STEVE INSKEEP, HOST:
Let's expand the list of suspects in the 2016 election. We know about Russian propaganda and social media troll farms. We've had congressional hearings into how social media giants, like Facebook, were manipulated to destabilize the country. Few investigators though have focused on us. Why did so many ordinary people apparently believe what the Russians told them? NPR's social science correspondent Shankar Vedantam has some research on that. Hi, Shankar.
SHANKAR VEDANTAM, BYLINE: Hey, Steve.
INSKEEP: So this is a reminder that when there's a con artist, someone gets conned - they may allow themselves to be conned.
VEDANTAM: That's exactly right, Steve. It was deception, but it wasn't simple. Contrary to what partisans on both sides think, voters are not idiots. They don't like being manipulated. So the question is, why were they manipulated? I was talking to Cailin O'Connor, at the University of California, Irvine. She's a mathematician and philosopher and co-author of the book "The Misinformation Age: How False Beliefs Spread." O'Connor told me about one very interesting technique used by these propagandists.
CAILIN O'CONNOR: They made Black Lives Matter groups. They made gun rights groups. They made LGBTQ groups. They made an animal lovers group weirdly.
VEDANTAM: So all over the political spectrum, from left to right - now that seems crazy except that it was based on a psychological insight. If you show someone you are on their side on an issue that is close to their heart, it becomes much easier to nudge them on other issues.
O'CONNOR: It seemed that what they were doing was trying to use shared beliefs and values to ground trust with people. And then once they grounded that trust, they could use these different pages to try to drive polarization within the United States.
INSKEEP: We're hearing that the propagandists took advantage of tribalism here, aren't we?
VEDANTAM: That's right.
INSKEEP: They're saying, I'm part of the Black Lives Matter tribe. You should listen to me - or some other tribe.
VEDANTAM: That's exactly right. Now, what makes this devilish, Steve, is that this is how all of us learn nearly everything we know. We first figure out whom to trust. And then we learn from those people. So none of us can go out and learn everything about the world on our own. So the only way we can function is to rely on what O'Connor calls the testimony of others. Children trust their parents. Students trust teachers. Listeners trust NPR. And once you have gained that trust, you can exploit it.
INSKEEP: Well, how do we guard against that then?
VEDANTAM: Well, in many ways, it's very difficult to guard against this because, in some ways, we are all vulnerable to believing those who seem to think like we do. Once I can convince you that I care about your issues, that I share your views, you become much more vulnerable to my manipulation. It's very hard to see how you could eliminate this without also eliminating all the useful things we learn from social trust.
INSKEEP: I suppose it just means we have to spend a lot more work figuring out what is true - not only online but in our day-to-day interactions in life.
VEDANTAM: And also to be skeptical about people who seem to agree with us.
INSKEEP: Shankar, it seems like you're agreeing with me here, but I'm really kind of beginning to doubt what you say.
VEDANTAM: (Laughter) I think that's right, Steve.
INSKEEP: NPR's Shankar Vedantam - or so he says - he is a social science correspondent for NPR News, also the host of a podcast that explores the unseen patterns in human behavior. You can trust him. It's called Hidden Brain.
(SOUNDBITE OF TIM ENGELHARDT'S "SAWTOOTH ORCHESTRA") Transcript provided by NPR, Copyright NPR.