Facial expression is a motion and positioning of the muscles beneath the skin of the face. These movements convey the emotional state of an individual to observers and are a form of nonverbal communication. They are a primary means of conveying social information between humans, but they also occur in most other mammals and some other animal species.
Humans can adopt a facial expression voluntarily or involuntarily, and the neural mechanisms responsible for controlling the expression differ in each case. Voluntary facial expressions are often socially conditioned and follow a cortical route in the brain. Conversely, involuntary facial expressions are believed to be innate and follow a subcortical route in the brain. Facial recognition can be an emotional experience for the brain and the amygdala is highly involved in the recognition process.
Beyond the accessory nature of facial expressions in spoken communication between people, they play a significant role in communication with sign language. Many phrases in sign language include facial expressions.
There is controversy surrounding the question of whether facial expressions are a worldwide and universal display among humans.
Creation
Facial muscles
Facial expressions are vital to social communication between humans. They are caused by the movement of muscles that connect to the skin and fascia in the face. These muscles move the skin, creating lines and folds and causing the movement of facial features, such as the mouth and eyebrows. These muscles develop from the second pharyngeal arch in the embryo. The temporalis, masseter, and internal and external pterygoid muscles, which are mainly used for chewing, have a minor effect on expression as well. These muscles develop from the first pharyngeal arch.
Neuronal pathways There are two brain pathways associated with facial expression; the first is voluntary expression. Voluntary expression travels from the primary motor cortex through the pyramidal tract, specifically the corticobulbar projections. The cortex is associated with display rules in emotion, which are social precepts that influence and modify expressions. Cortically related expressions are made consciously.
The second type of expression is emotional. These expressions originate from the extrapyramidal motor system, which involves subcortical nuclei. For this reason, genuine emotions are not associated with the cortex and are often displayed unconsciously. This is demonstrated in infants before the age of two; they display distress, disgust, interest, anger, contempt, surprise, and fear. Infants' displays of these emotions indicate that they are not cortically related. Similarly, blind children also display emotions, proving that they are subconscious rather than learned. Other subcortical facial expressions include the "knit brow" during concentration, raised eyebrows when listening attentively, and short "punctuation" expressions to add emphasis during speech. People can be unaware that they are producing these expressions.
Asymmetries The lower portions of the face are controlled by the opposite cerebral hemisphere, causing asymmetric facial expression. Because the right hemisphere is more specialized for emotional expression, emotions are more strongly expressed on the left side of the face, particularly for negative emotions. Asymmetries in expression can be seen in chimeric faces (facial portraits made by combining the left and right halves of faces with different expressions) and also in portraits which more often show the left, more emotional side of the face than the right.
Neural mechanisms in face perception
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 sub cortical 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.
Gender and facial cues More than anything though, what shapes a child's cognitive ability to detect facial expression is being exposed to it from the time of birth. The more an infant is exposed to different faces and expressions, the more able they are to recognize these emotions and then mimic them for themselves. Infants are exposed to an array of emotional expressions from birth, and evidence indicates that they imitate some facial expressions and gestures (e.g., tongue protrusion) as early as the first few days of life.Field, T. M., Woodson, R., Cohen, D., Greenberg, R., Garcia, R., & Collins, K. (1983). Discrimination and imitation of facial expressions by term and preterm neonates. Infant Behavior and Development, 6(4), 485-489.Rinn, William E. (1984). "The Neuropsychology of Facial Expression: A Review of the Neurological and Psychological Mechanisms for Producing Facial Expressions". Psychological Bulletin. 95 (1): 52–77. doi:10.1037/0033-2909.95.1.52. PMID 6242437. In addition, gender affects the tendency to express, perceive, remember, and forget specific emotions. For instance, angry male faces and happy female faces are more recognizable, compared to happy male faces and angry female faces.
Communication A 2020 study on "emotion residue" found that even when study participants attempted to make neutral facial expressions, their faces still retained emotion residue from prior expressions, and these prior expressions were able to be detected by observers.
A 1988 study on the "facial feedback" hypothesis found that study participants' mood was improved when they smiled. However, this study later failed a large replication attempt.
One experiment investigated the influence of gaze direction and facial expression on face memory. Participants were shown a set of unfamiliar faces with either happy or angry facial expressions, which were either gazing straight ahead or had their gaze averted to one side. Memory for faces that were initially shown with angry expressions was found to be poorer when these faces had averted as opposed to direct gaze, whereas memory for individuals shown with happy faces was unaffected by gaze direction. It is suggested that memory for another individual's face partly depends on an evaluation of the behavioral intention of that individual.
A 2025 study from Nottingham Trent University in England found that people who were facially expressive were more liked by social partners, which may be one reason why people produce, on average, 101 facial movements per minute during a given social interaction.
Multimodal communication
Researchers have suggested that facial expressions are often interpreted in conjunction with other forms of communication. In everyday interactions, people often rely on facial expressions. vocal tone, and speech content simultaneously to help interpret another person's emotions. Relying on multiple communication channels may provide an individual with additional information that helps interpret and understand another person's emotional state more accurately.
One study used video recordings of actors telling emotional stories using varying degrees of facial expressions, vocal tone, and speech content. The researchers found that emotional recognition was strongest when all three channels conveyed the same emotion. The study also suggested that participants experienced a greater degree of empathy when facial expressions, vocal tones, and speech content expressed the same emotion message. When even one of the communication channels was neutral or missing, the study showed that emotion recognition and empathy decreased.
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."In the blink of an eye." (October 21, 1999). Newsweek. 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.Rothwell, J. Dan. In the Company of Others: An Introduction to Communication. United States: McGraw-Hill, 2004.
Within their first year, Infants learn rapidly that the looking behaviors of others convey significant information. Infants prefer to look at faces that engage them in mutual gaze and that, from an early age, healthy babies show enhanced neural processing of direct gaze.Eye Contact Detection in Humans From Birth, PNAS Vol 99 N.14 2002.
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.Spitz, Rene A., and Wolf, K.M. "The Smiling Response: A Contribution to the Ontogenesis of Social Relations." Genetic Psychology Monographs. 34 (August 1946). pp. 57–125. Eye contact serves a variety of purposes. It regulates conversations, shows interest or involvement, and establishes a connection with others.
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;Caring for Patients from Different Cultures, by Geri-Ann Galanti, p. 34 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.
Dynamic facial expressions Researchers have traditionally studied facial expressions by using static photographs in their studies. In real-life communication, people do not see frozen facial expressions. Instead, in a real conversation, you see the face transition from one emotion to the next. Unlike static photographs, dynamic facial expressions allow an observer to view the development of an expression as it changes from a neutral expression to a fully expressed emotion. Dynamic facial expressions develop and change over time. Some researchers have argued that because of this, dynamic facial expressions may provide additional information about someone's emotional state that cannot be captured by a single photograph.
Watching an expression develop over time allows observers to witness the progression, timing, and intensity of an emotional response. This may contribute to a more accurate interpretation of a person's emotional state.