Why Quick Thinking Leads to Bad Decisions

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When people make hasty decisions, they tend to make more mistakes. Now, a new study on monkeys explains why: Brain cells become hypersensitive to new information, even bad information, making us likelier to draw faulty conclusions.

"When we try to do things too quickly, we tend to make more errors and then when we slow down we tend to be more accurate," said study co-author Richard Heitz, a neuroscientist at Vanderbilt University. "Your brain sees things differently when you're placed into a situation where you have to make snap decisions."

To explain the phenomenon, Heitz and his colleagues trained two macaque monkeys to play a game in which they had to pick out the letter L in a sea of Ts or vice versa.

Before each round, a colored circle flashed on the screen to indicate whether the macaques would be rewarded for speed or accuracy.

In the speed test, the monkeys only received a tasty squirt of juice if they found the right letter quickly. In the accuracy test, monkeys got a squirt of juice no matter how long it took for them to find the right letter, but had a "timeout" if they made a mistake.

The researchers then recorded the activity of neurons in the brain region responsible for higher reasoning, the prefrontal cortex.

When the monkeys learned the next trial would be a speed test, the electrical activity from those neurons increased even before starting the test, like cars revving their engines in preparation for a race. During the speed trials, the team found that neurons responsible for visual processing fired more strongly when the monkeys indicated they had found the right letter. The neurons were more sensitive, as if the objects on the screen actually appeared brighter to the brain when it had to make decisions quickly, Heitz told LiveScience.

That higher sensitivity may sound good, but "because they're amplified, you may react to them as if they're more important than they actually are," meaning even faulty answers could be seen as the correct ones, he said.

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Tia Ghose
Tia Ghose
Editor-in-Chief (Premium)

Tia is the editor-in-chief (premium) and was formerly managing editor and senior writer for Live Science. Her work has appeared in Scientific American, Wired.com, Science News and other outlets. She holds a master's degree in bioengineering from the University of Washington, a graduate certificate in science writing from UC Santa Cruz and a bachelor's degree in mechanical engineering from the University of Texas at Austin. Tia was part of a team at the Milwaukee Journal Sentinel that published the Empty Cradles series on preterm births, which won multiple awards, including the 2012 Casey Medal for Meritorious Journalism.