Ever wonder what keeps some people faithful while others are spreading their cooties all around town? Well, there's more to monogamy than sheer willpower, according to new research.

你是否好奇为什么有些人忠诚，而另一些人却到处沾花惹草？根据最新研究表明，一夫一妻制需要的不仅仅是单纯的意志力。

In a study published in the Personality and Social Psychology¹ Bulletin, scientists recruited nearly 250 heterosexual people and had them rate the attractiveness of members of the opposite sex…all in the name of science.

在一项发表在《人格与社会心理学报》的研究中，科学家招募了250名异性恋，并要求他们对其他异性成员的吸引力打分...一切以科学的名义。

In one experiment, people were shown a pic of someone of the opposite sex, as well as a profile that included whether they were single or in a relationship. People who were in a relationship tended to say that single people (who might be a "threat to their relationship," according to the study) were less attractive than other single people deemed them.

在一项实验中，在向人们展示异性的照片时，还附上照片上的人是单身或交往的信息。相比于单身的人，那些正在交往的人会觉得照片上的单身人士比较缺乏吸引力（研究说这是因为单身人士可能会“威胁到他们现在已有的关系”）。

In a second experiment, people were asked to report how satisfied they were in their relationship before ranking the attractiveness of others. People who said they were happy with their S.O. once again ranked single folks as less attractive. But, those who weren't all that satisfied in their relationship were more likely to say those singles were lookin' mighty² fine.

在第二项实验中，在要求参与者为其他人打分前，先询问他们对目前交往关系的满意程度。那些对自己的伴侣比较满意的人，会觉得照片上的单身人士吸引力较低。但是，对自己交往关系不满意的人，会觉得照片上的单身人士看起来不错。

While this is super interesting, what does it mean? Scientists say that when we'rehappy in a relationship, we want to keep things that way. As a result, we unconsciously downgrade the looks of other people in our minds so that they don't tempt³ us to cheat.

很有趣对吧，这意味着什么呢？科学家对此表示，当我们对自己的交往关系满意时，我们想保持现状。因而，我们会无意识地为其他人的外观打出低分，这样他们就不会诱使我们出轨。

Of course, there's a huge difference between thinking someone is hot and actually stepping out on your S.O., and it's totally possible to think Zac Efron is sexy while still being into your guy (ahem, just saying...).

当然，觉得某个人很火辣，和真的背着你的伴侣出轨之间有着巨大的不同。你可以在忠于你的伴侣的同时，仍觉得扎克·埃夫隆性感（咳咳，只是说说…）