Ariely points to a study he and his colleagues performed, where they looked at people’s brains as they told lies over and over again. “We saw that over time, their brains reacted less and less and less to lies, they were less sensitized,” he says.

“We start believing our own lies,” Ariely tells CNBC Make It.

Ariely also says human brains are good at remembering general statements or ideas, but they are not so good at remembering where the information came from, or sometimes even whether it is true.

It’s a psychological concept called source monitoring: “When our brain gets a message, we don’t separate very well the statement and where it came from, and we can often get very confused … and not remember,” says Ariely. “It’s why fake news works so well.”

Then, confirmation bias can kick in — people will focus on information and data that supports what they believe or want to be true, says Ariely.

…A good cause also makes a lie easier to buy.

“It’s a lot easier to do bad things when you think that you’re doing it for a really good cause,” says Deeter.

…“The reality is that data just doesn’t sit in our minds as much as stories do,” Ariely says in the documentary. ”[S]tories have emotions that data doesn’t. And emotions get people to do all kinds of things, good and bad.

HBO’s ‘The Inventor’: How Elizabeth Holmes fooled people about Theranos

hmmm