Tag Archives: Beliefs

Good bad choice.

Dopamine is the key allowing our brains to change beliefs — short-term ones, at least

Researchers have captured the first images of a brain changing its beliefs.

Good bad choice.

Image credits Fathromi Ramdlon.

It’s not easy being a brain. Among a host of other very complex tasks, this lump of gray matter is also responsible for accurately representing the surrounding world. Keeping these beliefs as true to reality as possible is literally a matter of life and death. As such, brains come equipped with mechanisms that allow them to ‘update’ their beliefs.

That tidbit likely comes as a surprise to anyone who has ever seen a comment section, however. Experience has thought us that most people hate having their beliefs challenged, and will defend them with a fury. So, what exactly makes a brain change a set of beliefs it holds? Well, a team of UK researchers was also very curious to know, so they set about studying the brains of participants as they changed (simple) beliefs.

It’s dope(amine)

“We form beliefs about the world based on the information we get from our senses. When our sensory perceptions surprise us, it could mean that the world has changed and this might cause us to update our beliefs,” explains lead researcher Matthew Nour, from the University College London and Kings College London.

“For example, if we are told that it’s sunny outside, and then we hear raindrops, then we modify our belief.”

Previous research has suggested that the neurotransmitter dopamine is related to the process of updating representations — at least in rodent brains. However, there was no direct evidence that human brains work through the same process, especially since it was very difficult to reliably measure dopamine functions in living people.

For the study, the team used a fMRI (functional magnetic resonance imaging) machine to peer into the brains of people as they were changing short-term beliefs and later tied these readings to the participants’ dopamine functions.

Volunteers were asked to respond to a series of sounds and images — some of which were meant to surprise. These latter ones, the team’s hypothesis went, would cause the participants to change their beliefs about the task environment, since ‘a surprise’ is something the brain didn’t expect, i.e. didn’t conform to its current beliefs. They used the fMRI scanner to measure changes in brain activity while these beliefs were changing, and measured activity in the dopamine system using PET scans — Positron Emission Tomography, which uses a small amount of radioactive tracer to measure dopamine receptors in the brain.

“We found that two key brain areas of the dopamine system (the midbrain and striatum) appear to be more active when a person updates their beliefs about the world, and this activity is related to measures of dopamine function in these regions,” Nour explains.

This is the first study to establish a direct link between dopamine activity and the process of updating beliefs in humans; the neurotransmitter has previously been linked to learning and the brain’s reward pathway.

Such findings could have several implications, especially pertaining to drugs or medicine that have a powerful impact on dopamine levels in the brain. Cocaine and amphetamine use, for example, “increase[s] brain dopamine release and can cause significant changes in our perceptions and beliefs about the surrounding world,” the team explains.

The paper could also improve our understanding of the several psychiatric disorders have also been tied to abnormal dopamine function. For example, in the case of schizophrenia, abnormal dopamine activity might impair the brain’s ability to update beliefs from outside input, potentially contributing to symptoms such as delusion.

Still, the findings are far from conclusive right now. The team looked at the brain activity of people changing simple beliefs about the causes of their perceptions. However, it points the way for future research into how the brain supports the formation of more general beliefs.

The paper “Dopaminergic basis for signaling belief updates, but not surprise, and the link to paranoia” has been published in the journal Proceedings of the National Academy of Sciences.


Feeback, not evidence, makes us confident we’re right — even when we’re not

We tend to only look at the most recent feedback when gauging our own levels of competence, a new paper reports. The findings can help explain why people or groups tend to stick to their beliefs even in the face of overwhelming evidence to the contrary.


Image credits Mohamed Hassan.

A team of researchers from the University of California, Berkeley (UC) thinks that feedback — rather than hard evidence — is what makes people feel certain of their beliefs when learning something new, or when trying to make a decision. In other words, people’s beliefs tend to be reinforced by the positive or negative reactions they receive in response to an opinion, task, or interaction, not by logic, reasoning, or data.

“Yes but you see, I’m right”

“If you think you know a lot about something, even though you don’t, you’re less likely to be curious enough to explore the topic further, and will fail to learn how little you know,” said study lead author Louis Marti, a Ph.D. student in psychology at UC Berkeley.

“If you use a crazy theory to make a correct prediction a couple of times, you can get stuck in that belief and may not be as interested in gathering more information,” adds study senior author Celeste Kidd, an assistant professor of psychology at UC Berkeley.

This dynamic is very pervasive, the team writes, playing out in every area of our lives — from how we interact with family, friends, or coworkers, to our consumption of news, social media, and the echo chambers that form around us. It’s actually quite bad news, as this feedback-based reinforcement pattern has a profound effect on how we handle and integrate new information into our belief systems. It’s especially active in the case of information that challenges our worldview, and can limit our intellectual horizons, the team explains.

It can also help explain why some people are easily duped by charlatans.

For the study, the team worked with over 500 adult subjects recruited through Amazon’s Mechanical Turk crowd-sourcing platform. Participants were placed in front of a computer screen displaying different combinations of colored shapes, and asked to identify which shapes qualify as a “Daxxy”.

If you don’t know what a Daxxy is, fret not — that was the whole point. Daxxies are make-believe objects that the team pulled out of a top hat somewhere, specifically for this experiment. Participants weren’t told what a Daxxy is, neither were they clued in as to what any of its defining characteristics were. The experiment aimed to force the participants to make blind guesses, and see how their choices evolve over time.

In the end, the researchers used these patterns of choice to see what influences people’s confidence in their knowledge or beliefs while learning.

Participants were told whether they picked right or wrong on each try, but not why their answer was correct or not. After each guess, they reported on whether or not they were certain of their answer. By the end of the experiment, the team reports, a trend was already evident: the subjects consistently based their certainty on whether they had correctly identified a Daxxy during the last four or five guesses, not all the information they had gathered throughout the trial.

“What we found interesting is that they could get the first 19 guesses in a row wrong, but if they got the last five right, they felt very confident,” Marti said. “It’s not that they weren’t paying attention, they were learning what a Daxxy was, but they weren’t using most of what they learned to inform their certainty.”

By contrast, Marti says, learners should base their certainty on observations made throughout the learning process — but not discount feedback either.

“If your goal is to arrive at the truth, the strategy of using your most recent feedback, rather than all of the data you’ve accumulated, is not a great tactic,” he said.

The paper “Certainty Is Primarily Determined by Past Performance During Concept Learning” has been published in the journal Open Mind.