Much of the research builds on the Persuasion Knowledge Model (PKM), which refers to individuals’ awareness and understanding of the persuasive intent behind marketing messages, shaping how they interpret and respond to such content ([4]; [5]; [28]). Several studies extend beyond PKM by employing Parasocial Relationship Theory, which describes the one-sided, emotionally invested relationships that audiences develop with media figures or influencers, helping to buffer negative effects of disclosures ([7]; [21]). Others incorporate the concept of transparency perception—the extent to which audiences believe that the influencer or brand is open and honest about sponsorship—as a key explanatory factor. Related frameworks such as Authenticity Management examine how influencers balance commercial content with relational trust ([2]; [10]), while Congruence Theory highlights the role of influencer-product fit ([11]). In youth-focused research, Theory of Mind has been used to explain developmental differences in disclosure recognition ([9]). Collectively, these frameworks underscore that disclosure effects are driven by multiple psychological and relational mechanisms.

Several studies emphasize that the manner in which sponsorship is disclosed strongly influences consumer responses. Standardized disclosures such as Instagram’s Paid Partnership tag improve recognition and brand recall but do not necessarily enhance parasocial interaction ([5]). Related work shows that the prominence of a disclosure, whether it is platform- or influencer-initiated ([14]), and the intensity of users’ platform engagement ([23]) can significantly shape outcomes. Importantly, disclosure effects may also operate in dual directions, producing skepticism through persuasion knowledge while simultaneously fostering trust through perceived transparency ([28]). Subtler or less explicit disclosures may help sustain engagement, though often at the cost of transparency ([1]). Beyond textual cues, message framing and design further moderate responses: two-sided messages can enhance authenticity and credibility ([16]), and visual strategies such as increasing product salience have been shown to reduce skepticism and offset negative effects of disclosure ([8]).

Disclosure effects are highly contingent on audience characteristics. Adolescents are more likely than adults to perceive disclosures negatively, showing weaker brand evaluations when sponsorship is recognized ([9]; [12]; [28]). At the same time, outcomes also depend on contextual factors. Perceptions of appropriateness are central: excessive self-disclosure is often judged as inauthentic, reducing trust and purchase intention ([2]). Usage intensity further differentiates responses, with heavy Instagram users generally evaluating disclosed posts more positively than lighter users ([23]). Finally, individual personality traits, such as materialism ([15]) or emotional intensity ([30]), can amplify or buffer disclosure effects, underscoring the complex interplay of demographic, contextual, and psychological factors.

The literature consistently identifies credibility, trust, and empathy as mediators of disclosure effects. Disclosures often enhance credibility, which in turn increases purchase intentions ([24]). Parasocial relationships reduce resistance and buffer negative responses ([7]; [25]). Studies also show that disclosures can improve perceived transparency, which sometimes offsets persuasion knowledge activation ([28]). Conversely, inappropriate or excessive self-disclosure by influencers is often judged as inauthentic, reducing trust and purchase intent ([2]). These findings suggest that relational and psychological mechanisms are central to explaining why disclosures can have both positive and negative effects.

While disclosures frequently reduce short-term outcomes such as ad effectiveness, brand attitudes, and purchase intentions ([11]; [30]) some evidence points to positive long-term consequences. [29] shows that while disclosed posts generate lower immediate engagement, they enhance long-term trust and credibility, leading to stronger engagement with subsequent non-sponsored content. Similarly, transparent disclosures can buffer the negative impact of commercialization on parasocial relationships ([18]). These findings reconcile contradictory results by highlighting the importance of distinguishing between immediate and sustained effects of disclosure.

For influencers, effective authenticity management involves striking a balance between transparency and creative content design ([3]). Explicit disclosures, when paired with narrative strategies or enhanced by visual salience, can sustain or even increase engagement ([8]; [31]). At the same time, overly detailed or inappropriate self-disclosure may erode trust ([2]). Successful influencers are those who integrate disclosure seamlessly into their content while maintaining authenticity, contextual relevance, and consistency with their established persona.

To synthesize these insights, Table 2 summarizes the key psychological mechanisms, moderating factors, and short- versus long-term outcomes identified across the reviewed studies, offering an integrative framework for understanding how sponsorship disclosures operate in social media influencer marketing.

Table 2.Conceptual framework linking mechanisms, moderators, and outcomes of sponsorship disclosure.

Despite the growing body of research on sponsorship disclosure, several limitations remain that require further investigation. Methodologically, much of the current evidence is derived from short-term experiments or cross-sectional surveys, designs that are insufficient to capture the enduring consequences of repeated disclosure exposure ([4]; [11]). Longitudinal research is therefore needed to examine how disclosures shape trust, engagement, and purchase behavior over time, particularly in light of recent evidence that immediate and long-term effects may diverge ([29]).

The scope of existing work is also limited in terms of platform coverage. Research has concentrated largely on Instagram, while rapidly expanding environments such as TikTok and other short-form video services remain comparatively underexplored ([19]; [26]). Given the centrality of these platforms to younger audiences, systematic investigation of their unique affordances, disclosure practices, and user interpretations is especially urgent.

Another limitation concerns potential language and regional bias in the reviewed literature. Most of the studies included in this review were published in English and conducted in Western or East Asian contexts, which may limit the generalizability of findings to other cultural and linguistic settings. This bias reflects the dominance of English-language journals in the academic publishing landscape and the uneven distribution of research resources across regions. Future work should actively incorporate studies published in other languages and from underrepresented markets to capture a more diverse range of consumer perspectives, regulatory environments, and influencer practices.

Taken together, these limitations point to the need for more diverse methodologies and broader research contexts to advance the field. Addressing them will not only enrich our understanding of sponsorship disclosure but also provide more robust guidance for policymakers, brands, and influencers navigating an increasingly complex digital advertising environment. In this sense, the trajectory of future research will play a decisive role in clarifying how disclosures function across time, cultures, and platforms, and in shaping practices that balance transparency, consumer protection, and the sustainability of influencer marketing ([4]; [6]; [13]; [19]; [22]; [26]; [29]).