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  • Can you read in the car?

  • If so, consider yourself pretty lucky.

  • For about one-third of the population, looking at a book while moving along in a car or a boat or train or plane quickly makes them sick to their stomach.

  • But why do we get motion sickness in the first place?

  • Well, believe it or not, scientists aren't exactly sure.

  • The most common theory has to do with mismatched sensory signals.

  • When you travel in a car, your body is getting two very different messages.

  • Your eyes are seeing the inside of a vehicle, which doesn't seem to be moving.

  • Meanwhile, your ear is actually telling your brain you're accelerating.

  • Wait, your ear?

  • Yeah, your ear actually has another important function besides hearing.

  • In its innermost part lies a group of structures known as the vestibular system, which gives us our sense of balance and movement.

  • Inside there are three semicircular tubules that can sense rotation, one for each dimension of space.

  • And there are also two hair-lined sacks that are filled with fluid.

  • So when you move, the fluid shifts and tickles the hairs, telling your brain whether you are moving horizontally or vertically.

  • With all these combined, your body can sense which direction you're moving in, how much you've accelerated, even at what angle.

  • So, when you are in the car, your vestibular system correctly senses your movement, but your eyes don't see it, especially if they are glued to a book.

  • The opposite can happen, too.

  • Say you are sitting in a movie theater and the camera makes a broad, sweeping move.

  • This time, it's your eyes that think you're moving while your ear knows that you're sitting still.

  • But why does this conflicting information have to make us feel so terrible?

  • Scientists aren't sure about that either, but they think that there's an evolutionary explanation.

  • You see, both fast moving vehicles and video recordings have only existed in the last couple of centuries, barely a blink in evolutionary time.

  • For most of our history, there just wasn't that much that could cause this kind of sensory mix-up.

  • Except for poisons.

  • And because poisons are not the best thing for survival, our bodies evolved a very direct but not very pleasant way to get rid of whatever we might have eaten that was causing the confusion.

  • This theory seems pretty reasonable, but it leaves a lot of things unexplained, like why women are more affected by motion sickness than men, or why passengers get more nauseous than drivers.

  • Another theory suggests that the cause may have more to do with the way some unfamiliar situations make it harder to maintain our natural body posture.

  • Studies have shown that being immersed in water or just changing your stance can greatly reduce the effects of motion sickness.

  • But, again, we don't really know what's going on.

  • We all do know some of the more common remedies for car queasiness

  • looking at the horizon, chewing gum, taking over-the-counter pills

  • but none of these are totally reliable, nor can they handle really intense motion sickness.

  • And sometimes, the stakes are far higher than just not being bored during a long car ride.

  • At NASA, where astronauts are hurled into space at 17,000 miles per hour, motion sickness is a serious problem.

  • So, in addition to researching the latest space-age technologies, NASA also spends a lot of time trying to figure out how to keep astronauts from vomiting up their carefully prepared space rations.

  • Much like understanding the mysteries of sleep or curing the common cold,

  • motion sickness remains one of those seemingly simple problems that, despite amazing scientific progress, we still know very little about.

  • Perhaps one day, the exact cause of motion sickness will be found, and with it, a completely effective way to prevent it.

  • But that day is still on the horizon.

Can you read in the car?

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B1 US TED-Ed sickness motion moving space theory

【TED-Ed】The mystery of motion sickness - Rose Eveleth

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    Go Tutor posted on 2014/02/25
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