Harris or Trump? The psychology behind how voters choose a candidate.

Election Day is almost here, and with razor-thin margins between Kamala Harris and Donald Trump, there are plenty of unknowns. That’s causing election anxiety among voters, candidates and political pundits alike: Will we get results on election night? Which way will key states — and counties — ultimately lean?

It really all comes down to our obsession with what voters are thinking; what, exactly, is going on through someone’s brain when that voter decides who to vote for — or even whether to vote at all? Believe it or not, political psychologists say it likely has less to do with what they’re thinking and a lot more with what they’re feeling.

Why do people vote at all?

When Nov. 5 rolls around, I could be doing any number of things. I could be relishing the fall weather and foliage; I could be working my way through Kelsey Weekman’s list of shows and movies I need to watch; I could be finishing my kid’s Halloween candy. Why, instead, do I and millions of other Americans choose to make our way to polling stations?

• It’s a form of self-expression. Keith Humphreys, a professor of psychiatry and behavioral sciences at Stanford University, says there’s no rational reason to vote for president. “There are over 100 million people who are going to vote, so the odds that your vote, my vote or any other individual vote will throw the election are essentially nil,” he tells Yahoo Life. Instead, Humphreys says the most likely reason people do it is as a form of self-expression. “It's the same reason why sometimes people look at protests and say, 'That's not going to persuade anybody.' But the point isn't persuading; it's expressing oneself.”

• It’s a habit. Christopher M. Federico, president of the International Society of Political Psychology, tells Yahoo Life that regular voters share a few characteristics: They tend to be well-educated and “have more societal resources,” and they tend to pay more attention to politics. But what really drives people to vote, Federico says, is that it’s just something they’ve gotten in the habit of doing. “You're more likely to do it the more you have done it in the past, and the more it feels like just something you do normally whenever there are elections,” Federico says of voting.

• Voters want to show solidarity — even with people they don’t know. “Ultimately, voting choices may not be driven by ‘what goes on in people’s heads’ as much as what makes them feel connected to a candidate or to others who are supporting a candidate,” Tania Israel, a psychologist and author of Facing the Fracture: How to Navigate the Challenges of Living in a Divided Nation, tells Yahoo Life. “In addition to alignment based on issues and values, they may be pulled to vote with their party to satisfy desire for belonging and group cohesion.” Federico says that in the last 30 years or so, partisan identity has become “stronger and more crystallized,” meaning that whether you identify as a Democrat or Republican is now an even stronger predictor of which candidate you will choose.

What about 'undecided voters'? What's going on in their heads when they finally make a decision?

According to reporting from the New York Times, just 3.7%, or 1.2 million people, were still truly undecided a few weeks ago. The Times analysis and that of the Harris and Trump campaigns describe these undecided voters as mostly younger voters, people of color and people without college degrees. So, when these undecided voters finally do make a decision, what sways them?

• They’re more likely to be influenced by emotion and by the people around them. Experts say voting is driven by emotion for most voters — and especially so for those who are undecided. “Nonpartisan, undecided or disengaged voters have less political knowledge and make their decisions later in the election cycle,” Israel says. “Their decisions may be based on candidate likability, influence of people around them and emotions such as hope and fear.”

• They’re more likely to decide based on whatever is going on in the news cycle when they cast their ballot. We all know about “October surprises,” where some major news breaks or an event happens at the last minute that has a big impact on an election. One memorable example is when then-FBI Director James Comey announced his investigation into Hillary Clinton’s emails; after that, her lead over Donald Trump in the 2016 presidential election narrowed. “In some cases, it's going to depend on what happens to be salient or at the top of the social agenda at a particular time,” Federico says. “What's going on in the last couple of news cycles right before an election [can] have a disproportionate effect among people who are in this position of being swing voters.”

Why do some people vote 'against their own interests'?

Many Americans are often accused of going “against their own interests” when it comes to a number of issues, from abortion rights to the economy. So why do they do it?

• They prioritize different interests than you do. “A lot of times when people say, ‘They're voting against their interests,’ it often just means they're voting against what you think is their interest,” Humphreys says. “But the way they look at it is, 'I don't really care about that; I care about this.'”

• They’re voting for moral or ideological interests, not economic interests. As political commentator Fareed Zakaria has observed, more research shows that many people are driven to vote for emotional, ideological and moral reasons rather than for monetary gain. Humphreys and Israel both point out that Republican and Democratic voters alike have been known to vote against their own economic interests, but whether that is a good or bad thing is often framed differently depending on which voter you’re talking about.

“I hear this question — most often from people on the political left — wondering why working-class people vote for Republicans, who are less likely to support unions and who tend to vote for tax breaks for wealthy Americans,” Israel says. “I often point out that, based on financial benefit alone, rich Democrats are also voting against their interests in favor of their values.”

Humphreys adds: “It's very common to denigrate working-class and poor people for 'voting against their interests.' But when rich people vote for higher taxes, everyone praises them and says, ‘How generous! How public-spirited!' Well, they just voted against their interests. Is that bad or is it good? When someone’s decision is aligned with our views, we likely think it’s laudable for them to vote consistent with their values — even if it goes against personal benefit.”