# What do fingernails on blackboards do?
**URL:** https://boards.straightdope.com/t/what-do-fingernails-on-blackboards-do/67495
**Category:** Factual Questions
**Created:** [June 4, 2001, 7:13am UTC](https://boards.straightdope.com/t/what-do-fingernails-on-blackboards-do/67495 "2001-06-04T07:13:38Z")
**Posts on this page:** 20
**Page:** 1
### Author:  [@partly\_warmer](https://boards.straightdope.com/u/partly_warmer)
#### Post date: [June 4, 2001, 7:13am UTC](https://boards.straightdope.com/t/what-do-fingernails-on-blackboards-do/67495/1 "2001-06-04T07:13:38Z")
The sound of fingernails scraped across a blackboard doesn’t bother me at all. From people’s behavior and their descriptions afterward, I guess that their reaction is the same as the one that tearing of ball cotton (such as that used packing the top of vitamin bottles) causes me. For me it is the sensation in my fingers, rather than the sound.
What is it that affects the nervous system this way? Why doesn’t everyone behave the same?
Also, I once knew someone who behaved this same way when glass was ground under foot on concrete. Does anybody else have these unusual sensitivities?
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### Author:  [@DMC](https://boards.straightdope.com/u/DMC)
#### Post date: [June 4, 2001, 7:27am UTC](https://boards.straightdope.com/t/what-do-fingernails-on-blackboards-do/67495/2 "2001-06-04T07:27:04Z")
I believe it’s due to the fact that there is a variance in the vibrations produced, which causes several different tones that aren’t harmonically related.
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### Author:  [@Raziel](https://boards.straightdope.com/u/Raziel)
#### Post date: [June 4, 2001, 7:28am UTC](https://boards.straightdope.com/t/what-do-fingernails-on-blackboards-do/67495/3 "2001-06-04T07:28:16Z")
I get the chills every time someone writes with a colored marker…and it makes that _icky_ vibrating noise.
Yuck.
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### Author:  [@Tequila\_Mockingbird](https://boards.straightdope.com/u/Tequila_Mockingbird)
#### Post date: [June 4, 2001, 7:29am UTC](https://boards.straightdope.com/t/what-do-fingernails-on-blackboards-do/67495/4 "2001-06-04T07:29:51Z")
For me it’s styrofoam squeaking as it’s rubbed against cardboard. Fingernails on a chalkboard don’t bother me at all. But that styrofoam, doesn’t matter if I am the one pulling it out the box or not, makes me cringe with my eyes closed.
As for your other questions, I have no idea and look forward to other responses on this.
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### Author:  [@Linear\_Crack](https://boards.straightdope.com/u/Linear_Crack)
#### Post date: [June 4, 2001, 7:36am UTC](https://boards.straightdope.com/t/what-do-fingernails-on-blackboards-do/67495/5 "2001-06-04T07:36:07Z")
> [@](#):
>
> \*Originally posted by partly\_warmer \*
> \*\*
> What is it that affects the nervous system this way? Why doesn’t everyone behave the same?
> \*\*
[This](http://faculty.washington.edu/chudler/news29.html) site might be a good place to start. #3
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### Author:  [@Astroboy14](https://boards.straightdope.com/u/Astroboy14)
#### Post date: [June 4, 2001, 7:46am UTC](https://boards.straightdope.com/t/what-do-fingernails-on-blackboards-do/67495/6 "2001-06-04T07:46:58Z")
For me it’s the sound of someone filing their fingernail… yeeeeahhh!! **shudder**
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### Author:  [@TheLoadedDog](https://boards.straightdope.com/u/TheLoadedDog)
#### Post date: [June 4, 2001, 8:20am UTC](https://boards.straightdope.com/t/what-do-fingernails-on-blackboards-do/67495/7 "2001-06-04T08:20:29Z")
IIRC, I heard that this kind of stuff is _learned_. I remember reading somewhere that very small children (\<4) don’t distinguish between nice smells and foul smells as the rest of us do, ie. the smell of feces isn’t recognised as “bad” until the kids are toilet trained and learn the meaning of “dirty”. Maybe the same goes for blackboard thing. Maybe some of us just “were away from school that particular day” and never learned to be bothered by it.
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### Author:  [@handy](https://boards.straightdope.com/u/handy)
#### Post date: [June 4, 2001, 3:00pm UTC](https://boards.straightdope.com/t/what-do-fingernails-on-blackboards-do/67495/8 "2001-06-04T15:00:50Z")
Being deaf, it doesn’t have any effect on me either but seeeing someone chew aluminum foil does.
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### Author:  [@DJScherr](https://boards.straightdope.com/u/DJScherr)
#### Post date: [June 4, 2001, 4:44pm UTC](https://boards.straightdope.com/t/what-do-fingernails-on-blackboards-do/67495/9 "2001-06-04T16:44:27Z")
The fingernails on blackboards don’t irritate me… what bugs me to no end is people chomping on ice cubes. Makes me cringe everytime I hear it.
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### Author:  [@Chronos](https://boards.straightdope.com/u/Chronos)
#### Post date: [June 4, 2001, 5:00pm UTC](https://boards.straightdope.com/t/what-do-fingernails-on-blackboards-do/67495/10 "2001-06-04T17:00:24Z")
Personally, it’s not the sound itself that bothers me, it’s the feel of my own fingers on the blackboard. Unfortunately, the sound always reminds me of the feeling, so I cringe in sympathy.
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### Author:  [@friedo](https://boards.straightdope.com/u/friedo)
#### Post date: [June 4, 2001, 5:21pm UTC](https://boards.straightdope.com/t/what-do-fingernails-on-blackboards-do/67495/11 "2001-06-04T17:21:16Z")
When I was in grammar school, our music teacher has a wooden block with five evenly space chalk-holding devices. This was used to draw five paralell horizontal lines on the blackboard. I will leave it to the music aficionados to haplessly guess what they were for.
One day we replaced the chalk with thumb tacks.
It changed me forever.
Ohhh, the screeching, the screeching. Whimper.
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### Author:  [@Jman](https://boards.straightdope.com/u/Jman)
#### Post date: [June 4, 2001, 5:34pm UTC](https://boards.straightdope.com/t/what-do-fingernails-on-blackboards-do/67495/12 "2001-06-04T17:34:11Z")
For me, it’s the feeling of rubbing a paper napkin (especially those with smooth surfaces) between my fingers. AHHHH… The cotton bal tearing isn’t good either. The other thing that makes me shiver is feeling or scraping unfinished porcelain.
Jman
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### Author:  [@TheLoadedDog](https://boards.straightdope.com/u/TheLoadedDog)
#### Post date: [June 4, 2001, 9:28pm UTC](https://boards.straightdope.com/t/what-do-fingernails-on-blackboards-do/67495/13 "2001-06-04T21:28:05Z")
> [@](#):
>
> \*Originally posted by Chronos \*
> \*\*Personally, it’s not the sound itself that bothers me, it’s the feel of my own fingers on the blackboard. Unfortunately, the sound always reminds me of the feeling, so I cringe in sympathy. \*\*
Now that you mention it, I think I feel the same way. It’s touch, not sound. The sound thing only used to happen to me whenever the teacher’s chalk would slip and let loose a sharp, but thankfully short, _SCREEEEEE_.
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### Author:  [@partly\_warmer](https://boards.straightdope.com/u/partly_warmer)
#### Post date: [June 4, 2001, 10:12pm UTC](https://boards.straightdope.com/t/what-do-fingernails-on-blackboards-do/67495/14 "2001-06-04T22:12:42Z")
> [@](#):
>
> \*Originally posted by Linear Crack \*
> \*\*
>
> > [@](#):
> >
> > \*Originally posted by partly\_warmer \*
> > \*\*
> > What is it that affects the nervous system this way? Why doesn’t everyone behave the same?
> > \*\*
>
> [This](http://faculty.washington.edu/chudler/news29.html) site might be a good place to start. #3
> \*\*
“Apparently, the nail/chalkboard sound is very similar to the warning cry of some monkeys. The authors of the “Chilling Sound” paper suggested that it is possible, just possible, that the response to these annoying sounds is some “leftover” reflex from a common primate ancestor”
That’s very interesting, but the theory doesn’t seem to cover all the things people have talked about here:
1. Some people (such as me) react to the vibration, not the sound, and aren’t affected this way by any sound.
2. People don’t seem to be affected by the same sound. What good would a warning sound be if not every monkey (person) was equally affected? Maybe a monkey’s warning covers a whole range of sounds?
3. That common primate ancestor must have used a completely different sound (or had different hearing), since I’ve never yet run in terror at the sound of chimps in the zoo. Elephants can be pretty scary, tho.
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### Author:  [@bughunter](https://boards.straightdope.com/u/bughunter)
#### Post date: [June 4, 2001, 10:42pm UTC](https://boards.straightdope.com/t/what-do-fingernails-on-blackboards-do/67495/15 "2001-06-04T22:42:18Z")
I see now that the specific stimulus varies from person to person, but that the general reaction is the same.
For me it’s attempting to write with a cedar pencil that has the lead broken such that only wood makes contact with the paper. This is the only thing that causes the skin on my back to crawl and my jaws to clench and my whole face to scrunch up like someone just dumped a bucket of ice water down the front of my shorts.
And yes, even imagining the stimulus is enough to evoke the reaction. \>_shudder_\<
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### Author:  [@Montfort](https://boards.straightdope.com/u/Montfort)
#### Post date: [June 5, 2001, 2:16pm UTC](https://boards.straightdope.com/t/what-do-fingernails-on-blackboards-do/67495/16 "2001-06-05T14:16:48Z")
Personally, I find the fingernails-on-chalkboard phenomenon annoying, but no more so than finding out that my roomate left the light on in the living room at night. It doesn’t bother me.
However, the lack of a conclusive answer inspires me to bump this in the hopes that Cecil and his minions see it and contemplate it for future columns.
After he figures out the Toynbee/Kubick plates, of course.
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### Author:  [@beefymeg](https://boards.straightdope.com/u/beefymeg)
#### Post date: [June 5, 2001, 3:51pm UTC](https://boards.straightdope.com/t/what-do-fingernails-on-blackboards-do/67495/17 "2001-06-05T15:51:43Z")
For me, it’s the sound of someone peeling paper off a popsicle. EEEWWWRRRGGG! I can’t even type it!
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### Author:  [@Skywatcher](https://boards.straightdope.com/u/Skywatcher)
#### Post date: [June 5, 2001, 5:07pm UTC](https://boards.straightdope.com/t/what-do-fingernails-on-blackboards-do/67495/18 "2001-06-05T17:07:48Z")
I have two, and they involve latex balloons. Rubbing one (squeek, squeek, squeek) and inflating one with a helium tank (high-pitched whoosh, sometimes followed with a loud bang).
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### Author:  [@Doubleclick](https://boards.straightdope.com/u/Doubleclick)
#### Post date: [June 5, 2001, 5:26pm UTC](https://boards.straightdope.com/t/what-do-fingernails-on-blackboards-do/67495/19 "2001-06-05T17:26:41Z")
All of mine seem to involve high pitch/frequency sounds:
Nails on chalkboard
Styrofoam being rubbed together
dog whistles
TV sets
florescent tube lights (God bless the man who invented the halogen lights in my office!)
The cotton thing send chills to, but only when put between my teeth…and then I believe that to be a tactile thing.
Good call on the foil situation Handy. (Love that name) Nothing worse than that reaction it was will your fillings…
Ack!
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### Author:  [@The\_Bad\_Astronomer](https://boards.straightdope.com/u/The_Bad_Astronomer)
#### Post date: [June 6, 2001, 5:11pm UTC](https://boards.straightdope.com/t/what-do-fingernails-on-blackboards-do/67495/20 "2001-06-06T17:11:21Z")
> [@](#):
>
> \*Originally posted by Doubleclick \*
> \*\*All of mine seem to involve high pitch/frequency sounds:
>
> Nails on chalkboard
> \*\*
I saw a demo where the sound of a three prong garden digger scraping a blackboard was decomposed into individual frequency components (that is, broken up into individual tones). The high pitch tones, when played alone, aren’t bad. It’s the _low_ pitch ones that cause the shivers. I don’t know what to make of that, but it’s neat.
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