These are strange, unsettling times. And for the past several months, I’ve been asking psychologists variations on a basic question: What research can best help us reckon with uncomfortable social and political realities — like the rise of Donald Trump, the widening partisan split, the divisiveness that comes with multiculturalism?

More than ever before, people of different ideological backgrounds seem to live in separate universes. One example: In the days after the inauguration, social scientists showed participants photos of Trump’s inaugural crowd and Obama’s. Those who had voted for Trump were more likely to say Trump had the larger turnout, despite obvious differences in the photos that demonstrated otherwise.

Psychology can help explain these tense times. Old theories, like motivated reasoning, are more clearly true than ever before. And new work has confirmed that humanity still contains its same base instincts of the prehistoric era.

Consider this a primer. Here are seven essential lessons on the hidden forces shaping our views and actions in the Trump era.

If you think I missed something that should be on this list, send me an email: brian@vox.com

1) Motivated reasoning: rooting for a team changes your perception of the world

One of the key psychological concepts for understanding politics is also one of the oldest.

It’s called motivated cognition, or motivated reasoning. And there’s no clearer example than in a paper published way back in the 1950s.

The Dartmouth versus Princeton football game of November 1951 was, by all accounts, brutal. One Princeton player broke his nose. One Dartmouth player broke his leg.

Princeton students blamed the Dartmouth team for instigating. The Dartmouth paper accused Princeton’s. In the contentious debates that ensued about "who started it," psychologists at the two schools united to answer this question: Why did each school have such a different understanding of what happened?

In the weeks after the Princeton-Dartmouth game, the psychologists Albert Hastorf and Hadley Cantril ran a very simple test. Their findings would become the classic example of a concept called motivated reasoning: Our tendency to come to conclusions we’re already favored to believe.

When they asked students at each of their universities to watch video highlights from the game, 90 percent of the Princeton students said it was Dartmouth that instigated the rough play. Princeton students were also twice as likely to call penalties on Dartmouth than their own team. The majority of Dartmouth students, on the other hand, said both sides were to blame for the rough play in the game, and called a similar number of penalties for both teams. Hastorf and Cantril’s conclusion wasn’t that one set of fans was lying. It’s that being a fan fundamentally changes the way you perceive the game.

The lesson is simple: “People are more likely to arrive at conclusions … that they want to arrive at,” the psychologist Ziva Kunda wrote in a seminal 1990 paper, making the case that motivated reasoning is real and pervasive.

And there’s plenty of proof of it today. When Gallup polled Americans the week before and the week after the presidential election, Democrats and Republicans flipped their perceptions of the economy. But nothing had actually changed about the economy. What changed was which team was winning.

Motivated reasoning plays into why people from poor communities were willing to vote for Trump, a candidate whose party is keen to pare back the social safety net and has a proposed a health care bill that will lead to millions more becoming uninsured.

One crucial thing to know about motivated reasoning is that you often don’t realize you’re doing it. We automatically have an easier time remembering information that fits our world views. We’re simply quicker to recognize information that confirms what we already know, which makes us blind to facts that discount it.

None of this psychology is to suggest that people who engage in motivated reasoning are stupid. No, they are just human. For example, a lot of evangelicals voted for Trump because of the simple fact he was the Republican presidential candidate, despite having reason to dismiss him after the Access Hollywood tape where he bragged about sexual assault leaked. Republican is the political team they play on. And that allowed them to find ways to justify their support.

Motivated reasoning can affect anyone, and liberals do it, too. Some are retweeting “rogue” federal Twitter accounts that have no verification that they’re indeed written by disgruntled federal staffers. At the Atlantic, Robinson Meyer asked Brooke Binkowski, the head of fact-checking website Snopes.com, if “fake news” targeted toward liberals is on the rise. “Of course yes!” she said. (See some examples here.)

Let’s remember that.

2) People who are the most well-informed about politics are often the most stubborn about it

If a group of people have the same, solid grounding in the same facts about politics, then everyone should come to the same conclusions, right? Wrong.

“Study after study has shown that this assumption is not supported by the data,” says Dietram Scheufele, who studies science communication at the University of Wisconsin.

In fact, studies show the exact opposite: The more informed people are about politics, the more likely they are to be stubborn about political issues.

This concept is related to motivated reasoning, but it’s important enough to warrant its own consideration. It shows how motivated reasoning becomes especially stubborn and ugly when it comes to politics.

“People are using their reason to be socially competent actors,” says Dan Kahan, a psychologist at Yale, and one of the leading experts on this phenomenon. Put another way: We have a lot of pressure to live up to our groups’ expectations. And the smarter we are, the more we put our brain power to use for that end.

In his studies, Kahan will often give participants different kinds of math problems.

When the problem is about nonpolitical issues — like figuring out the whether a drug is effective — people tend to use their math skills to solve it. But when they’re evaluating something political — let’s say, the effectiveness of gun control measures — the trend is that the better participants are at math, the more partisan they are in their responses.

“Partisans with weak math skills were 25 percentage points likelier to get the answer right when it fit their ideology,” Ezra Klein explained in a profile of Kahan’s work. “Partisans with strong math skills were 45 percentage points likelier to get the answer right when it fit their ideology. The smarter the person is, the dumber politics can make them.”

And it’s not just for math problems: Kahan finds that Republicans who have higher levels of science knowledge are more stubborn when it comes to questions on climate change. The pattern is consistent: The more information we have, the more we bend it to serve our political aims. That’s why the current debate over “fake news” is a bit misguided: It’s not the case that if only people had perfectly true information, everyone would suddenly agree.

So think of that when you hear politicians or pundits talk shop: They know a lot about politics, but they’re bending what they know to fall in line with their political goals. And they probably don’t realize they are doing this and can feel confident in their partisan conclusions because they feel well informed.

3) Evolution has left us with an “immune system” for uncomfortable thoughts.

There’s a reason why we engage in motivated reasoning, a reason why facts often don’t matter: evolution.

Critical thinking and reasoning skills evolved because they made it easier to cooperate in groups, Elizabeth Kolbert explains in a recent New Yorker piece. We’ve since adapted these skills to make breakthroughs in topics like science and math. But when pressed, we default to using our powers of mind to get along with our groups.

Psychologists theorize that’s because our partisan identities get mixed up with our personal identities. Which would mean that an attack on our strongly held beliefs is an attack on the self.

“The brain’s primary responsibility is to take care of the body, to protect the body,” Jonas Kaplan, a psychologist at the University of Southern California, says. “The psychological self is the brain’s extension of that. When our self feels attacked, our [brain is] going to bring to bear the same defenses that it has for protecting the body.”

It’s like we have an immune system for uncomfortable thoughts.

Recently, Kaplan has found more evidence that we tend to take political attacks personally. In a study recently published in Scientific Reports, he and collaborators took 40 self-avowed liberals who reported having “deep convictions,” put them inside in a functional MRI scanner, and started challenging their beliefs. Then they watched which parts of the participants’ brains lit up.

Their conclusion: When the participants were challenged on strongly held beliefs, there was more activation in the parts of the brain that are thought to correspond with self-identity and negative emotions.

4) The argument that’s most convincing to you is not convincing to your ideological opponents

There’s a dynamic playing out in the current health care debate, and in health care debates of ages past. Liberals make their arguments for expanding coverage in terms of equality and fairness (i.e., everyone should have a right to health care), while conservatives make their case grounded in self-determination (i.e., the government shouldn’t tell me how to live) and fiscal security (i.e., paying for health care will bankrupt us all).

According to a psychological theory called “moral foundations,” it’s no surprise that these arguments fail spectacularly at changing minds.

Moral foundations is the idea that people have stable, gut-level morals that influence their worldview. The liberal moral foundations include equality, fairness, and protection of the vulnerable. Conservative moral foundations favor in-group loyalty, moral purity, and respect for authority.

These moral foundations are believed to be somewhat consistent over our lifetimes, and they may have a biological basis as well. (There’s some fascinating experimental work that shows that conservatives are more excited — as measured by perspiration — by negative or alarming images.)

Moral foundations explain why messages highlighting equality and fairness resonate with liberals and why more patriotic messages like “make America great again” get some conservative hearts pumping.

The thing is, we often don’t realize that people have moral foundations different than our own.

When we engage in political debates, we all tend to overrate the power of arguments we find personally convincing — and wrongly think the other side will be swayed.

On gun control, for instance, liberals are persuaded by stats like, "No other developed country in the world has nearly the same rate of gun violence as does America." And they think other people will find this compelling, too.

Conservatives, meanwhile, often go to this formulation: "The only way to stop a bad guy with a gun is a good guy with a gun."

What both sides fail to understand is that they're arguing a point that their opponents may be inherently deaf to.

In a study, psychologists Robb Willer and Matthew Feinberg had around 200 conservative and liberal study participants write essays to sway political opponents on the acceptance of gay marriage or to make English the official language of the United States.

Almost all the participants made the same mistake.

Only 9 percent of the liberals in the study made arguments that reflected conservative moral principles. Only 8 percent of the conservative made arguments that had a chance of swaying a liberal.

No wonder why it’s so hard to change another person’s mind.

5) Many people seem unashamed of their prejudices

Nour Kteily, a psychologist at Northwestern University, conducts research on one of the darkest, most ancient, and most disturbing mental programs encoded into our minds: dehumanization, the ability to see fellow men and women as less than human.

Psychologists are no strangers to this subject. But the prevailing wisdom has been that most people are not willing to admit to having prejudice against others.

Wrong.

In Kteily’s studies, participants — typically groups of mostly white Americans — are shown this (scientifically inaccurate) image of a human ancestor slowly learning how to stand on two legs and become fully human. And then they are told to rate members of different groups — such as Muslims, Americans, and Swedes — on how evolved they are on a scale of 0 to 100.

Many people in these studies give members of other groups a perfect score, 100, fully human. But many others give others scores putting them closer to animals.

With the “Ascent of Man” tool, Kteily and collaborators Emile Bruneau, Adam Waytz, and Sarah Cotterill found that, on average, Americans rate other Americans as being highly evolved, with an average score in the 90s. But disturbingly, many also rated Muslims, Mexican immigrants, and Arabs as less evolved.

“We typically see scores that average 75, 76,” for Muslims, Kteily says. And about a quarter of study participants will rate Muslims on a score of 60 or below.

People who dehumanize are more likely to blame Muslims as a whole for the actions of a few perpetrators. They are more likely to support policies restricting the immigration of Arabs to the United States. People who dehumanize low-status or marginalized groups also score higher on a measure called “social dominance orientation,” meaning that they favor inequality among groups in society, with some groups dominating others.

And, in a study, blatant dehumanization of Muslims and Mexican immigrants was strongly correlated with Trump support — and the correlation was stronger for Trump than any of the other Republican candidates.

6) Fear has a powerful influence on political opinion

In the lead-up to the 2016 election, fear seemed to be everywhere.

After the terrorist attacks in Paris and Brussels, Donald Trump and conservative allies redoubled their promises to make borders more secure and ban whole religious groups from the country. Trump’s rhetoric often underscored an us-versus-them mentality — illegal immigrants from Mexico were raping our people; countries like China were destroying us on trade.

A lot of new psychological evidence suggests that stoking people’s racial and demographic fears helped Donald Trump win votes.

Negative, scary information is almost always more sticky and memorable than positive information

One of those studies explored the question of what white people feel when they are reminded that minorities will eventually be the majority. And it found that they begin to feel less warm toward members of other races. A more recent experiment showed that reminding white people of this trend increased support for Trump.

What this doesn’t mean is that all white people harbor extreme racial animus. It means fear is an all-too-easy button for politicians to press. We fear unthinkingly. It directs our actions. And it nudges us to believe the person who says he will vanquish our fears.

“People who think of themselves as not prejudiced (and liberal) demonstrate these threat effects,” says Jennifer Richeson, a leading researcher on racial bias.

There’s also this fact to contend with: Negative, scary information is almost always more sticky and memorable than positive information. “Negative events capture attention and information processing more readily, elicit strong emotions more easily, and are more memorable,” psychologists Daniel Fessler, Anne Pisor, and Colin Holbrook, wrote in a recent study.

They showed participants 14 “plausible but false” statements, like “Kale contains thallium, a toxic heavy metal, that the plant absorbs from soil.” Some of the statements, like the one above, implied a warning (“don’t eat Kale!”), others were positive, like “Eating carrots results in significantly improved vision.”

Participants often found the threatening statements more credible than the non-threatening one, and this was especially true among more conservative participants (and especially true for social conservatives, as compared to fiscal conservative). This is not because conservatives are more gullible. It’s because they tend to be more vigilant.

Savvy politicians understand this, and craft messages that stoke that innate vigilance (whether concern is warranted or not). It’s hard to blame people for being afraid of threats. It’s just in our nature. But you can blame politicians who prey on it.

Other researchers have arrived at similar findings.

Last year, Willer and Feinberg published a paper that found that racial attitudes predicted support for the conservative Tea Party movement. In one study, they showed participants an artificially darkened portrait of President Barack Obama — to maximally remind participants he’s African American. “White participants shown the darkened photo were more likely to report they supported the Tea Party relative to a control condition,” the study reported.

Similarly, they found that reminding study participants about a coming minority-majority America made them more likely to support the Tea Party platform.

7) Social norms that protect against prejudice can change in the blink of an eye

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

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

“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 says.

Recently 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 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.”

These 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.”

Further reading: a few more psychology concepts to understand our political age

There’s still many more questions psychologists want to answer about this political age. It’s not enough to define problems in prejudice and reasoning, psychologists are also seeking to solve them. But many answers are still out of reach.

Psychology has been called “the hardest science” because the human mind comes with so many messy inconsistencies that even the top researchers can get tangled up in. It can take decades to establish a psychological theory, and in just months, new evidence can tear it down. Despite its flaws, psychology is still the best scientific tool we have to understand how human behavior shapes the world.

There are a lot more concepts in psychology that can help us understand what’s going on in the world of politics. Here are a few more worth learning about.