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Scientists turn optimists into realists with a zap of a magnet

September 24, 2012|By Jon Bardin
  • In a file photo, a researcher shows off a TMS device. In a new study, researchers used TMS to eliminate the "good news/bad news bias," in which people value good news over bad news.
In a file photo, a researcher shows off a TMS device. In a new study, researchers… (Park Ji-Hwan / AFP/Getty…)

Humans have a well-known bias toward good news, often at the expense of reality. This bias, which social scientists call the "good news/bad news effect," has been blamed for events as diverse as the recent financial crisis, our often-poor preparation for natural disasters and, more generally, the pervasive human trait of optimism.

In a new study, however, scientists have figured out a way to dampen that optimism: By turning off a certain part of the brain believed to play a role in how we balance good and bad news.

The "good news/bad news effect" works like this: Imagine you received multiple pieces of information, say about the likelihood that you will develop fatal cancer in your lifetime. You might like to think that you will choose which opinion to believe based on the trustworthiness of the source (perhaps one is a specialist, another a general practitioner).

But research has consistently shown that your choice will be biased by who has delivered the most positive news. In short, you will trust good news over bad.

Research also has shown that a brain area called the inferior frontal gyrus (IFG) is somehow involved in managing this trait. We all have two IFGs, one on the left side of our brain and one on the right.

Studies in people have shown that the left IFG is involved in keeping track of information that is better than expected -- that optimistic cancer prognosis, for example. The right IFG, on the other hand, does the same thing with bad news. Studies of optimism have suggested that an asymmetry in how well these areas function might explain why we bias good news over bad, but the idea had been difficult to test.

Now a group of scientists from the U.S., England and Germany has figured out a way to bring optimists back down to Earth by applying magnetic pulses to the IFG. The technique, called transcranial magnetic stimulation (TMS), is non-invasive and safe, and can be used to either make an area active or keep it from becoming active. When scientists used it on the left IFG to temporarily reduce the area's function, bias toward good news dissipated. The subjects suddenly became more rational.

The researchers tested this by asking people to estimate how likely certain events were -- such as being the victim of a robbery or being diagnosed with cancer. They then told them the real frequency of the event and asked them again to estimate the likelihood of that event.

When the scientists applied TMS to the left IFG -- the one that is believed to be involved with "good news" updating -- the subjects incorporated bad news as much as good news, adjusting their estimates based on the information received, not on whether it was optimistic or pessimistic.

But when they applied the same pulse to the right IFG, or to a non-involved placebo area, the subjects continued to bias good news just as they had before. Because stimulating the right IFG did not increase the weighting of good news, the scientists say, the left IFG might serve as a brake on the right IFG, preventing us from incorporating bad news appropriately. The results were published Monday in the Proceedings of the National Academy of Sciences.

Why would people be so biased toward good news? The researchers suggest that it might be an adaptive trait, making us more likely to explore our environment for food, and also making us less likely to get stressed out or anxious.

So while scientists might be getting closer to understanding the complicated biology of optimism -- and have identified one brain area that clearly plays a role-the researchers also have a message for you:

You might not want to try this at home.

Return to the Science Now blog.

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