The Capitol siege last week came as a shock to many Americans who had no idea how intense election denialism, and to an extent white supremacy, has been brewing in American society.

Why it matters: Research shows that this type of mob thinking has become stronger and more frequent as more news and information has moved online. Experts also suggest President Trump played a key role in weaponizing human tendencies to distrust people who look or act different.

The way people determine what's true and what's false, especially online, relies heavily on people trusting sources of information over substance, according to experts.

• Rather than trying to fact-check everything, experts say, people use heuristics — a kind of mental shortcut for fact-checking that can rely on cues like whether the information is coming from people they think they can trust.
• "We can't slow everything down and analyze the world because we don't have those resources," says Gaurav Suri, an experimental psychologist and computational neuroscientist at San Francisco State University. As a result, "the people around us are important heuristics."

Racial identity is often a key heuristic that helps people interpret facts, says Britt Paris, an assistant professor of library and information science at Rutgers University.

• "A lot of time, the way people interpret things has more to do with pre-existing beliefs and backgrounds — the ways they were taught to critically analyze and interpret information — than necessarily looking for facts or evidence," she says.
• "Humans' natural tendency is to split up into groups, tribes of people who usually look and act like you, and try our best to out compete other groups, often violently," says Pete Ditto, a psychological science professor at the University of California, Irvine.

Trump has became an important heuristic and authoritative source of information for huge swaths of the population, Ditto said.

• "He has weaponized our natural tendency to look to others, particularly who seem to look and act like us, to understand the world," Ditto said. "Trump’s power comes from his willingness to weaponize some of the darker aspects of human nature."

The rapid digitization of news, expedited by the pandemic, means more people are relying less on personally fact-checking information, and more on using heuristics to determine what's true or false.

• "Where possible, we try to decrease our effort and increase the automated nature of our thinking, and heuristics are an important tool to do this with," says Suri.
• "Now because the internet, we have all of these people giving us heuristics."
• A Columbia University study found that more access to information through social platforms has decreased the likelihood that individuals will fact-check information. Instead, people are more likely to believe information as being true if it comes from a source they trust, regardless of whether it even sounds plausible.

What to watch: Research shows that people's attitudes toward some scientific issues are similarly determined more by who they identify with rather than what they know.

• This means that people will use similar heuristics to make factual determinations not just about the election, but also about issues that are equally important to society, like the efficacy of vaccines and the reality of climate change.

The bottom line: "We think that we we are rational creatures who analyze everything in front of us. The truth is, we don't hardly do that ever," says Suri.