In the aftermath of the 2016 presidential election, communities and groups including the Southern Poverty Law Center have observed a wave of hate crimes and harassment taking place across the country.

The incidents have prompted many to wonder whether the contentious nature of the campaign and the emboldening of the extreme right that helped Donald Trump win the presidency have altered social norms.

New Wharton research indicates that, in at least one case, it did.

Wharton business economics and public policy professor Corinne Low and Wharton doctoral student Jennie Huang are researching the differences in the communications styles of men and women, and how their negotiation tactics change depending on which gender they are interacting with.

Over a series lab experiments, conducted before and after Election Day, they observed a striking result: Post-election, study participants were less cooperative, more likely to use adversarial strategies and less likely to reach an agreement with a partner. The effect was driven by an increase in men acting more aggressively toward women.

“We didn’t know Trump was going to be elected; we didn’t set out to study Trump’s election,” Low says. “We had the [lab experiment] sessions on the calendar already, and post-election, we looked at the data and saw that people’s behavior was profoundly different.”

Aggression or Cooperation?

The lab sessions involved men and women, most of whom were Penn students, playing a “Battle of the Sexes” game in which they had to divide $20 with a partner. In some cases, participants were told the gender of their partner; in other cases, that information wasn’t provided. Each round had only two options for splitting the money: One partner would get $15 and the other would get $5, or vice versa; or, if they couldn’t agree, both would walk away with zero.

“It appears that whatever Trump represents – that rhetorical style, that presence – seems to have consequences for other people’s behaviors.”

Participants – 232 people in the pre-election sessions in early and late October and 154 in the post-election sessions that ran from November 14-16 — went through multiple rounds of negotiating. In about half the rounds, they were able to use an online chat tool, which allowed the researchers to observe the level of aggression or cooperation displayed in those conversations.

The paper also notes that at the time of the second set of lab experiments, participants may have been reeling from the election or from reports that a group of African-American Penn students had been targeted in a racist group messaging account.

Before the election, men were less likely to use aggressive negotiation tactics when they knew their partner was a woman – a pattern that could be classified as chivalry or a kind of “benevolent sexism,” Low says. “This tells us that if women’s outcomes are dependent on men’s whims, those whims could change. We could see the turning of the tide, and suddenly men are more aggressive.”

While an uptick in sexual harassment would be among the most serious manifestations of that kind of change, Low notes that there are also plenty of potential implications for our everyday lives — in and outside the office. When study participants became more aggressive, for example, they left more money on the table because they couldn’t reach a compromise. Payoffs went down by an average of a dollar after the election. “People’s behavior changed in a way that was less productive,” she says.

Previous research suggests that political and world events can affect people’s behavior, including their displays of generosity, cooperation and fairness. “It appears that whatever Trump represents – that rhetorical style, that presence – seems to have consequences for other people’s behaviors,” Low says. Many human rights and social justice groups have observed a spike in anti-Semitism and hate crimes following the election. “That’s anecdotal evidence that words matter,” Low says, “and what we have is lab evidence that this matters.”