Corrugator Supercilii Research Articles

Measuring facial mimicry: Affdex vs. EMG.

Facial mimicry is the automatic imitation of the facial affect expressions of others. It serves as an important component of interpersonal communication and affective co-experience. Facial mimicry has so far been measured by Electromyography (EMG), which requires a complex measuring apparatus. Recently, software for measuring facial expressions have become available, but it is still unclear how well it is suited for measuring facial mimicry. This study investigates the comparability of the automated facial coding software Affdex with EMG for measuring facial mimicry. For this purpose, facial mimicry was induced in 33 subjects by presenting naturalistic affect-expressive video sequences (anger, joy). The response of the subjects is measured simultaneously by facial EMG (corrugator supercilii muscle, zygomaticus major muscle) and by Affdex (action units lip corner puller and brow lowerer and affects joy and anger). Subsequently, the correlations between the measurement results of EMG and Affdex were calculated. After the presentation of the joy stimulus, there was an increase in zygomaticus muscle activity (EMG) about 400 ms after stimulus onset and an increase in joy and lip corner puller activity (Affdex) about 1200 ms after stimulus onset. The joy and the lip corner puller activity detected by Affdex correlate significantly with the EMG activity. After presentation of the anger stimulus, corrugator muscle activity (EMG) also increased approximately 400 ms after stimulus onset, whereas anger and brow lowerer activity (Affdex) showed no response. During the entire measurement interval, anger activity and brow lowerer activity (Affdex) did not correlate with corrugator muscle activity (EMG). Using Affdex, the facial mimicry response to a joy stimulus can be measured, but it is detected approximately 800 ms later compared to the EMG. Thus, electromyography remains the tool of choice for studying subtle mimic processes like facial mimicry.

Reading of ingroup politicians' smiles triggers smiling in the corner of one's eyes.

Spontaneous smiles in response to politicians can serve as an implicit barometer for gauging electorate preferences. However, it is unclear whether a subtle Duchenne smile-an authentic expression involving the coactivation of the zygomaticus major (ZM) and orbicularis oculi (OO) muscles-would be elicited while reading about a favored politician smiling, indicating a more positive disposition and political endorsement. From an embodied simulation perspective, we investigated whether written descriptions of a politician's smile would trigger morphologically different smiles in readers depending on shared or opposing political orientation. In a controlled reading task in the laboratory, participants were presented with subject-verb phrases describing left and right-wing politicians smiling or frowning. Concurrently, their facial muscular reactions were measured via electromyography (EMG) recording at three facial muscles: the ZM and OO, coactive during Duchenne smiles, and the corrugator supercilii (CS) involved in frowning. We found that participants responded with a Duchenne smile detected at the ZM and OO facial muscles when exposed to portrayals of smiling politicians of same political orientation and reported more positive emotions towards these latter. In contrast, when reading about outgroup politicians smiling, there was a weaker activation of the ZM muscle and no activation of the OO muscle, suggesting a weak non-Duchenne smile, while emotions reported towards outgroup politicians were significantly more negative. Also, a more enhanced frown response in the CS was found for ingroup compared to outgroup politicians' frown expressions. Present findings suggest that a politician's smile may go a long way to influence electorates through both non-verbal and verbal pathways. They add another layer to our understanding of how language and social information shape embodied effects in a highly nuanced manner. Implications for verbal communication in the political context are discussed.

Enhanced Empathic Pain by Facial Feedback.

The facial feedback hypothesis states that feedback from cutaneous and muscular afferents affects our emotion. Based on the facial feedback hypothesis, the purpose of this study was to determine whether enhancing negative emotion by activating a facial muscle (corrugator supercilii) increases the intensity of cognitive and emotional components of empathic pain. We also assessed whether the muscle contraction changed the pupil size, which would indicate a higher level of arousal. Forty-eight individuals completed 40 muscular contraction and relaxation trials while looking at images of five male and five female patients with neutral and painful facial expressions, respectively. Participants were asked to rate (1) how much pain the patient was in, and (2) how unpleasant their own feelings were. We also examined their facial muscle activities and changes in pupil size. No significant differences in pain or unpleasantness ratings were detected for the neutral face between the two conditions; however, the pain and unpleasantness ratings for the painful face were considerably higher in the contraction than relaxation condition. The pupils were considerably larger in the contraction than relaxation condition for both the painful and neutral faces. Our findings indicate that, by strengthening the corrugator supercilii, facial feedback can affect both the cognitive evaluative and affective sharing aspects of empathic pain.

Treating Glabellar Lines With Botulinum Toxin: Does Your Patient Need to Frown Steadily?

The variable relationship between the orbicularis supercilii and frontalis muscles may cause side effects with botulin toxin; steadily frowning is the usual recommendation. Eliminating the need to frown until all injections are over might enhance efficacy and lessen the neurotoxicity risks related to muscle exhaustion. The goal of this study was to investigate whether the digital caliper-assessed distances between the medial and lateral corrugator injection sites and the midline differed significantly in patients persistently frowning from patients resting. Seventy-six individuals with glabellar wrinkles treated with botulinum toxin in the authors' private practices for glabellar lines voluntarily contributed their retrospective data about the positions of injection sites. The investigators had freely chosen to inject the medial and lateral sections of the corrugator supercilii during persistent maximum frown or at rest. The mean differences in distances between the medial and lateral injection points and the estimated midline were clinically trivial (1.0 ± 1.28 and 1.5 ± 2.53 mm, respectively), although the distances between the relaxed and contracted medial and lateral injection sites exceeded 1.8 and 2.5 mm in 33.9% and 46.4% of patients, respectively. Distance differences, not significant before 40 years old, were statistically significant only for the lateral injections in older patients (on average, 1.9 ± 3.01 mm). The average distances from the medial and lateral injection points and the midline appear minimally different in patients who frown until all injections are over and, conversely, patients who rest. Persistently frowning might be advisable only in patients older than 40. Facial asymmetries may be a confounding factor.

Effects of disliked music on psychophysiology

While previous research has shown the positive effects of music listening in response to one’s favorite music, the negative effects of one’s most disliked music have not gained much attention. In the current study, participants listened to three self-selected disliked musical pieces which evoked highly unpleasant feelings. As a contrast, three musical pieces were individually selected for each participant based on neutral liking ratings they provided to other participants’ disliked music. During music listening, real-time ratings of subjective (dis)pleasure and simultaneous recordings of peripheral measures were obtained. Results showed that compared to neutral music, listening to disliked music evoked physiological reactions reflecting higher arousal (heart rate, skin conductance response, body temperature), disgust (levator labii muscle), anger (corrugator supercilii muscle), distress and grimacing (zygomaticus major muscle). The differences between conditions were most prominent during “very unpleasant” real-time ratings, showing peak responses for the disliked music. Hence, disliked music has a strenuous effect, as shown in strong physiological arousal responses and facial expression, reflecting the listener’s attitude toward the music.

Examining the consistency of continuous affect annotations and psychophysiological measures in response to emotional videos

Despite the growing necessity of understanding the dynamics of emotion by naturalistic stimuli, averaging time-locked responses seems insufficient to capture emotional experiences that change over time. Intersubject correlation (ISC) has been implemented to examine dynamic emotional experiences by quantifying the consistency of responses across individuals. While previous research has shown that enhanced psychophysiological ISC can capture dynamic emotional experiences in response to long-lasting videos that evoke dimensional emotions, it is not yet fully understood how psychophysiological consistency varies during videos that elicit distinct emotions, such as fear. In this study, we re-analyzed publicly available data consisting of continuous affect annotations and psychophysiological signals, namely heart rate (HR), electrodermal activity (EDA), electromyographic signals from zygomaticus major (EMG-z), and corrugator supercilii (EMG-c), in response to categorical emotional videos, namely amusing, boring, relaxing, and fearful. Results showed an overall increase in ISC in multiple measures during fearful videos, indicating that emotional experiences during fearful videos were reliably consistent across participants. The effect of amusing and boring videos on ISC revealed varying results depending on the measurements. In particular, larger ISC in valence rating, EDA, and EMG-z was found for amusing than boring videos, whereas larger ISC in HR and EMG-c was observed for boring than amusing movies. Lastly, decreased ISC for relaxing videos was observed across multiple measurements, showing inconsistent emotional experiences during relaxing videos. This study builds on previous research on physiological consistency during emotional experiences by examining how the consistency of continuous affect annotations and psychophysiological measures differs in response to videos that elicit distinct emotions.

Exploring the Influence of Context on Emotional Mimicry and Intention: An Affirmation of the Correction Hypothesis.

Emotional mimicry, a phenomenon frequently observed in our everyday interactions, is the act of replicating another individual's facial expression. The Emotion Mimicry in Context View and the Correction Hypothesis underscore the critical role of context and intention within emotional mimicry. In two distinct studies, participants were presented with facial expressions of models (happiness and anger) within various contexts (affiliative, distancing, and neutral). Concurrently, we recorded electromyography (EMG) to index emotional mimicry, while participants explicitly rated the models' intentions. We observed context swiftly influences emotional mimicry within 500 ms, notably when the intentions of contexts are opposing to the intentions of facial expressions, leading to weakened muscle responses and diminished perceived intention. Furthermore, a notable correlation was discovered in the mimicry of angry faces; the more distancing the context, the stronger the corrugator supercilii (CS) muscle activity after context processing. First, emotional mimicry should not be simply viewed as an output corresponding to the expresser's facial expressions but the dynamic process involving the active participation of the observer. Second, intention serves as a pivotal anchor, effectively integrating facial and contextual information. As such, we provided empirical support for the Correction Hypothesis.

Optomyography-based sensing of facial expression derived arousal and valence in adults with depression.

Continuous assessment of affective behaviors could improve the diagnosis, assessment and monitoring of chronic mental health and neurological conditions such as depression. However, there are no technologies well suited to this, limiting potential clinical applications. To test if we could replicate previous evidence of hypo reactivity to emotional salient material using an entirely new sensing technique called optomyography which is well suited to remote monitoring. Thirty-eight depressed and 37 controls (≥18, ≤40 years) who met a research diagnosis of depression and an age-matched non-depressed control group. Changes in facial muscle activity over the brow (corrugator supercilli) and cheek (zygomaticus major) were measured whilst volunteers watched videos varying in emotional salience. Across all participants, videos rated as subjectively positive were associated with activation of muscles in the cheek relative to videos rated as neutral or negative. Videos rated as subjectively negative were associated with brow activation relative to videos judged as neutral or positive. Self-reported arousal was associated with a step increase in facial muscle activation across the brow and cheek. Group differences were significantly reduced activation in facial muscles during videos considered subjectively negative or rated as high arousal in depressed volunteers compared with controls. We demonstrate for the first time that it is possible to detect facial expression hypo-reactivity in adults with depression in response to emotional content using glasses-based optomyography sensing. It is hoped these results may encourage the use of optomyography-based sensing to track facial expressions in the real-world, outside of a specialized testing environment.

Quantitative versus qualitative emotion regulation goals: Differential effects on emotional responses.

Emotion regulation (ER) involves both a goal (e.g., to feel less emotion) and a strategy (e.g., reappraisal). To clarify the impact of ER goals on emotional responding, we conducted a within-participant study (N = 156) in which we held the strategy constant (reappraisal) to isolate the impact of regulation goals. We compared the impact of a quantitative goal (changing emotion quantity/intensity) with that of a qualitative goal (changing emotion quality/type) on emotional responses to negative and positive pictures. We manipulated ER goals by cuing participants to continue viewing the picture (unregulated/no ER goal) or to reappraise it to decrease its predominant affective impact (quantitative goal) or increase its opposite-valence impact (qualitative goal). We assessed emotional responses through self-reported feelings and facial expressions (corrugator supercilii and zygomaticus major electromyography). Our findings suggest that the type of regulation goal has a differential effect on emotional responses, with qualitative goals being more effective in modulating both negative and positive emotions. For negative stimuli, attempts to use a quantitative goal decreased negative but not positive emotional responses (uncoupled negative deactivation). Conversely, attempts to use a qualitative goal decreased negative and increased positive emotional responses (reciprocal positive activation). For positive stimuli, the quantitative goal generated uncoupled positive deactivation, while the qualitative goal produced reciprocal negative activation. Results highlight the importance of considering specific regulation goals in shaping emotional responses. Future research in the field of ER may benefit from identifying and manipulating different goals and strategies to understand how to effectively regulate emotions.

Cases Of Meige’s Syndrome Controlled Following Administration Of Low-Dose Botulinum Toxin Type-A: A Serial Case Series

Background: Meige syndrome is a form of cranial dystonia characterised by blepharospasm and oromandibular dystonia, with a twice-fold higher prevalence in women as compared to men. The definitive pathophysiology underlying Meige syndrome remains unknown, but some studies have postulated the role of striatal dopaminergic activity. Currently, no curative treatments are available for Meige syndrome, but non-specific modalities include oral agents such as anti-cholinergics, dopaminergics, and benzodiazepines. Botulinum toxin Type-A (BoNTA) constitutes an effective treatment option in cases of Meige syndrome refractory to oral management. Case summary: We report three cases of female patients, age 42, 57, and 61 years, presenting with complaints of blepharospasm and oromandibular dystonia. Low-dose BoNTA injections were administered, 10 units total weekly divided into the orbicularis oculi, corrugator supercilii, frontalis, procerus, nasalis, zygomaticus, mentalis, dan risorius, and orbicularis oris areas. Following repeated administrations of BoNTA injections, the three patients no longer experience symptoms up till now. Conclusion: The authors report that low-dose BoNTA injections are effective in ameliorating dystonic symptoms associated with Meige syndrome, with low incidences of side effects.

Injection technique of the upper face with onabotulinumtoxinA in chronic migraine.

The objective is to review the technique of onabotulinumtoxinA injection treatment in the glabellar and frontal regions using the PREEMPT (Phase III REsearch Evaluating Migraine Prophylaxis Therapy) paradigm, with review of the aesthetic issues related to the procedure. OnabotulinumtoxinA is an effective medication for the prevention of chronic migraine. The PREEMPT injection paradigm has been validated in randomized clinical trials and real-world settings. This treatment includes injections in the forehead and glabella area. In addition, for aesthetic uses, glabella onabotulinumtoxinA injections are done in similar muscles specifically the procerus, corrugator supercilii, and frontalis muscles. Often patients who have been injected with onabotulinumtoxinA for chronic migraine have concerns about their appearance and will ask if they can see an aesthetic injector to improve this. This is a difficult issue as onabotulinumtoxinA should be injected with an interval of 10-12 weeks to avoid development of antibodies against onabotulinumtoxinA, so all injections (migraine and aesthetic) should ideally be done close together; however, if an aesthetic injection is done on the same day as a PREEMPT injection, the effect of the PREEMPT injection will not yet be visible as it takes time for onabotulinumtoxinA effects to be seen. Thus, there is a risk of a potential overdose in a particular area if aesthetic injections are done without input from the PREEMPT injector. This is a narrative review supported by photographic documentation showing the technique of onabotulinumtoxinA injection of the upper face, considering anatomical differences between patients, and combining the needs in neurology and aesthetic medicine fields. Practitioners treating chronic migraine often modify some of the principles of the PREEMPT paradigm. Many practitioners are unsure about injections in the glabellar and frontal areas. The authors present a technique for using the PREEMPT protocol and adapting this to the individual patient's anatomy to prevent an unsightly appearance or ptosis. In addition, sites are provided where an aesthetic injector could inject to improve the patient's appearance without overlapping with the PREEMPT injection sites. Adherence to the PREEMPT injection protocol provides an evidence-based approach to achieving clinical benefit for patients with chronic migraine. Aesthetic elements of the treatment of the glabella and forehead require additional attention. The authors provide practical considerations and recommendations regarding this.

An EMG-based wearable multifunctional Eye-control glass to control home appliances and communicate by voluntary blinks

The purpose of this work is to first apply the electromyogram (EMG) of corrugator supercilii muscles as the only signal to control home appliances and communicate with others by means of voluntary blinks, especially for the severely disabled. An EMG-based wearable eye-control glass is constructed as a multifunctional human–machine interface (HMI) device in this work. Twelve healthy subjects participated in the experiment to perform the home appliance eye-control task and the eye-communication task. This multifunctional eye-control glass is low-cost, easy-to-use, and wearable, and the experiment results indicate the high selectivity of voluntary blinks/natural blinks and left-eye blinks/right-eye blinks, excellent sensitivity, fast response time, high accuracy, low individual differences, and a prominent information transfer rate of the wearable device. This study provides a novel way for the construction of wearable eye-control devices to help healthy and disabled people conveniently control home appliances and communicate with the external world. It is gentler for users when applying this EMG-based wearable eye-control glass in various practical applications, like in the cinema or a meeting, than gesture and voice interactions. For disabled people without speaking ability, users can perform simple communication and express their needs with clinical staff with the help of this wearable device. Especially, this novel method greatly facilitates the daily lives of patients in the lock-in state through blink control. Moreover, the relationship between voluntary blinks and the movement of corrugator supercilii muscles is proven.

EEG and peripheral markers of viewer ratings: a study of short films.

Cinema is an important part of modern culture, influencing millions of viewers. Research suggested many models for the prediction of film success, one of them being the use of neuroscientific tools. The aim of our study was to find physiological markers of viewer perception and correlate them to short film ratings given by our subjects. Short films are used as a test case for directors and screenwriters and can be created to raise funding for future projects; however, they have not been studied properly with physiological methods. We recorded electroencephalography (18 sensors), facial electromyography (corrugator supercilii and zygomaticus major), photoplethysmography, and skin conductance in 21 participants while watching and evaluating 8 short films (4 dramas and 4 comedies). Also, we used machine learning (CatBoost, SVR) to predict the exact rating of each film (from 1 to 10), based on all physiological indicators. In addition, we classified each film as low or high rated by our subjects (with Logistic Regression, KNN, decision tree, CatBoost, and SVC). The results showed that ratings did not differ between genres. Corrugator supercilii activity ("frowning" muscle) was larger when watching dramas; whereas zygomaticus major ("smiling" muscle) activity was larger during the watching of comedies. Of all somatic and vegetative markers, only zygomaticus major activity, PNN50, SD1/SD2 (heart rate variability parameters) positively correlated to the film ratings. The EEG engagement indices, beta/(alpha+theta) and beta/alpha correlated positively with the film ratings in the majority of sensors. Arousal (betaF3 + betaF4)/(alphaF3 + alphaF4), and valence (alphaF4/betaF4) - (alphaF3/betaF3) indices also correlated positively to film ratings. When we attempted to predict exact ratings, MAPE was 0.55. As for the binary classification, logistic regression yielded the best values (area under the ROC curve = 0.62) than other methods (0.51-0.60). Overall, we revealed EEG and peripheral markers, which reflect viewer ratings and can predict them to a certain extent. In general, high film ratings can reflect a fusion of high arousal and different valence, positive valence being more important. These findings broaden our knowledge about the physiological basis of viewer perception and can be potentially used at the stage of film production.

Control over emotional facial expressions: Evidence from facial EMG and ERPs in a Stroop-like task

Facial expressions carry important social signals that must be precisely regulated despite potentially conflicting demands on veridicality, communicative intent, and the social situation. In a sample of 19 participants we investigated the challenges of deliberately controlling two facial expressions (smiles and frowns) by the emotional congruency with the expressions of adult and infant counterparts. In a Stroop-like task requiring participants’ deliberate expressions of anger or happiness, we investigated the impact of task-irrelevant background pictures of adults and infants showing negative, neutral, or positive facial expressions. Participants’ deliberate expressions were measured with electromyogram (EMG) of the M. zygomaticus major and M. corrugator supercilii. The latencies of EMG onsets revealed similar congruency effects for smiles and frowns with significant facilitation and inhibition components relative to the neutral condition. Interestingly, the facilitation effect for frown responses by negative facial expressions was significantly smaller vis a vis infant as compared to adult background faces. This diminished facilitation of frowns by infant’s expressions of distress may relate to the activation of caregiver behavior or empathy. We investigated the neural correlates of the observed performance effects by recording event-related-potentials (ERPs). Increased amplitudes in ERP components were observed in incongruent relative to neutral conditions, revealing interference effects on both types of deliberate facial expressions, at different processing stages, namely, structural facial encoding (N170), conflict monitoring (N2), to semantic analysis (N400).

Behavioral and neural underpinnings of empathic characteristics in a Humanitude-care expert.

Humanitude approaches have shown positive effects in elderly care. However, the behavioral and neural underpinnings of empathic characteristics in Humanitude-care experts remain unknown. We investigated the empathic characteristics of a Humanitude-care expert (YG) and those of age-, sex-, and race-matched controls (n = 13). In a behavioral study, we measured subjective valence and arousal ratings and facial electromyography (EMG) of the corrugator supercilii and zygomatic major muscles while participants passively observed dynamic facial expressions associated with anger and happiness and their randomized mosaic patterns. In a functional magnetic resonance imaging (MRI) study, we measured brain activity while participants passively observed the same dynamic facial expressions and mosaics. In a structural MRI study, we acquired structural MRI data and analyzed gray matter volume. Our behavioral data showed that YG experienced higher subjective arousal and showed stronger facial EMG activity congruent with stimulus facial expressions compared with controls. The functional MRI data demonstrated that YG showed stronger activity in the ventral premotor cortex (PMv; covering the precentral gyrus and inferior frontal gyrus) and posterior middle temporal gyrus in the right hemisphere in response to dynamic facial expressions versus dynamic mosaics compared with controls. The structural MRI data revealed higher regional gray matter volume in the right PMv in YG than in controls. These results suggest that Humanitude-care experts have behavioral and neural characteristics associated with empathic social interactions.

Effectiveness of emotion regulation strategies measured by self-report and EMG as a result of strategy used, negative emotion strength and participants’ baseline HRV

We investigated how emotion regulation (ER) effectiveness—on both a self-reported rating as well as emotional expression (corrugator supercilii muscle activity) level—is affected by the characteristics of the situation (low vs. high negativity), the strategy used (reinterpretation, distraction, suppression, no regulation control condition) and individual dispositions (low vs. high baseline Heart Rate Variability) as well as their interaction. For this purpose, 54 adult women participated in a laboratory study. All the included factors significantly influenced both corrugator activity and appraisals of pictures’ negativity (in specific experimental conditions). For example, for high HRV participants, (1) distraction, suppression and reinterpretation significantly decreased corrugator activity compared to the control condition, and (2) distraction decreased appraised picture negativity for high negativity photos. For low HRV participants, distraction and suppression were most effective in decreasing corrugator responses, while suppression was more effective than reinterpretation in decreasing perceived picture negativity in the high negativity condition. Subjectively reported effort and success in applying ER strategies were also dependent on manipulated and dispositional factors. Overall, our results lend support to the flexible emotion regulation framework, showing that emotion regulation effectiveness relies on situational context as well as individual dispositions and their interaction.

Crosstalk in Facial EMG and Its Reduction Using ICA

There is ample evidence that electromyography (EMG) signals from the corrugator supercilii and zygomatic major muscles can provide valuable information for the assessment of subjective emotional experiences. Although previous research suggested that facial EMG data could be affected by crosstalk from adjacent facial muscles, it remains unproven whether such crosstalk occurs and, if so, how it can be reduced. To investigate this, we instructed participants (n = 29) to perform the facial actions of frowning, smiling, chewing, and speaking, in isolation and combination. During these actions, we measured facial EMG signals from the corrugator supercilii, zygomatic major, masseter, and suprahyoid muscles. We performed an independent component analysis (ICA) of the EMG data and removed crosstalk components. Speaking and chewing induced EMG activity in the masseter and suprahyoid muscles, as well as the zygomatic major muscle. The ICA-reconstructed EMG signals reduced the effects of speaking and chewing on zygomatic major activity, compared with the original signals. These data suggest that: (1) mouth actions could induce crosstalk in zygomatic major EMG signals, and (2) ICA can reduce the effects of such crosstalk.

Effects of Imagery Rescripting on Emotional Responses During Imagination of a Socially Aversive Experience

Imagery rescripting (ImRs) of socially aversive memories is a promising intervention in the treatment of Social Anxiety Disorder. Little is known about the effects of ImRs on physiological responses to the rescripted socially aversive memory, which was the focus of this study in a healthy sample. Thirty individuals performed an imagination task measuring psychophysiological responses and subjective feelings (post-hoc) related to the rescripted memory, as well as to two control memories. In a within-subject design, participants completed the imagination task before and after a control intervention, and subsequently after one session ImRs of the socially aversive memory. At one-week follow-up, lasting effects on social anxiety and subjective feelings were assessed online (N = 26). ImRs of the socially aversive memory resulted in a significant reduction in negative feelings and activity of the corrugator supercilii, as well as a significant increase in valence and positive feelings related to the socially aversive memory compared to both control memories. However, only effects for positive feelings and corrugator supercilii were significantly stronger for ImRs compared to the control intervention. Lasting effects appeared for fear of negative evaluation and subjective emotional responses to the rescripted memory. These findings give preliminary evidence for the impact of ImRs on emotional aspects of the rescripted memory, indicating that ImRs might work through changing the representation of the aversive event in memory.

Pleasant Stroke Touch on Human Back by a Human and a Robot.

Pleasant touching is an important aspect of social interactions that is widely used as a caregiving technique. To address the problems resulting from a lack of available human caregivers, previous research has attempted to develop robots that can perform this kind of pleasant touch. However, it remains unclear whether robots can provide such a pleasant touch in a manner similar to humans. To investigate this issue, we compared the effect of the speed of gentle strokes on the back between human and robot agents on the emotional responses of human participants (n = 28). A robot or a human stroked on the participants' back at two different speeds (i.e., 2.6 and 8.5 cm/s). The participants' subjective (valence and arousal ratings) and physiological (facial electromyography (EMG) recorded from the corrugator supercilii and zygomatic major muscles and skin conductance response) emotional reactions were measured. The subjective ratings demonstrated that the speed of 8.5 cm/s was more pleasant and arousing than the speed of 2.6 cm/s for both human and robot strokes. The corrugator supercilii EMG showed that the speed of 8.5 cm/s resulted in reduced activity in response to both human and robot strokes. These results demonstrate similar speed-dependent modulations of stroke on subjective and physiological positive emotional responses across human and robot agents and suggest that robots can provide a pleasant touch similar to that of humans.

Comparing fear and anxiety chemosignals: Do they modulate facial muscle activity and facilitate identifying facial expressions?

Fear and anxiety are the most frequently studied emotional states in chemosignal research. Despite differences between these two emotional states, findings from research using fear and anxiety body odors (BOs) are often treated as part of a similar phenomenon. In this article, we examine possible similarities and differences between participants exposed to fear and anxiety BOs on 2 dependent variables commonly used in chemosignals' research: (1) the activation of facial muscles in displays of fear expressions (i.e. the medial frontalis and the corrugator supercilii); and (2) the time required to discriminate between negative emotional expressions (fear, anger, and disgust) and neutral ones. Our results show that fear (vs. rest) and anxiety (vs. exercise) BOs activate the medial frontalis, suggesting that both have a similar impact on receivers' facial muscles. However, we could not replicate previous findings regarding the influence of fear BOs in discriminating negative emotional faces from neutral ones. Two additional replication attempts failed to replicate the earlier results, indicating that the results reported in the literature with this specific paradigm should be interpreted cautiously. Suggestions for future research examining possible differences between fear and anxiety BOs are advanced.