Researchers from LUISS Guido Carli University have published a new study that examines whether and how subtle shifts in language arousal might shape consumer engagement and the way it affects perceptions of influencers’ trustworthiness.

The study, published in the Journal of Marketing, is titled “How High-Arousal Language Shapes Micro Versus Macro Influencers’ Impact” and is authored by Giovanni Luca Cascio Rizzo, Francisco Villarroel Ordenes, Rumen Pozharliev, Matteo De Angelis, and Michele Costabile.

Companies increasingly turn to popular social media personalities to promote their brands, products, and services. The influencer marketing economy was valued at $21.1 billion in 2023, and more than 90% of brands enlist influencers with a small audience (micro) or with massive reach (macro) to connect with consumers and achieve a variety of marketing goals, from creating awareness to increasing sales.

Influencers have the potential to diffuse marketing messages and drive actions, but it is unclear why some of their posts get a lot of engagement while others do not. One possibility is that consumers are increasingly aware that influencers get paid to promote products, raising questions about their motives. Additionally, anecdotal evidence suggests that when influencers use high-arousal language (e.g., “it’s totally amazing!”), it leads to questions about their trustworthiness, which in turn leads consumers to engage less with the content.

Micro vs. macro influencers

Consumers typically see micro influencers as regular people, so if they say something like “this shake is AMAZING!” consumers believe they really are excited about that shake and just want to share this discovery with their friends and followers. This belief in their sincerity increases consumers’ trust in micro influencers.

However, macro influencers do not seem like regular people. Consumers know these influencers receive substantial sums to say positive things about products, so they judge their posts as an attempt to persuade, just like any other form of advertising. Believing that someone has manipulative intentions tends to decrease trust. Yet the negative effect of high arousal posts by macro influencers could be mitigated if their posts offer more informative (vs. commercial) content or if the messages are more balanced.

The researchers collaborated with an influencer marketing agency to acquire a sample of 20,923 Instagram-sponsored posts across industries from 1,376 U.S. influencers. They measured engagement as the sum of likes and comments that a post receives. To measure language arousal, they combine a words-based lexicon (including terms like “hectic,” “amazing,” and “sensational”) with paralanguage (i.e., exclamation marks, capitalization, and emojis).

They used 100,000 followers as the cutoff to classify micro versus macro influencers. To measure how informative the post goal would be, they validated a dictionary with words like “explore,” “read,” and “watch.” Finally, more than 100 controls were employed, including details about the influencer, the text and images shared, and so forth. Combining the field data and controlled experiments led to some compelling results.

The researchers note, “For micro influencers, we find that a 10% increase in arousal is associated with a 5.4% increase in engagement, on average. Recommending a product by saying, ‘It’s superb’ rather than ‘It’s great,’ for example, would attract 49 additional likes or comments. However, our findings raise concerns for macro influencers. If macro influencers increase arousal in their posts by 10%, it reduces consumer engagement by 8.4%, on average.”

However, macro influencers are not completely forbidden to express excitement. Since signaling an informative goal is associated with a 1.8% increase in engagement, they can share informative rather than commercial posts. Also, admitting some concerns or noting some negative aspects of the promoted product can help macro influencers seem more genuine, which also increases engagement.

Finally, macro influencers can use high-arousal language if they also include words that signal trustworthiness (e.g., “learn,” “help”). Thus, brands and macro influencers should collaborate to make sure their posts include phrases like “that’s what I learned about this incredible product” rather than “that’s how to use this incredible product.”

From Instagram to TikTok

These findings are not limited to Instagram. The study provides evidence that language arousal also plays a role in TikTok, with relevant influences on its young target market. “We gauge influencers’ vocal cues and the level of pitch in their voices as proxies for arousal. A higher pitched voice can signal greater arousal, and in line with our Instagram study, we determine that a higher pitch, and higher arousal, voice exerts a negative effect for macro influencers,” the researchers say.

This research underscores the importance of aligning social media posts and language arousal strategies depending on the type of influencer. For micro influencers, using high-arousal language authentically can enhance engagement, but macro influencers should focus more on informative content to maintain their trustworthiness.

Exploring the impact of language arousal on emerging platforms like TikTok is especially crucial when it comes to targeting young, savvy consumer audiences effectively. This research could be extended to politicians, scientists, and other high-profile individuals and the statements they issue.