Zygomatic Muscle Regions Research Articles

The eye contact smile: The effects of sending and receiving a direct gaze

ABSTRACT Eye contact often elicits a smiling response. We investigated whether an individual’s awareness that the recipient perceives their direct gaze during eye contact has an influence on this smiling response. Participants wore glasses with either clear or dark lenses (preventing the other person from seeing their eyes). Measurements of electromyographic activity from the zygomatic and periocular muscle regions showed that the smiling responses were greater to seeing the other’s direct versus averted gaze. The participants’ own gaze direction had also an effect, and this effect was modified by the visibility of their eyes. Zygomatic responses were greater when the participants were aware that their eyes were visible. Thus, awareness of sending a direct gaze to another plays a role in the smiling response. In addition, participants’ self-evaluated level of social anxiety was positively correlated with the magnitude of the zygomatic responses to the other person’s direct versus averted gaze.

Emotional Empathy and Facial Reactions to Facial Expressions

This study investigates whether people high in emotional empathy are more facially reactive than are people low in emotional empathy when exposed to pictures of angry and happy facial expressions. Facial electromyographic activity was measured from the corrugator and the zygomatic muscle regions. In accordance with the predictions, the high empathic group reacted with larger corrugator activity to angry as compared to happy faces and with larger zygomatic activity to happy faces. However, the low empathic group did not differentiate between the angry and happy stimuli at all. The high empathic group, as compared to the low empathic group, also rated the angry faces as expressing more anger and the happy faces as being happier. It is concluded that high empathic people are particularly sensitive in reacting with facial reactions to facial expressions and that this ability is accompanied by a higher level of empathic accuracy.

Sex Differences Found in Facial EMG Activity Provoked by Viewing Pleasant and Unpleasant Photographs

50 male and 50 female participants' facial electromyographic (EMG) activity at the left corrugator and zygomatic muscle regions and self-reports of emotions were recorded while they were viewing Pleasant and Unpleasant photographs. Analysis showed that the ratio of EMG power between the periods of photograph viewing and baseline at the zygomatic muscle region was significantly higher than that at the corrugator muscle region while viewing Pleasant photographs and that the EMG ratio at the corrugator muscle region was significantly higher than that at the zygomatic muscle region while viewing Unpleasant photographs. Further analysis indicated that compared to men, women reported relatively higher feelings of pleasantness and generated significantly higher EMG ratios at the zygomatic muscle region while viewing Pleasant photographs and women reported significantly less feelings of pleasantness and generated significantly higher EMG ratios at the corrugator muscle region while viewing Unpleasant photographs. These results demonstrate the sex effects on emotion expression and associated EMG responses while viewing emotion provoking photographs.

Study of Posed Emotion in Facial EMG Asymmetry

37 subjects' facial electromyographic activity at the corrugator and zygomatic muscle regions were recorded while they were posing with happy and sad facial expressions. Analysis showed that the mean value of EMG activity at the left zygomatic muscle region was the highest, followed by the right zygomatic, left corrugator, and right corrugator muscle regions, while a happy facial expression was posed. The mean value of EMG activity at the left corrugator muscle region was the highest, followed by those for the right corrugator, left zygomatic, and right zygomatic muscle regions while a sad facial expression was posed. Further analysis indicated that the power of facial EMG activity on the left side of the face was stronger than on the right side of the face while posing both happy and sad expressions.

Effects of Viewing Pleasant and Unpleasant Photographs on Facial EMG Asymmetry

40 subjects' facial electromyographic (EMG) activity at the corrugator and zygomatic muscle regions were recorded while they were viewing pleasant and unpleasant photographs. Analysis showed that the EMG activity at the left zygomatic muscle region generated the highest power, followed by the right zygomatic, left corrugator, and right corrugator muscle regions, while viewing pleasant photographs. The EMG activity at the left corrugator muscle region generated the highest power, followed by the right corrugator, left zygomatic, and right zygomatic muscle regions, while viewing unpleasant photographs. Further statistical analysis indicated that the EMG activities at the left corrugator region generated significantly higher power than those at the right corrugator region while viewing unpleasant photographs. It was concluded that the intensity of facial EMG activity on the left side of the face was stronger than the right side of the face during the process of emotional expression.

Valence-dependent modulation of psychophysiological measures: Is there consistency across repeated testing?

The present study used the picture perception paradigm to examine the extent to which three well-documented psychophysiological measures demonstrate consistency across time in response to emotional stimuli. The three measures were the eye-blink startle response and the activation in two facial muscle regions (zygomatic and corrugator). Twenty-seven young women were assessed on two occasions, 2 weeks apart. Whereas activation in the corrugator and zygomatic muscle regions demonstrated the predicted patterns at both assessments (with some attenuation in the zygomatic muscle regions), the startle response had limited consistency across the two assessments. The startle response revealed the predicted linear pattern of valence modulation during the first assessment. During the second assessment, startle magnitude response was a quadratic function of valence ratings and a linear function of arousal ratings. The unexpected pattern of startle response during the second session appeared to be related to the content of the pleasant slides, with action slides generating quadratic valence modulation and erotic slides continuing to exhibit the expected linear valence modulation.

Schizophrenic patients show facial reactions to emotional facial expressions

Facial reactions in schizophrenic patients were assessed via electromyography (EMG) in response to pictures of facial expressions. Male patients and nonpatient controls viewed photographs of positive and negative facial expressions while EMG activity from the corrugator and zygomatic muscle regions was recorded. Both schizophrenic patients and controls exhibited greater zygomatic reactivity in response to positive pictures than in response to negative pictures and greater corrugator reactivity in response to negative pictures than in response to positive pictures. Schizophrenic patients exhibited greater corrugator reactivity than did nonpatient controls. Implications for understanding emotion expression and perception in schizophrenic patients are discussed.

Schizophrenic patients show facial reactions to emotional facial expressions

Facial reactions in schizophrenic patients were assessed via electromyography (EMG) in response to pictures of facial expressions. Male patients and nonpatient controls viewed photographs of positive and negative facial expressions while EMG activity from the corrugator and zygomatic muscle regions was recorded. Both schizophrenic patients and controls exhibited greater zygomatic reactivity in response to positive pictures than in response to negative pictures and greater corrugator reactivity in response to negative pictures than in response to positive pictures. Schizophrenic patients exhibited greater corrugator reactivity than did nonpatient controls. Implications for understanding emotion expression and perception in schizophrenic patients are discussed.

The effects of aerobic exercise on cardiovascular, facial EMG, and self-report responses to emotional imagery.

This study examined the effects of exercise on subsequent psychophysiological and self-report responses to emotional imagery, using excitation-transfer theory as a guiding conceptual model. Twenty-four female undergraduates engaged in aerobic exercise (stationary cycling) for 15 minutes, and an equal number of subjects rested quietly for the same time period. All subjects then engaged in anger and sadness imagery trials. Cardiovascular, facial electromyographic, and self-report responses to the imagery were assessed. The results indicated that the subjects in the exercise group showed less peripheral vasoconstriction in response to the imagery than did the quiet rest subjects. Subjects in both groups displayed greater electromyographic activity in the depressor and zygomatic muscle regions during anger than sadness imagery, and subjects in the exercise group tended to show greater corrugator tension during sadness than during anger imagery. Few differences between the groups were found on self-report measures. These findings are discussed with reference to previous research, theoretical implications, and future directions.

Facial reactions to facial expressions in subjects high and low in public speaking fear

This study investigated whether subjects high and low in public speaking fear react with different facial electromyographic (EMG) activities when exposed to negative and positive social stimuli. A High-fear and Low-fear group were selected by help of a questionnaire and were exposed to slides of angry and happy faces while facial-EMG from the corrugator and zygomatic muscle regions were measured. The subjects also rated the stimuli on different emotional dimensions. Consistent with earlier research it was found that Low fear subjects reacted with increased corrugator activity to angry faces and increased zygomatic activity to happy faces. The High fear group, on the other hand, did not distinguish between angry and happy faces. Rating data indicated that the High fear group perceived angry faces as being emotionally more negative. The present results are consistent with earlier studies, indicating that the facial-EMG technique is sensitive to detect differential responding among clinical interesting groups, such as people suffering from social fears.

Facial electromyographic reactions and autonomic activity to auditory stimuli

This study explored whether high- and low-intensity auditory stimuli evoke different facial electromyographic reactions and autonomic responses. Subjects were repeatedly exposed to 95-dB and 75-dB tones (1000 Hz, 40 ms rise and fall times) while their facial electromyograms from the corrugator and zygomatic muscle regions, heart rate, skin conductance responses, skin conductance half recovery time and ratings were measured. The 95-dB tone evoked a “negative” reaction with increased corrugator activity and an autonomic response pattern that carried aspects of a defense reaction, that is, slowly habituating skin conductance responses with retarded recovery rate and an initial tendency to heart rate acceleration. Furthermore, the 95-dB tone was rated as unpleasant. The 75-dB tone elicited an orienting response indicated by a distinct heart rate deceleration and fast habituating skin conductance responses with a relatively short recovery time. Thus, the present study demonstrated that the facial electromyographic technique is sensitive to simple environmental stimuli such as auditory stimuli and that the facial response is consistent with the autonomic response patterns and the experience of the stimuli.

Facial reactions to auditory stimuli: Sex differences

This study explored whether males and females differ in facial muscle activity when exposed to tone stimuli with different intensity. Males and females were repeatedly exposed to 95 dB and 75 dB 1000 Hz tones while their facial electromyographic (EMG) activity from corrugator and zygomatic muscle regions were measured. Skin conductance responses were also measured. It was found that 95 dB but not 75 dB tones evoked increased corrugator activity. This effect differed significantly between males and females. Thus, it was only females that reacted with a significant increased corrugator response to the high intensity tone. While facial responses differed between the sexes, the skin conductance response patterns did not. Consistent with previous research it is concluded that females are more facially expressive than are males.

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 2×2 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.

Perceived unpleasantness and facial reactions to auditory stimuli

This study examined whether facial electromyographic (EMG) reactions differentiate between identical tone stimuli which subjects perceive as differently unpleasant. Subjects were repeatedly exposed to a 1000 Hz 75 dB tone stimulus while their facial EMG from the corrugator and zygomatic muscle regions were measured. Skin conductance and heart rate responses were also measured. The subjects rated the unpleasantness of the stimulus and based on these ratings they were divided into two groups, High and Low in perceived unpleasantness. As predicted the facial EMG activity reflected the perceived unpleasantness. That is, the High group but not the Low group reacted with an increased corrugator response. The autonomic data, on the other hand, did not differ between groups. The results are consistent with the proposition that the facial muscles function as a readout system for emotional reactions and that facial muscle activity is intimately related to the experiential level of the emotional response system.

Facial reactions to fear‐relevant stimuli for subjects high and low in specific fear

This study was performed to investigate whether subjects high and low in fear of snakes react with different facial electromyographic (EMG) responses when exposed to snakes. Two groups of subjects were exposed to slides of snakes or flowers. After the experiment they rated their fear of snakes on a questionnaire and based on these ratings they were divided into high and low fear groups. Facial EMG was measured from the corrugator and zygomatic muscle regions. As predicted the high fear group reacted with a facial response interpretable as a negative emotional reaction whereas the low fear group did not. This difference was specific to snakes because high and low groups did not differ in responses to slides of flowers. The results are consistent with the proposition that facial EMG technique is a sensitive tool to distinguish reactions between subjects high and low in specific fears.

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: (1) Facial-EMG reactions (corrugator and zygomatic muscle regions); (2) autonomic activity (skin conductance, SCR; SCR half recovery time, T 2 ; heart rate, HR); and (3) 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.

Facial electromyography: a measure of affective processes during sexual arousal.

ABSTRACTForty female volunteers participated in a study to investigate whether facial EMGs could be used as measures of affect during sexual arousal. Audiotaped narratives were used to induce the following affect‐sexual states: 1) pleasant affect + sexual arousal, 2) unpleasant affect + sexual arousal, 3) pleasant affect + no sexual arousal, and 4) unpleasant affect + no sexual arousal. EMG activity was recorded bilaterally from the corrugator and zygomatic muscle regions. Corrugator muscle activity was significantly greater in response to the unpleasant stimulus conditions. This relationship held for both the non‐sexual and sexual conditions, suggesting that corrugator muscle activity may provide a reliable index of negative affect during sexual arousal. Zygomatic activity was significantly greater during the sexual as compared to the non‐sexual stimuli, but did not increase as a function of pleasant affect. Greater left than right corrugator muscle activity was observed in response to the sexual stimuli. Left muscle superiority was also noted for zygomatic muscle activity, in response to the sexual unpleasant stimulus. Issues related to the interpretation of lateralized muscle activity are discussed.