Here's why we shouldn't be surprised that a Trump supporter attacked a reporter on Monday

A supporter of President Donald Trump violently attacked a BBC cameraman during a campaign rally on Monday night in El Paso, Texas, shortly after President Donald Trump whipped up a frenzy of hatred against the news media.

However, multiple scientific studies have shown that this shouldn't come as a surprise, as Trump rallies often lead to increases in violent behavior whenever they occur.

For instance, a study led by researchers at University of Pennsylvania that published last year found that cities that hosted Trump rallies experienced an average of 2.3 more assaults per day than what normally occurred on days when Trump didn't hold rallies.

Christopher Morrison, the study's lead author, told the New York Times last year that this violence was not a problem for rallies held by any other presidential candidates.

"It appeared to be a phenomenon that’s unique to Donald Trump’s rally," he said.

Similarly, another study published in the journal Social Psychological and Personality Science found that Trump supporters were much more likely than even supporters of other GOP candidates to display "group-based dominance and authoritarian aggression."

What this means, the study's authors write in their abstract, is that "Trump voters were uniquely driven by the desire to dominate out-group members in an aggressive manner."

Study author Jake Womick of the University of Missouri, Columbia, said last year that the 2016 Republican primary served as a perfect Petri dish that allowed researchers to isolate the most authoritarian Republican voters from the garden-variety authoritarian GOP voters.

"It was important to conduct our research in a way that facilitated comparisons within each political party," he said. "So, it was the Trump campaign’s early success that really provided a fruitful opportunity to formally test theoretical relationships between authoritarian personality traits and real-world behavior."

Trump in 2016 regularly encouraged his supporters to commit acts of violence against protesters, and at one point even encouraged fans to "knock the crap out of" hecklers while pledging to support their legal bills.