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. Because we can't control microexpressions as it happens 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 six universal emotions: disgust, anger, fear, sadness, happiness, 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.
Microexpressions were first discovered by Haggard and Isaacs. In their 1966 study, Haggard and Isaacs outlined how they discovered these "micromomentary" expressions while "scanning motion picture films of psychotherapy hours, searching for indications of non-verbal communication between therapist and patient" Through a series of studies, Paul Ekman found a high agreement across members of diverse Western and Eastern literate cultures on selecting emotional labels that fit facial expressions. Expressions he found to be universal included those indicating anger, disgust, fear, happiness, sadness, and surprise. Findings on contempt are less clear, though there is at least some preliminary evidence that this emotion and its expression are universally recognized. Working with his long-time friend Wallace V. Friesen, Ekman demonstrated that the findings extended to preliterate Fore tribesmen in Papua New Guinea, whose members could not have learned the meaning of expressions from exposure to media depictions of emotion. Ekman and Friesen then demonstrated that certain emotions were exhibited with very specific display rules, culture-specific prescriptions about who can show which emotions to whom and when. These display rules could explain how cultural differences may conceal the universal effect of expression.
In the 1960s, William S. Condon pioneered the study of interactions at the fraction-of-a-second level. In his famous research project, he scrutinized a four-and-a-half-second film segment frame by frame, where each frame represented 1/25th second. After studying this film segment for a year and a half, he discerned interactional micromovements, such as the wife moving her shoulder exactly as the husband's hands came up, which combined yielded microrhythms.
Years after Condon's study, American psychologist John Gottman began video-recording living relationships to study how couples interact. By studying participants' facial expressions, Gottman was able to correlate expressions with which relationships would last and which would not. Gottman's 2002 paper makes no claims to accuracy in terms of binary classification, and is instead a regression analysis of a two factor model where skin conductance levels and oral history narratives encodings are the only two statistically significant variables. Facial expressions using Ekman's encoding scheme were not statistically significant. In Malcolm Gladwell's book "Blink", Gottman states that there are four major emotional reactions that are destructive to a marriage: defensiveness which is described as a reaction toward a stimulus as if you were being attacked, stonewalling which is the behavior where a person refuses to communicate or cooperate with another, criticism which is the practice of judging the merits and faults of a person, and contempt which is a general attitude that is a mixture of the primary emotions disgust and anger. Among these four, Gottman considers contempt the most important of them all.
Microexpressions are typically classified based on how an expression is modified. They exist in three groups:
- Simulated expressions: when a microexpression is not accompanied by a genuine emotion. This is the most commonly studied form of microexpression because of its nature. It occurs when there is a brief flash of an expression, and then returns to a neutral state.
- Neutralized expressions: when a genuine expression is suppressed and the face remains neutral. This type of micro-expression is not observable due to the successful suppression of it by a person.
- Masked expressions: when a genuine expression is completely masked by a falsified expression. Masked expressions are microexpressions that are intended to be hidden, either subconsciously or consciously.
In photographs and films
Microexpressions can be difficult to recognize, but still images and video can make them easier to perceive. In order to learn how to recognize the way that various emotions register across parts of the face, Ekman and Friesen recommend the study of what they call "facial blueprint photographs," photographic studies of "the same person showing all the emotions" under consistent photographic conditions. However, because of their extremely short duration, by definition, microexpressions can happen too quickly to capture with traditional photography. Both Condon and Gottman compiled their seminal research by intensively reviewing film footage. Frame rate manipulation also allows the viewer to distinguish distinct emotions, as well as their stages and progressions, which would otherwise be too subtle to identify. This technique is demonstrated in the short film Thought Moments by Michael Simon Toon. Paul Ekman also has materials he has created on his website that teach people how to identify microexpressions using various photographs, including photos he took during his research period in New Guinea.
Moods vs emotions
Moods differ from emotions in that the feelings involved last over a longer period. For example, a feeling of anger lasting for just a few minutes, or even for an hour, is called an emotion. But if the person remains angry all day, or becomes angry a dozen times during that day, or is angry for days, then it is a mood. Many people describe this as a person being irritable, or that the person is in an angry mood. As Paul Ekman described, it is possible but unlikely for a person in this mood to show a complete anger facial expression. More often just a trace of that angry facial expression may be held over a considerable period-a tightened jaw or tensed lower eyelid, or lip pressed against lip, or brows drawn down and together. Emotions are defined as a complex pattern of changes, including physiological arousal, feelings, cognitive processes, and behavioral reactions, made in response to a situation perceived to be personally significant.
Facial expressions are not just uncontrolled instances. Some may be in fact voluntary, another involuntary; thus one may be truthful and another false. Facial expression may be controlled or uncontrolled. Some people are born able to control their expressions (such as pathological liars), while others are trained, for example actors. "Natural liars" know about their ability to control microexpressions, and so do those who know them well. They have been getting away with things since childhood, fooling their parents, teachers, and friends when they wanted to. People can simulate emotion expressions, attempting to create the impression that they feel an emotion when they are not experiencing it at all. A person may show an expression that looks like fear when in fact he feels nothing, or feels sadness or some other emotion. Facial expressions of emotion are controlled for various reasons, whether cultural or by social conventions. For example, in the United States many little boys learn the cultural display rule, "little men do not cry or look afraid." There are also more personal display rules, not learned by most people within a culture, but the product of the idiosyncrasies of a particular family. A child may be taught never to look angrily at his father, or never to show sadness when disappointed. These display rules, whether cultural ones shared by most people or personal, individual ones, are usually so well-learned, and learned so early, that the control of the facial expression they dictate is done automatically without thinking or awareness.
Lies and leakage
There is no sign of deceit itself. There is no gesture, facial expression, nor muscle twitch that in and of itself means that a person is lying. There are only clues that the person is poorly prepared and clues of emotions that don't fit what the person is saying. These are what provide leakage or deception clues. Microexpressions are used as a way to detect if there is something off in a statement that a person mentions. They do not determine a lie but are a form of detecting concealed emotion. Dr. David Matsumoto explains that one must not conclude that someone is lying if a microexpression is detected but that there is more to the story than is being told.
A question commonly asked[by whom?] is whether facial expressions within microexpressions are universal no matter what their background. Charles Darwin wrote that facial expressions of emotion are universal, not learned differently in each culture; that they are biologically determined, the product of man's evolution. Many writers have disagreed with this statement. David Matsumoto however agreed with this statement in his study of sighted and blind Olympians. Using thousands of photographs captured at the 2004 Olympic and Paralympic Games, Matsumoto compared the facial expressions of sighted and blind judo athletes, including individuals who were born blind. All competitors displayed the same expressions in response to winning and losing. Matsumoto discovered that both blind and sighted competitors displayed similar facial expression, during winnings and loss. These results suggest that our ability to modify our faces to fit the social setting is not learned visually. Paul Ekman also agreed that some facial expressions are indeed universal while there are cultural differences in when the expressions are shown.
Facial Action Coding System
The Facial Action Coding System or FACS is used to identify facial expression. This identifies the muscles that produce the facial expressions. To measure the muscle movements the action unit (AU) was developed. This system measures the relaxation or contraction of each individual muscle and assigns a unit. More than one muscle can be grouped into an Action Unit or the muscle may be divided into separate action units. The score consists of duration, intensity and asymmetry. This can be useful in identifying depression or measurement of pain in patients that are unable to express themselves.
The Facial Action Coding System training manual, first published in 1978 with multimedia supplements, is designed to teach individuals how to detect and categorize facial movements. The guide provides lessons and practice for memorizing action units and combinations of action units. The manual's purpose is to enable practitioners to recognize different physiological attributes of facial expressions, but leaves the interpretation of this data up to other works. Users should not expect to become face-reading experts. It can be particularly useful to behavioral scientists, CG animators, or computer scientists when they need to know the exact movements that the face can perform, and what muscles produce them. It also has potential to be a valuable tool for psychotherapists, interviewers, and other practitioners who must penetrate deeply into interpersonal communications. A new version (2002) of FACS by Paul Ekman, Wallace V. Friesen, and Joseph C. Hager is now available with several core improvements, including more accurate representations of facial behaviors and cleaner, digital images. Other related tools for facial expression recognition training include the Micro Expression Training Tool (METT) and Subtle Expression Training Tool (SETT), both developed by Paul Ekman.
In the Wizards Project, previously called the "Diogenes Project", Paul Ekman and Maureen O'Sullivan studied the ability of people to detect deception. Of the thousands of people tested, only a select few were able to accurately detect when someone was lying. The Wizards Project researchers named these people "Truth Wizards". To date, the Wizards Project has identified just over 50 people with this ability after testing nearly 20,000 people. Truth Wizards use microexpressions, among many other cues, to determine if someone is being truthful. Scientists hope by studying wizards that they can further advance the techniques used to identify deception.
In popular culture
Microexpressions and associated science are the central premise for the 2009 television series Lie to Me, Based on discoveries of Paul Ekman. The main character uses his acute awareness of microexpressions and other body language clues to determine when someone is lying or hiding something.
They also play a central role in Robert Ludlum's posthumously published The Ambler Warning, in which the central character, Harrison Ambler, is an intelligence agent who is able to see them. Similarly, one of the main characters in Alastair Reynolds' science fiction novel, Absolution Gap, Aura, can easily read microexpressions.
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