Strong Convictions Can Blind Us to Info That Contradicts Our Beliefs

By Janice Wood
March 18th, 2023
Medically reviewed by Paul Sietes, MD.

When people are highly confident in a decision or a belief, they only take in information that confirms their decision, failing to process information that contradicts it, according to a new brain imaging study.

The study helps explain the neural processes that contribute to the confirmation bias entrenched in most people’s thought processes, according to researchers at University College London in England.

“We were interested in the cognitive and neural mechanisms causing people to ignore information that contradicts their beliefs, a phenomenon known as confirmation bias. For example, climate change skeptics might ignore scientific evidence that indicates the existence of global warming,” said Max Rollwage, lead author and a Ph.D. candidate at the Wellcome Centre for Human Neuroimaging at UCL and Max Planck UCL Centre for Computational Psychiatry & Ageing Research.

“While psychologists have long known about this bias, the underlying mechanisms were not yet understood,” he continued. “Our study found that our brains become blind to contrary evidence when we are highly confident, which might explain why we don’t change our minds in light of new information.”

For the study, 75 participants were asked to conduct a simple task: They had to judge whether a cloud of dots was moving to the left or right side of a computer screen. They then had to give a confidence rating of how certain they were in their response on a sliding scale from 50 percent sure to 100 percent certain, the researcher explained.

After this initial decision, they were shown the moving dots again and asked to make a final decision. The information was made even clearer the second time and could help participants change their minds if they had initially made a mistake, the researcher noted.

However, the study found that when people were confident in their initial decision, they rarely used this new information to correct their errors.

Additionally, 25 of the participants were asked to complete the experiment in a magnetoencephalography (MEG) brain scanner. The researchers monitored their brain activity as they processed the motion of the dots.

Based on this brain activity, the researchers evaluated the degree to which participants processed the newly presented information.

When people were not very confident in their initial choice, they integrated the new evidence accurately, the study found. However, when participants were highly confident in their initial choice, their brains were practically blind to information that contradicted their decision, but remained sensitive to information that confirmed their choice, the researchers said.

The researchers add that in real-world scenarios where people are more motivated to stand by their beliefs, the effect may be even stronger.

“Confirmation bias is often investigated in scenarios that involve complex decisions about issues such as politics. However, the complexity of such opinions makes it difficult to disentangle the various contributing factors to the bias, such as wanting to maintain self-consistency with our friends or social group,” said Dr. Steve Fleming, senior author.

“By using simple perceptual tasks, we were able to minimize such motivational or social influences and pin down drivers of altered evidence processing that contribute to confirmation bias,” he said.

In a previous, related study, the research team found that people who hold radical political views — at either end of the political spectrum — aren’t as good as moderates at knowing when they’re wrong, even about something unrelated to politics.

Because the neural pathways involved in making a perceptual decision are well understood in such simple tasks, this makes it possible for researchers to monitor the relevant brain processes involved, according to the researchers. They add that understanding the mechanism that causes confirmation bias may help in developing interventions that could reduce people’s blindness to contradictory information.

“These results are especially exciting to me, as a detailed understanding of the neural mechanisms behind confirmation bias opens up opportunities for developing evidence-based interventions,” Rollwage said. “For instance, the role of inaccurate confidence in promoting confirmation bias indicates that training people to boost their self-awareness may help them to make better decisions.”

The study was published in Nature Communications.

Source: University College London

Janice Wood is a long-time writer and editor who began working at a daily newspaper before graduating from college. She has worked at a variety of newspapers, magazines and websites, covering everything from aviation to finance to healthcare.