How the brain combines our opinions with online reviews
The human brain updates personal judgments using social advice by weighting both opinions according to how certain they are.
Source
Social Information Is Integrated into Value and Confidence Judgments According to Its Reliability
What they did
We recruited 22 participants, ultimately analyzing 18 participants who completed an fMRI experiment. In the first phase, participants rated their interest in 210 products and noted how sure they were of each choice. Later, in the scanner, they saw the items again alongside genuine online reviews before submitting a second preference rating and confidence score.
What they found
Participants updated their valuations to match online ratings more when they felt unsure about their initial judgment or when the online rating was backed by a larger pool of reviewers. Brain scans showed that a region called the ventromedial prefrontal cortex represented both liking and confidence along a spatial gradient. Additionally, activity in the dorsomedial prefrontal cortex tracked how much a participant updated their opinion on each trial, showing greater activity in individuals who successfully resisted peer influence.
The limits
What it doesn't show
The study relied on a small sample of 18 participants, which limits the generalizability of the findings to broader populations. Because the task simulated passive shopping decisions, it does not show how social information is integrated during high-stakes choices or in real-world social interactions. Furthermore, the fMRI results show correlation, meaning they cannot prove that the active brain areas are causally necessary for Bayesian integration.
Key terms
- Bayesian integration
- A statistical method where current beliefs are updated using new evidence based on the reliability of both sources.
- Ventromedial prefrontal cortex
- A brain region situated in the front-middle area that is heavily involved in processing value and making decisions.
- Dorsomedial prefrontal cortex
- A brain area located above the ventromedial prefrontal cortex that is associated with social cognition and monitoring changes in beliefs.
- Kullback-Leibler divergence
- A mathematical tool used to measure the difference or shift between two probability distributions.
- Social conformity
- The tendency of individuals to align their opinions, beliefs, and behaviors with those of a group.
- Precision
- A statistical concept representing the inverse of variance, used to quantify how certain or reliable an information source is.
Flashcards
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Quiz yourself
According to the Bayesian framework of social integration, under what conditions will individuals update their beliefs the most toward a social consensus?
Common questions
How did the researchers define uncertainty in this study?
Uncertainty was captured in two ways: first, by asking participants how confident they felt in their own initial ratings, and second, by looking at the number of reviews supporting the online consensus.
What is the spatial gradient discovered in the prefrontal cortex?
The researchers found that value estimates (how much someone liked a product) were processed in the more ventral (lower) parts of the medial prefrontal cortex, while confidence estimates were processed in the more dorsal (upper) parts.
Why did people with higher brain activity in the dorsomedial prefrontal cortex resist social influence more?
The dorsomedial prefrontal cortex tracks differences between your own opinion and the group's. Individuals who paid more attention to these mismatches may have been better equipped to preserve their original opinions.
How were participants motivated to take the ratings seriously?
They were told that one product would be chosen randomly at the end of the experiment to be given to them, and that products they rated higher had a better chance of being selected.
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