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Why Do I Sometimes Scratch One Body Part and Feel It on Another?

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Ever scratch an itch on your stomach and feel the scratch on your elbow? Or scratch your leg and feel a prickly sensation on your neck? You’re not alone. Lots of people report feeling a sensation from a scratch in places far from where they’re scratching, including scratches on the ear that produce tickles in the throat and mixed signals between their thumb and their tongue. 

It’s one of those delightfully weird things your body does, and it’s been studied, albeit infrequently, for hundreds of years. English clergyman/scientist Stephen Hales first described the phenomenon in the 1730s, referring to it as “instances of the sympathy of the nerves.” About a century later, physiologist Johannes Muller came along and applied one of those cool words to it that the Germans are really good at coming up with: mitempfindungen. Since then, we’ve just called it “referred itch” in English. 

For most people, referred itch is just a weird annoyance. It doesn’t do any damage or have any ill effects, and so it doesn’t get a whole lot of research attention. Scientists haven’t even been able to nail down how common it is. One study found that it only happens in 10 percent of the population. Another said 20 percent. Still others put the figure at anywhere between half and ninety percent of people. 

How and why it happens is anybody’s guess, but scientists have a handful of hypotheses to explain what’s going on. One idea is that referred itch is the product of our complex system of nerves being “rather irregularly distributed” throughout the body. British physician Phillip Evans wrote in the 1970s that it was difficult for him to envision “such a diffuse system providing sensations that are so clearly imagined to be in small and easily localised areas of skin.” In other words, in our haphazard map of nerves, some sensations are bound to be confused. 

Another explanation in a similar vein is that some branches of a nerve may travel out in a much different path than the others and wind up in some far-flung part of the body. Again, the nervous system gets a little confused and a “stimulus at the end of one branch is interpreted as coming from a point of ending of the other.”  

It could also be that the mix up isn’t in the nerves, but the brain. In the parts of the brain that deal with our sense of touch, regions that receive and process information from different parts of the body overlap. “Hand and shoulder areas … overlap the trunk area, and the area for the thumb overlaps that for the upper part of the tongue,” Evans wrote. “There is so much overlapping that it is difficult to see how referred itches arising from different parts of the body can be coherently separated in the cortex.” 

Finally, for some people, chronic referred itches could happen in parts of the body “rendered abnormal by damage to the nervous system.”

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Why You Should Never Take Your Shoes Off On an Airplane
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What should be worn during takeoff?

Tony Luna:

If you are a frequent flyer, you may often notice that some passengers like to kick off their shoes the moment they've settled down into their seats.

As an ex-flight attendant, I'm here to tell you that it is a dangerous thing to do. Why?

Besides stinking up the whole cabin, footwear is essential during an airplane emergency, even though it is not part of the flight safety information.

During an emergency, all sorts of debris and unpleasant ground surfaces will block your way toward the exit, as well as outside the aircraft. If your feet aren't properly covered, you'll have a hard time making your way to safety.

Imagine destroying your bare feet as you run down the aisle covered with broken glass, fires, and metal shards. Kind of like John McClane in Die Hard, but worse. Ouch!

Bruce Willis stars in 'Die Hard' (1988)
20th Century Fox Home Entertainment

A mere couple of seconds delay during an emergency evacuation can be a matter of life and death, especially in an enclosed environment. Not to mention the entire aircraft will likely be engulfed in panic and chaos.

So, the next time you go on a plane trip, please keep your shoes on during takeoff, even if it is uncomfortable.

You can slip on a pair of bathroom slippers if you really need to let your toes breathe. They're pretty useless in a real emergency evacuation, but at least they're better than going barefoot.

This post originally appeared on Quora. Click here to view.

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Big Questions
Where Should You Place the Apostrophe in President's Day?
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Happy Presidents’ Day! Or is it President’s Day? Or Presidents Day? What you call the national holiday depends on where you are, who you’re honoring, and how you think we’re celebrating.

Saying "President’s Day" infers that the day belongs to a singular president, such as George Washington or Abraham Lincoln, whose birthdays are the basis for the holiday. On the other hand, referring to it as "Presidents’ Day" means that the day belongs to all of the presidents—that it’s their day collectively. Finally, calling the day "Presidents Day"—plural with no apostrophe—would indicate that we’re honoring all POTUSes past and present (yes, even Andrew Johnson), but that no one president actually owns the day.

You would think that in the nearly 140 years since "Washington’s Birthday" was declared a holiday in 1879, someone would have officially declared a way to spell the day. But in fact, even the White House itself hasn’t chosen a single variation for its style guide. They spelled it “President’s Day” here and “Presidents’ Day” here.


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Maybe that indecision comes from the fact that Presidents Day isn’t even a federal holiday. The federal holiday is technically still called “Washington’s Birthday,” and states can choose to call it whatever they want. Some states, like Iowa, don’t officially acknowledge the day at all. And the location of the punctuation mark is a moot point when individual states choose to call it something else entirely, like “George Washington’s Birthday and Daisy Gatson Bates Day” in Arkansas, or “Birthdays of George Washington/Thomas Jefferson” in Alabama. (Alabama loves to split birthday celebrations, by the way; the third Monday in January celebrates both Martin Luther King, Jr., and Robert E. Lee.)

You can look to official grammar sources to declare the right way, but even they don’t agree. The AP Stylebook prefers “Presidents Day,” while Chicago Style uses “Presidents’ Day.”

The bottom line: There’s no rhyme or reason to any of it. Go with what feels right. And even then, if you’re in one of those states that has chosen to spell it “President’s Day”—Washington, for example—and you use one of the grammar book stylings instead, you’re still technically wrong.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

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