We Know We're Lazy Thinkers

man-thinking — While we may take mental shortcuts, new research suggests we are at least somewhat aware of our laziness. (Image credit: Alexander Kirch, Shutterstock)

We may be lazy thinkers, but at least we're not deluded about it.

People know when they've used mental shortcuts to solve a problem, a new study shows, and they're usually less confident about those results.

"Although we might be cognitive misers, we are not happy fools who blindly answer erroneous questions without realizing it," the authors write in the paper.

Studies, like those done by Nobel-prize winning economist Daniel Kahnemen, have shown that people are cognitive misers, meaning that the brain tends to seek solutions to problems that take the least mental effort. In practice, that means people answer easy questions in place of hard ones.

But in the past, researchers didn't know if this mental substitution was conscious or unconscious.

To find out, researchers Wim De Neys and his colleagues from the National Center for Scientific Research (CNRS) in France asked 248 French university students a simple question:

"A bat and ball together cost $1.10. The bat costs $1 more than the ball. How much does the ball cost?"

Without thinking much, most people say the bat costs $1 and the ball costs 10 cents. But that's wrong. (The right answer, that the ball costs 5 cents and the bat costs $1.05, requires some subtraction).

Consistent with past research, only about 21 percent of the students gave the correct answer, probably because their brains were avoiding the mental effort of doing math and assuming the bat costs $1 total, not $1 more than the ball.

The researchers also asked students a similar question, but without the relative price statement: A magazine and a banana together cost $2.90. The magazine costs $2. How much does the banana cost?

This time, 98 percent of the students got the right answer, probably because they were not tempted to shortcut the actual subtraction and go with their gut.

And when asked, the students said they were much more confident about the magazine and banana answer than they were about the bat and ball one.

That suggests the students knew on some level they had taken a mental shortcut that reduced the reliability of their answer, the researchers write.

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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.