How Does Social Media Influencer Marketing Affect Consumer Purchase Behaviour?

Abstract

Influencer marketing has become a structural component of the Indian marketing communications budget, yet the theoretical account of how influencer communication converts audience attention into consumer buying behaviour remains fragmented. Research in this field draws on at least four distinct theoretical traditions — source credibility theory, parasocial interaction theory, dual-process models of persuasion, and the theory of planned behaviour — which have developed largely in parallel and are seldom integrated into a single explanatory structure. The result is a literature that documents effects without agreeing on the mechanism that produces them. This paper is conceptual rather than empirical. Its purpose is to review, organise and synthesise the theoretical and empirical scholarship on influencer marketing, and to propose an integrated framework capable of guiding subsequent empirical work in the Indian context. A structured narrative review methodology was applied to peer-reviewed literature published between 1953 and 2021, supplemented by industry and regulatory documentation from the Advertising Standards Council of India, the Internet and Mobile Association of India, and published consultancy research. The synthesis yields four propositions. First, influencer marketing is best understood as a trust-transfer mechanism rather than as direct persuasion: the influencer supplies a credibility signal that the consumer applies to the brand, and it is the resulting brand trust that carries the effect on purchase intention. Second, the two dominant explanatory constructs in the literature — credibility and parasocial relationship — are analytically distinct rather than interchangeable, and are likely to differ in relative importance across product categories. Third, the industry practice of selecting influencers on follower count is not well supported by the theoretical literature, which predicts an inverse relationship between commercial saturation and persuasive effect. Fourth, disclosure transparency, usually treated as a regulatory constraint, is better theorised as a credibility antecedent that contributes to trust formation. The paper contributes an integrated conceptual framework, a mapping of the theoretical lineage of the field, and a set of testable propositions specific to the Indian market. It does not report primary data; empirical validation of the proposed framework is identified as the principal direction for further research.