Gender differences in facial reactions to facial expressions

This study explored whether males and females differ in facial muscle reactivity when exposed to facial expressions. The study also examined whether the sex of the stimulus faces differentially influences the response patterns to facial stimuli. Thus, the sex was manipulated in a 2 x 2 factorial design by exposing males and females to slides of angry and happy faces displayed by both sexes. Facial electromyographic (EMG) activity was measured from the corrugator and zygomatic muscle regions. The subjects were also required to rate the stimuli on different dimensions. The results showed that angry faces evoked increased corrugator activity whereas happy faces evoked increased zygomatic activity. As predicted, these effects were more pronounced for females, particularly for the response to happy faces. Interestingly, there were no facial EMG effects for gender of stimulus. It was further found that males and females perceived the stimuli similarly. The results are consistent with previous findings indicating that females are more facially reactive than are males.     

Facial reactions to happy and angry facial expressions: evidence for right hemisphere dominance

Previous research on asymmetric effects of emotional expression and brain-hemispheric asymmetry has supported opposing theories of hemispheric dominance in the control of emotional reactions. In the present study, 32 subjects were exposed to pictures of happy and angry facial stimuli while facial electromyographic (EMG) activity from the zygomatic major and the corrugator supercilii muscle regions was detected from the left and right sides of the face. The subjects reacted spontaneously and rapidly with larger zygomatic EMG activity to happy facial stimuli and larger corrugator EMG activity to angry stimuli. These distinct reactions were significantly larger on the left side of the face. It is concluded that the present results support the hypothesis that the right brain hemisphere is predominantly involved in the control of spontaneously evoked emotional reactions.     

Facial reactions to fear-relevant and fear-irrelevant stimuli

Earlier research has shown that subjects exposed to different facial expressions react spontaneously with different facial electromyographic (EMG) response patterns. In the present study subjects were exposed to fear-relevant (snakes/spiders) and fear-irrelevant (flowers/mushrooms) stimuli, while facial EMG activity, skin conductance responses (SCRs) and heart rate (HR) were measured. The stimuli evoked different response patterns. Fear-relevant stimuli elicited increased corrugator muscle activity, whereas fear-irrelevant stimuli evoked increased zygomatic muscle activity. Fear-relevant stimuli also evoked HR deceleration and larger SCR magnitudes. The present data are consistent with the theory that the face constitutes an emotional 'readout/output-system'.     

Facial reactions, autonomic activity and experienced emotion: a three component model of emotional conditioning

The present study was designed to evaluate whether aversively conditioned responses to facial stimuli are detectable in all three components of the emotional response system, i.e. the expressive/behavioral, the physiological/autonomic and the cognitive/experienced component of emotion. Two groups of subjects were conditioned to angry or happy facial expression stimuli using a 100 dB noise as UCS in a differential aversive conditioning paradigm. The three components of the emotional response system were measured as: Facial-EMG reactions (corrugator and zygomatic muscle regions); autonomic activity (skin conductance, SCR; SCR half recovery time, T/2; heart rate, HR); and ratings of experienced emotion. It was found that responses in all components of the emotional response system were detectable in the angry group as greater EMG and autonomic resistance to extinction and greater self-reported fear. More specifically the angry group showed a resistant conditioning effect for the facial-EMG corrugator muscle that was accompanied by resistant conditioning for SCR frequency, slower SCR recovery, resistant conditioning in HR and a higher self-reported fear than the happy group. Thus, aversive conditioning to angry facial stimuli induce a uniform negative emotional response pattern as indicated by all three components of the emotional response system. These data suggest that a negative 'affect program' triggers responses in the different emotional components. The results suggest that human subjects are biologically prepared to react with a negative emotion to angry facial stimuli.     

Emotion in motion: Facial dynamics affect infants' neural processing of emotions

Research investigating the early development of emotional processing has focused mainly on infants' perception of static facial emotional expressions, likely restricting the amount and type of information available to infants. In particular, the question of whether dynamic information in emotional facial expressions modulates infants' neural responses has been rarely investigated. The present study aimed to fill this gap by recording 7-month-olds' event-related potentials to static (Study 1) and dynamic (Study 2) happy, angry, and neutral faces. In Study 1, happy faces evoked a faster right-lateralized negative central (Nc) component compared to angry faces. In Study 2, both happy and angry faces elicited a larger right-lateralized Nc compared to neutral faces. Irrespective of stimulus dynamicity, a larger P400 to angry faces was associated with higher scores on the Negative Affect temperamental dimension. Overall, results suggest that 7-month-olds are sensitive to facial dynamics, which might play a role in shaping the neural processing of facial emotional expressions. Results also suggest that the amount of attentional resources infants allocate to angry expressions is associated to their temperamental traits. These findings represent a promising avenue for future studies exploring the neurobiological processes involved in perceiving emotional expressions using dynamic stimuli.     

Virtual friend or threat? The effects of facial expression and gaze interaction on psychophysiological responses and emotional experience

The present study aimed to investigate the impact of facial expression, gaze interaction, and gender on attention allocation, physiological arousal, facial muscle responses, and emotional experience in simulated social interactions. Participants viewed animated virtual characters varying in terms of gender, gaze interaction, and facial expression. We recorded facial EMG, fixation duration, pupil size, and subjective experience. Subject's rapid facial reactions (RFRs) differentiated more clearly between the character's happy and angry expression in the condition of mutual eye-to-eye contact. This finding provides evidence for the idea that RFRs are not simply motor responses, but part of an emotional reaction. Eye movement data showed that fixations were longer in response to both angry and neutral faces than to happy faces, thereby suggesting that attention is preferentially allocated to cues indicating potential threat during social interaction.     

Hemispheric Asymmetry in Conditioning to Facial Emotional Expressions

In the present experiment, we report a right hemisphere advantage for autonomic conditioning to facial emotional expressions. Specifically, angry, but not happy, facial expressions showed significantly more resistance to extinction when presented initially to the right as compared to the left hemisphere. Slides of happy and angry faces were used as conditioned stimuli (CS+ and CS-) with shock as the unconditioned stimulus (UCS). Half of the subjects (n = 15) had the angry face as CS+ (and the happy face as CS-), the other half had the happy face as CS+ (and the angry face as CS-). During acquisition, the CSs were presented foveally. During extinction, using the Visual Half-Field (VHF) technique, half of the CS+ and CS- trials were randomly presented in the right visual half-field (initially to the left hemisphere), and half of the trials were presented in the left half-field (initially to the right hemisphere). Stimuli were presented for 210 ms during acquisition, and for 30 ms during extinction. Bilateral skin conductance responses (SCRs) were recorded. The results showed effects of acquisition only for the angry CS+ group. During extinction, there was a significant Conditioning X Half-field interaction which was due to greater SCRs to the CS+ angry face when it was presented in the left half-field. It is concluded that the present results reveal hemisphere asymmetry effects in facial emotional conditioning.     

Electromyographic responses to emotional facial expressions in 6-7year olds: A feasibility study

Preliminary studies have demonstrated that school-aged children (average age 9-10years) show mimicry responses to happy and angry facial expressions. The aim of the present study was to assess the feasibility of using facial electromyography (EMG) as a method to study facial mimicry responses in younger children aged 6-7years to emotional facial expressions of other children. Facial EMG activity to the presentation of dynamic emotional faces was recorded from the corrugator, zygomaticus, frontalis and depressor muscle in sixty-one healthy participants aged 6-7years. Results showed that the presentation of angry faces was associated with corrugator activation and zygomaticus relaxation, happy faces with an increase in zygomaticus and a decrease in corrugator activation, fearful faces with frontalis activation, and sad faces with a combination of corrugator and frontalis activation. This study demonstrates the feasibility of measuring facial EMG response to emotional facial expressions in 6-7year old children.     

Converging Evidence for the Advantage of Dynamic Facial Expressions

Neuroimaging evidence suggests that dynamic facial expressions elicit greater activity than static face stimuli in brain structures associated with social cognition, interpreted as greater ecological validity. However, a quantitative meta-analysis of brain activity associated with dynamic facial expressions is lacking. The current study investigated, using three fMRI experiments, activity elicited by (a) dynamic and static happy faces, (b) dynamic and static happy and angry faces, and (c) dynamic faces and dynamic flowers. In addition, using activation likelihood estimate (ALE) meta-analysis, we determined areas concordant across published studies that (a) used dynamic faces and (b) specifically compared dynamic and static emotional faces. The middle temporal gyri (Experiment 1) and superior temporal sulci (STS; Experiment 1 and 2) were more active for dynamic than static faces. In contrasts with the baseline the amygdalae were more active for dynamic faces (Experiment 1 and 2) and the fusiform gyri were active for all conditions (all Experiments). The ALE meta-analyses revealed concordant activation in all of these regions as well as in areas associated with cognitive manipulations (inferior frontal gyri). Converging data from the experiments and the meta-analyses suggest that dynamic facial stimuli elicit increased activity in regions associated with interpretation of social signals and emotional processing.     

Automatic emotion regulation in response inhibition: The temporal dynamics of emotion counter‐regulation during a go/no‐go task

Recent behavioral studies indicate that emotion counter‐regulation automatically allocates attention to events that are opposite in the valence to the experienced emotional state. The present study explored the effect of emotion counter‐regulation on response inhibition by using ERPs in a go/no‐go paradigm. We recruited 58 subjects and randomly assigned them to either the angry priming group (watching Nanjing Massacre movie clips) or the neutral priming group (watching “mending a computer” movie clips). The behavioral results revealed that participants in the angry priming group responded significantly more accurately to go happy and no‐go angry faces than go angry and no‐go happy faces. The analyses of ERPs revealed that the amplitudes of the no‐go N2 and no‐go P3 were significantly larger for the happy faces than for the angry faces in the angry priming group. However, no such effects were found in the neutral priming group. These results suggest that highly aroused angry emotion could prompt a priority response to happy emotion stimuli and restrict the responses to angry emotion stimuli through emotion counter‐regulation.     

Facial electromyographic responses to vocal affect expressions

In this study we investigated facial electromyographic (EMG) responses to vocal affect expressions. We also measured emotion-related action tendencies by requesting the subjects to indicate their tendency to approach or withdraw from the person uttering the stimulus word. In addition, emotional contagion (EC) was measured with a questionnaire-based scale. The results showed that hearing the expression of anger increased EMG activity in the subjects' brow region more than hearing contentment. In contrast, the expression of contentment activated the periocular muscle region more than anger. The expressions of anger elicited behavioral withdrawal responses, whereas the neutral expressions and contentment evoked approach responses. Subjects scoring low and high on EC exhibited different patterns of EMG responses. The results support the view that negative and positive affects are contagious from hearing human vocal affect expressions.     

Electromyographic responses to static and dynamic avatar emotional facial expressions

Facial muscular reactions to avatars' static (neutral, happy, angry) and dynamic (morphs developing from neutral to happy or angry) facial expressions, presented for 1 s each, were investigated in 48 participants. Dynamic expressions led to better recognition rates and higher intensity and realism ratings. Angry expressions were rated as more intense than happy expressions. EMG recordings indicated emotion-specific reactions to happy avatars as reflected in increased M. zygomaticus major and decreased M. corrugator supercilii tension, with stronger reactions to dynamic as compared to static expressions. Although rated as more intense, angry expressions elicited no significant M. corrugator supercilii activation. We conclude that facial reactions to angry and to happy facial expressions hold different functions in social interactions. Further research should vary dynamics in different ways and also include additional emotional expressions.     

The effects of pictures of emotional faces on tonic and phasic autonomic cardiac control in women and men

The aim of the present study was to examine autonomic function in response to negatively and positively valenced pictures under different levels of conscious recognition. Heart period variability (HPV) and heart rate (HR) reactivity were studied in 53 males and females who were being shown pictures of angry and happy faces. The pictures, which were backwardly masked, were presented once every 30 s during a 5-min period and under three conditions (counterbalanced for type of facial expression): below the level of conscious recognition (17 ms), at an intermediate level (56 ms), and at a clearly recognizable level (2370 ms). Analyses of HR power spectrum (for 5 min in each condition) in the high frequency region (HF: 0.15-0.5 Hz) that reflects respiratory sinus arrhythmia, as well as analysis of phasic heart rate responses (7.5 s in 0.5 epochs following every picture presentation) were carried out. The main findings were that HF-power was higher, and cardiac midinterval acceleration lower, in response to angry as opposed to happy faces, a result obtained only for the men, however. No interaction effect between facial expression and the three exposure conditions was found, suggesting that the pictures induced emotional activation both subliminally and supraliminally. The results were discussed in terms of increased attention to aversive stimuli.     

Early glycinergic axon contact with the Mauthner neuron during zebrafish development

One important aspect of empathy is a “resonance mechanism”, which includes emotional cue detection, facial mimicry (measured by electromyography, EMG) and a specific cortical response. This study explored the convergence of these three measures of affective empathy. The twenty students who took part in the study were required to empathise with the situation by entering into the other person's situation. The four emotions portrayed were anger, fear, happiness, and neutral, and the subjects were instructed to make a two-alternative response (emotion or no emotion) to each emotion. A repeated transcranial magnetic stimulation was used to produce a temporary inhibition of the medial prefrontal cortex (MPFC). The results support the hypothesis that there is a direct relationship between emotional cue recognition, EMG-measured facial response and prefrontal activity. First, both facial expression detection and autonomic mimicry in reaction to emotional faces were systematically modulated in response to inhibition of the MPFC. Second, the MPFC was implicated in facial cue detection and the subsequent autonomic response because an impaired performance on both measures was observed when this brain area was inhibited. Third, this effect increased when negative-valenced stimuli (angry and fearful faces) were presented to the subjects. These results revealed a significant effect of the MPFC on both cue detection and facial mimicry that was distinctly related to different types of emotions.     

Threat sensitivity as assessed by automatic amygdala response to fearful faces predicts speed of visual search for facial expression

It has been argued that the amygdala represents an integral component of a vigilance system that is primarily involved in the perception of ambiguous stimuli of biological relevance. The present investigation was conducted to examine the relationship between automatic amygdala responsivity to fearful faces which may be interpreted as an index of trait-like threat sensitivity and spatial processing characteristics of facial emotions. During 3T fMRI scanning, pictures of human faces bearing fearful, angry, and happy expressions were presented to 20 healthy volunteers using a backward masking procedure based on neutral facial expressions. Subsequently, a computer-based face-in-the-crowd task using schematic face stimuli was administered. The neural response of the (right) amygdala to masked fearful faces correlated consistently with response speed to negative and neutral faces. Neither amygdala activation during the masked presentation of angry faces nor amygdala activation during the presentation of happy faces was correlated with any of the response latencies in the face-in-the-crowd task. Our results suggest that amygdala responsivity to masked facial expression is differentially related to the general visual search speed for facial expression. Neurobiologically defined threat sensitivity seems to represent an important determinant of visual scanning behaviour.     

Facial Muscle Patterning and Subjective Experience During Affective Imagery: Sex Differences

Facial electromyographic (EMG) activity was recorded from the zygomatic, corrugator, masse-ter and frontalis muscle regions in 30 male and 30 female subjects. Forty-eight items were selected to reflect happy, sad, angry and fearful situations. Subjects imagined each of the items for 40 sec and rated how they felt on a scale tapping the four emotions. The results indicated that for certain emotions, muscle regions and ratings, females (as compared to males): 1) generated facial EMG patterns of greater magnitude (relative to rest) during affective imagery, 2) reported a stronger experience of emotion to the imagery, 3) showed greater within-subject correlations between the experience of emotions and facial EMG, 4) evidenced somewhat higher corrugator and significantly lower masseter EMG activity during rest, and 5) generated greater facial EMG changes during a post-imagery, voluntary facial expression condition. Cultural and biological interpretations of the data are considered. The importance of evaluating gender in psychophysiological studies of emotion is stressed.     

Are two threats worse than one? The effects of face race and emotional expression on fear conditioning

Facial cues of racial outgroup or anger mediate fear learning that is resistant to extinction. Whether this resistance is potentiated if fear is conditioned to angry, other race faces has not been established. Two groups of Caucasian participants were conditioned with two happy and two angry face conditional stimuli (CSs). During acquisition, one happy and one angry face were paired with an aversive unconditional stimulus whereas the second happy and angry faces were presented alone. CS face race (Caucasian, African American) was varied between groups. During habituation, electrodermal responses were larger to angry faces regardless of race and declined less to other race faces. Extinction was immediate for Caucasian happy faces, delayed for angry faces regardless of race, and slowest for happy racial outgroup faces. Combining the facial cues of other race and anger does not enhance resistance to extinction of fear.     

Relationships between facial electromyography and subjective experience during affective imagery

Sixty subjects were exposed for 40 s each to 48 imagery situations designed to reflect happy, sad, angry and fearful conditions. Facial electromyographic (EMG) activity from zygomatic, corrugator, masseter and lateral frontalis muscle regions was recorded, and experienced emotion was measured on a scale tapping these four emotions. Results showed that: (1) zygomatic activity reliably differentiated happy imagery, corrugator activity reliably differentiated sad imagery, but masseter activity did not differentiate angry imagery and lateral frontalis activity did not differentiate fearful imagery; (2) different intensities of specific emotional imagery situations evoked the expected differential patterns of self-report and EMG; (3) higher correlations between self-report and EMG for ‘present’, rather than ‘future’ ratings of experienced emotion emerged for positive affect only; and (4) the use of a standardized imagery scale, rather than the self-generated, personally-relevant affective situations used in previous studies, allowed for more sensitive measurement of the relationship between facial muscle activity and subjective experience of emotion during affective imagery.     

Right hemisphere representation of autonomic conditioning to facial emotional expressions

In this experiment, a lateralized right hemisphere effect was found for electrodermal associative learning to facial emotional expressions. Sixty-two subjects were presented simultaneously with a slide of a happy face in the right or left visual half field (VHF) and a slide of an angry face in the opposite VHF. Four groups were formed by the combination of the two VHF positions of angry/happy faces and the administration/omission of shock unconditioned stimuli. The results showed that simultaneous presentation of the angry face to the right hemisphere and the happy face to the left hemisphere, together with shock, resulted in a strong conditioned association with the angry face and a relatively weak association with the happy face. Furthermore, simultaneous presentation of the angry face to the left hemisphere and the happy face to the right hemisphere, together with shock, resulted in a relatively weak association with both stimuli. No significant differences were found for the no-shock control groups. The present results confirm previous findings of a right hemisphere advantage for representation of associative learning.     

Facial expressions as excitatory and inhibitory stimuli for conditioned autonomic responses

Several lines of evidence suggest that emotional responses to facial expressions of emotion have a biological basis. The present study involved 4 experiments where pictures of angry, happy or neutral facial expressions were used as conditioned stimuli in aversive Pavlovian electrodermal conditioning. From an evolutionary perspective it was expected that an angry face should have an excitatory effect on aversively conditioned responses, whereas a happy face should have an inhibitory effect. It was also expected that the effect should be specific for the stimulus person showing the display. The data showed that the stimulus person was a critical mediating factor for obtaining persistent conditioning effects, that is to say, responses which showed resistance to extinction. Persistent responding was primarily manifested when the stimulus person displayed anger during extinction. On the other hand, this effect was inhibited when the person displayed a happy face during extinction. Furthermore, resistance to extinction was increased or decreased dependent on whether the person expressed anger or happiness during acquisition. Thus, consistent with predictions, angry and happy faces exhibited an excitatory and inhibitory effect, respectively, and these effects were mediated by the stimulus person.