摘要:在我看來，咬指甲并不是揭示了什么人格特征，也不是一些對人類有益進(jìn)化行為的不良反映。它是我們身體構(gòu)造的產(chǎn)物，是手對嘴行為如何在人類大腦中建立以及習(xí)慣心理的產(chǎn)物。

　　Why do we bite our nails?

　　What do ex-British prime minster Gordon Brown, Jackie Onassis, Britney Spears and I all have in common? We all are (or were) nail biters.

　　It's not a habit I'm proud of. It's pretty disgusting for other people to watch, ruins the appearance of my hands, is probably unhygienic and sometimes hurts if I take it too far. I've tried to quit many times, but have never managed to keep it up.

　　Lately I've been wondering what makes someone an inveterate nail-biter like me. Are we weaker willed? More neurotic? Hungrier? Perhaps, somewhere in the annals of psychological research there could be an answer to my question, and maybe even hints about how to cure myself of this unsavoury habit.

　　英國前首相戈登·布朗(Gordon Brown)、杰奎琳·肯尼迪(Jackie Onassis)、布蘭妮·斯皮爾斯(Britney Spears)之間有什么共同點(diǎn)呢?他們都愛(或曾經(jīng)都愛)咬指甲。

我們?yōu)楹螘?huì)咬指甲

　　這嗜好我可不喜歡。被別人看到多惡心呀，把雙手的形象全毀了，很可能不衛(wèi)生，如果咬得太深還會(huì)受傷。我也幾次試圖想要戒掉，但從未持之以恒。

　　最近，我總在想是什么讓像我這樣愛咬指甲的人惡習(xí)難改呢?難道和其他人相比我們意志更薄弱?更神經(jīng)質(zhì)?更有欲望?也許心理學(xué)研究的文獻(xiàn)能夠給我答案，也許還能給我一些暗示，教我如何自我擺脫這個(gè)令人討厭的習(xí)慣。

　　My first dip into the literature shows up the medical name for excessive nail biting: 'onychophagia'. Psychiatrists classify it as an impulse control problem, alongside things like obsessive compulsive disorder. But this is for extreme cases, where psychiatric help is beneficial, as with other excessive grooming habits like skin picking or hair pulling. I'm not at that stage, falling instead among the majority of nail biters who carry on the habit without serious side effects. Up to 45% of teenagers bite their nails, for example; teenagers may be a handful but you wouldn't argue that nearly half of them need medical intervention. I want to understand the 'subclinical' side of the phenomenon – nail biting that isn't a major problem, but still enough of an issue for me to want to be rid of it.

　　第一次瀏覽文獻(xiàn)就發(fā)現(xiàn)了過度咬指甲的醫(yī)學(xué)術(shù)語：“咬甲癖”(onychophagia)。心理學(xué)家把它歸于一種沖脈控制問題，即類似強(qiáng)迫癥問題。但這僅指極端案例，精神病學(xué)對此的幫助頗有成效，對其他過度怪癖也是如此，如：皮膚搔抓癥，拔毛癖。我可沒到那種程度，只是和大多數(shù)愛咬指甲的人一樣，一直有這樣的癖好，但沒什么嚴(yán)重的不良反應(yīng)。45%以上的青少年愛咬指甲，比如：青少年可能只占一小部分，但你不會(huì)說他們中一半人需要接受醫(yī)學(xué)治療。我想要了解這種現(xiàn)象臨床癥狀不明顯的一面——咬指甲沒什么大驚小怪，但它對我來說依然是件大事，得去克服。

　　It’s mother’s fault

　　都是媽媽的錯(cuò)

　　Psychotherapists have had some theories about nail biting, of course. Sigmund Freud blamed it on arrested psycho-sexual development, at the oral stage (of course). Typical to Freudian theories, oral fixation is linked to myriad causes, such as under-feeding or over-feeding, breast-feeding too long, or problematic relationship with your mother. It also has a grab-bag of resulting symptoms: nail biting, of course, but also a sarcastic personality, smoking, alcoholism and love of oral sex. Other therapists have suggested nail-biting may be due to inward hostility – it is a form of self-mutilation after all – or nervous anxiety.

　　當(dāng)然，心理學(xué)家在咬指甲方面有許多理論。西格蒙德•弗洛伊德(Sigmund Freud)把它歸結(jié)于性心理發(fā)育不良，當(dāng)然是在口腔期。典型的弗洛伊德理論認(rèn)為，口欲滯留的原因有很多，諸如：喂食不足或喂食過盛、哺乳時(shí)間過長、或與母親關(guān)系不睦。

　　Like most psychodynamic theories these explanations could be true, but there's no particular reason to believe they should be true. Most importantly for me, they don't have any strong suggestions on how to cure myself of the habit. I've kind of missed the boat as far as extent of breast-feeding goes, and I bite my nails even when I'm at my most relaxed, so there doesn't seem to be an easy fix there either. Needless to say, there's no evidence that treatments based on these theories have any special success.

　　Unfortunately, after these speculations, the trail goes cold. A search of a scientific literature reveals only a handful of studies on treatment of nail-biting. One reports that any treatment which made people more aware of the habit seemed to help, but beyond that there is little evidence to report on the habit. Indeed, several of the few articles on nail-biting open by commenting on the surprising lack of literature on the topic.

　　當(dāng)然，心理學(xué)家在咬指甲方面有許多理論。西格蒙德•弗洛伊德(Sigmund Freud)把它歸結(jié)于性心理發(fā)育不良，當(dāng)然是在口腔期。典型的弗洛伊德理論認(rèn)為，口欲滯留的原因有很多，諸如：喂食不足或喂食過盛、哺乳時(shí)間過長、或與母親關(guān)系不睦。

　　像大多心理動(dòng)力論這樣解釋也許是說的通的，但沒有特別的理由說服我們?nèi)ハ嘈胚@些解釋是對的。對我來說最重要的是：他們并沒有任何強(qiáng)有力的說法，如何自己戒掉這個(gè)習(xí)慣。就母乳喂養(yǎng)的程度而言，我早已過了那時(shí)期。甚至在我最放松的情況下我也咬指甲，所以似乎也沒有什么簡單的解決辦法。更不用說，現(xiàn)今沒有證據(jù)證明基于這些理論上的治療有任何特別的成效。

　　可惜在種種猜測之后，也慢慢無從所知了。檢索相關(guān)科學(xué)文獻(xiàn)只發(fā)現(xiàn)一些基于如何治療咬指甲癖的研究。其中一項(xiàng)研究指出：任何讓人們愈發(fā)認(rèn)識到咬指甲這個(gè)癖好的治療似乎是有所幫助的，但除此之外并沒有什么有關(guān)該癖好的報(bào)道。事實(shí)上，幾篇為數(shù)不多關(guān)于咬指甲的文章公開評述該問題上的文獻(xiàn)嚴(yán)重不足。

　　Creature of habit

　　習(xí)慣的奴隸

　　Given this lack of prior scientific treatment, I feel free to speculate for myself. So, here is my theory on why people bite their nails, and how to treat it.

　　Let's call it the ‘anti-theory’ theory. I propose that there is no special cause of nail biting – not breastfeeding, chronic anxiety or a lack of motherly love. The advantage of this move is that we don't need to find a particular connection between me, Gordon, Jackie and Britney. Rather, I suggest, nail biting is just the result of a number of factors which – due to random variation – combine in some people to create a bad habit.

　　鑒于之前沒有接受過科學(xué)治療，我可以輕松地自我省視。所以以下就是我自己的理論，解釋為什么人們會(huì)咬指甲，以及如何治療這個(gè)毛病。

　　讓我們把這個(gè)理論稱為“反理論”之理論。我假設(shè)沒有特殊的原因引發(fā)咬指甲——不是因?yàn)槭裁茨溉槲桂B(yǎng)、長期焦慮、缺乏母愛。把這些統(tǒng)統(tǒng)都排除的好處是我們不需要在我和戈登、杰奎琳、布蘭妮之間找出一個(gè)特別的連接點(diǎn)。我認(rèn)為：咬指甲僅僅是由于諸多因素引發(fā)的——由于隨機(jī)變異——一些人形成壞習(xí)慣的結(jié)合。

　　First off, there is the fact that putting your fingers in your mouth is an easy thing to do. It is one of the basic functions for feeding and grooming, and so it is controlled by some pretty fundamental brain circuitry, meaning it can quickly develop into an automatic reaction. Added to this, there is a ‘tidying up’ element to nail biting – keeping them short – which means in the short term at least it can be pleasurable, even if the bigger picture is that you end up tearing your fingers to shreds. This reward element, combined with the ease with which the behaviour can be carried out, means that it is easy for a habit to develop; apart from touching yourself in the genitals it is hard to think of a more immediate way to give yourself a small moment of pleasure, and biting your nails has the advantage of being OK at school. Once established, the habit can become routine – there are many situations in everyone's daily life where you have both your hands and your mouth available to use.

　　首先，有這樣一個(gè)事實(shí)：把你的手指放進(jìn)嘴里是件很容易的事。這是喂養(yǎng)最基本的功能之一。所以它是受一些最基本腦神經(jīng)元回路控制的，也就是說它能迅速發(fā)展成為一種自動(dòng)條件反射。此外，對咬指甲有一種“打理”因素——讓指甲始終是短的——這就意味著就短期而言至少它能讓人心情舒暢，即使其主要是讓你的手指苦不堪言。這種獎(jiǎng)勵(lì)因素同行為者采取的愉悅相結(jié)合，意味著這種癖好能夠輕松養(yǎng)成;除了手淫之外，真的很難想象有什么更為直接的方式讓自己愉悅片刻了，而且咬指甲的好處就是在學(xué)校這么做完全沒問題。這種癖好一旦建立，就會(huì)變成常規(guī)——每個(gè)人的日常生活都有許多你都得使用你的雙手和嘴的情況。

　　Understanding nail-biting as a habit has a bleak message for a cure, unfortunately, since we know how hard bad habits can be to break. Most people, at least once per day, will lose concentration on not biting their nails.

　　Nail-biting, in my view, isn't some revealing personality characteristic, nor a maladaptive echo of some useful evolutionary behaviour. It is the product of the shape of our bodies, how hand-to-mouth behaviour is built into (and rewarded in) our brains and the psychology of habit.

　　And, yes, I did bite my nails while writing this column. Sometimes even a good theory doesn't help.

　　把咬指甲當(dāng)作是一種癖好去理解，對治療的作用并不大，因?yàn)檫z憾的是我知道擺脫壞習(xí)慣有多難。大多數(shù)人一天中至少一次會(huì)無意識地咬指甲。

　　在我看來，咬指甲并不是揭示了什么人格特征，也不是一些對人類有益進(jìn)化行為的不良反映。它是我們身體構(gòu)造的產(chǎn)物，是手對嘴行為如何在人類大腦中建立以及習(xí)慣心理的產(chǎn)物。

　　是的，我在寫這篇專欄的時(shí)候確實(shí)咬指甲了。有時(shí)就算是一個(gè)好理論也幫不上忙。