Emotion perception

Modes of perception

Emotions can be perceived through visual, auditory, olfactory, taste and physiological sensory processes. Nonverbal actions can provide social partners with information about subjective and emotional states. This nonverbal information is believed to hold special importance and sensory systems and certain brain regions are suspected to specialize in decoding emotional information for rapid and efficient processing.

Visual

The visual system is the primary mode of perception for the way people receive emotional information. People use emotional cues displayed by social partners to make decisions regarding their affective state. Emotional cues can be in the form of facial expressions, which are actually a combination of many distinct muscle groups within the face, or bodily postures (alone or in relation to others), or found through the interpretation of a situation or environment known to have particular emotional properties (i.e., a funeral, a wedding, a war zone, a scary alley, etc.). While the visual system is the means by which emotional information is gathered, it is the cognitive interpretation and evaluation of this information that assigns it emotional value, garners the appropriate cognitive resources, and then initiates a physiological response. This process is by no means exclusive to visual perception and in fact may overlap considerably with other modes of perception, suggesting an emotional sensory system comprising multiple perceptual processes all of which are processed through similar channels.

Facial perception

A great deal of research conducted on emotion perception revolves around how people perceive emotion in others' facial expressions. Whether the emotion contained in someone's face is classified categorically or along dimensions of valence and arousal, the face provides reliable cues to one's subjective emotional state. As efficient as humans are in identifying and recognizing emotion in another's face, accuracy goes down considerably for most emotions, with the exception of happiness, when facial features are inverted (i.e., mouth placed above eyes and nose), suggesting that a primary means of facial perception includes the identification of spatial features that resemble a prototypical face, such that two eyes are placed above a nose which is above a mouth; any other formation of features does not immediately constitute a face and requires extra spatial manipulation to identify such features as resembling a face.

Discrete versus dimensional views

Research on the classification of perceived emotions has centered around the debate between two fundamentally distinct viewpoints. One side of the debate posits that emotions are separate and discrete entities whereas the other side suggests that emotions can be classified as values on the dimensions of valence (positive versus negative) and arousal (calm/soothing versus exciting/agitating). Psychologist Paul Ekman supported the discrete emotion perspective with his groundbreaking work comparing emotion perception and expression between literate and preliterate cultures. Ekman concluded that the ability to produce and perceive emotions is universal and innate and that emotions manifest categorically as basic emotions (anger, disgust, fear, happiness, sadness, contempt, surprise, and possibly contempt). The alternative dimensional view garnered support from psychologist James Russell, who is best known for his contributions toward the circumplex of emotion. Russell described emotions as constructs which lie on the dimensions of valence and arousal and it is the combination of these values which delineate emotion. Psychologist Robert Plutchik sought to reconcile these views and proposed that certain emotions be considered "primary emotions" which are grouped either positively or negatively and can then be combined to form more complex emotions, sometimes considered "secondary emotions", such as remorse, guilt, submission, and anticipation. Plutchik created the "wheel of emotions" to outline his theory.

Culture

Culture plays a significant role in emotion perception, most notably in facial perception. Although the features of the face convey important information, the upper (eyes/brow) and lower (mouth/nose) regions of the face have distinct qualities that can provide both consistent and conflicting information. As values, etiquette, and quality of social interactions vary across cultures, facial perception is believed to be moderated accordingly. In western cultures, where overt emotion is ubiquitous, emotional information is primarily obtained from viewing the features of the mouth, which is the most expressive part of the face. However, in eastern cultures, where overt emotional expression is less common and therefore the mouth plays a lesser role in emotional expression, emotional information is more often obtained from viewing the upper region of the face, primarily the eyes. These cultural differences suggest a strong environmental and learned component in emotion expression and emotion perception.

Context

Although facial expressions convey key emotional information, context also plays an important role in both providing additional emotional information and modulating what emotion is actually perceived in a facial expression. Contexts come in three categories: stimulus-based context, in which a face is physically presented with other sensory input that has informational value; perceiver-based context, in which processes within the brain or body of a perceiver can shape emotion perception; and cultural contexts that affect either the encoding or the understanding of facial actions.

Auditory

The auditory system can provide important emotional information about the environment. Voices, screams, murmurs, and music can convey emotional information. Emotional interpretations of sounds tend to be quite consistent. Traditionally, emotion perception in the voice has been determined through research studies analyzing, via prosodic parameters such as pitch and duration, the way in which a speaker expresses an emotion, known as encoding. Alternatively, a listener who attempts to identify a particular emotion as intended by a speaker can decode emotion. More sophisticated methods include manipulating or synthesizing important prosodic parameters in speech signal (e.g., pitch, duration, loudness, voice quality) in both natural and simulated affective speech. Pitch and duration tend to contribute more to emotional recognition than loudness. Music has long been known to have emotional qualities and is a popular strategy in emotion regulation. When asked to rate emotions present in classical music, music professionals could identify all six basic emotions with happiness and sadness the most represented, and in decreasing order of importance, anger, fear, surprise, and disgust. The emotions of happiness, sadness, fear, and peacefulness can be perceived in a short length of exposure, as little as 9–16 seconds including instrumental-only music selections.

Olfactory

Aromas and scents also influence mood, for example through aromatherapy, and humans can extract emotional information from scents just as they can from facial expressions and emotional music. Odors may be able to exert their effects through learning and conscious perception, such that responses typically associated with particular odors are learned through association with their matched emotional experiences. In-depth research has documented that emotion elicited by odors, both pleasant and unpleasant, affects the same physiological correlates of emotion seen with other sensory mechanisms.

Somatic

Theories on emotion have focused on perception, subjective experience, and appraisal. Predominant theories of emotion and emotion perception include what type of emotion is perceived, how emotion is perceived somatically, and at what stage of an event emotion is perceived and translated into subjective, physical experience.

James–Lange theory

Following the influence of René Descartes and his ideas regarding the split between body and mind, in 1884 William James proposed the theory that it is not that the human body acts in response to a person's emotional state, as common sense might suggest, but rather, people interpret their emotions on the basis of their already present bodily state. In the words of James, "we feel sad because we cry, angry because we strike, afraid because we tremble, and neither we cry, strike, nor tremble because we are sorry, angry, or fearful, as the case may be." James believed it was particular and distinct physical patterns that map onto specific experienced emotions. Contemporaneously, psychologist Carl Lange arrived at the same conclusion about the experience of emotions. Thus, the idea that felt emotion is the result of perceiving specific patterns of bodily responses is called the James–Lange theory of emotion. In support of the James–Lange theory of emotion, Silvan Tomkins proposed the facial feedback hypothesis in 1963; he suggested that facial expressions actually trigger the experience of emotions and not the other way around. This theory was tested in 1974 by James Laird in an experiment where Laird asked participants to hold a pencil either between their teeth (artificially producing a smile) or between their upper lip and their nose (artificially producing a frown) and then rate cartoons. Laird found that these cartoons were rated as being funnier by those participants holding a pencil in between their teeth. In addition, Paul Ekman recorded extensive physiological data while participants posed his basic emotional facial expressions and found that heart rate raised for sadness, fear, and anger yet did not change at al for happiness, surprise, or disgust, and skin temperature raised when participants posed anger but not other emotions. While contemporary psychologists still agree with the James–Lange theory of emotion, human subjective emotion is complex and physical reactions or antecedents do not fully explain the subjective emotional experience.

Cannon–Bard theory of emotion

Walter Bradford Cannon and his doctoral student Philip Bard agreed that physiological responses played a crucial role in emotions, but did not believe that physiological responses alone could explain subjective emotional experiences. They argued that physiological responses were too slow relative to the relatively rapid and intense subjective awareness of emotion and that often these emotions are similar and imperceptible to people at such a short timescale. Cannon proposed that the mind and body operate independently in the experience of emotions such that differing brain regions (cortex versus subcortex) process information from an emotion-producing stimulus independently and simultaneously resulting in both an emotional and a physical response. This is best illustrated by imagining an encounter with a grizzly bear; you would simultaneously experience fear, begin to sweat, experience an elevated heart rate, and attempt to run. All of these things would happen at the same time.

Two-factor theory

Stanley Schachter and his doctoral student Jerome Singer formulated their theory of emotion based on evidence that without an actual emotion-producing stimulus, people are unable to attribute specific emotions to their bodily states. They believed that there must be a cognitive component to emotion perception beyond that of just physical changes and subjective feelings. Schachter and Singer suggested that when someone encounters such an emotion-producing stimulus, they would immediately recognize their bodily symptoms (sweating and elevated heart rate in the case of the grizzly bear) as the emotion fear. Their theory was devised as a result of a study in which participants were injected with either a stimulant (adrenaline) that causes elevated heart rate, sweaty palms and shaking, or a placebo. Participants were then either told what the effects of the drug were or were told nothing, and were then placed in a room with a person they did not know who, according to the research plan, would either play with a hula hoop and make paper airplanes (euphoric condition) or ask the participant intimate, personal questions (angry condition). They found that participants who knew what the effects of the drug were attributed their physical state to the effects of the drug; however, those who had no knowledge of the drug they received attributed their physical state to the situation with the other person in the room. These results led to the conclusion that physiological reactions contributed to emotional experience by facilitating a focused cognitive appraisal of a given physiologically arousing event and that this appraisal was what defined the subjective emotional experience. Emotions were thus a result of a two-stage process: first, physiological arousal in a response to an evoking stimulus, and second, cognitive elaboration of the context in which the stimulus occurred.