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To have a head for heights means that one has no acrophobia, an irrational fear of heights, and is not particularly prone to fear of falling or suffering from vertigo, the spinning sensation that can be triggered, for example, by looking down from a high place. Unlike acrophobia, a natural fear of heights is a normal phenomenon and not an illness. When one finds oneself in an exposed place at a great height above the ground below, one feels one's own posture as unstable. A normal fear of heights can also generate feelings of anxiety as well as autonomic symptoms like outbreaks of sweat. A head for heights is frequently stated as a requirement when mountain hiking or climbing for a particular route as well as paragliding and hang-gliding. It is also needed for certain jobs, for example by chimney sweeps, roofers, steeplejacks and window cleaners. Mohawk ironworkers have worked for generations erecting New York skyscrapers,〔(【引用サイトリンク】url=http://www.sites.si.edu/exhibitions/booming%20out.pdf )〕 though it is only a myth they have some innate skill for doing so.〔(【引用サイトリンク】url=http://www.wnyc.org/story/192807-sky-walking-raising-steel-mohawk-ironworker-keeps-tradition-alive/ )〕 == Causes of fear of heights == There are logical biological causes of fear of falling. Firstly, there is the innate so-called "cliff edge phenomenon", whereby even toddlers, as well as many animals, avoid large drops, even without having previously had a bad experience.〔 Vertigo itself is caused by a destabilization of the posture which, when it occurs at height, results from too large a distance from the eyes to the nearest visible solid object and is referred to as "distance vertigo" or "height vertigo". In order to see the object in space, the head starts to sway imperceptibly and "location reflex" then causes the body to sway with it. At the same time, the body stabilizes its position using the periphery of the retina, but when someone looks down they now lack this stabilizing factor. This physiological swaying is normally counteracted by the body's vestibular system and proprioceptive sense. However, for example, if there is damage to the sense of balance, in fact, the risk of falling is increased. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「head for heights」の詳細全文を読む スポンサード リンク
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