In 2011, psychologists Jennifer Richeson and Maureen Craig made a dark and troubling prediction about the future of race relations in the United States. A few years earlier, the census had released demographic data that showed America was heading toward becoming a minority-majority country. By 2050, minorities would make up more than 50 percent of the population. Richeson and Craig worried that many white people would feel threatened by these demographic changes and act to neutralize the threat.

“If whites begin to perceive themselves as the numerical minority,” Craig and Richeson wrote in the journal Daedalus ”...the changing demographics may inspire white Americans to acknowledge that they do indeed have a racial group membership and that they should work on behalf of it.”

That’s what we saw over the weekend in Charlottesville: Alt-right and neo-Nazi demonstrators descended on the college town, chanting, “You will not replace us,” in reference to minorities and Jews. During the two days of marches, rallies, and counterprotests, violence broke out, three people were killed, and dozens more were injured.

The motivations of the white supremacist protesters couldn’t be clearer.

“White supremacist leaders and groups are tapping into that sense of vulnerability,” Richeson says in an email. And they see race relations as a zero-sum game.

Related The Charlottesville protests are white fragility in action

There are several lines of evidence converging on the idea that America is becoming a more hostile place for immigrants and outsiders — that Richeson and Craig’s prediction is becoming broadly true.

There’s also the case that Donald Trump himself — with his demeaning and dehumanizing rhetoric toward immigrants and his tepid response to the protests — is only adding fuel to this fire.

The case that it’s becoming more acceptable to show prejudice

Richeson and Craig have run experiments showing white participants who read about demographic change are — on average — more likely to respond to statements like, “I would rather work alongside people of my same ethnic origin,” in the affirmative. And other labs have found that a similar demographic cue increased support for Trump during the primaries. If anything, what these experiments show is white fear of losing status is an easy button to push. It’s not hard to find empirical evidence of overt racial prejudice: Another recent effort found many study participants are willing to admit they think Muslims and other minorities in the Unites States are “less evolved.”

Elsewhere, research does find that in the age of Trump — the age that started with an assertion that Mexicans were sending rapists to the US — it’s becoming more acceptable to be outwardly prejudiced.

The most recent: A working paper from the National Bureau of Economic Research asked if Trump’s election acted as a validation of anti-immigrant sentiment. If you could become president while stoking xenophobia — building walls, restricting immigration, trumpeting “America first,” etc. — would that make xenophobia more socially acceptable?

Turns out the answer is yes: More participants in the study became willing to openly donate money to an anti-immigrant organization after the election. (Before the election, too, more participants were more willing to openly donate if they were told Trump’s victory was assured in their state.)

“If Trump had not come on the scene, a lot of Americans would refuse to authorize a donation to an anti-immigrant organization unless they were promised anonymity,” Cass Sunstein wrote in a May column in Bloomberg. “But with Trump as president, people feel liberated.”

It’s only a preliminary bit of evidence, and behavior in an online experiment (as the authors of the NBER paper did) can’t easily be generalized to the real world. But work in psychology does support the idea that bad, prejudiced behavior really does trickle down.

How Trump can change perceptions about what’s socially acceptable in displaying prejudice

Some psychologists think Trump’s rhetoric and the rise of the alt-right movement that supported him are similarly encouraging people who already have prejudicial views to act upon those views.

“I don’t think Trump created new prejudices in people — not that quickly and not that broadly. What he did do is change people’s perceptions about what is okay and what is not okay,” University of Kansas psychologist Chris Crandall told me in March.

That’s essentially what the authors of the NBER paper found.

That paper tested participants before and after the election. Before the election, 34 percent of participants said they’d donate to the anti-immigrant organization when those donations were to be made public. About 54 percent said were willing to donate if the donations were kept private. The difference between the two shows there was a social stigma attached to donating to the group. After the election, that stigma lessened: 48 percent of people said they’d donate in the public conditions. (The experiment was more complicated than that. Read a more in-depth take here.)

Crandall has also found preliminary evidence that this is the case.

Last year, Crandall and his student Mark White asked 400 Trump and Clinton supporters to rate how normal it is to disparage members people of various marginalized groups — like the obese, Muslims, Mexican immigrants, and the disabled — both before the election and in the days after.

Both Clinton and Trump supporters were more likely to report that it was acceptable to discriminate against these groups after the election. For Trump to say the disparaging things he said during the campaign, and then be rewarded for them, sent a powerful sign.

“It took away the suppression from the very highly prejudiced people,” Crandall said. “And those are people acting.”

Crandall’s results are preliminary (i.e., not yet published in a journal), but they’re reflective of the established literature: Exposure to misbehavior simply makes it more acceptable.

Here’s one example. In 2004, sociologists Thomas Ford and Mark Ferguson found that exposure to a racist or sexist joke increased tolerance of further discrimination in people who held prejudicial views. Hearing the off-color joke, they write, “expands the bounds of appropriate conduct, creating a norm of tolerance of discrimination.”

Kids become more aggressive when they see aggressive adults. Adults do the same.

The lesson here: We learn about how to behave by watching others.

In the 1960s, Stanford psychologist Albert Bandura showed how easy it is to teach kids to act violently — by showing them an adult acting violently.

In this famous experiment, Bandura showed young children — between 3 and 6 years old — a video of an adult wailing on an inflatable “bobo doll” (see in the video below). Other children in the study did not see an adult behaving aggressively to the doll.

And sure enough, the kids who saw the aggressive behavior were more aggressive themselves when playing with the doll later on.

It’s a simple experiment with a simple conclusion: As humans, even at an early age, we learn what’s socially acceptable by watching other people.

After the election, we witnessed an unsettling number of brazen hate crimes and vandalism against Muslim and Jewish institutions. Again: It’s hard to directly link these crimes to the charged political climate. But as with Bandura’s experiment, there’s evidence that social norms against prejudice change when people in power start talking and behaving badly.

And that they have. Trump constantly dog whistles, uses dehumanizing language against, and stokes fears of minorities and outsiders. And the most extreme white nationalists are getting the message.

“Indeed, David Duke and the KKK have made it clear that they see Trump's goals to ‘make American great again’ as the same as their goals to ‘take their county back,’”

Trump might not directly support this interpretation. But it’s hard to deny, as Vox’s German Lopez argues, that Trump is pandering to those with a white nationalist worldview.