Influencer Marketing Consumer Purchase Intention Literature Review

1. Introduction

The rapid expansion of social media has reshaped the way brands communicate with consumers, and few developments illustrate this shift more clearly than the rise of influencer marketing. Influencers — individuals who have cultivated sizeable and engaged followings on platforms such as Instagram, TikTok and YouTube — now occupy a central position in the promotional strategies of organisations across the beauty, fashion, technology and retail sectors. Unlike traditional celebrity endorsement, influencer marketing is frequently characterised by a perception of relatability and everyday authenticity, which many practitioners believe makes an influencer’s recommendation feel more like advice from a knowledgeable friend than a paid advertisement (Abidin, 2016; Audrezet, de Kerviler and Moulard, 2020).

From a marketing perspective, the outcome that matters most is whether this form of communication actually moves consumers closer to a purchase. Purchase intention — the self-reported likelihood that a consumer will buy a product within a given period — is widely used as a proximal indicator of future buying behaviour and as a dependent variable in advertising effectiveness research. Understanding which features of an influencer, their content and their audience relationship drive purchase intention is therefore of direct relevance to both scholars and practitioners who allocate growing promotional budgets to this channel.

The academic literature on influencer marketing has grown quickly but somewhat unevenly. Much of it borrows from older theory on source credibility and celebrity endorsement, while a newer strand foregrounds concepts such as parasocial relationships and perceived authenticity that are specific to the social media context. The result is a fragmented evidence base in which studies measure overlapping constructs under different labels, making it difficult for a newcomer to see the overall shape of the field. This review addresses that problem by organising the literature into coherent themes rather than listing studies one by one.

Accordingly, the review pursues three objectives: first, to synthesise the empirical and conceptual literature linking influencer characteristics and content to consumer purchase intention; second, to appraise the quality and consistency of that evidence; and third, to identify a gap that an undergraduate research project could realistically address. The remainder of the review sets out the search strategy, presents a thematic synthesis of the evidence, offers a critical appraisal, and concludes by articulating a research gap and its implications.

2. Search Strategy and Review Methodology

A structured, narrative review approach was adopted. Rather than attempting the exhaustive, protocol-driven coverage of a full systematic review, the search aimed to locate the most influential and representative sources on influencer marketing and purchase intention, supplemented by the foundational theoretical works that underpin the field. This scope is appropriate for an undergraduate-level review, where the goal is to demonstrate command of the key debates rather than to produce a formal meta-analysis.

Three academic databases were searched: Business Source Complete, Scopus and Google Scholar. The searches combined terms describing the independent variable (for example, “influencer marketing”, “social media influencer”, “Instagram endorsement”) with terms describing the dependent variable (“purchase intention”, “buying intention”, “consumer behaviour”), linked using Boolean operators. Reference lists of the most relevant articles were also hand-searched to capture seminal works that keyword searches can miss — a technique often called backward citation chaining. The parameters applied are summarised in the table below.

The figures reported in the final row are illustrative, reflecting a plausible screening funnel for a review of this scope rather than the output of a formal PRISMA count. Presenting the process transparently, however, allows a reader to judge how the sources were selected and reduces the risk of unacknowledged selection bias.

3. Thematic Synthesis of the Literature

Reading across the retained sources, the evidence clusters around four recurring explanations for why influencers affect purchase intention. These are the perceived credibility of the influencer, the parasocial relationship they build with followers, the congruence between influencer and brand, and the way sponsored content is disclosed. The table below maps the key sources to each theme before the themes are discussed in turn.

3.1 Source Credibility and Influencer Characteristics

The largest body of work frames the influencer primarily as a message source and draws on the source credibility tradition established by Hovland, Janis and Kelley (1953). Within this tradition, Ohanian (1990) developed a widely used scale conceptualising endorser credibility as a combination of trustworthiness, expertise and attractiveness, and these three dimensions continue to structure much contemporary research. Erdogan’s (1999) earlier review of celebrity endorsement provides the historical bridge between this classical work and the influencer era, arguing that endorsers are most effective when audiences perceive them as credible and relevant to the advertised category.

Applied to social media, this logic is supported by Djafarova and Rushworth (2017), whose qualitative study of young female Instagram users suggested that perceived trustworthiness and relatability were more important than conventional celebrity status in shaping purchase decisions. Lou and Yuan (2019) extended the argument quantitatively, proposing an influencer marketing model in which the informational value and credibility of branded content jointly build trust, which in turn predicts positive responses to the promoted brand. A recurring finding across these studies is that trustworthiness tends to carry more weight than attractiveness for purchase-related outcomes, which marks a subtle but important departure from the celebrity literature, where physical attractiveness was often emphasised.

The strength of this theme lies in its clear theoretical lineage and its ready operationalisation through validated scales. Its weakness is that credibility is frequently treated as a stable attribute of the influencer, whereas in practice it is likely to be co-constructed through ongoing interaction with followers. Treating credibility as a fixed input may therefore overstate how much a brand can simply “select” a credible influencer and overlook the relational processes examined in the next theme.

3.2 Parasocial Relationships and Perceived Authenticity

A second theme explains influencer effectiveness through the relationship followers believe they have with the influencer, rather than through the influencer’s attributes in isolation. The concept of parasocial interaction, introduced by Horton and Wohl (1956) to describe the one-sided sense of intimacy audiences develop with media figures, has been revived to account for the apparent closeness between influencers and their followers. Because influencers share seemingly spontaneous glimpses of daily life, followers may come to feel they know the influencer personally, and this perceived bond can make endorsements feel like trusted personal recommendations.

Perceived authenticity is closely bound up with this relationship. Audrezet, de Kerviler and Moulard (2020) argued that influencers manage an ongoing tension between commercial opportunity and authenticity, and that followers reward those who appear to endorse only products consistent with their genuine identity. Where sponsorship is perceived as opportunistic or inconsistent with the influencer’s persona, the parasocial bond — and with it the persuasive advantage — can be undermined. Jin, Muqaddam and Ryu (2019) compared responses to Instagram influencers and traditional celebrities and found that the more ordinary, accessible figure often generated stronger feelings of connection and, in turn, more favourable brand attitudes.

This theme offers a persuasive explanation for why influencer marketing can outperform conventional advertising even when the influencer is less famous or glamorous than a celebrity. Its principal limitation is measurement: parasocial relationships and authenticity are subjective, difficult to quantify consistently, and at risk of overlapping with credibility constructs. Without careful construct definition, studies may effectively measure the same underlying perception under three different names, a problem returned to in the critical appraisal.

3.3 Influencer–Brand Congruence and the Match-Up Hypothesis

A third theme concerns the fit between the influencer and the endorsed brand. The match-up hypothesis holds that an endorsement is most effective when the image of the endorser aligns with the attributes of the product, and McCracken’s (1989) meaning transfer model offers a cultural explanation: endorsers carry symbolic meanings that are transferred to the brand and then, through purchase, to the consumer. When influencer and brand share a coherent set of meanings, the transfer is smooth and the endorsement is believable; when they do not, consumers may perceive the partnership as incongruent and discount it.

Empirical work in the social media context broadly supports this view while adding nuance. Schouten, Janssen and Verspaget (2020) found that product–endorser fit, identification and credibility jointly explained advertising effectiveness, and that influencers could outperform celebrities partly because audiences identified with them more readily. De Veirman, Cauberghe and Hudders (2017) added an important qualification regarding follower counts: although a large following can signal popularity, a very high follower number combined with the influencer following few others can reduce perceived likeability, and high follower counts did not straightforwardly improve brand attitude when product divergence was high. This suggests that congruence operates at several levels — between influencer and product, and between the influencer’s apparent status and the impression of relatability that underpins their appeal.

The congruence theme usefully connects the influencer literature to decades of endorsement research, lending it theoretical depth. However, much of the evidence relies on experimental manipulations of fictitious influencers or single product categories, which raises questions about how well the findings transfer to the messy reality of ongoing, multi-brand influencer partnerships.

3.4 Sponsorship Disclosure and Persuasion Knowledge

The final theme shifts attention from the influencer to the consumer’s awareness of the commercial nature of the message. The Persuasion Knowledge Model of Friestad and Wright (1994) proposes that consumers draw on an evolving understanding of marketers’ tactics to interpret and sometimes resist persuasion attempts. When a sponsored post is clearly disclosed as advertising, this knowledge may be activated, potentially prompting more sceptical processing. Regulatory requirements in many markets now oblige influencers to label paid content, making disclosure a practically significant variable.

The empirical picture here is mixed and therefore instructive. Evans, Phua, Lim and Jun (2017) found that explicit disclosure language increased recognition of advertising, which in some conditions dampened positive responses. Boerman (2020) reported that standardised disclosure could raise advertising recognition without necessarily collapsing engagement, particularly for micro- and meso-influencers whose relationships with followers may buffer the effect. Taken together, these studies suggest that disclosure does not uniformly suppress purchase intention; its effect appears to depend on the strength of the parasocial relationship, the credibility of the influencer and the way the disclosure is framed.

This theme is valuable because it introduces a counter-force to the generally positive accounts offered by the other three themes, reminding reviewers that persuasion is not automatic. Its unresolved question — precisely when disclosure helps, hinders or has no effect — is one of the clearest openings for further research and feeds directly into the gap identified below.

4. Critical Appraisal of the Literature

Viewed as a whole, the literature provides reasonably consistent evidence that influencer credibility, parasocial connection and influencer–brand congruence are positively associated with purchase intention, while the role of sponsorship disclosure is more conditional. Yet several limitations temper confidence in these conclusions and should be weighed by any student building on this work.

First, there is substantial construct overlap. Credibility, authenticity and parasocial relationship are theoretically distinct but empirically entangled, and studies rarely test them together in a single model. As a result, it is difficult to establish which construct is doing the explanatory work, and apparent agreement between studies may partly reflect different labels for similar perceptions. Hudders, De Jans and De Veirman (2021) make a similar observation in their conceptual review, calling for clearer integration of the field’s proliferating concepts.

Second, the methodological base is dominated by cross-sectional surveys and short laboratory-style experiments, frequently using student or young-adult samples recruited through convenience sampling. Such designs capture associations and immediate reactions well but cannot establish whether stated purchase intention translates into actual purchase, nor whether effects persist over time. The reliance on self-reported intention as a proxy for behaviour is a particular concern, given the well-documented gap between what consumers say they will buy and what they ultimately do.

Third, the evidence is platform- and category-skewed. Instagram and beauty or fashion products are heavily over-represented, while fast-growing short-video platforms and categories such as financial services or technology receive far less attention. Finally, the pace of change in the sector means that findings can date quickly as platform features, disclosure regulation and audience norms evolve. These limitations do not invalidate the literature, but they do mean its conclusions are best treated as well-supported tendencies rather than settled laws.

5. Research Gap and Directions for Future Research

The appraisal points to a specific and manageable gap. While each of the four themes has been examined in isolation, far fewer studies consider how they interact — and the disclosure theme in particular is rarely integrated with the relational themes. The literature does not yet offer a clear answer to a practically important question: does clear sponsorship disclosure weaken purchase intention more for influencers with whom followers have a weak parasocial relationship than for those with a strong one? In other words, can a strong, authentic follower relationship buffer the scepticism that disclosure may trigger?

This gap is attractive for an undergraduate project for three reasons. It is theoretically grounded, drawing together the Persuasion Knowledge Model with parasocial relationship theory rather than inventing new constructs. It is practically relevant, speaking directly to how brands and influencers should manage disclosure under tightening regulation. And it is feasible within the resource constraints of an undergraduate dissertation, because it can be investigated with a single online experiment that manipulates disclosure (present versus absent) and measures parasocial relationship strength and purchase intention using established scales.

A suitable project might therefore test the following overarching proposition: that sponsorship disclosure reduces purchase intention overall, but that this effect is moderated by the strength of the parasocial relationship, such that the reduction is smaller for strongly bonded followers. Beyond this specific study, the review suggests three broader directions for the field: integrating its overlapping constructs into a single tested model; extending research beyond Instagram and beauty products to other platforms and categories; and incorporating behavioural or longitudinal measures that move past self-reported intention. Addressing even one of these would strengthen the evidence base considerably.

6. Conclusion

This review set out to synthesise the literature on influencer marketing and consumer purchase intention, to appraise it critically, and to identify a research gap. The synthesis showed that scholarship clusters around four explanations for influencer effectiveness: source credibility, parasocial relationships and authenticity, influencer–brand congruence, and sponsorship disclosure. Across the first three themes the evidence is broadly positive and mutually reinforcing, suggesting that trustworthy, authentic and well-matched influencers tend to lift purchase intention; the fourth theme introduces a necessary note of caution, showing that consumer awareness of commercial intent can moderate these effects in ways that remain incompletely understood.

The critical appraisal highlighted construct overlap, methodological narrowness and platform skew as the main threats to confident conclusions, and these limitations shaped the gap identified: the under-examined interaction between disclosure and parasocial relationship strength. By framing a focused, feasible question around that interaction, an undergraduate researcher can make a modest but genuine contribution while demonstrating command of the key debates. In a marketing environment where influencer spend continues to grow and regulation continues to tighten, understanding when transparency and trust reinforce rather than undermine one another is both an academically interesting and a commercially useful endeavour.

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