Facial EMG Responses to Emotional Expressions Are Related to Emotion Perception Ability

Although most people can identify facial expressions of emotions well, they still differ in this ability. According to embodied simulation theories understanding emotions of others is fostered by involuntarily mimicking the perceived expressions, causing a “reactivation” of the corresponding mental state. Some studies suggest automatic facial mimicry during expression viewing; however, findings on the relationship between mimicry and emotion perception abilities are equivocal. The present study investigated individual differences in emotion perception and its relationship to facial muscle responses - recorded with electromyogram (EMG) - in response to emotional facial expressions. N° = °269 participants completed multiple tasks measuring face and emotion perception. EMG recordings were taken from a subsample (N° = °110) in an independent emotion classification task of short videos displaying six emotions. Confirmatory factor analyses of the m. corrugator supercilii in response to angry, happy, sad, and neutral expressions showed that individual differences in corrugator activity can be separated into a general response to all faces and an emotion-related response. Structural equation modeling revealed a substantial relationship between the emotion-related response and emotion perception ability, providing evidence for the role of facial muscle activation in emotion perception from an individual differences perspective.     

A two-process theory of facial perception of emotions.

A two-process probabilistic theory of emotion perception based on a non-linear combination of facial features is presented. Assuming that the upper and the lower part of the face function as the building blocks at the basis of emotion perception, an empirical test is provided with fear and happiness as target emotions. Subjects were presented with prototypical fearful and happy faces and with computer-generated chimerical expressions that were a combination of happy and fearful. Subjects were asked to indicate the emotions they perceive using an extensive list of emotions. We show that some emotions require a conjunction of the two halves of a face to be perceived, whereas for some other emotions only one half is sufficient. We demonstrate that chimerical faces give rise to the perception of genuine emotions. The findings provide evidence that different combinations of the two halves of a fearful and a happy face, either congruent or not, do generate the perception of emotions other than fear and happiness.     

场景的一致性效应及其机制

有关场景一致性效应的研究发现,人们对与背景语义一致的前景物体的命名、分类、搜索和再认等都快于与背景不一致的物体.和与情境一致的物体相比,与情境不一致的物体在中央顶区等部位,会诱发一个幅度更大的负波(N390).旁海马皮层/旁海马位置区(PHC/PPA)和压部后皮层(RSC)是负责场景加工的重要脑区.场景一致性效应的时间进程可能首先由低空间分辨率(LSF)信息激活眶额皮层(OFC)(130 ms左右)、PHC/PPA和RSC,之后LSF信息与高空间分辨率(HSF)信息在颞叶进行整合.在诸多理论模型中,情境促进模型从生理角度对一致性效应作了较充分的解释.     

When Early Experiences Build a Wall to Others’ Emotions: An Electrophysiological and Autonomic Study

Facial expression of emotions is a powerful vehicle for communicating information about others’ emotional states and it normally induces facial mimicry in the observers. The aim of this study was to investigate if early aversive experiences could interfere with emotion recognition, facial mimicry, and with the autonomic regulation of social behaviors. We conducted a facial emotion recognition task in a group of “street-boys” and in an age-matched control group. We recorded facial electromyography (EMG), a marker of facial mimicry, and respiratory sinus arrhythmia (RSA), an index of the recruitment of autonomic system promoting social behaviors and predisposition, in response to the observation of facial expressions of emotions. Results showed an over-attribution of anger, and reduced EMG responses during the observation of both positive and negative expressions only among street-boys. Street-boys also showed lower RSA after observation of facial expressions and ineffective RSA suppression during presentation of non-threatening expressions. Our findings suggest that early aversive experiences alter not only emotion recognition but also facial mimicry of emotions. These deficits affect the autonomic regulation of social behaviors inducing lower social predisposition after the visualization of facial expressions and an ineffective recruitment of defensive behavior in response to non-threatening expressions.     

The Odor Context Facilitates the Perception of Low-Intensity Facial Expressions of Emotion

It has been established that the recognition of facial expressions integrates contextual information. In this study, we aimed to clarify the influence of contextual odors. The participants were asked to match a target face varying in expression intensity with non-ambiguous expressive faces. Intensity variations in the target faces were designed by morphing expressive faces with neutral faces. In addition, the influence of verbal information was assessed by providing half the participants with the emotion names. Odor cues were manipulated by placing participants in a pleasant (strawberry), aversive (butyric acid), or no-odor control context. The results showed two main effects of the odor context. First, the minimum amount of visual information required to perceive an expression was lowered when the odor context was emotionally congruent: happiness was correctly perceived at lower intensities in the faces displayed in the pleasant odor context, and the same phenomenon occurred for disgust and anger in the aversive odor context. Second, the odor context influenced the false perception of expressions that were not used in target faces, with distinct patterns according to the presence of emotion names. When emotion names were provided, the aversive odor context decreased intrusions for disgust ambiguous faces but increased them for anger. When the emotion names were not provided, this effect did not occur and the pleasant odor context elicited an overall increase in intrusions for negative expressions. We conclude that olfaction plays a role in the way facial expressions are perceived in interaction with other contextual influences such as verbal information.     

Categorical Perception of Fear and Anger Expressions in Whole,Masked and Composite Faces

Human observers are remarkably proficient at recognizing expressions of emotions and at readily grouping them into distinct categories. When morphing one facial expression into another, the linear changes in low-level features are insufficient to describe the changes in perception, which instead follow an s-shaped function. Important questions are, whether there are single diagnostic regions in the face that drive categorical perception for certain parings of emotion expressions, and how information in those regions interacts when presented together. We report results from two experiments with morphed fear-anger expressions, where (a) half of the face was masked or (b) composite faces made up of different expressions were presented. When isolated upper and lower halves of faces were shown, the eyes were found to be almost as diagnostic as the whole face, with the response function showing a steep category boundary. In contrast, the mouth allowed for a substantially lesser amount of accuracy and responses followed a much flatter psychometric function. When a composite face consisting of mismatched upper and lower halves was used and observers were instructed to exclusively judge either the expression of mouth or eyes, the to-be-ignored part always influenced perception of the target region. In line with experiment 1, the eye region exerted a much stronger influence on mouth judgements than vice versa. Again, categorical perception was significantly more pronounced for upper halves of faces. The present study shows that identification of fear and anger in morphed faces relies heavily on information from the upper half of the face, most likely the eye region. Categorical perception is possible when only the upper face half is present, but compromised when only the lower part is shown. Moreover, observers tend to integrate all available features of a face, even when trying to focus on only one part.     

Congenital facial palsy and emotion processing: The case of Moebius syndrome

According to the Darwinian perspective, facial expressions of emotions evolved to quickly communicate emotional states and would serve adaptive functions that promote social interactions. Embodied cognition theories suggest that we understand others' emotions by reproducing the perceived expression in our own facial musculature (facial mimicry) and the mere observation of a facial expression can evoke the corresponding emotion in the perceivers. Consequently, the inability to form facial expressions would affect the experience of emotional understanding. In this review, we aimed at providing account on the link between the lack of emotion production and the mechanisms of emotion processing. We address this issue by taking into account Moebius syndrome, a rare neurological disorder that primarily affects the muscles controlling facial expressions. Individuals with Moebius syndrome are born with facial paralysis and inability to form facial expressions. This makes them the ideal population to study whether facial mimicry is necessary for emotion understanding. Here, we discuss behavioral ambiguous/mixed results on emotion recognition deficits in Moebius syndrome suggesting the need to investigate further aspects of emotional processing such as the physiological responses associated with the emotional experience during developmental age.     

Rapid facial mimicry in orangutan play

Emotional contagion enables individuals to experience emotions of others. This important empathic phenomenon is closely linked to facial mimicry, where facial displays evoke the same facial expressions in social partners. In humans, facial mimicry can be voluntary or involuntary, whereby its latter mode can be processed as rapid as within or at 1s. Thus far, studies have not provided evidence of rapid involuntary facial mimicry in animals.This study assessed whether rapid involuntary facial mimicry is present in orangutans (Pongo pygmaeus; N=25) for their open-mouth faces (OMFs) during everyday dyadic play. Results clearly indicated that orangutans rapidly mimicked OMFs of their playmates within or at 1s. Our study revealed the first evidence on rapid involuntary facial mimicry in non-human mammals. This finding suggests that fundamental building blocks of positive emotional contagion and empathy that link to rapid involuntary facial mimicry in humans have homologues in non-human primates.     

Context modulation of facial emotion perception differed by individual difference

Background

Certain facial configurations are believed to be associated with distinct affective meanings (i.e. basic facial expressions), and such associations are common across cultures (i.e. universality of facial expressions). However, recently, many studies suggest that various types of contextual information, rather than facial configuration itself, are important factor for facial emotion perception.

Methodology/Principal Findings

To examine systematically how contextual information influences individuals’ facial emotion perception, the present study estimated direct observers’ perceptual thresholds for detecting negative facial expressions via a forced-choice psychophysical procedure using faces embedded in various emotional contexts. We additionally measured the individual differences in affective information-processing tendency (BIS/BAS) as a possible factor that may determine the extent to which contextual information on facial emotion perception is used. It was found that contextual information influenced observers'' perceptual thresholds for facial emotion. Importantly, individuals’ affective-information tendencies modulated the extent to which they incorporated context information into their facial emotion perceptions.

Conclusions/Significance

The findings of this study suggest that facial emotion perception not only depends on facial configuration, but the context in which the face appears as well. This contextual influence appeared differently with individual’s characteristics of information processing. In summary, we conclude that individual character traits, as well as facial configuration and the context in which a face appears, need to be taken into consideration regarding facial emotional perception.     

Adaptation Aftereffects in Vocal Emotion Perception Elicited by Expressive Faces and Voices

The perception of emotions is often suggested to be multimodal in nature, and bimodal as compared to unimodal (auditory or visual) presentation of emotional stimuli can lead to superior emotion recognition. In previous studies, contrastive aftereffects in emotion perception caused by perceptual adaptation have been shown for faces and for auditory affective vocalization, when adaptors were of the same modality. By contrast, crossmodal aftereffects in the perception of emotional vocalizations have not been demonstrated yet. In three experiments we investigated the influence of emotional voice as well as dynamic facial video adaptors on the perception of emotion-ambiguous voices morphed on an angry-to-happy continuum. Contrastive aftereffects were found for unimodal (voice) adaptation conditions, in that test voices were perceived as happier after adaptation to angry voices, and vice versa. Bimodal (voice + dynamic face) adaptors tended to elicit larger contrastive aftereffects. Importantly, crossmodal (dynamic face) adaptors also elicited substantial aftereffects in male, but not in female participants. Our results (1) support the idea of contrastive processing of emotions (2), show for the first time crossmodal adaptation effects under certain conditions, consistent with the idea that emotion processing is multimodal in nature, and (3) suggest gender differences in the sensory integration of facial and vocal emotional stimuli.     

Relationships among Facial Mimicry,Emotional Experience,and Emotion Recognition

Background

The relationships between facial mimicry and subsequent psychological processes remain unclear. We hypothesized that the congruent facial muscle activity would elicit emotional experiences and that the experienced emotion would induce emotion recognition.

Methodology/Principal Findings

To test this hypothesis, we re-analyzed data collected in two previous studies. We recorded facial electromyography (EMG) from the corrugator supercilii and zygomatic major and obtained ratings on scales of valence and arousal for experienced emotions (Study 1) and for experienced and recognized emotions (Study 2) while participants viewed dynamic and static facial expressions of negative and positive emotions. Path analyses showed that the facial EMG activity consistently predicted the valence ratings for the emotions experienced in response to dynamic facial expressions. The experienced valence ratings in turn predicted the recognized valence ratings in Study 2.

Conclusion

These results suggest that facial mimicry influences the sharing and recognition of emotional valence in response to others'' dynamic facial expressions.     

Neural structures associated with recognition of facial expressions of basic emotions.

People with Huntington''s disease and people suffering from obsessive compulsive disorder show severe deficits in recognizing facial expressions of disgust, whereas people with lesions restricted to the amygdala are especially impaired in recognizing facial expressions of fear. This double dissociation implies that recognition of certain basic emotions may be associated with distinct and non-overlapping neural substrates. Some authors, however, emphasize the general importance of the ventral parts of the frontal cortex in emotion recognition, regardless of the emotion being recognized. In this study, we used functional magnetic resonance imaging to locate neural structures that are critical for recognition of facial expressions of basic emotions by investigating cerebral activation of six healthy adults performing a gender discrimination task on images of faces expressing disgust, fear and anger. Activation in response to these faces was compared with that for faces showing neutral expressions. Disgusted facial expressions activated the right putamen and the left insula cortex, whereas enhanced activity in the posterior part of the right gyrus cinguli and the medial temporal gyrus of the left hemisphere was observed during processing of angry faces. Fearful expressions activated the right fusiform gyrus and the left dorsolateral frontal cortex. For all three emotions investigated, we also found activation of the inferior part of the left frontal cortex (Brodmann area 47). These results support the hypotheses derived from neuropsychological findings, that (i) recognition of disgust, fear and anger is based on separate neural systems, and that (ii) the output of these systems converges on frontal regions for further information processing.     

Body Actions Change the Appearance of Facial Expressions

Perception, cognition, and emotion do not operate along segregated pathways; rather, their adaptive interaction is supported by various sources of evidence. For instance, the aesthetic appraisal of powerful mood inducers like music can bias the facial expression of emotions towards mood congruency. In four experiments we showed similar mood-congruency effects elicited by the comfort/discomfort of body actions. Using a novel Motor Action Mood Induction Procedure, we let participants perform comfortable/uncomfortable visually-guided reaches and tested them in a facial emotion identification task. Through the alleged mediation of motor action induced mood, action comfort enhanced the quality of the participant’s global experience (a neutral face appeared happy and a slightly angry face neutral), while action discomfort made a neutral face appear angry and a slightly happy face neutral. Furthermore, uncomfortable (but not comfortable) reaching improved the sensitivity for the identification of emotional faces and reduced the identification time of facial expressions, as a possible effect of hyper-arousal from an unpleasant bodily experience.     

Situational Context and Perceived Threat Modulate Approachability Judgements to Emotional Faces

Facial expressions of emotion play a key role in guiding social judgements, including deciding whether or not to approach another person. However, no research has examined how situational context modulates approachability judgements assigned to emotional faces, or the relationship between perceived threat and approachability judgements. Fifty-two participants provided approachability judgements to angry, disgusted, fearful, happy, neutral, and sad faces across three situational contexts: no context, when giving help, and when receiving help. Participants also rated the emotional faces for level of perceived threat and labelled the facial expressions. Results indicated that context modulated approachability judgements to faces depicting negative emotions. Specifically, faces depicting distress-related emotions (i.e., sadness and fear) were considered more approachable in the giving help context than both the receiving help and neutral context. Furthermore, higher ratings of threat were associated with the assessment of angry, happy and neutral faces as less approachable. These findings are the first to demonstrate the significant role that context plays in the evaluation of an individual’s approachability and illustrate the important relationship between perceived threat and the evaluation of approachability.     

Time Perception and Dynamics of Facial Expressions of Emotions

Two experiments were run to examine the effects of dynamic displays of facial expressions of emotions on time judgments. The participants were given a temporal bisection task with emotional facial expressions presented in a dynamic or a static display. Two emotional facial expressions and a neutral expression were tested and compared. Each of the emotional expressions had the same affective valence (unpleasant), but one was high-arousing (expressing anger) and the other low-arousing (expressing sadness). Our results showed that time judgments are highly sensitive to movements in facial expressions and the emotions expressed. Indeed, longer perceived durations were found in response to the dynamic faces and the high-arousing emotional expressions compared to the static faces and low-arousing expressions. In addition, the facial movements amplified the effect of emotions on time perception. Dynamic facial expressions are thus interesting tools for examining variations in temporal judgments in different social contexts.     

Comparison of emotion recognition from facial expression and music

The recognition of basic emotions in everyday communication involves interpretation of different visual and auditory clues. The ability to recognize emotions is not clearly determined as their presentation is usually very short (micro expressions), whereas the recognition itself does not have to be a conscious process. We assumed that the recognition from facial expressions is selected over the recognition of emotions communicated through music. In order to compare the success rate in recognizing emotions presented as facial expressions or in classical music works we conducted a survey which included 90 elementary school and 87 high school students from Osijek (Croatia). The participants had to match 8 photographs of different emotions expressed on the face and 8 pieces of classical music works with 8 offered emotions. The recognition of emotions expressed through classical music pieces was significantly less successful than the recognition of emotional facial expressions. The high school students were significantly better at recognizing facial emotions than the elementary school students, whereas girls were better than boys. The success rate in recognizing emotions from music pieces was associated with higher grades in mathematics. Basic emotions are far better recognized if presented on human faces than in music, possibly because the understanding of facial emotions is one of the oldest communication skills in human society. Female advantage in emotion recognition was selected due to the necessity of their communication with the newborns during early development. The proficiency in recognizing emotional content of music and mathematical skills probably share some general cognitive skills like attention, memory and motivation. Music pieces were differently processed in brain than facial expressions and consequently, probably differently evaluated as relevant emotional clues.     

A female advantage in the recognition of emotional facial expressions: test of an evolutionary hypothesis

A set of computerized tasks was used to investigate sex differences in the speed and accuracy of emotion recognition in 62 men and women of reproductive age. Evolutionary theories have posited that female superiority in the perception of emotion might arise from women's near-universal responsibility for child-rearing. Two variants of the child-rearing hypothesis predict either across-the-board female superiority in the discrimination of emotional expressions (“attachment promotion” hypothesis) or a female superiority that is restricted to expressions of negative emotion (“fitness threat” hypothesis). Therefore, we sought to evaluate whether the expression of the sex difference is influenced by the valence of the emotional signal (Positive or Negative). The results showed that women were faster than men at recognizing both positive and negative emotions from facial cues, supporting the attachment promotion hypothesis. Support for the fitness threat hypothesis also was found, in that the sex difference was accentuated for negative emotions. There was no evidence that the female superiority was learned through previous childcare experience or that it was derived from a sex difference in simple perceptual speed. The results suggest that evolved mechanisms, not domain-general learning, underlie the sex difference in recognition of facial emotions.     

Recognition profile of emotions in natural and virtual faces

Background

Computer-generated virtual faces become increasingly realistic including the simulation of emotional expressions. These faces can be used as well-controlled, realistic and dynamic stimuli in emotion research. However, the validity of virtual facial expressions in comparison to natural emotion displays still needs to be shown for the different emotions and different age groups.

Methodology/Principal Findings

Thirty-two healthy volunteers between the age of 20 and 60 rated pictures of natural human faces and faces of virtual characters (avatars) with respect to the expressed emotions: happiness, sadness, anger, fear, disgust, and neutral. Results indicate that virtual emotions were recognized comparable to natural ones. Recognition differences in virtual and natural faces depended on specific emotions: whereas disgust was difficult to convey with the current avatar technology, virtual sadness and fear achieved better recognition results than natural faces. Furthermore, emotion recognition rates decreased for virtual but not natural faces in participants over the age of 40. This specific age effect suggests that media exposure has an influence on emotion recognition.

Conclusions/Significance

Virtual and natural facial displays of emotion may be equally effective. Improved technology (e.g. better modelling of the naso-labial area) may lead to even better results as compared to trained actors. Due to the ease with which virtual human faces can be animated and manipulated, validated artificial emotional expressions will be of major relevance in future research and therapeutic applications.     

Asymmetric Engagement of Amygdala and Its Gamma Connectivity in Early Emotional Face Processing

The amygdala has been regarded as a key substrate for emotion processing. However, the engagement of the left and right amygdala during the early perceptual processing of different emotional faces remains unclear. We investigated the temporal profiles of oscillatory gamma activity in the amygdala and effective connectivity of the amygdala with the thalamus and cortical areas during implicit emotion-perceptual tasks using event-related magnetoencephalography (MEG). We found that within 100 ms after stimulus onset the right amygdala habituated to emotional faces rapidly (with duration around 20–30 ms), whereas activity in the left amygdala (with duration around 50–60 ms) sustained longer than that in the right. Our data suggest that the right amygdala could be linked to autonomic arousal generated by facial emotions and the left amygdala might be involved in decoding or evaluating expressive faces in the early perceptual emotion processing. The results of effective connectivity provide evidence that only negative emotional processing engages both cortical and subcortical pathways connected to the right amygdala, representing its evolutional significance (survival). These findings demonstrate the asymmetric engagement of bilateral amygdala in emotional face processing as well as the capability of MEG for assessing thalamo-cortico-limbic circuitry.     

Women's Greater Ability to Perceive Happy Facial Emotion Automatically: Gender Differences in Affective Priming

There is evidence that women are better in recognizing their own and others' emotions. The female advantage in emotion recognition becomes even more apparent under conditions of rapid stimulus presentation. Affective priming paradigms have been developed to examine empirically whether facial emotion stimuli presented outside of conscious awareness color our impressions. It was observed that masked emotional facial expression has an affect congruent influence on subsequent judgments of neutral stimuli. The aim of the present study was to examine the effect of gender on affective priming based on negative and positive facial expression. In our priming experiment sad, happy, neutral, or no facial expression was briefly presented (for 33 ms) and masked by neutral faces which had to be evaluated. 81 young healthy volunteers (53 women) participated in the study. Subjects had no subjective awareness of emotional primes. Women did not differ from men with regard to age, education, intelligence, trait anxiety, or depressivity. In the whole sample, happy but not sad facial expression elicited valence congruent affective priming. Between-group analyses revealed that women manifested greater affective priming due to happy faces than men. Women seem to have a greater ability to perceive and respond to positive facial emotion at an automatic processing level compared to men. High perceptual sensitivity to minimal social-affective signals may contribute to women's advantage in understanding other persons' emotional states.