Performance usually improves with practice, but not if training is a rotten time. A new study shows that people’s ability to identify noises declines when the sounds are paired with putrid smells—a phenomenon that may allow our brain to detect danger more quickly.

In a study published in May in Nature Neuroscience, neurobiologist Rony Paz of the Weizmann Institute of Science in Rehovot, Israel, and his colleagues exposed volunteers to auditory tones presented with no other stimuli or immediately followed by a rancid or fragrant odor delivered through a nose mask.

After this training session, the subjects were played a series of tone pairs—notes of very similar or identical frequencies—and asked whether the tones in each pair were the same or different. The subjects became better at distinguishing tones similar to those that had been presented alone or with a pleasant scent. But their ability to discriminate tones resembling those linked to a foul stench worsened—an effect that persisted one day later.

Such sensory confusion could be an adaptation that allows our defenses to rapidly mobilize. “This likely made sense in our evolutionary past,” Paz says. “If you’ve previously heard the sound of a lion attacking, your survival might depend on a similar noise sounding the same to you.”

3 Comments

1. 1. Mythusmage 11:41 PM 12/9/11

   There is a simple explanation, bad smells are distracting. Distractions make it hard to learn.

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2. 2. Marc Levesque 07:00 PM 12/10/11

   I'm guessing that the idea that you need to "retreat" from a bad smell is a pretty solid evolutionary story.
   
   But after reading only the above free access text I'm not following what the quoted researcher means.
   
   It seems to me that if you play tones to a subject that are closely associated to a tone that was previously associated with a bad smell, then the subjects drive to retreat tends to override the subjects incentive to discriminate between tones.

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3. 3. SnowLeopard 11:34 PM 12/10/11

   I agree, bottom line is that bad smell is a distraction, and distractions make learning hard.
   
   If the volunteers were instead asked to distinguish between smells in a noisy environment, the results would probably be worse than the same test taken in a quiet place.

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