The declining effectiveness of traditional online advertising has led brands to increasingly utilize influencer marketing. Influencers, with their substantial follower bases, wield significant power in shaping consumer opinions and purchasing decisions. Consumer engagement, encompassing proactive involvement in spreading advertisements and creating value, is a critical metric for assessing the success of influencer marketing campaigns. This study aims to understand the factors that drive consumer engagement in this context, addressing the need for deeper research into the stimulating factors and psychological mechanisms involved.

The study uses the Stimulus-Organism-Response (S-O-R) model as a theoretical framework. This model, initially from behavioral psychology, was expanded to include the individual's cognitive component. The study integrates the S-O-R framework with Self-Determination Theory (SDT), which emphasizes the role of psychological needs (competence, relatedness, and autonomy) in shaping behavior. The literature review highlights the applicability of SDT to online user behavior, particularly regarding knowledge-sharing and electronic word-of-mouth, which are components of consumer engagement. Different existing definitions of consumer engagement are reviewed and the study proposes to focus on content consumption, contribution, and creation.

The study employed a survey using the Wenjuanxing platform, recruiting participants through social media platforms like WeChat, Douyin, and Weibo. 600 questionnaires were initially collected, with 78 invalid responses excluded, resulting in 522 valid responses. The questionnaire measured variables including parasocial identification, source credibility, informative value, ad targeting accuracy, subjective norms, self-disclosure willingness, innovativeness, information trust, content consumption, content contribution, and content creation using a seven-point Likert scale. Smart PLS was used for Partial Least Squares Path Analysis (PLS) due to the exploratory nature of the research framework. The methodology included reliability and validity tests (Cronbach's alpha, Composite Reliability, Average Variance Extracted, Variance Inflation Factor), discriminant validity checks, and common method bias assessment to ensure data quality. Bootstrap testing was employed to assess the significance of the paths in the research model.

The study's key findings are presented in several tables. Table 3 shows reliability and convergent validity analysis, demonstrating acceptable values for Cronbach's alpha, Composite Reliability, and Average Variance Extracted. Table 4 presents discriminant validity analysis confirming that the average variance extracted values are greater than Pearson correlation coefficients. Table 5 displays the hypothesis testing results using bootstrap analysis, indicating which hypotheses were supported. The findings reveal that self-disclosure willingness, innovativeness, and information trust positively influence consumer engagement behaviors across different levels (content consumption, contribution, and creation). Innovativeness was found to have the strongest impact on higher-level engagement. Furthermore, influencer factors (parasocial identification, source credibility), advertisement information factors (informative value, ad targeting accuracy), and social factors (subjective norms) all significantly influence psychological motivators and subsequent consumer engagement behaviors. The results demonstrate that while influencers primarily impact initial traffic (content consumption), the quality of advertisement information plays a crucial role in higher-level engagement (content contribution and creation). Social factors further enhance engagement through their influence on psychological motivators.

The findings suggest that a comprehensive understanding of consumer engagement in influencer marketing requires considering both external stimuli (influencer, advertisement, and social factors) and internal psychological motivators (self-disclosure, innovativeness, and information trust). The model developed in this study bridges the gap between influencer marketing and consumer engagement research, expanding the theoretical framework for studying advertising effectiveness in the new media context. The significant impact of advertisement information factors highlights the continued importance of high-quality content in the digital age, despite the influence of social media personalities. The study’s findings are particularly significant for advertisers to better allocate resources and avoid over-reliance on influencers at the expense of content quality.

This study contributes to the literature by developing a comprehensive model of consumer engagement in social media influencer marketing based on the S-O-R framework and integrating self-determination theory. The findings emphasize the crucial role of information quality and social influence in driving higher-level engagement. Future research could explore the interaction effects between different factors, compare the findings across various social media platforms, and investigate cultural variations in consumer engagement patterns.

The study's limitations include the focus on a specific set of variables within the broader influencer, advertisement, and social factors. The sample was drawn primarily from social media users in China, limiting the generalizability of the findings to other cultural contexts. Further investigation is needed to explore the interaction effects between variables and extend the model to encompass a broader range of influencer marketing contexts and platforms.