How do lie detectors work?

Experts explain how lie detectors work, what happens in the brain when we tell lies and how accurate polygraph tests are.

How accurate are lie detector tests?

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  • In a 2002 study, 60% of people were found to lie at least once during a 10-minute conversation, with most people telling an average of two or three lies. The polygraph, invented in the early 1920s, detects physiological responses to lying (such as elevated heart and respiratory rates as well as spiked in blood pressure.
  • Three main areas of the brain are stimulated during deception - the frontal lobe, the limbic system, and the temporal lobe.
  • According to the American Polygraph Association (made up largely of polygraph examiners), the estimated accuracy of a polygraph can be up to 87%.
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NASA finds water on sunlit moon surface for first time

Water may be far more abundant on the lunar surface than previously thought.

Lunar surface

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  • Scientists have long thought that water exists on the lunar surface, but it wasn't until 2018 that ice was first discovered on the moon.
  • A study published Monday used NASA's Stratospheric Observatory for Infrared Astronomy to confirm the presence of molecular water..
  • A second study suggests that shadowy regions on the lunar surface may also contain more ice than previously thought.
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6 things science is revealing about your skin and hygiene

Unfortunately, "less is better" is not a catchy marketing slogan.

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  • For his new book, "Clean: The New Science of Skin," physician James Hamblin didn't shower for five years.
  • Soap is a relatively simple concoction; you're mostly paying for marketing and scent.
  • While hygiene is important, especially during a pandemic, Hamblin argues that we're cleaning too much.
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Coffee and green tea may lower death risk for some adults

Tea and coffee have known health benefits, but now we know they can work together.


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Surprising Science
  • A new study finds drinking large amounts of coffee and tea lowers the risk of death in some adults by nearly two thirds.
  • This is the first study to suggest the known benefits of these drinks are additive.
  • The findings are great, but only directly apply to certain people.
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Why San Francisco felt like the set of a sci-fi flick

But most city dwellers weren't seeing the science — they were seeing something out of Blade Runner.

Brittany Hosea-Small / AFP / Getty Images
Surprising Science

On Sept. 9, many West Coast residents looked out their windows and witnessed a post-apocalyptic landscape: silhouetted cars, buildings and people bathed in an overpowering orange light that looked like a jacked-up sunset.

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AI reveals the Sahara actually has millions of trees

A study finds 1.8 billion trees and shrubs in the Sahara desert.

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Surprising Science
  • AI analysis of satellite images sees trees and shrubs where human eyes can't.
  • At the western edge of the Sahara is more significant vegetation than previously suspected.
  • Machine learning trained to recognize trees completed the detailed study in hours.
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