Science Daily

ScienceDaily (Apr. 27, 2011) — Researchers at Brown University have found that specific genetic variations can predict how persistently people will believe advice they are given, even when it is contradicted by experience.

The story they tell in a paper in the April 20 issue of the Journal of Neuroscience is one of the byplay between two brain regions that have different takes on how incoming information should influence thinking. The prefrontal cortex (PFC), the executive area of the brain, considers and stores incoming instructions such as the advice of other people (e.g., "Don't sell those stocks.") The striatum, buried deeper in the brain, is where people process experience to learn what to do (e.g., "Those stocks often go up after I sell them.")

Researchers including Michael Frank, assistant professor of cognitive, linguistic, and psychological sciences at Brown, have studied the striatum intensely, but have been curious about the effect that the advice-influenced PFC has on its function. It turns out that in a learning task, people are guided more by advice at the start. Their genes determine how long it takes before they let the lessons of experience prevail.

"We are studying how maintaining instructions in the prefrontal cortex changes the way that the striatum works," said lead author Bradley Doll, a graduate student in Frank's lab. "It biases what people learn about the contingencies they are actually experiencing."

In their experiment, the researchers studied people with and without genetic variations that affected the activity of the neurotransmitter dopamine in the PFC and striatum. A variation in a gene called COMT that affects dopamine in the PFC, for example, helps people remember and work with advice.

People with a variation on the gene DARPP-32 that affects the response to dopamine in the stratium allowed people to learn more quickly from experience when no advice was given, but also made them more readily impressionable to the bias of the PFC when instruction was given. Like a "yes man" who is flexible to a fault, the striatum would give more weight to experiences that reinforced the PFC's belief, and less weight to experiences that contradicted it. Researchers call this confirmation bias, which is ubiquitous across many domains, such as astrology, politics, and even science.

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