Your body uses three senses to keep you balanced–to tell you what’s up and down.

 

　　One of the senses is your eyes. They tell you how you’re oriented with the world around you. Then there’s your body sense. It’s the seat-of-the-pants pressure you feel in your muscles and joints from gravity and movement.

 

　　Finally, there are the semi-circular canals of your inner ears. These canals are lined with tiny hairs and filled with liquid. When you move, the fluid bends the hairs, and they tell your brain what’s happening.

 

　　But if you lose your visual clues, the other senses can trick you. It’s called spatial disorientation, or vertigo.

 

　　Consider a pilot who’s flying in clouds, so she has no visual clues. She enters a left turn, and her inner ears say “you’re turning.” But soon the fluid settles down, and the hairs stop moving. The pilot is still in the turn, but her ears say she’s flying straight.

 

　　And her body sense won’t help. Without visual clues, it might think the g-forces of the turn are caused by a climb. So now the pilot’s ears and body sense are telling her different things, and both are probably wrong.

 

　　Scuba divers can have this same dangerous confusion in murky water, and avalanche victims–buried in snow–may not know which way to start digging.

 

　　So when the body lies, other signals must be used. Pilots rely on instruments, divers follow their air bubbles to the surface, and a little spit will tell the avalanche victims which way is up.

 

　　如何判读自己身体在向上还是向下？

 

　　我们的身体有三种感官方式，帮助我们维持平衡，并告诉我们是向上还是向下。

 

　　第一种感官是我们的视觉。视觉将告诉你在周围世界中的方位。然后便是我们的身体感受，即利用我们的肌肉的直觉结合重力和动作以进行感知。

 

　　最后一种感知是我们内耳的半圆环管。这些环管上覆盖着微小的毛状纤维，并充满了液体。当你移动时，液体的流动压弯毛状纤维，从而让你的大脑知道发生了什么。

 

　　但是如果你丧失了视觉感官，那么另外两种感官方式可能会欺骗你。这叫做空间定向障碍，也就是眩晕。

 

　　试想一个飞行员正穿梭于云层之中，她看不到任何东西。她把飞机往左转，这时候内耳会告诉她“你正在转向”。但是很快，环管内的流体停止流动，毛状纤维也跟着停了下来。虽然飞机依然在转弯，但是她的耳朵却让她误认为在直线飞行。

 

　　这时，他的身体感受也起不了作用了。没有视觉感官的情况下，飞行员可能将转弯产生的离心力当做攀爬时的重力。于是她的耳朵和身体感受传递了不同的信息，并且都是错误的信息。

 

　　带水肺的潜水员也会在昏暗的水深之处遭遇相同的困境，而发生雪崩时，埋在雪里的受害者也不知道该从哪个方向挖出去。

 

　　所以身体发出错误的感知信号时，我们就必须利用其它信息。飞行员观察仪表数据，潜水员跟随上浮的气泡可以浮出水面，雪崩受害者则可以通过吐出的唾液了解哪个方向是向上。