微表情是一种人类在试图隐藏某种情感时无意识做出的、短暂的面部表情。他们对应着七种世界通用的情感：厌恶、愤怒、恐惧、悲伤、快乐、惊讶和轻蔑。

在1960年代，William Condon率先进行了针对瞬间交互的研究。在他著名的研究项目中，他逐帧地仔细观察了一段四秒半的影片片段，每帧是二十五分之一秒。在对这段影片片段研究一年半之后，他已经可以明辨一些交互时的小动作，比如当丈夫把手伸过来的瞬间，妻子会以一种微弱的节奏移动她的肩膀。

美国心理学家John Gottman通过对情侣录像来分析两人间的交互。通过研究这些微动作，Gottman可以预言哪些情侣会继续恋情，而哪些将会分手。

A microexpression is a brief, involuntary facial expression shown on the face of humans according to emotions experienced. They usually occur in high-stakes situations, where people have something to lose or gain. Microexpressions occur when a person is consciously trying to conceal all signs of how they are feeling, or when a person does not consciously know how they are feeling. Unlike regular facial expressions, it is difficult/impossible to hide microexpression reactions. Microexpressions cannot be controlled as they happen in a fraction of a second, but it's possible to capture someone's expressions with a high speed camera and replay them at much slower speeds. Microexpressions express the seven universal emotions: disgust, anger, fear, sadness, happiness, contempt, and surprise. Nevertheless, in the 1990s, Paul Ekman expanded his list of emotions, including a range of positive and negative emotions not all of which are encoded in facial muscles. These emotions are amusement, contempt, embarrassment, anxiety, guilt, pride, relief, contentment, pleasure, and shame. They are very brief in duration, lasting only 1/25 to 1/15 of a second.