文章来源：《Science News》
原文见刊日期：2022年2月12日
Young children are always watching — including when people swap spit through actions like food sharing. Such behavior helps tots infer who is in close relationships with one another, a study suggests.
孩子们总是在看——包括人们通过分享食物等行为交换唾液。一项研究表明，这样的行为有助于孩子们推断谁与他人关系密切。
Typically, people are more likely to engage in activities that can lead to an exchange of saliva, such as kissing or sharing an ice cream cone, with family members or close friends than with an acquaintance or colleague. So saliva sharing can be a marker of “thick relationships,” or people who have strong attachments, says MIT developmental psychologist Ashley Thomas.
通常情况下，人们更有可能与家人或亲密的朋友进行会导致唾液交换的活动，如接吻或分享冰淇淋蛋卷，而不是与熟人或同事。因此，麻省理工学院发展心理学家阿什利·托马斯说，唾液分享可能是“亲密关系”或有强烈依恋的人的标志。
To see if young children might use saliva sharing as a social cue for intimate bonds, Thomas and colleagues ran experiments of people engaging with puppets.
为了观察年幼的孩子是否会将分享唾液作为亲密关系的社交线索，托马斯和他的同事们进行了一项实验，让人们与木偶互动。
When shown a puppet seemingly crying, kids as young as 8 months old were more likely to look at an adult who had previously shared saliva with the puppet than at an adult who hadn’t, the team reports in Science.
研究小组在《科学》杂志上报告称，当看到一个看起来在哭泣的木偶时，8个月大的孩子更有可能把目光投向之前和木偶有过唾液交流的成年人，而不是没有和木偶有过唾液交流的成年人。
Scientists, of course, can’t know exactly what babies are thinking. But tracking where they look offers hints. The team used where the kids looked first when a puppet showed distress as a proxy for their understanding of the relationship.
当然，科学家无法确切知道婴儿在想什么。但追踪婴儿的目光可以提供一些线索。当木偶表现出痛苦时，研究小组用孩子们首先看的地方代表婴儿对关系的理解。
In some experiments, the team showed 8- to 10-month-olds or 16- to 18-month-olds videos of a woman sharing an orange slice with a puppet. A second video depicted another woman and the puppet playing with a ball. During a final video, which showed the puppet crying while seated between the two women, the kids’ eyes were more often drawn to the woman who had shared the orange.
在一些实验中，研究小组向8至10个月大或16至18个月大的孩子展示了一名妇女与木偶分享橘子片的视频。第二个视频描绘了另一个女人和木偶玩球。在最后一段视频中，当木偶坐在两个女人中间哭泣时，孩子们的眼睛往往会被分享橘子的女人吸引。
The team saw similar results when one woman interacted with two puppets. The woman stuck her finger in her mouth and then in one puppet’s mouth to share saliva. For the other, she touched only her forehead and then the puppet’s forehead. After the woman showed distress, kids spent more time looking at the puppet that had seemingly swapped saliva.
当一名女性与两个木偶互动时，该团队看到了类似的结果。这名女子先把手指放进自己的嘴里，再放进一个木偶的嘴里，分享唾液。在与另一只木偶的互动中，她只用手碰了碰自己的额头，然后再用手碰木偶的额头。在这名妇女表现出痛苦之后，孩子们花更多的时间看那个似乎交换了唾液的木偶。
It’s unclear how the findings relate to children’s daily lives. Future studies could switch out actresses for family members or teachers to better understand the role saliva may play in distinguishing relationships. Other cues, such as hugging, may also play a role, Thomas says.
目前尚不清楚这些发现与儿童的日常生活有何关系。未来的研究可能会把女演员换成家庭成员或教师，以更好地理解唾液在区分人际关系中可能发挥的作用。托马斯说，拥抱等其他暗示也可能起作用。
The study focused only on U.S. children. Still, the work is exciting, says clinical developmental psychologist Darby Saxbe of the University of Southern California. It would be interesting, she says, to see how kids from groups that have different hygiene or eating traditions react.
这项研究只关注美国儿童。南加州大学的临床发展心理学家Saxbe说，尽管如此，这项工作还是令人兴奋的。她说，看看来自不同卫生习惯或饮食传统的群体的孩子如何反应会很有趣。