Facial expression

Photographs from the 1862 book Mécanisme de la Physionomie Humaine by Guillaume Duchenne. Through electric stimulation, Duchenne determined which muscles were responsible for different facial expressions. Charles Darwin would later republish some of these photographs in his own work on the subject, which compared facial expressions in humans to those in animals.

A facial expression is one or more motions or positions of the muscles in the skin. These movements convey the emotional state of the individual to observers. Facial expressions are a form of nonverbal communication. They are a primary means of conveying social information among humans, but also occur in most other mammals and some other animal species.

Humans can adopt a facial expression to read as a voluntary action. However, because expressions are closely tied to emotion, they are more often involuntary. It can be nearly impossible to avoid expressions for certain emotions, even when it would be strongly desirable to do so; a person who is trying to avoid insulting an individual he or she finds highly unattractive might nevertheless show a brief expression of disgust before being able to reassume a neutral expression. Microexpressions are one example of this phenomenon. The close link between emotion and expression can also work in the other direction; it has been observed that voluntarily assuming an expression can actually cause the associated emotion (Schnall & Laird, 2003; Soussignan, 2002 as cited in Papa & Bonanno, 2008).

Some expressions can be accurately interpreted even between members of different species- anger and extreme contentment being the primary examples. Others, however, are difficult to interpret even in familiar individuals. For instance, disgust and fear can be tough to tell apart.

Because faces have only a limited range of movement, expressions rely upon fairly minuscule differences in the proportion and relative position of facial features, and reading them requires considerable sensitivity to same. Some faces are often falsely read as expressing some emotion, even when they are neutral, because their proportions naturally resemble those another face would temporarily assume when emoting.

Communication

Eye contact

See also: Eye contact

A person's face, especially their eyes, creates the most obvious and immediate cues that lead to the formation of impressions. This article discusses eyes and facial expressions and the effect they have on interpersonal communication.

A person's eyes reveal much about how they are feeling, or what they are thinking. Blink rate can reveal how nervous or at ease a person may be. Research by Boston College professor Joe Tecce suggests that stress levels are revealed by blink rates. He supports his data with statistics on the relation between the blink rates of presidential candidates and their success in their races. Tecce claims that the faster blinker in the presidential debates has lost every election since 1980. Though Tecce's data is interesting, it is important to recognize that non-verbal communication is multi-channeled, and focusing on only one aspect is reckless. Nervousness can also be measured by examining each candidates' perspiration, eye contact and stiffness.

Eye contact is another major aspect of facial communication. Some have hypothesized that this is due to infancy, as humans are one of the few mammals who maintain regular eye contact with their mother while nursing. Eye contact serves a variety of purposes. It regulates conversations, shows interest or involvement, and establishes a connection with others.

Eye contact regulates conversational turn taking, communicates involvement and interest, manifests warmth, and establishes connections with others…[and] it can command attention, be flirtatious, or seem cold and intimidating… [it] invites conversation. Lack of eye contact is usually perceived to be rude or inattentive.

But different cultures have different rules for eye contact. Certain Asian cultures can perceive direct eye contact as a way to signal competitiveness, which in many situations may prove to be inappropriate. Others lower their eyes to signal respect, and similarly eye contact is avoided in Nigeria, and between men and women in Islam; however, in western cultures this could be misinterpreted as lacking self-confidence.

Even beyond the idea of eye contact, eyes communicate more data than a person even consciously expresses. Pupil dilation is a significant cue to a level of excitement, pleasure, or attraction. Dilated pupils indicate greater affection or attraction, while constricted pupils send a colder signal.

Face overall

The face as a whole indicates much about human moods as well. Specific emotional states, such as happiness or sadness, are expressed through a smile or a frown, respectively. There are seven universally recognized emotions shown through facial expressions: fear, anger, surprise, contempt, disgust, happiness, and sadness. Regardless of culture, these expressions are the same. However, the same emotion from a specific facial expression may be recognized by a culture, but the same intensity of emotion may not be perceived. For example, studies have shown that Asian cultures tend to rate images of facial emotions as less intense than non-Asian cultures surveyed. This difference can be explained by display rules, which are culture-specific guidelines for behavior appropriateness. In some countries, it may be more rude to display an emotion than in another. Showing anger toward another member in a group may create problems and disharmony, but if displayed towards a competitive rival, it could create in-group cohesion.

Sign languages

Facial expression is used in sign languages to convey specific meanings. In American Sign Language (ASL), for instance, raised eyebrows combined with a slightly forward head tilt indicate that what is being signed is a yes/no question. Lowered eyebrows are used for wh-word questions. Facial expression is also used in sign languages to show adverbs and adjectives such as distance or size: an open mouth, squinted eyes, and tilted back head indicate something far while the mouth pulled to one side and the cheek held toward the shoulder indicate something close, and puffed cheeks mean very large. It can also show the manner in which something is done, such as carelessly or routinely. Some of these expressions, also called non-manual signs, are used similarly in different sign languages while others are different from one language to another. For example, the expression used for 'carelessly' in ASL means 'boring or unpleasant' in British Sign Language.

Facial expressions

There are six classically defined facial expressions:

• Joy
• Surprise
• Fear
• Anger
• Disgust
• Sadness

Some other examples of feelings that can be expressed are:

• Anger
• Concentration
• Confusion
• Contempt
• Desire
• Disgust
• Excitement
• Empathy
• Fear
• Flirt
• Frustration
• Glaring
• Happiness
• Love
• Sadness
• Snarl, mainly involving the levator labii superioris alaeque nasi muscle
• Surprise

Universality of facial expressions

The Universality Hypothesis is assumption that certain facial expressions are signals of specific emotions (happiness, sadness, anger, fear, surprise, disgust) that are recognized by people everywhere, regardless of culture or language. The evolutionary basis of these kinds of facial expressions can be traced back to Darwin’s “The Expression of Emotion in Man and Animals.” Reviews of the Universality Hypothesis have been both supportive (Ekman, Friesen, and Ellsworth, 1972; Izard, 1971) and critical (Woodworth and Schlosberg, 1954; Russell, 1994).

Support for the Universality Hypothesis

Ekman's work on facial expressions had its starting point in the work of psychologist Silvan Tomkins.[2] Ekman showed that facial expressions of emotion are not culturally determined, but universal across human cultures.

To demonstrate the Universality Hypothesis, Ekman tested the South Fore people of New Guinea, a pre-industrial culture that was isolated from Western culture. The Fore were told brief stories about emotional events (happiness, sadness, anger, fear, surprise, disgust). After each story they were asked to select the matching facial expression from an array of three faces (Ekman & Friesen, 1971). The Fore selected the correct face on 64%-90% of trials – but had difficulty telling the fear face from the surprise face. Children selected from an array of only 2 faces and their results were similar to adults’. Subsequent cross-cultural studies with other cultures found also similar results (Ekman, 1987).

Questioning the Universality Hypothesis

People on both sides of this debate agree that the face expresses emotion. The question is: What specific emotional information do we read from a facial expression? Is a specific discrete emotion as claimed by the Universality Hypothesis? Or is it other more general information which we then piece together with other contextual information to determine how a person feels (Aviezer; Carroll & Russell, 1996)?

One difficulty with the evidence presented in support of the Universality Hypothesis is the method typically used to demonstrate universality inflates recognition scores (Russell, 1994). Although each factor may contribute only a small to the inflation, combined they can produce exaggerated scores.

1. The Universality Hypothesis is about our ability to recognize spontaneous facial expressions as they occur naturally. Yet the facial expressions used to test this hypothesis are posed. Studies of spontaneous facial expressions are rare and find that participants’ recognition of the expressions is lower than of the corresponding posed expressions (Matsumoto et al., 2009; Naab & Russell, 2007).

2. In most studies, participants are shown more than one facial expression (Ekman recommends six of each expression). But people judge facial expressions relative to others that they have seen (Thayer, 1980) and participants who judge more than one facial expression have higher recognition rates than those who judge only one (Russell, 1994).

3. The response format that is most commonly used in emotion recognition studies is forced choice. In forced choice, for each facial expression, participants are asked to select their response from a short list of emotion labels. The forced choice method determines the emotion attributed to the facial expressions via the labels that are presented (Russell, 1994). That is, participants will select the best match to the facial expression even if it is not the emotion label they would have provided spontaneously and even if they would not have labeled the expression as an emotion at all (Wagner, 2000).

Universality as Evolutionary Significant

Darwin argued that the expression of emotions has evolved in humans from animals, who would have used similar methods of expression. Darwin believed that expressions were unlearned and innate in human nature and were therefore evolutionary significant for survival. Darwin obtained evidence of this through research on different cultures, species and on infants. Cross-cultural studies had shown that there are similarities in the way emotions are expressed across diverse cultures, but studies have even shown that there are similarities between species in how emotions are expressed. Research has shown that chimpanzees are able to communicate many of the same facial expression through the complex movements of the facial muscles. The facial cues were so similar that Ekman’s Facial Action Coding System could be applied to the chimps in evaluating their expressions. Of course, differences between the species physical facial properties, such as white sclera and everted lips in chimps, would mean that some expressions could not be compared. Similarly, Darwin observed that infants’ method of expression not only was similar to those of adults, but seemed to be instinctive, as they were able to display emotional expressions they had not themselves yet witnessed. It is clear that facial morphology may also impact upon expression recognition in important ways and therefore infant facial morphology may also serve some specific communicative function. These similarities in morphology and movement in emotional expression are important for the interpretation of emotions. Darwin was particularly interested in the functions facial expression as evolutionarily important for survival. He looked at the functions of facial expression in terms of the utility of expression in the life on the animal and in terms of specific expressions in species. Darwin deduced that animals were communicating feelings of different emotional states with specific facial expressions. He further concluded that the this communication was important for survival of animals in group-dwelling species; the skill to effectively communicate or interpret another animal’s feelings and behaviors would be a principal trait in naturally fit species.

Neural Mechanisms in Recognizing Facial Expressions

The amygdala plays an important role in facial recognition. Functional imaging studies have found that when shown pictures of faces, there is a large increase in the activity of the amygdala. The amygdala receives visual information from the thalamus via the subcortical pathways. The amygdala may also have a significant role in the recognition of fear and negative emotions. It is believed that the emotion disgust is recognized through activation of the insula and basal ganglia. The recognition of emotion may also utilize the occipitotemporal neocortex, orbitofrontal cortex and right frontoparietal cortices.

Muscles of facial expression

See also: facial muscles

• Auricularis anterior muscle
• Buccinator muscle
• Corrugator supercilii muscle
• Depressor anguli oris muscle
• Depressor labii inferioris muscle
• Depressor septi nasi muscle
• Frontalis muscle
• Levator anguli oris muscle
• Levator labii superioris alaeque nasi muscle
• Levator labii superioris muscle
• Mentalis muscle
• Modiolus muscle
• Nasalis muscle
• Orbicularis oculi muscle
• Orbicularis oris muscle
• Platysma muscle
• Procerus muscle
• Risorius muscle
• Zygomaticus major muscle
• Zygomaticus minor muscle

See also

• Affect display
• Emotion
• Emotion classification
• Gurn
• Facial Action Coding System, Paul Ekman
• Laughter, Gelotology, Freitas-Magalhães
• Metacommunicative competence
• Bell's Palsy

External links

• The Naked Face, August 5, 2002. Annals of Psychology
• Facial Expressions Resources Page contains links to research concerning facial expressions
• Bell's Palsy information site Information for sufferer's of facial palsy/facial paralysis