The real reason people close their eyes when they kiss is because the brain can't deal with more than two things at once.

接吻时闭眼的真正原因是大脑无法同时处理两件以上的事。

That is the finding of academics who have explored one of the great mysteries of the human psyche¹.

探索人类心灵奥秘的学者们给出了这一结论。

When people pucker² up the brain finds it difficult to process the sensation if cognitive³ power is also being used to analyse what we see, said psychologists from Royal Holloway, University of London.

伦敦大学皇家霍洛威学院的心理学家们表示，当人们撅起嘴唇接吻的时候，他们的大脑在这个过程中很难同时用于分析另外一个感官——视觉——看到了什么。

'Tactile⁴ awareness⁵ depends on the level of perceptual load in a concurrent⁶ visual task,' said Polly Dalton and Sandra Murphy, from the university, in the Journal of Experimental Psychology⁷: Human Perception and Performance.

波莉·道尔顿和桑德拉·墨菲在《实验心理学杂志》上发表了一篇名为《人类感知与表现》的文章。文中写道：“人们的触觉感知取决于他们在同时发生的视觉感知中的感知负荷。”

The cognitive psychologists reached their conclusion without studying people actually kissing.

认知心理学家的此项研究没有以真正接吻的人为研究对象。

Instead people were asked do visual tests while their response to something touching their hands was measured.

研究人员对受试者进行了视觉测试，同时用东西触碰他们的手，观察记录他们的反应。

The academics found that the visual field overrides⁸ tactile responses - meaning people would struggle to continue kissing if what they were looking at became more difficult to process.

研究人员发现，视觉反应凌驾于触觉反应之上，也就是说，如果大脑处理接吻时所见之物的处理难度加大，接吻就很难持续。

Dr Dalton told The Sunday Times: 'If we are focusing strongly on a visual task, this will reduce our awareness of stimuli⁹ in other senses.

道尔顿博士告诉《星期日泰晤士报》：“如果我们的注意力都集中在视觉任务处理上，对其他感知的感觉能力就会减弱。”

'It is important for designers to be aware of these effects, because auditory and tactile alerts are often used in situations of high visual demand, such as driving a car or flying an aircraft.'

“对实验设计人员来说，认识到这类影响非常重要，因为对视觉注意力要求较高的情景经常会用到听觉和触觉感知，比如驾驶汽车或飞机。”

The findings could also explain why people often shut their eyes whilst reading braille or when dancing.

这一发现也解释了为什么人们在阅读盲文或跳舞时通常都会闭着眼睛。

Dr Dalton added: 'These results could explain why we close our eyes when we want to focus attention on another sense. Shutting out the visual input¹⁰ leaves more mental resources to focus on other aspects of our experience.'

道尔顿博士还说：“这项结果能够解释人们为什么将注意力集中在另一感知时会闭眼。关闭视觉输入能够为其他感知留出更多精力。”