When Donald Trump steps up to a microphone, his words often make waves. Whether delivering a State of the Union address or sparring in a debate, his style is unmistakably his own. But what exactly sets him apart? A new study published in PNAS Nexus delves into this question, harnessing the power of machine learning to analyze decades of presidential speeches. What they found was striking. Trump’s speech is distinct in its use of direct and short sentences, bluntness, and frequent antagonism, marking a stark change in presidential communication.

A Closer Look at Presidential Speech Patterns

Led by Chenhao Tan, assistant professor at the University of Chicago and director of the Chicago Human+AI lab, the research team wanted to understand what exactly makes Trump’s rhetoric so unique and appealing to the masses (or at least half the voting population) and how his discourse compares to other presidents.

“We have been interested in how large language models can help us understand and quantify presidential discourse. One of the salient phenomena is the uniqueness of Trump’s speeches, and this work allows us to answer this question quantitatively,” Tan explained in an interview with PsyPost.

To build a comprehensive view, the team examined 35 debate transcripts, 67 State of the Union addresses, and 187 campaign speeches from U.S. presidents since 1960. By applying machine learning to these records, they developed a “uniqueness” metric to capture variations in language style. Using large language models — not all that different from the ones used by ChatGPT — they analyzed how each president’s choice of words differed not only from each other but from typical language patterns within their own political party.

Trump’s Style: Simple and Divisive Language

A striking feature that emerged from the data is Trump’s reliance on shorter, more direct sentences across all types of speeches. This trend, consistent from campaign rallies to formal addresses, stood in sharp contrast to the more nuanced and measured language often associated with his predecessors. Trump’s language, researchers found, leans toward simplicity and repetition. And this combination not only makes his message easy to digest but also amplifies its impact.

Trump’s words, however, do more than just simplify his message. The study introduced a divisiveness lexicon — a curated list of 178 words commonly used to belittle or discredit opponents, such as “corrupt,” “stupid,” and “disgrace.” The research team measured how frequently each president used these terms, and Trump’s rhetoric was shown to be particularly laden with them.

“Donald Trump’s political rhetoric is unique among modern presidents and is defined, in part, by his use of antagonistic language, particularly when directed at political opponents,” Tan said.

Indeed, Trump’s style even diverges significantly from other Republican presidents, suggesting that his rhetoric is not just a variation within party lines but an entirely distinct brand of discourse — one that is sure to be copied by others in the future.

His choice of words when discussing rivals often includes unique descriptors that frame his opponents in harshly negative terms. The researchers suggest this may contribute to an atmosphere of increased division in public discourse.

Beyond Party Lines: A Unique Rhetorical Approach

What the study highlights is that Trump’s confrontational language is not merely an expression of political differences but part of a larger trend toward personalization in politics. While other presidents have occasionally used emotionally charged language, Trump’s consistent emphasis on divisive terms and direct attacks on opponents made him a unique outlier.

“We were expecting Trump to not stand out in State of the Union speeches, since these speeches are more standard,” Tan noted. “However, he is still very different in these speeches. I was also surprised by how different Trump is from other Republicans.”

While the study may reveal some interesting details about Trump’s distinctive style of rhetoric, it also has limitations. Campaign speech data, for instance, was harder to obtain for earlier presidents, limiting comparisons across generations. Additionally, the study focused exclusively on public speeches, leaving out social media where presidents of all leanings tend to communicate very differently than in their official speeches.

Of course, even without the help of AI, many researchers came to similar conclusions in previous works. A UCLA working paper titled “Donald Trump’s Words” examined 99 of Trump’s speeches from 2015 to 2024, noting an increased use of violent language and a shift from economic topics to more divisive rhetoric. The study identified a form of “negative populism” characterized by frequent use of the pronoun “they” and pejorative terms for elites, suggesting that Trump’s language has become more confrontational over time.

Looking forward, Tan and his team hope their findings will help the public better understand the linguistic strategies presidents use. “We hope to help the public make informed decisions in democratic processes,” Tan said, pointing to a website they developed to help visualize these speech patterns: ChicagoHAI Election NLP.

The findings were reported in the journal PNAS Nexus.