Examining the Boomerang Effect in Promoting Influenza Vaccination: The Roles of Psychological Reactance, Message Fatigue, and Normative Perceptions

Annual influenza epidemics occur worldwide, posing a threat to public health (World Health Organization [WHO], 2024). Due to the heightened susceptibility during the influenza seasons, annual influenza vaccines are recommended as the most effective preventive measure against infection risks, thereby offering both health and economic benefits (CDC, 2024; Gatwood et al., 2022). However, achieving adequate vaccination coverage remains an ongoing challenge, with lower vaccination rates in the general population and evident disparities in coverage between countries, and among target groups (e.g., adults with chronic conditions; Goldin et al., 2024; WHO, 2025).

To optimize influenza vaccination adoption, it is crucial to communicate with the public about the risks of infection and the benefits of vaccination, while strategically recommending the vaccine. However, these efforts can be vulnerable to “noise,” which disrupts the communication process and creates a discrepancy between the intended purposes and audience’s interpretation (Cho & Salmon, 2007). As a result, the boomerang effect may occur, where the outcomes are opposite to the intended purposes.

In our study, we aim to investigate the boomerang effect by examining psychological reactance as the underlying mechanism that mediates the relationship between persuasive efforts and their unintended, opposite outcomes (Brehm & Brehm, 1981; Byrne & Hart, 2009). We examined the antecedents of psychological reactance, which include both the immediate perception of threat to freedom and message fatigue resulting from prolonged exposure to persuasive efforts (So et al., 2016). Furthermore, we examined perceived descriptive norms and injunctive norms as the boundary conditions for the overall pattern of psychological reactance to better understand how normative perceptions shape the associations between the associations within the study model. Grounded in the theoretical framework of psychological reactance theory previous empirical findings, we propose three hypotheses and two research questions:

H1: Psychological reactance is positively associated with intention to reject influenza vaccination (i.e., boomerang effect).
H2: Perceived threat to freedom regarding the choice of influenza vaccination is positively associated with psychological reactance.
H3: Message fatigue towards influenza vaccination messages is positively associated with psychological reactance.
RQ1: Do perceived descriptive norms moderate the pattern of psychological reactance? If so, then how does it moderate that pattern?
RQ2: Do perceived injunctive norms moderate the pattern of psychological reactance? If so, then how does it moderate that pattern?

Method
Participants and Procedures
We conducted an online experiment with a total of 648 adults, aged 18 to 45, living in the United States, who were recruited from a third-party survey company. After providing their consent, participants were randomly assigned to either freedom threatening language (n = 331) condition or non-freedom threatening condition (n = 317). After viewing the messages, participants answered questions addressing all study variables and provided demographic information.

Analytic Procedures
To test H1 to H3, we conducted Structural Equation Modeling (SEM) to assess the proposed model and introduced influenza vaccination history of previous year, age, and gender as control variables.

To answer RQ1 and RQ2, we employed multigroup SEM technique to compare the overall pattern of the psychological reactance model between individuals with high versus low perceived descriptive/injunctive norms. This technique provided an overall picture of how associations within the model manifested at each level of the examined conditions, rather than focusing on a single path of the model.

Key Findings
The Antecedents of Psychological Reactance
Both perceived threat to freedom and message fatigue acted as the antecedents of psychological reactance. In detail, persuasive messages employing forceful and explicate language to recommend influenza vaccination could threaten individuals’ autonomy to make a choice, subsequently triggering psychological reactance and resulting in the boomerang effect. Added to perceived threat to freedom, message fatigue, cultivated by the prolonged exposure to the homogenous topics within an information-rich environment was also positively associated with psychological reactance.

By integrating perceived threat to freedom and message fatigue as antecedents, along with the aversive nature of psychological reactance, crafting message strategies that carefully manage message features, timing, and delivery volume matters. Such strategies could mitigate psychological reactance induced by persuasive attempts, either in the short term or over extended periods, thereby enhancing the effectiveness of persuasive efforts.

Perceived Descriptive Norms as Contributory Conditions
The findings showed that perceived descriptive norms could serve as contributory conditions to the overall pattern of psychological reactance (Holbert & Park, 2019). Specifically, the associations within the model were stronger among individuals with high perceived descriptive norms compared to those with low perceived descriptive norms. However, this pattern was similar for both individuals with low and high perceived injunctive norms. Although perceived descriptive and injunctive norms are related in that they both provide information about adaptive behavior in a given situation, they are conceptually distinct from one another. Perceived descriptive norms indicate what is commonly done, while perceived injunctive norms indicate what should be done, along with the social sanctions for noncompliance (Chung & Rimal, 2016; Lapinski & Rimal, 2005). Our findings further supported this distinction, showing that the estimated prevalence of a given behavior embedded in perceived descriptive norms could create social pressure for individuals to conform, thus amplifying psychological reactance (Legros & Cislaghi, 2020). These contributory conditions of perceived descriptive norms highlight the importance of carefully adjusting persuasive efforts based on individuals’ pre-existing perceptions of descriptive norms. By doing so, it may be possible to mitigate psychological reactance and, in turn, promote the adoption of health behaviors.

Conclusion
In our study, informed by the psychological reactance theory, we examined psychological reactance as the underlying mechanism of the boomerang effect within the context of influenza vaccination communication. We extended message fatigue as an additional antecedent of psychological reactance along with perceived threat to freedom, both of which triggered psychological reactance that subsequently result in boomerang effect. Furthermore, we demonstrated that perceived descriptive norms act as contributory conditions for the overall pattern of psychological reactance. These findings theoretically advance psychological reactance theory and contribute to the literature on message design and theory-informed communication strategies in health communication.