Before the beard trend, I preferred the look of a clean-shaven man. Then beards went mainstream. Now, after seeing countless men donning this look, I find myself giving five o’clock shadows a second glance. Apparently, I’m not alone.

　　胡须还没风靡的时候，我更喜欢男人把胡子刮干净。之后，胡须成了主流审美。现在，看多了胡须男，我对清晨刮过脸傍晚又长出的胡茬的那一型总会多看两眼。显然不只我是这样。

　　“I find men with beards more attractive. Before it was not important, but now half of the men I know have beards,” one survey respondent told The Guardian when asked about facial hair.

　　一名受访者在接受英国《卫报》关于面部毛发的采访时说：“我觉得留胡须的男人更有魅力。以前胡须对男人的外表并不重要，但现在我认识的一半男人都留着胡须。”

　　It’s often thought that we are hardwired by millennia of natural selection to gravitate towards certain traits, like facial symmetry. We know our standards of beauty change over time – but those shifts have been thought to be relatively long-term, responding to the media and popular culture. And even if we know that our sense of beauty still differs somewhat from person to person, most of us believe that we each have a certain ‘type’ that stays somewhat constant throughout our lifetime.

　　普遍认为，经过数千年的自然选择，我们会特别倾向于某些特征，比如面部对称。我们都知道审美标准会不断改变，变化一般都是源于大众媒体和流行文化，而且每个标准维持的时间也相对较长。尽管我们知道人们的审美标准不一，但大都认为人一生会有某种保持不变的“喜欢类型”。

　　But it turns out ‘over time’ is a shorter window than it once was. Our standards of beauty don’t just change over months or years. They can change in an instant.

　　但事实证明，“随着时间的推移”所指代的周期比从前更短了。我们的审美标准可能几年就变，也可能几个月就变，甚至还可能一下就变。

　　“Beauty still is in the eye of the beholder, but our on-going work suggests that the beholder may be changing constantly,” says Haiyang Yang, assistant professor at the Johns Hopkins University Carey Business School and author of a study that found that our sense of beauty can change based on other people’s opinions. “It can be argued that the advent of the internet age may be causing people to change their beauty standards faster than ever before in human history.”

　　美国约翰霍普金斯大学凯里商学院助理教授杨海洋(音译)说：“审美标准仍然存在于观者眼中，但我们正在进行的研究表明，观者的看法可能会不断改变。”他发表的一项研究认为，审美会根据他人的意见发生变化。“可以说，互联网时代的到来可能正让人们的审美标准比以往任何时候都变得更快。”

　　You can blame how much we’re bombarded today with images of other people – as well as, yes, internet dating.

　　你可以将此归咎于他人的图片轰炸，以及，网上约会。

　　Recent research has found that our judgments of attractiveness not only change, but that we actually see the next face as more or less attractive, based on faces we have just seen. With a dating site or app, of course, this happens repeatedly and in mere milliseconds.

　　近期的研究发现，我们对吸引力的判断不仅会改变，而且还会对比先前看到的面孔判断下一张是否更好看。有了约会网站或程序，这是常有的事儿，而且改变速度是以毫秒计算的。

　　In one study at the University of Sydney, female participants rated 60 men as ‘attractive’ or ‘not attractive’ after pictures of their faces flashed on a screen for about one-third of a second. Researchers found that participants were more likely to rate a face as attractive if they thought the preceding face was attractive. (This went the other way, too: they were also more likely to rate a face as unattractive if they thought the preceding face was unattractive.) When participants viewed 242 female faces and were asked to rate their attractiveness on a scale of one to eight, they viewed people as more or less beautiful based on their previous responses – so much so that their perception of beauty changed with each new face.

　　悉尼大学的一项研究中，受访女性会在屏幕上逐一看到60名男性面孔，并对他们依次按照“有吸引力”或“没有吸引力”进行评价，每张面孔出现的时间大约为三分之一秒。研究人员发现，如果受访者认为前一张面孔有吸引力，就更有可能评定下一张也有吸引力。(反之亦然：如果认为前一张脸没有吸引力，就更有可能评定下一张也没有。)让受访者看完242张女性面孔后请她们按照一到八的等级评定吸引力程度，发现对前一张面孔的评测会影响对下一张的评定——以至于对每一张新面孔的审美都在变化。

　　The reason comes down to how the brain handles new information. “Your brain can’t process all the information that’s continuously flooding into your visual system from your eyes, so it creates shortcuts where it can,” says Jessica Taubert, lead author of the study at the University of Sydney, where she is a postdoctoral researcher. “Your brain relies on previous visual cues so it doesn’t have to constantly reanalyse that information.”

　　原因可以归结为大脑处理新信息的方式。悉尼大学负责这项研究的第一作者兼博士后研究员陶伯特(Jessica Taubert)说：“大脑无法处理从眼睛不断涌入到视觉系统的所有信息，因此有捷径就走，会依赖之前的视觉线索，这样就不必费劲地不断重新分析这些视觉信息。”

　　In this case, the shortcut used is what scientists refer to as ‘serial dependence’: we expect the physical state of an object to remain stable from one moment to the next. For example, when you glance at a coffee mug and look away, you expect its identity to be the same when you look at it again.

　　这里的捷径就是科学家所说的“序列依赖性”——我们期望物体的物理状态保持稳定。例如，你扫了一眼咖啡杯然后把目光移开，再看它时，你想着它还是那只咖啡杯。

　　A similar concept applies in online dating. As millions of lovebirds scour digital profiles, their brains assume while they are fixated on a face that its identity will remain the same – attractive or not attractive. They quickly swipe to the next profile and are presented with what could be best described as an illusion. Their brains haven’t had time to reanalyse the information as a new face belonging to a new person, so they perceive the next face as they perceived the last.

　　类似原理也适用于网络约会。数以百万的求偶者在网上快速浏览着约会对象的照片，无论看到的面孔吸引与否，大脑都认为这张脸不会改变。人们迅速打开下一个人的照片，看到的更像是一种幻觉。大脑没有那么多时间重新分析信息，认出新面孔是不同的人，于是认为跟前一张脸是同一张。

　　“The fact that our brains quickly adapt to our visual environment is not new. What is new is the speed at which our environment can change,” says Teresa Pegors, a former assistant professor of psychology at Azusa Pacific University and co-author of the study.

　　美国阿兹塞太平洋大学前心理学助理教授佩戈尔斯(Teresa Pegors)也是该研究的共同作者，她说：“我们早就知道大脑能够快速适应视觉环境，但如今环境改变的速度却前所未有。”

　　“This can make beauty a constantly shifting target and is one piece, though certainly not the only or even most important piece, in the equation of why it is harder to be content with a single partner over the long haul.”

　　“这就会令审美不停改变，也是为何人们越来越难以长期对同一个伴侣感到满意，但这只是一小部分原因，也不是最重要的。”