Ask any random collection of strangers what they look for in a friend, and odds are you’ll get pretty similar answers across the board: someone who’s fun to be around. Someone who shares your sense of humor. Someone you can trust.

　　随便问一群陌生人，他们在交友时都看中什么,得到的答案一定极其相似：相处时能给你带来快乐的人、能够欣赏你的幽默感的人、你能信任的人。

　　But often, friendship begins long before any of those things can come to light in any meaningful way. According to one survey, around 60 percent of men and half of women believe in love at first sight; at least that many, I’d wager, have experienced that moment when you meet someone new and feel the friendship blooming in your gut — you just understand, instinctively, that a bond is about to form.

　　不过，通常友情早在人们意识到这些之前就已经开始了。一项研究显示，约60%的男性和50%的女性相信一见钟情;并且我敢打赌，有许多人已经经历过这样的时刻：当你结识新朋友，感觉到友谊开始在你们的体内流动——你们即将缔结友情的契约。

　　Call it a spark, call it chemistry, call it friendship at first sight; whatever it is, it can happen in just a small handful of seconds, which is the amount of time we need to form a first impression of someone (if that — one study suggests that we make our judgments just a tenth of a second after seeing a face).

　　无论你称之为燃起火花、发生化学反应，还是一见钟情的友谊，它只在几秒钟内就发生了。这就是我们对一个人形成第一印象的时间(正如一项研究表明，在我们看到他人后，十分之一秒便已经作出了判断)。

　　In a study published in Nature in 2009, researchers identified two areas of the brain that become especially active when we meet someone new: the amygdala, the area of the brain that deals with emotion, and the posterior cingulate cortex, which is linked to autobiographical memory. As Karla Starr noted in Psychology Today, the posterior cingulate cortex also helps us weigh decisions and assign value to objects; we go through a very similar process with humans. “And after we’ve assigned a value to a person, we make the decision about how to orient ourselves to that person,” she wrote. “Do we want to get closer? Knowing what this person’s value is to us, do we want this person to be involved in our network?”

　　在2009年发表在《自然》杂志上的一项调查中，研究人员发现，在我们遇到陌生人时，大脑中的两个区域变得异常活跃：杏仁体，即大脑中处理情感的区域，以及后扣带回，与自体的记忆有关。正如卡拉. 斯塔尔在杂志《今日心理学》中所指出的，后扣带回同样帮助我们权衡决策以及为对象分配价值，我们人类经历了一个非常类似的过程。“当我们为一个人分配了价值后，我们决定自己将如何与那个人相处，”她这样写道，“我们想要变得亲近吗?知道某个人的价值后，我们是否想让这个人加入我的社交圈呢?”

　　The answer is actually a compilation of several smaller judgments, explains Kelly Campbell, a psychology professor at California State University, San Bernardino. “What are the things we care about in a friend? We care about someone who’s going to be fun, that we can enjoy ourselves with … You need emotional support, social support, you want then to be loyal and trustworthy, you don’t want to feel judged,” she says. “When you first see the person, you don’t realize how many judgments you’re making, but you’re actually gathering information that’s telling you if this person fills those needs for you.”

　　这个问题的答案实际上是几个小判断共同编译而成的，来自于圣博娜迪诺加州州立大学的一位心理学教授凯利.凯贝尔这样解释。“对于朋友，我们关心是事情是什么呢?我们关心的是这个人需要很有趣，这样在相处的过程中我们都很享受……你需要感情的支持，社会的支持，你希望他们是忠诚可靠的，你不想感觉被他人审视，”她这样说，“当你第一眼看到一个人，你不知道你在做多少的判断，但实际上你正在收集的信息会告诉你这个人是否能够填补你的那些需求。”

　　Last year, Campbell headed up a study in The Social Science Journal on “friendship chemistry,” which she and her colleagues defined as “an instant connection between friends that is easy and makes the relationship seem natural.” (Friendship chemistry, Campbell noted, is one subset of “interpersonal chemistry,” which includes romantic relationships.) The phenomenon wasn’t always mutual, they found, but it seemed to strike certain groups more than others: Those who scored higher on the personality traits of agreeableness, openness, and conscientiousness, for example, were more likely to say that they’d experienced friendship chemistry.

　　去年，坎贝尔在《社会科学》杂志上发表了一项名为“友谊化学”的研究，她和她的同事将此定义为“与朋友之间发生瞬时联系是轻而易举的，并且这能使我们之间的关系显得更加自然。”(坎贝尔指出，友谊化学是“人际化学”的一个子集，除此之外还包括恋爱关系。)他们发现，这个现象并不总是相互的，但这看起来更能打动指定的群体：例如，那些有亲和力、开朗以及责任心等个性的人，往往能获得较高的印象分的，更有可能经历过友谊化学。

（编辑：何莹莹）