哪種走路姿勢更容易被搶？

The way people move can influence the likelihood of an attack by a stranger. The good news, though, is that altering it can reduce the chances of being targeted.

"The power has gone to his head" is an oft-heard accusation. So are leaders losing touch with reality when they act in a power-hungry way?

How you move gives a lot away. Maybe too much, if the wrong person is watching. We think, for instance, that the way people walk can influence the likelihood of an attack by a stranger. But we also think that their walking style can be altered to reduce the chances of being targeted.

A small number of criminals commit most of the crimes, and the crimes they commit are spread unevenly over the population: some unfortunate individuals seem to be picked out repeatedly by those intent on violent assault. Back in the 1980s, two psychologists from New York, Betty Grayson and Morris Stein, set out to find out what criminals look for in potential victims. They filmed short clips of members of the public walking along New York's streets, and then took those clips to a large East Coast prison. They showed the tapes to 53 violent inmates with convictions for crimes on strangers, ranging from assault to murder, and asked them how easy each person would be to attack.

The prisoners made very different judgements about these notional victims. Some were consistently rated as easier to attack, as an "easy rip-off". There were some expected differences, in that women were rated as easier to attack than men, on average, and older people as easier targets than the young. But even among those you’d expect to be least easy to assault, the subgroup of young men, there were some individuals who over half the prisoners rated at the top end of the "ease of assault" scale (a 1, 2 or 3, on the 10 point scale).

The researchers then asked professional dancers to analyse the clips using a system called Laban movement analysis – a system used by dancers, actors and others to describe and record human movement in detail. They rated the movements of people identified as victims as subtly less coordinated than those of non-victims.

Although Professors Grayson and Stein identified movement as the critical variable in criminals' predatory decisions, their study had the obvious flaw that their films contained lots of other potentially relevant information: the clothes the people wore, for example, or the way they held their heads. Two decades later, a research group led by Lucy Johnston of the University of Canterbury, in New Zealand, performed a more robust test of the idea.

The group used a technique called the point light walker. This is a video recording of a person made by attaching lights or reflective markers to their joints while they wear a black body suit. When played back you can see pure movement shown in the way their joints move, without being able to see any of their features or even the limbs that connect their joints.

Research with point light walkers has shown that we can read characteristics from joint motion, such as gender or mood. This makes sense, if you think for a moment of times you've recognised a person from a distance, long before you were able to make out their face. Using this technique, the researchers showed that even when all other information was removed, some individuals still get picked out as more likely to be victims of assault than others, meaning these judgements must be based on how they move.

Walk this way

But the most impressive part of Johnston’s investigations came next, when she asked whether it was possible to change the way we walk so as to appear less vulnerable. A first group of volunteers were filmed walking before and after doing a short self defence course. Using the point-light technique, their walking styles were rated by volunteers (not prisoners) for vulnerability. Perhaps surprisingly, the self-defence training didn't affect the walkers’ ratings.

In a second experiment, recruits were given training in how to walk, specifically focusing on the aspects which the researchers knew affected how vulnerable they appeared: factors affecting the synchrony and energy of their movement. This led to a significant drop in all the recruits' vulnerability ratings, which was still in place when they were re-tested a month later.

There is school of thought that the brain only exists to control movement. So perhaps we shouldn't be surprised that how we move can give a lot away. It's also not surprising that other people are able to read our movements, whether it is in judging whether we will win a music competition, or whether we are bluffing at poker. You see how someone moves before you can see their expression, hear what they are saying or smell them. Movements are the first signs of others’ thoughts, so we've evolved to be good (and quick) at reading them.

The point light walker research a great example of a research journey that goes from a statistical observation, through street-level investigations and the use of complex lab techniques, and then applies the hard won knowledge for good: showing how the vulnerable can take steps to reduce their appearance of vulnerability.人們走路的方式可能會影響被陌生人襲擊的機率。但好消息是通過改變走路方式，能夠降低被搶機率。

你走路的方式能透漏很多信息。對一些不法分子來講，甚至是過多的信息。例如，我們認爲人們走路的方式可能會影響被陌生人襲擊的機率，但是可以通過改變走路方式來降低此機率。

大部分的犯罪行爲是由少數犯罪分子做的，而受害者也十分分散，分佈不均：有一些人很不幸，似乎總是成爲蓄意暴力襲擊的目標。追溯到上世紀80年代，來自紐約的兩名心理學家貝蒂·格雷森（Betty Grayson）和莫里斯·斯坦因（Morris Stein）開始研究什麼的樣的人是罪犯所尋找的潛在受害者。他們將在紐約大街上獨自行走的路人拍攝下來，送到東海岸的大監獄，將其展示給53名曾因襲擊陌生人入獄的暴力囚犯。他們的襲擊行爲輕重不一，從侮辱到謀殺。並詢問他們每個路人易被攻擊的程度。

囚犯對這些假定受害者評價不一。有些人總被指出很容易被搶。其中有一些是之前預料到的結果。比如，囚犯認爲女士比男士更容易被襲擊，老年人比年輕人更易成爲目標。但即使在通常認爲很難被攻擊的男性中，也有一些人被超過半數的囚犯標爲極容易被搶。（在10分制標準中，他們僅得1、2或3分）

研究人員邀請專業的舞蹈家用拉邦動作分析理論（Laban movement analysis）來研究這些短片中的行人。這一理論常被舞蹈家、演員以及其他人員用來描述和記錄人類運動的細節。他們指出，那些容易成爲攻擊對象的人的運動與其他人相比略微不協調。

雖然格雷森與斯坦因教授將人們的行動方式視爲罪犯決定採取行動的關鍵條件，但他們的研究有明顯的漏洞。在視頻中，有很多潛在的相關信息，例如人們的着裝、擡頭的方式等。20年後，由露西·約翰斯頓（Lucy Johnston）領導的一個坎特伯雷大學研究小組在新西蘭對此想法進行了更有力的測試。

他們利用了光點式步行者技術（point light walker）。被觀察者要身着一身黑衣，並將光源或標記物附在他們的關節上進行錄像。當回放時，你只能看到關節的運動，不會受其他身體部位甚至是四肢的干擾。

光電步行者技術的調查顯示，我們可能從關節的運動判斷一個人的性別和心情。這是很有道理的，你可以思考一下，當你想認清遠處走來的一個人，在你看到他們的面容之前，你是怎麼樣做的。利用此項技術研究人員表明，即使其他的信息都被過濾掉，某些人與其他人相比仍然更容易被視爲攻擊的受害者。這就意味着這些判斷是根據他們的運動方式。

試試這樣走路

約翰斯頓最令人注目的調查是她對是否可以通過改變走路方式降低被襲擊的機率的研究。她對第一組研究對象上防禦課前後進行了錄像。利用光點式步行者技術，志願者們（不是囚犯）對這些研究對象的易傷性進行了打分。但出人意料，自衛訓練並沒有影響他們的打分。

在第二組實驗中，對研究對象給予走路姿勢的訓練，特別專注於那些調查人員已知的會影響他們易傷性的方面，即他們運動的協調性和力量方面。這在打分中大大降低了他們成爲受害者的概率。一個月後，對他們再次進行測試，結果依然如此。

有一派學者認爲，大腦的存在是爲了控制運動。因此對於我們的走路方式可能會透漏很多信息這一點，我們不應感到太過驚訝。在判斷我們能否贏得音樂比賽、打牌時是不是在虛張聲勢時，別人能讀懂我們的運動也是很正常的。在看到別人的表情前，聽到他們的聲音亦或是聞到他們的氣味前，我們總能看到他們的運動方式。運動是他人思想的第一個標識，因此我們進化到有能力很快地讀懂他們。

光點式步行者技術調查法是一個通過街頭調查以及複雜的實驗技術逐步從統計觀察運用到實踐的很好的研究例證，展示出弱者如何一步一步降低其易傷性的過程。