Social media influencer marketing is big business. 2024 estimates value the global market at $24 billion, and it shows little sign of slowing down. International brands invest heavily in partnerships with social media personalities to promote their products, build credibility and reach new audiences. But while influencer campaigns are widespread, they're not always strategically executed.
In addition to researching influencers, last year I began my own journey as @duchess_of_the_dram on Instagram, where I explore my passion for Whisky tasting and tourism. This hands-on experience has given me valuable insight into what resonates with audiences – and how different types of posts perform in practice.
My latest research, with my University of Edinburgh Business School colleague Dr Ben Marder, builds on these experiences to explore what makes Instagram influencers' posts persuasive and how marketers can apply psychological insights to make better decisions. It examines how different types of influencers, from micro to mega, are perceived by their audiences, and how this affects the impact of their messaging.
At the heart of our research is a simple question: Should an influencer tag the brand they're promoting? The answer depends on who they are and how many followers they have.
Through experiments and a large-scale analysis of real Instagram content, we found that micro-influencers – those with fewer than 100,000 followers – are more persuasive when they tag the brand directly. Their audiences are psychologically closer to them. Followers often see them as relatable, reachable – even like friends. So, when micro-influencers include concrete cues, such as tagging a brand or describing a product in detail, it aligns with how their audience already processes the content: in a low-level, detail-oriented way. The message lands more naturally and feels more trustworthy.
In contrast, mega-influencers – social media celebrities – are more effective when they don't tag the brand, but simply show it. Think: posing with a Porsche rather than writing "sponsored by Porsche". Their audience admires them, but doesn’t perceive them as peers. Their followers process their content more abstractly, thinking about aspirational lifestyles or broad brand associations. So, a subtle or indirect brand reference aligns better with this high-level thinking. A soft sell feels more authentic and persuasive than a blatant plug.
This difference in perception ties directly into construal level theory, a well-established consumer psychology framework that explains how we interpret messages differently depending on psychological distance. That distance could relate to time (is the event happening now or in the future?), likelihood (is it hypothetical or certain?) or – in this case – social proximity.
So what does this mean for marketers?
Be more deliberate in how you engage with influencers. If you're working with micro-influencers, your creative brief should include clear tagging, naming and showcasing of your brand. These tactics are more likely to lead to engagement – likes, comments and ultimately sales.
With mega-influencers, however, subtlety pays off. A visually compelling post, where the brand appears naturally in the setting without being explicitly tagged, aligns better with how audiences process those messages. Channel strategy matters, too. When influencers post content to their own feeds, their voice and creative style give it authenticity. But if brands repost or share that content, especially when the influencer is well-known, it can add a sense of legitimacy.
Of course, all sponsored content must comply with advertising standards. But within those parameters, there's more strategic room than many brands realise. Too often, influencers at all levels follow the same format – tagging brands, repeating hashtags – when a more psychologically attuned approach could be more effective.
Ultimately, this research isn't about choosing between micro or mega influencers. It's about understanding how each works best – and designing your campaign to reflect that. A well-informed brief, rooted in psychology, can be the difference between a post people see and a post that sticks.
Dr Kirsten Cowan
Dr Kirsten Cowan is a Senior Lecturer in Marketing at the University of Edinburgh Business School, specialising in influencer marketing, consumer psychology and digital engagement.