People will apparently ignore conflicting evidence and double down on their own beliefs, even if it costs them financially.

The phenomenon was recently demonstrated in a study led by Stefano Palminteri from École Normale Supérieure and published in PLOS Computational Biology. A group of 20 people took part – admittedly a small sample size, but the findings are interesting nonetheless.

"[W]hen presented with new evidence, people tend to discard information that suggests they have made a mistake," said the researchers. "This selective neglect of useful information may have adaptive value, by increasing self-confidence and self-esteem."

The study involved two tasks. In the first, the volunteers were asked to pick one of two made-up symbols multiple times. Each symbol had a different financial reward, in the form of points, and over time the volunteers learned which symbols were most valuable. The volunteers earned a bigger payoff the more points they accrued.

The experiment was then repeated, but this time the volunteers were told the values of both symbols. Interestingly, they continued to pick the same symbols they chose in the first experiment, regardless of financial reward.

“When considering factual and counterfactual learning together, it appears that people tend to preferentially take into account information that confirms their current choice,” the researchers wrote.

This adds a new twist to confirmation bias, where people only listen to evidence that supports their existing beliefs. The findings show that people do this even if they know they will lose out as a result. Hey, that sounds familiar. Did somebody say Brexit?

"Brexit will be lead to several socio-economics outcomes," Palminteri told IFLScience. "If ever these outcomes are negative, our findings and our model predict that Brexiters will not learn a lesson from them."

Previous studies have suggested that people believe in conspiracy theories because they want to feel unique. One study involving more than 1,000 people showed that those who want to be unique are more likely to believe a particular theory. Another found that irrational beliefs are driven by a desire to stick out from the crowd.

"The novelty of our study is that we show that it applies also to a 'concrete' reward and punishment learning situation," said Palminteri. 

In the age of climate change denial, Trump, Brexit, and so on, it seems conspiracy theories are more relevant than ever. Ultimately, it’s just extremely hard to make people change their minds. If someone really believes that humans aren’t causing global warming, or leaving a union will have negative consequences, you probably won’t be able to convince them otherwise – even if you prove it will cost them.

(H/T: New Scientist)