经济学人：慷慨的触摸

Evolutionary psychology

A touch of generosity

慷慨的触摸

Aug 14th 2008
From The Economist print edition

Touch can inspire munificence towards those you trust

触摸可以带来信任的慷慨行为

PEOPLE touch each other a lot, even strangers. We shake hands, slap backs, kiss and caress. Such behaviour can increase co-operation, which is good from an evolutionary point of view. It has even been shown that waitresses who touch patrons tend to be tipped more generously.

彼此触摸是人的惯常行为。我们握手、拍背、亲吻并且抚摸。这类行为可以促进合作，从进化的角度具有积极意义。甚至有迹象表明那些主动触摸老主顾的服务生能够得到更多的小费。

It is known that stroking rats can raise the level of oxytocin, a hormone active in the brain and implicated in various social interactions, such as maternal attachment. In humans higher oxytocin levels have been linked to physiological phenomena like contractions during childbirth, or orgasm. But the link to physical contact is so far unclear. Interestingly, the level of hormone appears to rise in people who are trusted. And more of it seems to inspire greater generosity towards strangers.

我们知道，抚摸能够增进白鼠分泌后叶催产素，这是一种和多种社会行为相关的荷尔蒙，比如母爱。对人类来说，后叶催产素和多种生理现象关联，比如分娩期的子宫收缩以及性高潮。但这种激素和身体接触的关联还远不够清晰。有趣的是，在相互信任的伙伴间，这种激素会维持一个较高的水平。而且这种激素的高水平很可能导致对陌生人的慷慨行为。

This prompted Vera Morhenn of the University of California, San Diego, and her colleagues, to examine the physiological mechanism underlying this and to see whether munificence towards strangers could be manipulated through touch. In their experiment, published in Evolution and Human Behavior, they split 96 male and female graduate students into three groups. The first and second received a professional massage but the third did not. Then the first and third group took part in a "trust game".

位于圣地亚哥的加州大学，Vera Morhenn和她的同事正着手研究基于此的生理机制，并通过实验来验证是否通过接触可以控制指向陌生人的慷慨行为。他们的实验过程发表在了《进化和人类行为》上，实验当中，他们把96名男女研究生分成3组。第一组和第二组实验前接受了专业的身体按摩，而第三组没有接受。接下来他们把第一组和第三组的成员投入"信任游戏"当中。

Participants were paired at random and seated in front of a computer, physically removed from their anonymous partner. Each also got $10 in cash, supposedly for showing up. The rules stipulated that for each pair, one person, the giver, could cede a part of their money to the other, the trustee. This amount would then be tripled and credited to the trustee, who was subsequently prompted by the computer to sacrifice a part of his stash by returning some to the giver.

参与者两两随机组合，为避免身体接触他们每对用电脑同匿名的伙伴隔开。同时电脑显示他们每人有10美元现金。规则是，其中的一方――"给予者"――可以把他们一部分现金给对方（受托方）。这个金额会以3倍的数量计入受托方的名下，接下来，电脑提醒受托方，把他储备的一部分返还给给予者。

Standard game theory predicts that in an anonymous one-off exchange like this the trustee ought to keep the gift and not reciprocate. The giver, too, ought to refrain from donating, since his sacrifice is bound to remain unrequited. Yet that is not what tends to happen with real people. Givers often give and trustees frequently return the favour. (Studies of identical and non-identical twins suggest that co-operative behaviour in trust games is heritable.) In effect, the giver's donation reflects his confidence in the trustee's willingness to reciprocate. In other words, it signals trust.

标准游戏理论预言，在类似这样的匿名状态下的一次性交易中，受托方很可能把馈赠据为己有而不会返还；同理，给予者在得不到回报的情况下也会拒绝馈赠。不过在真人之间这好像没有发生。给予和返还行为在两者之间经常发生。（对同卵和异卵双胞胎的研究表明信任前提下的合作行为是有遗传特性的）。结果是，给予者的行为引发的互信，激发了受托方的返还动机。换一种说法，这是彼此信任的信号。

To test the physiology, Dr Morhenn took blood samples at the start and end of each game and looked for changes in oxytocin levels. She found no effect in the massaged group who did not participate in the game, implying that trust does indeed act as some sort of trigger. But in the players the hormone rose in those who were massaged and fell slightly in those who were not.

为进行生理测试，Morhenn博士在游戏开始和结束的时候都对实验对象抽取的血样，以检测后叶催产素水平的变化。她发现接受按摩但未参与游戏的一组激素水平没有变化，显示出信任确实是催发激素的某种激活要素。而在参与游戏者当中，接受过按摩的荷尔蒙升高，而没有接受的却在缓慢地下降。

Despite receiving statistically identical trust signals from givers, the massaged trustees with their higher oxytocin levels returned a whopping 243% more than their unrubbed counterparts. A clue to why evolution might favour such a double-trigger mechanism may come from the other finding that women appear more susceptible than men to tactile manipulation. Perhaps that is to ensure maternal care of their own brood. If so, such effects seem to extend beyond the mother's bosom.

尽管，双方接收到是统计上同一的信任信号，接受过按摩的受托方，伴随着高激素水平，返回数量比未接受按摩的受托方高出达243%。进一步显示出，进化偏爱这种双重触发机制大概是有原因的，也可能说明了为什么女人对触觉会比男人敏感。因为这能确保产妇有足够慷慨动机保护自己的产儿。如果是这样的话，触发机制似乎有超越对自已孩子的慷慨的可能。