The nose knows: Humans can smell fear

By Celeste Tholen Rosenlof | Posted - Nov 14th, 2012 @ 9:09pm



SALT LAKE CITY — Without saying a word or using gestures, one human can tell if another is in fear, a new study says.

Researcher Gün Semin at the Utrecht University in the Netherlands conducted a series of experiments determining that humans can actually smell fear or disgust from the sweat of another.

The new study, released in this month’s issue of Psychological Science, had men watch the horror movie "The Shining" and distasteful clips of MTV's "Jackass." The men were closely instructed not to eat strong-smelling foods, drink alcohol, smoke, exercise heavily or wear scented hygiene and personal-care products for two days before the study so researchers could collect clean samples of their sweat.

How does our brain process smell?
  • Airborne molecules of a volatile substance give off oderants
  • Air current sweep oderants up through nostrils and into the olfactory epithelium
  • Oderants stimulate olfactory receptor cells
  • Olfactory receptor cells send electrical impulse to the olfactory bulb
  • An impulse is then sent to the glomerulus, which passes information onto the brain
  • The brain interprets the 'oderant patterns' into what we know as scent
Info: How Stuff Works

After researchers collected the samples, 36 women were exposed to them while taking a visual monitoring test. The study authors found that across the board, women who were exposed to the “fear” samples would become wide-eyed in response. When exposed to the samples taken from disgusted men, however, women would respond with a grimace.

Women were chosen, authors said, because previous research has shown females are more sensitive to the scent of males than the opposite.

The significance, study authors say, is that the chemicals in sweat create an emotional synchrony between sender and receiver. They said this might help explain crowd behavior.

"Our research suggests that emotional chemo-signals can be potential contributors to emotional contagion in situations involving dense crowds," Semin wrote.

Further, it is evidence that humans communicate outside of language and visual cues.

"These findings are contrary to the commonly accepted assumption that human communication runs exclusively via language or visual channels," Semin wrote.

This study builds on previous studies that show romantic partners are able to smell some emotions of their partners.

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Celeste Tholen Rosenlof

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