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Why does nails on a chalkboard give you chills?
Why does nails on a chalkboard give you chills?β
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β "HΓΆrflΓ€che" (modified) is part of the public domain. |
We're particularly sensitive to these frequencies because the shape of the outer ear boosts sound waves in that range. Why? Well, that's where we don't have all the answers, but we do have a theory.
As it turns out, the sound waves of nails on a chalkboard are strikingly similar to that of a chimpanzee scream. Both fall between 2,000-5,000 Hz.
β Top: Nature | Bottom: Perception & Psychophysicsβ |
From an evolutionary standpoint, it makes sense that our ears would naturally resonate with the frequency of a chimpanzee scream. If we can hear our fellow chimpanzee call out to let us know about a potential threat, we can escape.
This primal theory gained more credibility when a 2012 fMRI study found that sounds in this range (specifically testing nails on a chalkboard) activated the amygdala, the part of the brain responsible for triggering our fight-or-flight fear response.
So the next time you hear nails being scraped on a chalkboard, you can be grateful that the only threat you face is auditory discomfort and not a lion threatening to eat you and your chimpanzee family.
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π Wikipedia article of the week
βLace cardβ
"A lace card (also called a whoopee card, ventilator card, flyswatter card, or IBM doily[citation needed]) is a punched card with all holes punched. They were mainly used as practical jokes to cause disruption in card readers. Card readers tended to jam when a lace card was inserted, as the resulting card had insufficient structural integrity to avoid buckling inside the mechanism."
π Catch up on other curious questions
- βWhy do flies rub their legs together?ββ
- βWhat causes the "butterflies in your stomach" feeling?ββ
- βHow does lightning work?ββ
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