Why We’re Afraid of Heights

26 Aug

This video and others like it have graced social media sites for the last couple of years. If this is to be believed, Russian youth have apparently evolved beyond fear.

I like to think of myself as a fairly height-capable person, but even watching that makes me queasy. But it does bring up an interesting question. Why do heights make people nervous? The answer may lie the systems our bodies use to balance themselves and how they interact. We have three balance systems: visual (eyes), vestibular (our inner ear), and somatasensory (touch and muscle feedback). The delicacy of the situation lies in the visual system and how it works.

Firstly, we have to understand how the visual system orients itself. The natural sway of your head and body makes the images your eye receives seem to move ever so slightly. This happens so often you don’t really notice it, but you can see it first hand by simply focusing on an object then moving your head back and forth. This visual shift is totally natural and is in fact one of the clues your body uses to balance and orient itself in its environment.

A researcher named Liebowitz calculated in 1955 that your brain needs 20 minutes of arc (that is, one-third of one degree) of visual movement to balance itself against a stationary object. If you figure out the normal distance a person’s head sways while standing still (about 2 cm) and do some quick geometry, it ends up that this 20-minutes threshold is achieved at about 3 meters (about 10 feet). To put it simply, this means that your brain uses anything you can see within three meters to orient itself, like a man leaning on a nearby pole for balance. Anything outside this sphere doesn’t move quite enough for our brains to lean on it. You can kind of feel this by sitting and staring at a distant object, like a telephone pole or car. If you focus on a far object long enough you start to feel a bit wobbly. Your brain can’t use the visual sway to balance itself. There is a way to counteract this, however – try the same experiment again while walking and the feeling goes away. If you’re walking, your head is moving far more than 2 cm. This pushes the 20-minutes threshold back.

There is a limit, however. Anything over 15-20 meters away would need you to move your head at least 10 cm to keep visual balance. But try swinging your body back and forth a foot at a time and you’ll quickly feel queasy, no matter what you’re staring at. This much body movement would mess with your other two balance systems – your inner ear and muscles would get too disoriented and you’d fall.

This is why heights make people feel unbalanced. Above fifteen meters, our body is working on only two out of three systems. The body warns us about this disorientation through the emotions of nervousness, danger, and fear.

As to why some people are legitimately afraid of heights, it comes down to how they react to these danger signals. Risk-takers and adrenaline junkies, who tend to ignore fear signals, are more comfortable at heights while more sensitive people pay attention to these emotions and stay away. The kids who run up and down bridges probably aren’t afraid of much in the first place. If you are afraid of heights and want help with it, there are two ways to deal with these emotions. You can either learn to be like a risk-taker and ignore these signals or learn how to correct the feeling of imbalance in the first place. The former would require introspection and possibly psychotherapy, but there are a few quick tricks for the latter. Fixing your gaze on nearby objects helps since it restores 20-minute sphere and the visual balance signals. If that doesn’t work, you can bolster your sensory system by touching a nearby object or sitting down.

In essence, don’t look down and hold something. Good advice, yeah? Want another height challenge? If Russian bridges don’t satisfy you, how about beautiful El Camino del Rey?

Sources: Salassa and Zapala (2009), Fitzpatrick and McCloskey (1994)

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Posted by on August 26, 2012 in Uncategorized


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