Student thesis: Doctoral ThesisDoctor of Philosophy


As a commercial phenomenon evidenced primarily in advertising, celebrity endorsement dates back to at least the 1800s. The development of mass media during the 1900s facilitated the emergence of entertainers, athletes, and other successful people as 'celebrities'. This, in turn, triggered the appeal of inviting these figures as promoters of brands and products in advertising. Just as the growth of traditional media fuelled the initial emergence of celebrity endorsement, the contemporary relevance of the phenomenon has been propagated by the spread of digital and social media.

Social media has given rise to new breeds of celebrity and consequently to new forms of endorsement – influencer endorsement. Social media influencers, while seen as everyday people, have attained thousands or even millions of followers via their social media platforms. They establish a strong online identity by self-presentation. Like celebrity endorsements, these social media influencers can enhance consumers' responses to many brands and successfully convert their persuasive power into sales through their endorsements and recommendations. While more companies and brands are choosing social media influencers to represent them, there is a noticeable lack of academic insight explaining the prominence of social media influencers over traditional celebrities in endorsements.

Essay 1 interprets existing endorsement theories and models to the realm of social media influencers and then provides an overall model to test the extent to which consumer outcomes depend on the endorser status through meta-analysis. Moreover, as with other relationships, the relationships social media influencers develop with their followers can be negatively affected if influencers misbehave. While the negative impacts of misbehaviours on consumer responses have been widely examined in previous research, most focus on traditional celebrities. This leaves a gap in our understanding of consumer reactions to misbehaving social media influencers. Essay 2 delves into this, probing the nuances of social media influencer misbehaviours and the variance in consumer reactions.

Furthermore, unlike traditional celebrities who gain persuasive power from achievements outside social media, social media influencers create appealing online personas through content creation. Even though prior research explores the content’s attributes, often emphasizing “what is said”, the intricacies of "how it is said" (i.e., linguistic style) remain unclear. Essay 3 illuminates the effects of social media influencers’ linguistic choices on consumers’ emotional reactions through a text-mining study, shedding light on crafting a linguistic style that aligns with influencers' social identities.

This thesis offers several contributions. First, it integrates insights from endorsement literature with a meta-analysis, offering extensive knowledge on endorsements. It delves into the conceptual ties between social media influencers and consumer outcomes and outlines a research agenda highlighting future avenues in influencer studies. Secondly, utilizing a blend of empirical data analysis and controlled experiments, this research demonstrates the fallout of perceived misconduct on consumer outcomes, mediated by moral reasoning, depends largely on the perceived intent and severity of the misconduct. By doing so, the thesis addresses the lack of academic insights into consumer reactions toward misbehaving social media influencers.

Thirdly, the thesis proposes two linguistic styles that positively affect consumer outcomes, indicates the moderating roles of influencers' social identities, and identifies the intersection of influencers' gender and race in their social media communication.

Keywords: Social Media Influencers, Celebrity Endorsements, Misbehaviours, Stereotypes
Date of Award1 Oct 2023
Original languageEnglish
Awarding Institution
  • King's College London
SupervisorKirk Plangger (Supervisor) & Matteo Montecchi (Supervisor)

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