Unless you've been living under a virtual rock, you've heard the news through social media — Chris Christie was kicked off an Amtrak quiet car for screaming on the phone, then stormed off yelling at his "secret service."

There's one big problem: A witness says the story's not quite true — or at least grossly mischaracterized (one part is certainly wrong — the governor gets his protection from State Police, not the Secret Service).

And another big problem: Once you've heard something, it's awfully difficult to unhear it, said Dan Cassino, a political science professor at Fairleigh Dickinson University.

"People are incredibly credible about things they see online," he said. "When we look at the research on this — people do not understand the correction. People ignore the correction. The corrections tend to increase their belief in the original erroneous story."

Wait, what was that last part? Correcting an error makes people more likely to believe it?

"What people glean from that second story is 'Ok, something about Christie shouting on the quiet car of Amtrak. I remember that was a thing.' It leads them to reinforce that initial impression," Cassino said.

A study titled "When Corrections Fail" by Brendan Nyhan, an assistant professor in the Department of Government at Dartmouth College, and Jason Reifler, an assistant professor at the Department of Political Science of Georgia State University, found the problem even worse among those with strong ideological beliefs.

In other words, the people most committed to absorbing the news were also the most likely to let their impressions from a first story solidify — and shut out anything else.

Here's how things went down Sunday:

At 11:13 a.m. Gawker.com published a story titled "Chris Christie, Sipping a Smoothie, Was Kicked Off an Amtrak Car For Screaming on His Phone." The story, quoting passenger Alexander Mann, said Christie "got on last minute yelling at his two secret service agents I think because of a seat mixup, sat down and immediately started making phone calls on the quiet car. After about 10 minutes the conductor asked him to stop or go to another car. He got up and walked out again yelling at his secret service. He was drinking a McDonald’s strawberry smoothie."

At 1:46 p.m., journalist Katie Klabusich Tweeted that she'd been right there with Christie, and Gawker got the story all wrong.

She went on to say Christie had apparently gotten on the wrong car, and when told it was the quiet car, told the person on the other end of the phone he had to go. He moved on to another car without incident, she said.

"Did he appear annoyed? Sure. Apparently having a s--t logistics day & someone f--led up. Was he screaming, causing a scene? Hardly."

Judging by her own left-leaning writing, Klabusich is no big Christie fan. In fact she tweeted later in the day there were better reasons to write critically about him — including his statements Sunday morning saying Black Lives Matter encourages the killing of police officers.

Gawker updated its story at about 4:30 p.m. to acknowledge Klabusich's account and a statement from the governor's spokespeople, saying that once Christie realized he was in the quiet car he "promptly left once he realized the serious nature of his mistake."

By then, the damage had been done. The matter had been widely re-reported in other media (including by NJ101.5, which also updated its post to acknowledge Klabusich's account and which wrote a new story reflecting it).

But there's that pesky problem, Cassino said — the correction, clarification or added context often doesn't help.

"The way to stop bad evidence from getting out there is to not report the bad evidence in the first place," he said. Once a matter has been reported, "it’s going to be very difficult" to set the record straight.

There are other factors in play in the Christie story, he said.

For one, the story sounds like something that could be true of New Jersey's boisterous and often brash governor.

Everybody remembers time in 2012 when a passerby made a snide remark about Christie's education policy passing the governor along the boardwalk, and a visibly angry governor turned back with, "You’re a real big shot. You’re a real big shot shooting your mouth off." TMZ distributed video of the incident.

Or what about the time Christie told a man who kept interrupting his about Hurricane Sandy recovery in Belmar to "sit down and shut up?"

"It confirms a lot of suspicious people already had about Christie," Cassino said. "'Yeah, OK, that sounds like Chris Christie — that makes sense.' It becomes incredibly hard to disconfirm that."

People's opinions about public figures aren't entirely based in facts, he said. 

"Once people hear something bad about Christie, They say 'OK, I like Christie a little bit less now,' and then they forget the reason why they like him a little bit less now," Cassino said.

And even if people are skeptical — Gawker's not a leading name in news, after all — when they see it shared by friends and loved ones they trust, they're inclined to believe it, Cassino said.

"Why does anybody do anything on social media? They want to brand themselves — individuals are branding themselves — by retweeting stories. They want to be first," he said.

It's a bigger problem for media, where being first can often mean the highest ratings, or the most pageviews.

"I think reporters recognize their responsibility to get the story right ... but it's getting harder and harder to do that," he said. "But it's not out of character for reporters to recognize that as a problem."

Ultimately, it may not have much impact on Christie's already basement-level polling figures in the Republican primary race for president, Cassino said. After all, people already have strong opinions of Christie one way or another.

But it's a sign of a trend Cassino finds troubling.

"We see absolutely no sign that people are becoming less credulous," Cassino said. People are becoming more likely to click on things, and to retweet things. We don't see that slowing down."

Messages by New Jersey 101.5 to Gawker and to the original story's author, Melissa Cronin, have not yet been returned.