’ purchase intention, while excessively high or low expression certainty weakens its effect. Furthermore, perceived competence and perceived warmth mediate this process. Moderate expression certainty enhances consumers’ perceptions of the streamer’s professionalism and sincerity, thereby promoting purchase behavior. However, overly high expression certainty may reduce perceived warmth, leading to decreased consumer trust. This study further reveals the key role of language style in live-stream e-commerce and provides practical insights for optimizing streamers’ language strategies and improving live-stream effectiveness. The study’s limitations and directions for future research are also discussed.