No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Guidelines for human electromyographic research
Abstract
Guidelines are proposed for the collection, analysis, and description of electromyographic (EMG) data. The guidelines cover technological issues in EMG recording, social aspects of EMG experimentation, and limits to inferences that can be drawn in EMG research. An atlas is proposed for facial EMG electrode placements, and standard EMG terminology is suggested.
... While most research on facial expressions today has been conducted on the basis of video data or mainly video supplemented by electromyography (EMG) data. Nevertheless, the use of fEMG has been the true gold standard for the high-precision recording of facial expressions in the psychophysiological laboratory for decades (Fridlund and Cacioppo, 1986;Wingenbach, 2023). In particular, facial surface EMG is capable of detecting very subtle muscle activity, including muscle relaxation (e.g., of the eyebrows), below what would be observable with the naked eye Larsen et al., 2003). ...
... The fEMG setup was a bipolar recording setup consisting of 2 channels covering the Frontalis and Corrugator Supercili facial muscles. These positions are defined by the guidelines of the Society for psychophysiological research (Fridlund and Cacioppo, 1986), with slight deviations from the standard sensor positions (see Figure 2), based on extensive pre-testing to minimize the amount of crosstalk, and to account for the slightly larger size of our electrodes compared to the original guideline paper. These deviations were based on intensive pre-testing to optimize the quality of the recording. ...
... Raw EMG data typically includes a substantial amount of electrical noise, which should be removed (Tassinary et al., 2007). Traditionally, remaining noise (e.g., 50/60 Hz noise) and artifacts are then removed via filtering prior to any statistical analyses (Fridlund and Cacioppo, 1986;Tassinary et al., 2007). Within the field of biosignals-based ML, however, this latter type of noise may be better accounted for by the ML algorithm than by a filter, which might filter out some relevant data along with the noise. ...
Facial expressions play a crucial role in non-verbal and visual communication, often observed in everyday life. The facial action coding system (FACS) is a prominent framework for categorizing facial expressions as action units (AUs), which reflect the activity of facial muscles. This paper presents a proof-of-concept study for upper face action unit recognition (AUR) using electromyography (EMG) data. The study recorded facial EMG data of a subject over four sessions, who imitated facial expressions corresponding to four different AUs. The subject-dependent models that were trained achieved high accuracy in near-real time and were able to classify AUs not directly underneath the recording sites.
... Electromyography (EMG) records electrical activity caused by muscle contractions acquired by putting electrodes on the skin's surface. This non-invasive recording of electromyograms is known as surface electromyography (sEMG) [3,4]. Such myoelectric signals are sophisticated and non-stationary and can be expressed as equ (1) [5,6]: ...
... These muscles control the vocal cords' tension and the larynx's position, which are essential for speech production. [3] For the initial investigation, we collected silent speech sEMG signal of English vowels from a single muscle Orbicularis Oris (M1), which is further extended for two other muscles, i.e., the Masseter (M2) and the Digastric (M3). To summarise the rest of the paper's structure, here it is: in section 2, we describe the detailed methodology, which includes details about the sensor, validation vocabulary, details of muscles under observation, data collection technique, the process of dataset preparation, and employed customized classification techniques. ...
... Fig 2 depictstypical muscle locations of a human face[3]. ...
Over the last two decades, myoelectric signals have been widely used in fields including rehabilitation devices and human-machine interfaces. This study aimed to develop an algorithm for surface electromyography (sEMG) data acquisition utilizing low-cost hardware and validate its performance using English vowels as silent speech content. The sEMG data were collected from the three facial muscles of one healthy subject. The sEMG signals were pre-processed, and various time-domain and statistical features were extracted in real time. The raw data and features were then used to train and test three customized machine learning classifiers: k-nearest neighbor (KNN), support vector machine (SVM), and artificial neural network (ANN). All customized classifiers achieved almost equivalent accuracy rates of 0.83 ± 0.01 in recognizing the English vowels with an improvement of 27.27% (KNN), 3.75% (SVM), and 51.85% (ANN) utilizing the same low-cost data acquisition hardware. Our findings are substantially closers to the results of commercial hardware setups, which raise the possibility of potential usage of low-cost sEMG data acquisition systems with the proposed algorithm in place of commercial hardware setups for rehabilitation devices and other related sectors of human-machine interaction.
... During non-invasive facial electromyography, all such emotional and/or non-emotional facial activity can be recorded with high temporal resolution, by means of small electrodes attached to the skin over particular target muscles. Figure 1 displays standard electrode positions for recording EMG from specific facial muscles, including, for example, the corrugator supercilii (involved in frowning), the levator labii superioris (involved in wrinkling the nose to express disgust), and the zygomaticus major and orbicularis oculi (involved in smiling; see [42,44,45] Facial EMG has been used to study many things, including the facial correlates of physical and cognitive effort (e.g., [46][47][48][49]), and the patterns of lip movement during articulation (e.g., [50,51]). However, building on earlier work that used facial EMG to track covert articulation during reading, Schwartz and colleagues (e.g., [52]) were the first to use EMG to keep track of emotion: when participants were asked to imagine happy, sad, and angry situations, the researchers observed increased corrugator activity during sad and angry emotional imagery as well as decreased corrugator activity during happy emotional imagery. ...
... All studies (55) Muscle is sensitive to language-driven emotion manipulation 45 Corrugator-dominated effects Our review also indicates that although the corrugator and the zygomaticus are the muscles most often used to assess the impact of language-driven emotion manipulations (see Table 1), the corrugator is, on average, more sensitive, at least with the particular verbal materials and tasks used here (see Table 2): of the 37 studies recording from both muscles, 92% reported emotion-related effects in the corrugator, while only 68% reported such effects in the zygomaticus (with also some unexpected effect direction reversals in the latter). The reasons for this differential sensitivity have been discussed in detail elsewhere (e.g., [17,42]). ...
Beyond recognizing words, parsing sentences, building situation models, and other cognitive accomplishments, language comprehension always involves some degree of emotion too, with or without awareness. Language excites, bores, or otherwise moves us, and studying how it does so is crucial. This chapter examines the potential of facial electromyography (EMG) to study language-elicited emotion. After discussing the limitations of self-report measures, we examine various other tools to tap into emotion, and then zoom in on the electrophysiological recording of facial muscle activity. Surveying psycholinguistics, communication science, and other fields, we provide an exhaustive qualitative review of the relevant facial EMG research to date, exploring 55 affective comprehension experiments with single words, phrases, sentences, or larger pieces of discourse. We discuss the outcomes of this research, and evaluate the various practices, biases, and omissions in the field. We also present the fALC model, a new conceptual model that lays out the various potential sources of facial EMG activity during language comprehension. Our review suggests that facial EMG recording is a powerful tool for exploring the conscious as well as unconscious aspects of affective language comprehension. However, we also think it is time to take on a bit more complexity in this research field, by for example considering the possibility that multiple active generators can simultaneously contribute to an emotional facial expression, by studying how the communicator’s stance and social intention can give rise to emotion, and by studying facial expressions not just as indexes of inner states, but also as social tools that enrich everyday verbal interactions.Key wordsReviewEMGFacial electromyographyPsycholinguisticsCommunication scienceEmotionPsychophysiologySimulationMimicryEvaluation
... Impedances were kept below 50 kOhm. Electrode positions followed the guidelines by Fridlund and Cacioppo (1986) with the ground electrode on the center of the forehead (Fridlund & Cacioppo, 1986). Data was sampled with 1000 Hz using a V-Amp amplifier (BrainProducts, Gilching, Germany). ...
... Impedances were kept below 50 kOhm. Electrode positions followed the guidelines by Fridlund and Cacioppo (1986) with the ground electrode on the center of the forehead (Fridlund & Cacioppo, 1986). Data was sampled with 1000 Hz using a V-Amp amplifier (BrainProducts, Gilching, Germany). ...
Human social interactions are highly coordinated in time and involve the reciprocal exchange of facial emotional expressions. While timing has been identified as an important factor in social communication via gaze or speech, so far there has been no systematic investigation on how the temporal delays in the exchange of facial emotional expressions between interactive partners influence the experience of responsiveness. In the present study, 40 participants were cued to direct a facial emotional expression (angry or happy) towards a virtual agent in front of them and the virtual agent would then react with a congruent facial expression. The temporal delay between the cue and the reaction was manipulated as an independent variable. Exact delays between facial expressions were determined based on the onset latencies of participants’ facial expressions measured via facial EMG (M. Zygomaticus and M. Corrugator). Ratings of experienced responsiveness of the virtual agent were collected as a dependent measure. Using a linear mixed effect model in a growth curve analysis revealed that experienced responsiveness peaked at delays around 700 ms. Moreover, experienced responsiveness at shorter temporal delays was higher when happy versus angry facial expressions were exchanged, while the reversed pattern was found at longer delays. Our results demonstrate a crucial role of timing in non-verbal communication, suggesting that temporal relations between facial expressions are processed as social information. Furthermore, our results can inform the implementation of virtual social interactions.
... Before the electrodes's attachment, the experimenter removed any makeup, applied the abrasive paste to the electrode sites, and cleaned them with salicylic alcohol. Using bipolar placement, the Ag/AgCl electrodes were placed with saline-based electrode gel over the corrugator supercilli and the zygomaticus major regions on the left side of the face, according to the guidelines provided by Fridlund and Cacioppo (1986). A ground electrode was placed below the hairline in the middle of the forehead. ...
Facial mimicry of visually observed emotional facial actions is a robust phenomenon. Here, we examined whether such facial mimicry extends to auditory emotional stimuli. We also examined if participants’ facial responses differ to sounds that are more strongly associated with congruent facial movements, such as vocal emotional expressions (e.g., laughter, screams), or less associated with movements, such as non-vocal emotional sounds (e.g., happy, scary instrumental sounds). Furthermore, to assess whether facial mimicry of sounds reflects visual-motor or auditory-motor associations, we compared individuals that vary on lifetime visual experience (sighted vs. blind). To measure spontaneous facial responding, we used facial electromyography to record the activity of the corrugator supercilii (frowning) and the zygomaticus major (smiling) muscles. During measurement, participants freely listened to the two types of emotional sounds. Both types of sounds were rated similarly on valence and arousal. Notably, only vocal, but not instrumental, sounds elicited robust congruent and selective facial responses. The facial responses were observed in both sighted and blind participants. However, the muscles’ responses of blind participants showed less differentiation between emotion categories of human vocalizations. Furthermore, the groups differed in the shape of the time courses of the zygomatic activity to human vocalizations. Overall, the study shows that emotion-congruent facial responses occur to non-visual stimuli and are more robust to human vocalizations than instrumental sounds. Furthermore, the amount of life-time visual experience matters little for the occurrence of cross-channel facial mimicry, but it shapes response differentiation.
... We measured this using two 7 mm Ag/AgCl mini-electrodes that we filled with electrolyte gel (Signa, Parker Laboratories). Using double-stick adhesive tape, we placed the two electrodes just above the eyebrow, at the place where the muscle is located (Fridlund & Cacioppo, 1986). A third electrode was placed on the middle of the forehead (just below the hairline) and served as a ground measure. ...
This article attempts to explain the current situation of the Turkish media system through the media systems approach as a case study with special attention to the concept of media capture. We propose that the Turkish media system’s shift is heavily influenced by media capture. We associate four of Hallin and Mancini’s media systems concepts related to the effects of media capture in the Turkish media system shift: rise of political parallelism, erosion of journalistic professionalism (ethics), controlling role of the state, and government-friendly ownership concentration. In explaining the shift from a pluralist polarised to captured media in Turkey, we acknowledge the potential for new, independent, and alternative media to emerge. The article also comments that the potential reason for this shift from a captured liberal to a captured media in Turkey is the climate of fear that has allowed successive governments in Turkey to attempt media capture. In general, this article attempts to provide insight into the current relationship between media and politics in Turkey.
... We measured this using two 7 mm Ag/AgCl mini-electrodes that we filled with electrolyte gel (Signa, Parker Laboratories). Using double-stick adhesive tape, we placed the two electrodes just above the eyebrow, at the place where the muscle is located (Fridlund & Cacioppo, 1986). A third electrode was placed on the middle of the forehead (just below the hairline) and served as a ground measure. ...
The negativity bias hypothesis in political communication contends that people are more aroused by negative vs. positive news. Soroka et al. (2019) provide evidence for this negativity bias in a study in 17 countries across six continents. We find suggestive evidence for Soroka et al.’s (2019) central finding that negativity causes an increase in skin conductance levels in a conceptually close, well-powered, and preregistered replication. We extend Soroka et al. (2019) in three ways. First, we theorise, test, and confirm that negative (vs. positive) news causes an increase in activity of the corrugator major muscle above the eyebrow (using facial electromyography activity) and is associated with a negative affect. Second, we find people self-reporting negative news causes negative affect but that positive (instead of negative) news increases self-reported arousal. Third, we test Soroka et al.’s (2019) argument in another context, the Netherlands. Our article suggests that negative news is, especially, causing negative affect. Doing so, we contribute to the negativity bias argument in political communication research and, at the same time, show the importance of replication in empirical communication research.
... FEMG acquisition and pre-processing. For the retrieval part of the ROAM and the movie task in session 1, facial EMG was collected with two pairs of sintered Ag/AgCl EMG electrodes with six mm sensors that were placed in the zygomaticus major and the corrugator supercilii region of the left side of the face, according to established guidelines 109 . A reference electrode was placed below the hairline in the horizontal center of the forehead. ...
People suffering from dysphoria retrieve autobiographical memories distorted in content and affect, which may contribute to the aetiology and maintenance of depression. However, key memory difficulties in dysphoria remain elusive because theories disagree how memories of different valence are altered. Here, we assessed the psychophysiological expression of affect and retrieved episodic detail while participants with dysphoria (but without a diagnosed mental illness) and participants without dysphoria relived positive, negative, and neutral memories. We show that participants with dysphoria retrieve positive memories with diminished episodic detail and negative memories with enhanced detail, compared to participants without dysphoria. This is in line with negativity bias but not overgeneral memory bias theories. According to confirmatory analyses, participants with dysphoria also express diminished positive affect and enhanced negative affect when retrieving happy memories, but exploratory analyses suggest that this increase in negative affect may not be robust. Further confirmatory analyses showed that affective responses to memories are not related to episodic detail and already present during the experience of new emotional events. Our results indicate that affective memory distortions may not emerge from mnemonic processes but from general distortions in positive affect, which challenges assumptions of memory theories and therapeutics. Protocol registration: The Stage 1 protocol for this Registered Report was accepted in principle on the 18rd of March 2021. The protocol, as accepted by the journal, can be found at https://doi.org/10.6084/m9.figshare.14605374.v1.
... The experimenter cleaned the skin of the participants' cheeks using 70% isopropyl alcohol wipes. Two pairs of disposable electrodes were placed over the bilateral ZM muscles, following electromyography (EMG) guidelines (Fridlund and Cacioppo, 1986). To identify the best positioning of the electrodes and ensure that a weak smile could be induced comfortably, fNMES intensity was gradually increased until visible muscle contractions were observed. ...
The role of facial feedback in facial emotion recognition remains controversial, partly due to limitations of the existing methods to manipulate the activation of facial muscles, such as voluntary posing of facial expressions, or holding a pen in the mouth. These procedures are indeed limited in their control over which muscles are (de)activated when and to what degree. To overcome these limitations and investigate in a more controlled way if facial emotion recognition is modulated by one’s facial muscle activity, we used computer-controlled facial neuromuscular electrical stimulation (fNMES). In a pre-registered EEG experiment, ambiguous facial expressions were categorised as happy or sad by 47 participants. In half of the trials, weak smiling was induced through fNMES delivered to the bilateral Zygomaticus Major muscle for 500 ms. The likelihood of categorising ambiguous facial expressions as happy was significantly increased with fNMES, as shown with frequentist and Bayesian linear mixed models. Further, fNMES resulted in a reduction of P1, N170 and LPP amplitudes. These findings suggest that fNMES-induced facial feedback can bias facial emotion recognition and modulate the neural correlates of face processing. We conclude that fNMES has potential as a tool for studying the effects of facial feedback.
... We did this using two 70-millimeter Ag/AgCl electrodes that were filled with electrolyte gel (Signa, Parker Laboratories). Using double-sided adhesive tape, we placed the two electrodes just above the eyebrow-directly where the muscle is located (Fridlund & Cacioppo, 1986). A third electrode was placed on the middle of the forehead (just below the hairline) and served as a the ground measure. ...
Opinion formation and information processing are affected by unconscious affective responses to stimuli—particularly in politics. Yet we still know relatively little about such affective responses and how to measure them. In this study, we focus on emotional valence and examine facial electromyography (fEMG) measures. We demonstrate the validity of these measures, discuss ways to make measurement and analysis more robust, and consider validity trade-offs in experimental design. In doing so, we hope to support scholars in designing studies that will advance scholarship on political attitudes and behavior by incorporating unconscious affective responses to political stimuli—responses that have too often been neglected by political scientists.
... Subsequently, electrodes of the electrostimulator [CMNS6-1 (Wuxi Jiajian Medical Device Co, Ltd)] were connected in pairs to needles at chosen paired points, delivering an intermittent wave stimulation (30 Hz) stimulus with current amplitude raising at 0.5-mA steps based on the patient's tolerance to provoke incomplete tonic contraction of denervated mimetic muscles. In the TES group, patients received stimulation using manually trimmed adhesive pre-gelled electrodes (1.0 cm 2 , HAOBRO MEDICAL DEVICE Co., Ltd., Suzhou, China) placed on specified sites following established electromyography guidelines [21], which were associated with the orbicularis oculi, frontalis, zygomaticus major, and orbicularis oris muscles. Employing a computerized stimulator (XYZP-II, XIANGYU MEDICAL Co., Ltd., Anyang, China), the stimulation involved a 1-s-long train of bipolar rectangular pulse (250 Hz) with a phase duration of 0.04 ms, and the current amplitude was adjusted in 0.5 mA increments, taking into consideration the patient's tolerance, to elicit movements including eye-closure, forehead wrinkle, smile, and lip pucker. ...
Purpose
To evaluate the effectiveness and safety of electroacupuncture (EA) using intermittent wave stimulation in enhancing facial symmetry and nerve function in chronic Bell’s palsy patients.
Methods
A 6-week assessor-blinded, randomized trial followed by an 18-week observational period was conducted. Sixty individuals with chronic Bell's palsy, showing no signs of recovery after 12 months, were equally divided to receive either 18 sessions of EA using intermittent wave stimulation or Transcutaneous Electrical Stimulation (TES), administered thrice weekly over 6 weeks. The primary outcome measure was the change in the total facial nerve index (TFNI) score from baseline to Week 6, with secondary outcomes including TFNI scores at Weeks 12 and 24, as well as the change in Sunnybrook Facial Grading System (SFG) score from baseline to Week 6, and SFG scores at Weeks 12 and 24.
Results
The EA group showed a significant improvement, with a mean total facial nerve index score increase of 24.35 (4.77) by Week 6 compared with 14.21 (5.12) in the Transcutaneous Electrical Stimulation group (P<.001). This superiority persisted during the 24-week follow-up. While no significant difference was observed in the Sunnybrook Facial Grading System score change from baseline to Week 6, variations were noted at Weeks 12 and 24. No major adverse effects were reported.
Conclusion
EA with intermittent wave stimulation notably enhanced facial symmetry in chronic Bell’s palsy patients over Transcutaneous Electrical Stimulation by Week 6, maintaining this edge throughout the follow-up.
... All signals were continuously recorded at a sampling rate of 500 Hz. The EMG activity of the corrugator supercilii and zygomaticus major muscles was obtained from the right side of the face using bipolar placement of 4-mm Ag/AgCl surface electrodes, following the method described by Fridlund and Cacioppo [23]. The raw EMG signal was amplified and filtered to remove frequencies below 10 Hz and above 350 Hz. ...
... Facial EMG recording focused on the corrugator facial muscle because this is a reliable index of expression of negative affective states (Cacioppo, Bush, & Tassinary, 1992). EMG activity was recorded via 4-mm-diameter Sensor-Medics (Yorba Linda, CA) Ag-AgCl electrodes filled with Beckman electrolyte and attached by adhesive collars over the corrugator site, following guidelines by Fridlund and Cacioppo (1986). The EMG electrodes were connected to a Coulbourn Instruments (Allentown, PA) highgain bioamplifier (S75-01) that was set to filter signals less than 90 Hz or more than 1000 Hz. ...
This study compared 20 real, hypnotized and 20 simulating, unhypnotized participants who were administered a hypnotic induction and then presented with emotionally distressing and neutral visual images. Half were administered a hypnotic suggestion for emotional numbing. Reals and simulators who received the emotional numbing suggestion reported comparably less responsivity to distressing stimuli than others. Whereas emotionally numb reals displayed little change in electromyographic (EMG) activity during the distressing stimuli, simulators displayed marked reduction in EMG activity. Reals (not simulators) displayed a dissociation between their affective response and awareness of the negative content of the stimuli following the numbing suggestion.
... The corrugator response was measured by recording EMG activity from the corrugator muscle region above the left eye with the use of small Sensormedic electrodes filled with electrolyte paste. The placement that we used was recommended by Fridlund and Cacioppo (1986). The raw EMG signal was amplified (by 30000), and frequencies below 90 Hz and above 1000 Hz were filtered with a Coulbourn S75-01 bioamplifier. ...
Previous research with both animal and human subjects has shown that startle reflex magnitude is potentiated in an aversive stimulus context, relative to responses elicited in a neutral or appetitive context. In the present experiment, the same pleasant, unpleasant, and neutral picture stimuli were repeatedly presented to human subjects. Startle reflex habituation was assessed in each stimulus context and was compared with the habituation patterns of heart rate, electrodermal, and facial corrugator muscle responses. All systems showed initial differentiation among affective picture contents and general habituation over trials. The startle reflex alone, however, continued to differentiate among pleasant, neutral, and unpleasant pictures throughout the presentation series. These results suggest that (a) the startle probe reflex is relatively uninfluenced by stimulus novelty, (b) the startle modulatory circuit (identified with amygdala-reticular connections in animals) varies systematically with affective valence, and (c) the modulatory influence is less subject to habituation than is the obligatory startle pathway or responses in other somatic and autonomic systems.
... The experimenter cleaned the skin on the left side of the face (which displays stronger affective reactions than the right side on right-handed individuals; Dimberg and Petterson 2000), first with alcohol and then with an abrasive lotion (Lemon Prep; Mavidon). Two electrodes (Ag-AgCl) were then applied in a bipolar fashion over each of the target muscles, following the guidelines by Fridlund and Cacioppo (1986). A reference electrode was placed on the participant's forehead. ...
A growing body of research suggests that emotional chemosignals in others’ body odour (BO), particularly those sampled during fearful states, enhance emotional face perception in conscious and preconscious stages. For instance, emotional faces access visual awareness faster when presented with others’ fear BOs. However, the effect of these emotional signals in self-BO, i.e., one’s own BO, is still neglected in the literature. In the present work, we sought to determine if emotional self-BOs modify the access to visual awareness of emotional faces. Thirty-eight women underwent a breaking-Continuous Flash Suppression (bCFS) task in which they were asked to detect fearful, happy, and neutral faces, as quickly and accurately as possible, while being exposed to their fear, happiness, and neutral self-BOs. Self-BOs were previously collected and later delivered via an olfactometer, using an event-related design. Results showed a main effect of emotional faces, with happy faces being detected significantly faster than fearful and neutral faces. However, our hypothesis that fear self-BOs would lead to faster emotional face detection was not confirmed, as no effect of emotional self-BOs was found – this was confirmed with Bayesian analyses. Although caution is warranted when interpreting these results, our findings suggest that emotional face perception is not modulated by emotional self-BOs, contrasting with the literature on others’ BOs. Further research is needed to understand the role of self-BOs in visual processing and emotion perception.
... To conceal the real purpose of the study participants were initially told they 255 were participating in a study on language of politics that involved a reading task during which skin 256 conductance levels would be recorded via sensors placed on the face. Site preparation and electrode 257 placement were done following standard procedure guidelines (Fridlund & Cacioppo, 1986;258 Tassinary & Cacioppo, 2000). The skin was cleaned and prepared for electrode placement to reduce 259 skin impedance to less than 10 kΩ. ...
Capturing political support from spontaneous smile reactions detected in others’ faces can be used to gauge electorate preference. But will a smile elicited in the corner of one’s eye while reading of a favored politician smiling indicate positive disposition and political support for target candidates? From an embodied simulation perspective, we tested whether reading of an ingroup or outgroup politician smiling would trigger morphologically different smiles in faces of readers. In a reading task in the laboratory, participants were presented with subject-verb phrases describing left and right-wing politicians smiling or frowning while their facial muscular reactions were measured via electromyography (EMG) recording from the zygomaticus major (ZM, lip puller muscle), orbicularis oculi (OO, eye corner muscle) and the corrugator supercili (CS, wrinkler of the eyebrows). We expected and found that participants responded with a smile detected at the lip puller (ZM) and eye corner (OO) facial muscles when exposed to portrayals of smiling politicians of same political orientation, and reported more positive emotions towards these latter. When reading about outgroup politicians smiling, there was a weaker activation of the lip corner (ZM) muscle and no activation of the eye corner (OO) muscle, while emotions reported towards outgroup politicians were significantly more negative. Also, a more enhanced frown response (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.
... It is not recommended to increase interelectrode distance to enhance EMG amplitude since this does not only lead to a larger contribution of low-frequency EMG components from the target muscle [32], but also to greater crosstalk from other muscles within this frequency region [33]. Reducing crosstalk by limiting the EMG recording bandwidth to higher frequencies-like 90-500 Hz as earlier proposed [34]-is not recommended because during a measurement session, the EMG power spectrum may shift to lower frequencies as an effect of fatigue [8] so that the recorded signal within the limited bandwidth is no longer representative of the real EMG amplitude. ...
The potential significance of facial EMG responses as an index of language processing is discussed. First, functional and metabolic differences between different facial muscles are presented, as well as the consequences which such differences may have for activating the brain through afferent feedback signals from the facial skin. Different facial muscles, particularly those in the upper and lower part of the face, are differently controlled by the brain which is related to functional differences between these muscle groups. Next, it is described how facial EMG signals can be recorded, how surface electrodes should be placed, and how EMG responses should be analyzed and standardized. Following these methodological issues, the potential significance of different categories of facial EMG responses during behavioral studies, including language processing, is outlined, in particular emotional responses, responses indicating attention to external stimuli, and responses related to mental effort demanded by cognitive information processing tasks. Finally, the validity of facial muscle activity during linguistic processes is specifically addressed. It is also suggested how the validity of EMG responses as an index of subvocal speech, an important aspect of language processing, may be improved.Key wordsFacial musclesMeasuring EMGEmotionAttentionInformation processingMental effortLinguistic processesSubvocal speech
... The Masseter originates from the maxilla and zygomatic arch and inserts to the ramus of the mandible to elevate and protrude; it assists in side-to-side movements of the mandible. The Mentalis originates from the mandible and inserts into the skin of the chin to elevate and protrude the lower lip, to pull skin into a pout (Fridlund and Cacioppo 1996). ...
... The happy expression stimulus shown in this figure is for illustration purposes; the actual stimuli used in the task came from the Mindreading set(Baron-Cohen et al., 2004). The individual shown in this figure consents to their image being published.Facial EMG Recording & ProcessingEMG activity was measured using sensors positioned over the Zygomaticus Major (ZM) and Corrugator Supercilii (CS) in accordance with the guidelines proposed byFridlund and Cacioppo (1986). The skin was first cleaned using 70% alcohol wipes, after which 4mm Ag/AgCl surface sensors (Discount Disposables, USA) filled with isotonic electrode gel (Mansfield R&D, UK) were attached bipolarly to the left side of the face using 5mm collars (Discount Disposables), at a distance of 10mm apart. ...
Understanding and sharing others’ emotions (i.e., empathy) requires the ability to manage one’s own emotions (i.e., emotion regulation). Indeed, empirical evidence suggests that empathy and emotion regulation are related. This evidence is largely based on self-report measures of both constructs. The current study examined how task measures that assess processes related to empathy are associated with self-reported emotion dysregulation in a young adult sample. An eye-tracking-based perspective-taking task was used as a proxy measure of cognitive empathy. A spontaneous facial mimicry (SFM) task, wherein the activation of the Zygomaticus Major and the Corrugator Supercilii was measured during the passive viewing of happy and angry faces, was used as a proxy measure of affective empathy. The perspective-taking task metric showed a negative relationship with emotion dysregulation. The overall SFM metric was not significantly associated with emotion dysregulation. Follow-up analyses revealed that SFM for angry faces was inversely proportional to emotion dysregulation; no such relationship was observed for SFM for happy faces. These findings build upon prior work by demonstrating a positive relationship between adaptive emotion regulation and a behavioral measure of cognitive empathy. The findings for affective empathy are suggestive of a valence-specific relationship between SFM and emotion regulation.
... These muscles were selected as indices of facial mimicry because several previous studies employing facial EMG indicated that observation of angry and happy facial expressions induced corrugator supercilii and zygomatic major muscle activities, respectively [e.g., (42)]. The Ag/AgCl electrodes were placed according to established guidelines (43,44). A ground electrode was placed on the forehead. ...
Background
Humanitude approaches have shown positive effects in elderly care. However, the behavioral and neural underpinnings of empathic characteristics in Humanitude-care experts remain unknown.
Methods
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.
Results
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.
Conclusion
These results suggest that Humanitude-care experts have behavioral and neural characteristics associated with empathic social interactions.
... The experimenter cleaned the skin on the left side of the face (which displays stronger affective reactions than the right side on right-handed individuals; Dimberg and Petterson 2000), first with alcohol and then with an abrasive lotion (Lemon Prep; Mavidon). Two electrodes (Ag-AgCl) were then applied in a bipolar fashion over each of the target muscles, following the guidelines by Fridlund and Cacioppo (1986). A reference electrode was placed on the participant's forehead. ...
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.
... To avoid relying solely on self-report data to assess ER effectiveness, we incorporated electromyographical (EMG) measurements into the experiment. EMG measurements are widely used to investigate the behavioral level of emotional responsiveness-they provide us with information about the level of activity of particular facial muscles that are engaged in the emotional expression of certain emotions 52 www.nature.com/scientificreports/ rugator supercilii facial muscle activity measured with EMG is sensitive to the effects of the regulation of emotion via reinterpretation and suppression 54,55 . ...
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.
... Electromyography. The muscle activity of the left corrugator supercilii and zygomaticus major were assessed using 4 mm Ag/AgCl electrodes placed according to the recommendations of Fridlund and Cacioppo (1986). The recording was subdivided into segments for each trial ranging from -1,000 msec. ...
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.
... For EMG, two electrodes were attached to each muscle of interest (with a distance of 1 cm), namely, zygomaticus major, medial frontalis, and corrugator supercilii. The guidelines by Fridlund and Cacioppo [47] were followed to place the electrodes. Only the left side was monitored, since right-handed individuals exhibit stronger emotional reactions on the left side of the face (e.g., [33]). ...
Abnormal sensory perception is among the earliest symptoms of autism spectrum disorders (ASD). Despite mixed findings, olfactory perception seems to be altered in ASD. There is also evidence that automatic responses to odours can serve as biomarkers of ASD. However, this potential use of odour-based biomarkers for ASD is still underexplored. In this study, we aimed to investigate whether physiological responses to social and non-social odours, measured with electrocardiography (ECG) and facial electromyography (EMG), can be used to characterise and predict ASD in adults. For that, we extracted 32 signal features from a previously collected database of 11 adults with ASD and 48 adults with typical development (TD). Firstly, non-parametric tests were performed, showing significant differences between the ASD and the TD groups in 10 features. Secondly, a k-nearest-neighbour classifier with a leave-one-out strategy was employed, obtaining an F1-score of 67%. Although caution is needed due to the small sample size, this study provides preliminary evidence supporting the use of physiological responses to social and non-social odours as a potential diagnostic tool for ASD in adults.
Introduction
Emotion regulation (ER) is a complex process that manifests gradually over time. This study investigated the temporal dynamics of ER in modifying positive emotions in terms of both negative affect (NA) and positive affect (PA) dimensions.
Methods
After participants had been exposed to pleasant pictures for 8,000 ms, they received instructions to either continue viewing the picture (no regulation) or reappraise it with a neutral meaning (neutralize goal) or negative meaning (transform goal) for another 8,000 ms. We obtained corrugator supercilii and zygomaticus major electromyography (EMG) as objective measures of NA and PA.
Results
For the no-regulation condition, upon instruction onset, we observed maintained low levels of corrugator and high levels of zygomaticus EMG reactivity, indicating sustained PA activation. Compared to the no-regulation condition, for the neutralize goal, we observed no change in corrugator reactivity, which remained at a low level, while zygomaticus reduction started at 1,000 ms after instruction onset, indicating decreased PA and generation of a neutral emotional state. For the transform goal, we observed corrugator increase and zygomaticus decrease both starting at 1,500 ms after instruction onset and co-existing throughout the regulation period. These results indicate increased NA and decreased PA, relating to generation of a negative emotional state. The transform goal differed from the neutralize goal in terms of corrugator increase starting at 2,500 ms after instruction onset. Albeit simultaneous onset of changes on corrugator and zygomaticus reactivity under the transform goal, model-fitting analyses indicated that the best-fitting trajectory was one that first emphasized PA reduction until, at 3,000 ms, it turned into primary NA increase.
Discussion
These distinct temporal patterns highlight the possibility of effecting one-dimensional PA change with the neutralize goal and sequential two-dimensional change (first decreasing PA, then increasing NA) with the transform goal. This research sheds light on the time course of emotional change brought about by different regulatory goals.
Surface facial electromyography (EMG) is commonly used to detect emotions from subtle facial expressions. Although there are established procedures for collecting EMG data and some aspects of their processing, there is little agreement among researchers about the optimal way to process the EMG signal, so that the study-unrelated variability (noise) is removed, and the emotion-related variability is best detected. The aim of the current paper was to establish an optimal processing pipeline for EMG data for identifying emotional expressions in facial muscles. We identified the most common processing steps from existing literature and created 72 processing pipelines that represented all the different processing choices. We applied these pipelines to a previously published dataset from a facial mimicry experiment, where 100 adult participants observed happy and sad facial expressions, whilst the activity of their facial muscles, zygomaticus major and corrugator supercilii , was recorded with EMG. We used a resampling approach and subsets of the original data to investigate the effect and robustness of different processing choices on the performance of a logistic regression model that predicted the mimicked emotion (happy/sad) from the EMG signal. In addition, we used a random forest model to identify the most important processing steps for the sensitivity of the logistic regression model. Three processing steps were found to be most impactful: baseline correction, standardisation within muscles, and standardisation within subjects. The chosen feature of interest and the signal averaging had little influence on the sensitivity to the effect. We recommend an optimal processing pipeline, share our code and data, and provide a step-by-step walkthrough for researchers.
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.
Like the lines themselves, concerns about facial wrinkles, particularly glabellar lines - the prominent furrows between the eyebrows - intensify with age. These lines can inadvertently convey negative emotions due to their association with negative facial expressions. We investigated the effects of repeated frowning on the development of temporary glabellar lines through the activation of the corrugator muscle. In addition, as communication via facial expressions requires precise control over the muscles of the face in such a way as to avoid contradictory signals, we hypothesized that smiling and activation of the zygomatic major may inhibit the corrugator. Our findings reveal that repeated frowning creates temporary wrinkles between the eyebrows, caused by the slight but cumulative activation of the corrugator muscle. Further we found that the act of smiling activates zygomatic major and suppresses the corrugator reducing the appearance of glabellar lines. The results offer a novel perspective on smiling and suggests that smiling not only facilitates positive emotional exchanges but may also help maintain a youthful facial appearance.
Successful and efficient emotion regulation (ER) is a key mechanism for mental health. However, acute stress may impact the ability to cognitively regulate negative emotions due to its immediate effects on executive functioning. Based on previous studies, we expected that the time at which ER is tested after a stressor might have a decisive influence, with impairments in ER being more pronounced immediately after stress as compared to a later post-stress phase. To investigate such a time-dependent effect of stress on ER, we investigated 50 healthy adults (26 female) who were exposed to either the Trier Social Stress Test (n = 25) or a control condition (n = 25). Afterwards subjects conducted a cognitive ER task during which they were instructed to either regulate (cognitive reappraisal) or passively view neutral and negative visual stimuli. The ER task was divided into an early (0–20 minutes) and a late post-stress phase (20–40 minutes). Salivary cortisol and α-amylase were assessed as markers of the neuroendocrine stress response. Self-reported emotional state, the mean activity of the late positive potential measured via electroencephalogram (EEG), and corrugator electromyographic activity (EMG) were used as indices of ER. While the groups did not differ in the early post-stress phase, our results suggest a stress-related impairment in ER in the late post-stress phase. This effect was evident in all ER outcome variables (subjective rating, EEG, and EMG data). These results suggest a time-specific stress effect on cognitive reappraisal, which would have implications for reappraisal as a possible stress management technique.
Objectives
Anticipatory anxiety and heightened responses to uncertainty are central features of anxiety disorders (ADs) that contribute to clinical impairment. Anxiety symptoms typically emerge during childhood, and even subthreshold‐AD symptoms are associated with distress and risk for future psychopathology. This study compared facial emotional response to threat and uncertainty between preadolescent girls with ADs, girls with subthreshold‐AD symptoms, and controls.
Methods
Facial emotional responding was characterized in preadolescent girls (age 8–11) with a range of anxiety symptoms: no/low anxiety (controls, n = 41), subthreshold‐AD (n = 73), and DSM‐5 diagnoses of separation, social, and/or generalized ADs (n = 45). A threat anticipation paradigm examined how image valence (negative/neutral) and image anticipation (uncertain/certain timing) impacted activity of the corrugator supercilii, a forehead muscle implicated in the “frown” response that is modulated by emotional stimuli (negative > neutral). Corrugator magnitude and corrugator timecourse were compared between groups.
Results
Findings demonstrate greater corrugator activity during anticipation and viewing of negative stimuli, as well as increased corrugator reactivity in subthreshold‐AD and AD girls. Timecourse analyses of negative versus neutral stimuli revealed that AD and subthreshold‐AD girls had greater uncertainty‐related increases in corrugator activity compared to controls.
Conclusion
Results extend the physiological characterization of childhood pathological anxiety, highlighting the impact of subthreshold‐AD symptoms.
Touch care has clinically positive effects on older adults. Touch can be delivered using robots, addressing the lack of caregivers. A recent study of younger participants showed that stroke touch delivered via robot produced subjective and physiologically positive emotional responses similar to those evoked by human touch. However, whether robotic touch can elicit similar responses in older adults remains unknown. We investigated this topic by assessing subjective rating (valence and arousal) and physiological signals [corrugator and zygomatic electromyography (EMG) and skin conductance response (SCR)] to gentle stroking motions delivered to the backs of older participants by robot and human agents at two different speeds: 2.6 and 8.5 cm/s. Following the recent study, the participants were informed that only the robot strokes them. We compared the difference between the younger (their data from the previous study) and the older participants in their responses when the two agents (a robot and a human) stroked them. Subjectively, data from both younger and older participants showed that 8.5 cm/s stroking was more positive and arousing than 2.6 cm/s stroking for both human and robot agents. Physiologically, data from both younger and older participants showed that 8.5 cm/s stroking induced weaker corrugator EMG activity and stronger SCR activity than the 2.6 cm/s stroking for both agents. These results demonstrate that the overall patterns of the older groups responses were similar to those of the younger group, and suggest that robot-delivered stroke touch can elicit pleasant emotional responses in older adults.
Individuals with severe depressive symptoms present diminished facial expressions compared to healthy individuals. This reduced facial expression, which occurs in most depressive patients could impair social relationships. The current study sought to investigate whether pictures with social interaction cues could elicit different modulations of facial expressions and mood states in individuals with depressive symptoms compared to healthy individuals. A total of 85 individuals were divided into depressive and non-depressive groups based on their beck depression inventory scores. Participants viewed pictures containing neutral (objects), affiliative (people interacting socially), and control (people not interacting) scenes. Electromyographic signals were collected during the entire period of visualization of the blocks, and emotional questionnaires were evaluated after each block to assess sociability and altruism (prosocial states). In non-depressed individuals, affiliative pictures increased the activity of the zygomatic muscle compared to both neutral and control pictures and reduced fear of rejection compared to neutral pictures. During the visualization of the affiliative block, zygomatic major muscle activation was higher and fear of rejection was lower in the non-depressive individuals than in the depressive. These effects reflected the low expressions of smiling and sociability to affiliative pictures in depressive individuals. These findings highlight the importance of smiling and prosocial states in social interactions, especially in these individuals.
The response of older people to the COVID-19 pandemic has attracted much attention as they are at increased risk of adverse outcomes. A longitudinal study has shown that improvement in global cognitive, executive and language functioning in healthy older adults enrolled at the University of the Third Age appears to play a protective role against emotional dysregulation and mood changes during the pandemic. To date, no study has examined emotional dysregulation through COVID-19-related images using facial electromyographic recordings in healthy older adults. Therefore, we aimed to analyze the relationships between zygomaticus and corrugator reactivity, neuropsychological measures, and the affective dimensions of arousal, dominance, and valence. The results showed an unexpected association between higher zygomaticus activity and higher levels of apathy, depression, and anxiety. In contrast, increased contracture of the corrugator was associated with poorer performance on cognitive tests (global cognition, memory, executive functions) and physical status, i.e., walking speed. These results are consistent with the reappraisal of emotional stimuli in response to the challenges of the pandemic. Interestingly, COVID-19-related stimuli triggered the activation of bottom-up affectivity strategies associated with higher mood levels and interacted with top-down factors that play an important role in the dysregulation of cognitive control.
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.
A growing number of health-related sciences, including audiology, have increasingly recognized the importance of affective phenomena. However, in audiology, affective phenomena are mostly studied as a consequence of hearing status. This review first addresses anatomical and functional bidirectional connections between auditory and affective systems that support a reciprocal affect-hearing relationship. We then postulate, by focusing on four practical examples (hearing public campaigns, hearing intervention uptake, thorough hearing evaluation, and tinnitus), that some important challenges in audiology are likely affect-related and that potential solutions could be developed by inspiration from affective science advances. We continue by introducing useful resources from affective science that could help audiology professionals learn about the wide range of affective constructs and integrate them into hearing research and clinical practice in structured and applicable ways. Six important considerations for good quality affective audiology research are summarized. We conclude that it is worthwhile and feasible to explore the explanatory power of emotions, feelings, motivations, attitudes, moods, and other affective processes in depth when trying to understand and predict how people with hearing difficulties perceive, react, and adapt to their environment.
Facial neuromuscular electrical stimulation (fNMES), which allows for the non-invasive and physiologically sound activation of facial muscles, has great potential for investigating fundamental questions in psychology and neuroscience, such as the role of proprioceptive facial feedback in emotion induction and emotion recognition, and may serve for clinical applications, such as alleviating symptoms of depression. However, despite illustrious origins in the 19th-century work of Duchenne de Boulogne, the practical application of fNMES remains largely unknown to today’s researchers in psychology. In addition, published studies vary dramatically in the stimulation parameters used, such as stimulation frequency, amplitude, duration, and electrode size, and in the way they reported them. Because fNMES parameters impact the comfort and safety of volunteers, as well as its physiological (and psychological) effects, it is of paramount importance to establish recommendations of good practice and to ensure studies can be better compared and integrated. Here, we provide an introduction to fNMES, systematically review the existing literature focusing on the stimulation parameters used, and offer recommendations on how to safely and reliably deliver fNMES and on how to report the fNMES parameters to allow better cross-study comparison. In addition, we provide a free webpage, to easily visualise fNMES parameters and verify their safety based on current density. As an example of a potential application, we focus on the use of fNMES for the investigation of the facial feedback hypothesis.
Supplementary Information
The online version contains supplementary material available at 10.3758/s13428-023-02262-7.
Effects of alcohol and cognitive demands on reactions to threat were examined using startle response potentiation to index negative emotion. Men and women received nonalcoholic or alcoholic beverages prior to a series of trial blocks, signaled by light cues indicating that shocks might be delivered (“threat” blocks) or that none would occur (“safe” blocks). Within half of the blocks, participants intermittently viewed pleasant photographic slides. Alcohol attenuated overall startle reactivity, but robust fear potentiation (larger startle magnitudes and shorter latencies during threat versus safe blocks) did not differ by beverage condition. Decomposition of the Beverage × Threat × Slide interaction revealed significant fear potentiation in all conditions, except the one in which alcohol was combined with slides. Thus, dampening of stress response by alcohol may depend on diminished ability to process competing cognitive demands.
Although many studies have investigated spectators' cinematic experience, only a few of them explored the neurophysiological correlates of the sense of presence evoked by the spatial characteristics of audio delivery devices. Nevertheless, nowadays both the industrial and the consumer markets have been saturated by some forms of spatial audio format that enrich the audio-visual cinematic experience, reducing the gap between the real and the digitally mediated world. The increase in the immersive capabilities corresponds to the instauration of both the sense of presence and the psychological sense of being in the virtual environment and also embodied simulation mechanisms. While it is well-known that these mechanisms can be activated in the real world, it is hypothesized that they may be elicited even in a virtual acoustic spatial environment and could be modulated by the acoustic spatialization cues reproduced by sound systems. Hence, the present study aims to investigate the neural basis of the sense of presence evoked by different forms of mediation by testing different acoustic space sound delivery (Presentation modes: Monophonic, Stereo, and Surround). To these aims, a behavioral investigation and a high-density electroencephalographic (HD-EEG) study have been developed. A large set of ecological and heterogeneous stimuli extracted from feature films were used. Furthermore, participants were selected following the generalized listener selection procedure. We found a significantly higher event-related desynchronization (ERD) in the Surround Presentation mode when compared to the Monophonic Presentation mode both in Alpha and Low-Beta centro-parietal clusters. We discuss this result as an index of embodied simulation mechanisms that could be considered as a possible neurophysiological correlation of the instauration of the sense of presence.
Individuals have a repertoire of emotion regulation (ER) strategies at their disposal, which they can use more or less flexibly. In ER flexibility research, strategies that facilitate goal achievement are considered adaptive and therefore are subjectively valuable. Individuals are motivated to reduce their emotional arousal effectively and to avoid cognitive effort. Perceived costs of ER strategies in the form of effort, however, are highly subjective. Subjective values (SVs) should therefore represent a trade-off between effectiveness and subjectively required cognitive effort. However, SVs of ER strategies have not been determined so far. We present a new paradigm for quantifying individual SVs of ER strategies by offering monetary values for ER strategies in an iterative process. N = 120 participants first conducted an ER paradigm with the strategies distraction, distancing, and suppression. Afterwards, individual SVs were determined using the new CAD paradigm. SVs significantly predicted later choice for an ER strategy (χ² (4, n = 119) = 115.40, p < 0.001, BF10 = 1.62 × 10²¹). Further, SVs were associated with Corrugator activity (t (5, 618.96) = 2.09, p = 0.037, f² = 0.001), subjective effort (t (5, 618.96) = − 13.98, p < 0.001, f² = 0.035), and self-reported utility (t (5, 618.96) = 29.49, p < 0.001, f² = 0.155). SVs were further associated with self-control (t (97.97) = 2.04, p = 0.044, f² = 0.002), but not with flexible ER. With our paradigm, we were able to determine subjective values. The trait character of the values will be discussed.
Protocol registration
The stage 1 protocol for this Registered Report was accepted in principle on July 19, 2022. The protocol, as accepted by the journal, can be found at: https://doi.org/10.17605/OSF.IO/FN9BT.
Neural oscillations have emerged as a paradigm of reference for EEG and MEG research. In this chapter, we highlight some the possibilities and limits of modelling the dynamics of complex stimulus perception as being shaped by internal oscillators. The reader is introduced to the main physiological tenets underpinning the use of neural oscillations in cognitive neuroscience. The concepts of entrainment and neural tracking are illustrated with particular reference to speech and language processes.Key wordsNeural oscillationsNeural entrainmentCortical trackingSynchronySpeechLanguage
Facial mimicry as well as the accurate assessment of one's performance when judging others’ emotional expressions have been suggested to inform successful emotion recognition. Differences in the integration of these two information sources might explain alterations in the perception of others’ emotions in individuals with Social Anxiety Disorder and individuals on the autism spectrum. Using a non-clinical sample (N = 57), we examined the role of social anxiety and autistic traits in the link between facial mimicry, or confidence in one’s performance, and emotion recognition. While participants were presented with videos of spontaneous emotional facial expressions, we measured their facial muscle activity, asked them to label the expressions and indicate their confidence in accurately labelling the expressions. Our results showed that confidence in emotion recognition was lower with higher social anxiety traits even though actual recognition was not related to social anxiety traits. Higher autistic traits, in contrast, were associated with worse recognition, and a weakened link between facial mimicry and performance. Consequently, high social anxiety traits might not affect emotion recognition itself, but the top-down evaluation of own abilities in emotion recognition contexts. High autistic traits, in contrast, may be related to lower integration of sensorimotor simulations, which promote emotion recognition.
Introduction
Vocal analysis of fundamental frequency (f0) represents a suitable index to assess emotional activation. However, although f0 has often been used as an indicator of emotional arousal and different affective states, its psychometric properties are unclear. Specifically, there is uncertainty regarding the validity of the indices of f0mean and f0variabilitymeasures (f0dispersion, f0range, and f0SD) and whether higher or lower f0 indices are associated with higher arousal in stressful situations. The present study therefore aimed to validate f0 as a marker of vocally encoded emotional arousal, valence, and body-related distress during body exposure as a psychological stressor.
Methods
N = 73 female participants first underwent a 3-min, non-activating neutral reference condition, followed by a 7-min activating body exposure condition. Participants completed questionnaires on affect (i.e., arousal, valence, body-related distress), and their voice data and heart rate (HR) were recorded continuously. Vocal analyses were performed using Praat, a program for extracting paralinguistic measures from spoken audio.
Results
The results revealed no effects for f0 and state body dissatisfaction or general affect. F0mean correlated positively with self-reported arousal and negatively with valence, but was not correlated with HRmean/maximum. No correlations with any measure were found for any f0variabililtymeasures.
Discussion
Given the promising findings regarding f0mean for arousal and valence and the inconclusive findings regarding f0 as a marker of general affect and body-related distress, it may be assumed that f0mean represents a valid global marker of emotional arousal and valence rather than of concrete body-related distress. In view of the present findings regarding the validity of f0, it may be suggested that f0mean, but not f0variabilitymeasures, can be used to assess emotional arousal and valence in addition to self-report measures, which is less intrusive than conventional psychophysiological measures.
Coherence between subjective experience and bodily responses in emotion is assumed to have a positive influence on well-being, which might be particularly valuable in late adulthood. Previous studies of young adults’ continuous subjective, behavioral, and physiological responses to emotional films reported emotional mind–body coherence. In contrast, research regarding emotional coherence in older adults has been scarce. In this study, we examined emotional coherence in older adults between continuous valence ratings and behavioral responses (facial electromyography [EMG] of the corrugator supercilii and zygomatic major muscles), as well as between continuous arousal ratings and physiological measures (electrodermal activity [EDA] and fingertip temperature), in response to four emotion-eliciting film clips (anger, sadness, contentment, and amusement) film clips and an emotionally neutral clip. Intraindividual cross-correlation analyses revealed that the coherence between valence ratings and corrugator EMG activity for the anger-eliciting film was weaker in older adults than in young adults, who completed an identical experiment. Age differences also emerged in the coherence of arousal ratings with EDA and fingertip temperature measures, respectively, while participants watched the anger-eliciting and contentment-eliciting films; while negative correlations were found for older adults, positive correlations were found for young adults. These results indicate that emotional mind–body coherence somewhat differs quantitatively and qualitatively between older and young adults.
The natural process of mimicking the facial expressions of others is well established, as are the deficits in this reflexive behavior for individuals with clinical disorders such as depression. This study examines the extent of this deficit in non-clinical individuals with high transient negative mood, and whether it extends to both automatic and effortful emotion expression behavior. One hundred and thirty-six participants were shown happy, sad, and neutral faces, while electromyography (EMG) recorded facial muscle responses. Automatic (reflexive) mimicry was assessed while participants simply viewed facially expressive photographs, while effortful mimicry was monitored when individuals were told to intentionally copy the expressions in the photographs. Results indicated that high levels of negative mood were primarily associated with deficits in effortful mimicry of happy expressions, although some similar evidence was found in automatic mimicry of happy faces. Surprisingly, there were also ties between negative moods and inaccuracies in effortful mimicry of sad expressions (but not automatic mimicry). Inaccurate automatic and effortful mimicry were also tied with lower self-reported social support and greater loneliness. These results indicate that even in healthy individuals, transient and minor changes in negative mood are tied to deficiencies in facial mimicry at both the automatic and effortful level.
Objective: Despite alarming evidence on sexual violence against women, little is known about men’s emotional responses to rape and how these may be involved in sexual violence dynamics. Accordingly, our aim was to capture how rape scenarios are emotionally appraised. Methods: The current study evaluated men’s (N = 30) self-reported and psychophysiological emotional responses (facial EMG, electrodermal activity) to a rape scene, and contrasted it with their responses to stimuli depicting nonsexual violence and nonviolent male-female interactions. The associations between men’s emotional responses and their endorsement of rape myths, personality, and sexual traits were also examined. Results: Findings revealed that the rape scene resulted in higher negative affect, both subjectively and indexed by increased facial EMG (corrugator activity), than the other two stimuli. Additionally, personality traits of neuroticism, lower agreeableness, lower consciousness, psychopathic tendencies, as well as lower sexual inhibition proneness, were all associated with higher subjective sexual arousal toward rape. Conclusions: Findings add to the literature on the putative emotional processes underpinning the appraisal of sexual violence against women.
The notion that humans avoid effortful action is one of the oldest and most persistent in psychology. Influential theories of effort propose that effort valuations are made according to a cost-benefit trade-off: we tend to invest mental effort only when the benefits outweigh the costs. While these models provide a useful conceptual framework, the affective components of effort valuation remain poorly understood. Here, we examined whether primitive components of affective response—positive and negative valence, captured via facial electromyography (fEMG)—can be used to better understand valuations of cognitive effort. Using an effortful arithmetic task, we find that fEMG activity in the corrugator supercilii—thought to index negative valence—1) tracks the anticipation and exertion of cognitive effort and 2) is attenuated in the presence of high rewards. Together, these results suggest that activity in the corrugator reflects the integration of effort costs and rewards during effortful decision-making.
Background
Compared to healthy controls (HCs), adult Tic Disorder (TD) patients exhibit a lower interoceptive accuracy (IAcc) in heartbeat perception. Since the lower IAcc is not evident in children, the age at which tics develop, but in adults only (Pile et al., 2018, https://doi.org/10.1007/s10803-018-3608-8), lower IAcc may reflect a pathological mechanism relevant with regard to tics, premonitory urges (PUs) or the resulting impairment. Although tics are a motor phenomenon, up to date, IAcc has been assessed only with a heartbeat-counting task. This study aims at comparing cardiac and muscular IAcc using two different paradigms and investigates how IAcc is related to premonitory urges in youth.
Method
Interoceptive measures (heartbeat-counting task, muscle tension paradigm) of 28 youth with TD were compared to 23 control participants and related to self-rated premonitory urges and tic symptoms.
Results
TD patients did not differ from HCs in any IAcc measures. However, within TD patients, IAcc explained additional variance in PUs when controlling for tic severity. Muscular IAcc in TD patients is related to urges and tics, but the direction of this association is unclear. IAcc is lower in TD patients than in HCs, indicating imprecise sensory input which is more easily overcome by priors within the predictive coding framework.
Conclusions
Muscle tension feedback tasks could extend interoceptive trainings aimed at improving IAcc to improve accuracy of urge perception (more precise sensory input) to foster the ability to control tics via HRT. Longitudinal studies could provide further insights in causal relationships between IAcc, premonitory urges and tics.
Objectives
Surface electromyography (sEMG) is a standard method for psycho-physiological research to evaluate emotional expressions or in a clinical setting to analyze facial muscle function. High-resolution sEMG shows the best results to discriminate between different facial expressions. Nevertheless, the test-retest reliability of high-resolution facial sEMG is not analyzed in detail yet, as good reliability is a necessary prerequisite for its repeated clinical application.
Methods
Thirty-six healthy adult participants (53% female, 18–67 years) were included. Electromyograms were recorded from both sides of the face using an arrangement of electrodes oriented by the underlying topography of the facial muscles (Fridlund scheme) and simultaneously by a geometric and symmetrical arrangement on the face (Kuramoto scheme). In one session, participants performed three trials of a standard set of different facial expression tasks. On one day, two sessions were performed. The two sessions were repeated two weeks later. Intraclass correlation coefficient (ICC) and coefficient of variation statistics were used to analyze the intra-session, intra-day, and between-day reliability.
Results
Fridlund scheme, mean ICCs per electrode position: Intra-session: excellent (0.935–0.994), intra-day: moderate to good (0.674–0.881), between-day: poor to moderate (0.095–0.730). Mean ICC’s per facial expression: Intra-session: excellent (0.933–0.991), intra-day: good to moderate (0.674–0.903), between-day: poor to moderate (0.385–0.679). Kuramoto scheme, mean ICC’s per electrode position: Intra-session: excellent (0.957–0.970), intra-day: good (0.751–0.908), between-day: moderate (0.643–0.742). Mean ICC’s per facial expression: Intra-session: excellent (0.927–0.991), intra-day: good to excellent (0.762–0.973), between-day: poor to good (0.235–0.868). The intra-session reliability of both schemes were equal. Compared to the Fridlund scheme, the ICCs for intra-day and between-day reliability were always better for the Kuramoto scheme.
Conclusion
For repeated facial sEMG measurements of facial expressions, we recommend the Kuramoto scheme.
Background:
Cognitive bias theories propose that reducing threat hypervigilance in mental disorders can augment cognitive behavioral therapy (CBT) outcomes. However, no studies have tested whether adding attention bias modification (ABM) can effectively enhance CBT's effects on anxiety sensitivity (AS), electromyography (EMG), and skin conductance (SC) for panic disorder (PD). This pilot randomized controlled trial (RCT) thus aimed to evaluate the efficacy of CBT + ABM (vs. CBT plus attention training placebo; PBO) on those outcomes.
Method:
This study is a secondary analysis (Baker et al., 2020). Adults with PD were randomized to receive CBT + ABM (n = 11) or CBT + PBO (n = 12). Before each of the first five CBT sessions, CBT + ABM and CBT + PBO participants completed a 15-min ABM task or attention training PBO, respectively. AS and depression severity as well as SC and EMG during habituation to a loud-tone startle paradigm were assessed. Hierarchical Bayesian analyses were conducted.
Results:
During pre-post-treatment and pre-follow-up, CBM + ABM (vs. CBT + PBO) led to a notably greater reduction in ASI-Physical (between-group d = -1.26 to -1.25), ASI-Cognitive (d = -1.16 to -1.10), and depression severity (d = -1.23 to -0.99). However, no between-group difference was observed for ASI-Social, EMG, or SC indices.
Discussion:
Adding a brief computerized ABM intervention to CBT for PD protocols may enhance therapeutic change.
Present physiological techniques of attitude measurement tap attitude intensity but not attitude direction. An alternative physiological technique, based upon the phenomenon of semantic generalization of conditioned autonomic responses, was tested to determine whether it would provide a bidirectional indicator of attitude. 24 white undergraduates with favorable or unfavorable self-reported attitudes toward blacks were conditioned to statements having no racial content which they had previously evaluated as "bad." Subsequently, they were presented with statements with racial content; the latter were sentences which would be differentially evaluated as "good" or "bad" by persons with dissimilar racial attitudes. It was hypothesized that racial attitude would predict conditioned autonomic responses elicited by the generalization statements. Groups differing in racial attitude could be distinguished on the basis of their conditioned responses to the race-related generalization statements. (20 ref)
When subjects imagine happy, sad, and angry situations, different patterns of facial muscle activity are produced which can
be measured by electromyography. These subtle, typically covert, facial expression patterns differentiate depressed from nondepressed
subjects. Facial electromyography can provide a sensitive, objective index of normal and clinical mood states.
Physiological measures have traditionally been viewed in social psychology as useful only in assessing general arousal and therefore as incapable of distinguishing between positive and negative affective states. This view is challenged in the present report. Sixteen subjects in a pilot study were exposed briefly to slides and tones that were mildly to moderately evocative of positive and negative affect. Facial electromyographic (EMG) activity differentiated both the valence and intensity of the affective reaction. Moreover, independent judges were unable to determine from viewing videotapes of the subjects' facial displays whether a positive or negative stimulus had been presented or whether a mildly or moderately intense stimulus had been presented. In the full experiment, 28 subjects briefly viewed slides of scenes that were mildly to moderately evocative of positive and negative affect. Again, EMG activity over the brow (corrugator supercilia), eye (orbicularis oculi), and cheek (zygomatic major) muscle regions differentiated the pleasantness and intensity of individuals' affective reactions to the visual stimuli even though visual inspection of the videotapes again indicated that expressions of emotion were not apparent. These results suggest that gradients of EMG activity over the muscles of facial expression can provide objective and continuous probes of affective processes that are too subtle or fleeting to evoke expressions observable under normal conditions of social interaction.
Electromyographic (EMG) responses of self-reported high- and low-anxious females were recorded during a 15-min anticipation period followed by 5 min of 105-dB binaural white noise stimulation. A computer-controlled scanning electromyograph sampled integrated surface EMG activity from a total of eight muscle sites on the head, neck, and limbs. High-anxious subjects evinced higher mean EMG levels than low-anxious subjects both preceding and during the stimulus period. Microanalysis of the within-subjects data arrays involving P-factoring on principal components provided the first detailed diachronic observations of striate-muscle action in trait-anxious subjects. Little evidence was found for a general tension factor in either low-anxious or high-anxious subjects. Furthermore, no differences were observed in multiple-site covariance structures between the two groups; the EMG elevations in the high-anxious subjects consisted of largely uncorrelated response bursts. The data mitigate prevalent conceptions of increased tonic muscular contraction during arousal and anxiety. Anxiety, we believe, reflects activation more than immobilization or defense.
In the present investigation, the frontalis surface EMG was differentially recorded during static voluntary submaximal contractions. First, mean rectified EMG (MREMG) and EMG signal bandwidth were examined for two different bilateral EMG derivations (superior and inferior) with the electrodes placed in horizontal direction and two unilateral derivations (left and right) with the electrodes placed in vertical direction. MREMG was significantly different between the four derivations but absolute differences were small. Bandwidth also varied significantly with derivation. Second, the influence of inter-electrode distance and electrode size was examined for unilateral derivations. The influence of inter-electrode distance on MREMG was significant but the absolute effect was marginal. We suggest that a clear effect is to be expected only within the range of small distances (smaller than 10 mm). The significant effect disappeared when MREMG was expressed as proportion of the MREMG during maximal contraction. This normalization seems to allow better intra-individual or inter-individual comparisons of integrated EMG, especially when different recording methods are used. The influence of inter-electrode distance on bandwidth was not significant. Electrode size had no significant influence on MREMG and bandwidth. EMG power spectra indicated that integrated frontalis EMG can be validly measured only when using recording equipment with a frequency response of 5–500 Hz.
SYNOPSIS
In this study, resting EMG levels were measured in the frontalis and temporalis muscle in patients suffering from muscle contraction headache, migraine, or mixed muscle contraction-migraine headache. The EMG levels of these groups were never significantly higher than those of a control group of subjects without headaches. Significantly higher levels, however, were found in both muscles in the migraine and mixed headache groups if the resting EMG levels were expressed as a percentage of the EMG level during maximal contraction. There was a tendency for proportional EMG levels of both muscles in the muscle contraction headache group to be significantly elevated. Headache patients generally showed lower maximal EMG levels than control subjects. The significance of this finding is discussed in relation to the etiology of the headaches. It is concluded that proportional EMG levels are a better index of the state of contraction than absolute EMG levels and are preferable in investigations of headache.
Forty-three subjects were stimulated in the laboratory to "fear" and "anger," during which the following physiological reactions were recorded: (1) heart rate, (2) ballistocardiogram, (3) respiration rate, (4) face temperature, (5) hand temperature, (6) skin conductance, and (7) integrated muscle potential. The scores used were the maximum rise and maximum fall from the preceding resting level and the number of responses of a critical value per unit time. Of the 14 scores thus obtained, 7 showed significant discrimination between anger and fear. Diastolic blood pressure rises, heart rate falls, number of rises in skin conductance, and muscle potential increases, were greater for anger than for fear, whereas skin conductance increases, number of muscle potential increases, and respiration rate increases were greater for fear than for anger. Profile difference scores, computed from appropriate combinations of these differences, were found to be greater than zero in 42 of the 43 cases and to have a mean which deviated very significantly from zero, which rejects the null hypothesis that there is no difference in physiological reaction between anger and fear. The patterns obtained for anger and fear argue against the Arnold proposal that anger is a strong reaction of both the sympathetic and parasympathetic branches of the autonomic nervous systems, whereas fear is but a sympathetic reaction. Another finding was the very low correlations among the physiological reactions and the significantly higher intercorrelations for anger than for fear, which was interpreted as indicating greater physiological integration during anger. Between-subject variance was significantly greater than within-subject variance, which supports the findings of Lacey and Malmo that there is considerable specificity in physiological response patterns. The physiological response patterns of anger were suggested as being similar to those produced by injections of epinephrine and nor-epinephrine combined, and those of fear as being similar to injections of epinephrine. Copyright (C) 1953 by American Psychosomatic Society
ABSTRACTA multivariate pattern-classification system was developed for the study of facial electromy-ographic (EMG) patterning in 12 female subjects during affect-laden imagery and for posed facial expressions. A parameter-extraction procedure identified the dynamic EMG signal properties which accorded the maximal degree of self-reported emotion discrimination. Discriminant analyses on trialwise EMG vectors allowed assessment of specific EMG-site conformations typifying rated emotions of happiness, sadness, anger, and fear. The discriminability among emotion-specific EMG conformations was correlated with subjective ratings of affective-imagery vividness and duration. Evidence was obtained suggesting that the EMG patterns encoded complex, “blended” reported affective states during the imagery. Classification analyses produced point-predictions of reported emotional states in 10 of the 12 subjects, and provided the first computer pattern recognition of self-reported emotion from psychophysiological responses.
Four normal male subjects were exposed to 5 30-min alternate-day sessions of continuous frontalis EMG biofeedback training preceded by 15-min adaptation periods. A computer-controlled scanning electromyograph sampled integrated EMG activity from the frontalis and seven adjunctive muscle groups. Tensional profiles for all eight muscle groups were assembled every 1.84 sec, resulting in an 8 × 960 data array for each session. Statistical analyses revealed that although frontalis EMG levels decreased significantly in the training, those of adjunctive recording sites did not. Cross correlation analyses for session 1 frontalis and adjunctive site EMG levels showed typically negligible correlations at all temporal lags, although some neck sites showed moderate cross correlation with the frontalis in 2 subjects. Separate principal-component analyses for sessions 1 and 5 produced little evidence for a general muscle tension factor. Low coefficients of congruence between session 1 and session 5 truncated-component solutions demonstrated little replicability of tensional linkages from the first to the last session.
In light of the continuing popularity of frontalis EMG feedback for general relaxation purposes, a pertinent question is whether this procedure is superior to feedback from other muscles. This question was addressed by comparing a frontalis feedback group (n = 12) with a forearm feedback group (n = 10) in a one-session experiment. The experimental session included a 10-min rest period preceded by verbal relaxation instructions and demonstration of the respective feedback contingencies, and followed by a 30-min feedback period. EMG records were obtained from forehead, forearm, neck, masseter, sternomastoid, and lower leg. In the two target muscles, significant group differences developed during rest, but no additional significant effects were produced during feedback. Regarding the four untrained sites, EMG tended to decrease in the forehead group, but not significantly below the levels of the forearm group. Simultaneous EMG cross-correlations within 5-min intervals based on successive 1-sec averages showed significant covariation between muscles in the head and neck area; the source of this covariation was uncertain, however—electrical “crosstalk” and generalized muscular responding were two possibilities discussed.
In EMG biofeedback it has been suggested that covariation in tension levels between a trained and untrained muscle increases with continued training of the target muscle. Predictions of this sort are in contrast to the notion of response generalization which would predict decreased covariation between trained and untrained muscles with continued training. This study examined covariation between facial and forearm EMG levels during facial EMG biofeedback, and evaluated changes in such covariation which occurred with continued facial EMG training. Two groups of individuals were trained either to increase or to decrease facial muscle tension in 3 laboratory sessions during which simultaneous measures of facial and forearm EMG were obtained at 1-min intervals. Comparison of facial EMG measures for these groups with those for a third, noncontingent control group revealed bidirectional conditioned effects for each training session. Some covariation between forearm and facial EMG was apparent for all groups. However, examination of change in covariation across sessions revealed that covariation decreased for groups receiving facial muscle training, whereas covariation levels exhibited by the noncontingent feedback group remained stable. This finding was consistent with the concept of response generalization but not with the notion of muscle tension generalization as employed in EMG biofeedback.
Twenty-eight normal adults participated in an experimental test of two assumptions underlying the use of electromyographic (EMG) biofeedback as a general relaxation training technique: (1) that trained EMG reduction in one muscle generalizes to untrained muscles; and (2) that subjective feelings of relaxation are related to EMG reduction. An experimental group received 5 sessions, during the middle 3 of which EMG biofeedback training was offered on the frontalis muscle. Throughout all sessions, EMG recordings were also taken from the forearm and lower leg, and ratings of subjective relaxation feelings were obtained at regular intervals. A control group, matched with the experimental group on baseline frontalis EMG, received 5 similar sessions without feedback. Employing a maximum p of .05, the results revealed no evidence of generalization of EMG reduction from the frontalis to the untrained sites, nor any tendency for successful frontalis EMG reduction to result in increased feelings of relaxation beyond what was obtainable from relaxing without the benefit of training. The results were interpreted as suggesting that EMG biofeedback cannot yet be accepted as a viable general relaxation training technique.
The effects of fatigue and repetition of the task on the surface electromyographic signal were examined during 4 sessions using an isometric motor control task. The muscle chosen for this study was one of the main ankle dorsiflexors (m. tibialis anterior). The electromyographic output and a functional (force) output of this muscle were recorded during two conditions: a SHORT-F condition in which the effect of task repetition on the relationship between force and IEMG was studied, and a LONG-F condition in which the effect of fatigue was studied. The results indicated that repetition of the task resulted in a significant increase in the ratio between the electromyographic and functional output of the m. tibialis anterior, indicating an increase in efficiency across the 4 sessions. Fatigue on the other hand resulted in a significant decrease in the ratio between the electromyographic and functional output of the m. tibialis anterior, indicating a decrease in efficiency. Fatigue also resulted in a significant and rapid increase in the electromyographic activity. The implications of these results for the therapeutic use of the electromyographic signal were discussed.
Issues in the design and analysis of psychophysiological research are outlined. Then strategies for design and analysis are reviewed. Evoked response potential (ERP) data are discussed as an important example. The nature of the research and the measurement methodology place unusual demands on the experimenter. Controlling error rates, exploratory versus confirmatory research, and the problem of many variables are important issues. Strategies for design and analysis follow naturally from the principles presented. Useful design strategies include pilot studies, cross validation, and “leapfrog” strategies. Useful analysis strategies include restricted ANOVA/MANOVA and unrestricted ANOVA/MANOVA.
The extraction of mean amplitude from integrated electromyographic (IEMG) responses provides a valid but limited measure of muscle action potentials (MAPs). More comprehensive topographical analyses of IEMG responses based on frequency analyses are unsatisfactory since IEMG responses are aperiodic, and autoregressive procedures may be unsatisfactory since autocorrelations constitute an irreversible transformation of the original waveform, represent a substantial loss of information in contrast to the original waveform, and harbor little apparent relationship to MAPs. In a Theoretical Investigation, a mathematical procedure is developed to quantify topographical features of both the amplitude and temporal dimensions of the IEMG response. Procedures for extracting these parameters and the relationship between each and the recruitment of MAPs are illustrated. In a Validation Study, surface electromyograms are recorded from the preferred forearm under various conditions of mild isometric forearm contraction. Results support the viability, reproducibility, and validity of the topographical analysis.
Twenty-six subjects performed orthographic, grammatical, evaluative, and self-referent orienting tasks. During each trial, integrated facial and forearm EMG activity, HR, and T-wave amplitude were monitored; following each trial, response latency and either reported task difficulty (Replication 1) or cognitive effort (Replication 2) were assessed; and recall was assessed at the conclusion of the session. Recall was poorest when words were judged in terms of their orthographic appearance, moderate when words were judged in terms of their grammatical or evaluative features, and best when words were judged for their self-descriptiveness, even though response latency was longest and reported effort was greatest for the grammatical task. Results also revealed that somatovisceral responses varied across tasks, with clear differences emerging between semantic and nonsemantic processing and between evaluative and self-referent processing. Results suggest that cognitive effort, rather than encoding efficacy, influences task-evoked somatic responses.
Recent investigations of reflex modification in humans have employed several measurement techniques to record reflexive eyeblink responses. To facilitate comparisons across measurement techniques, three experiments evaluated the congruence between eyelid displacement and bioelectric measures of blink amplitude under lead stimulus conditions designed to facilitate, inhibit, or not alter blink amplitude. A potentiometric measure of eyelid displacement was recorded from the right eye of 53 undergraduates, while electrodes centered above and below the left eye detected the bioelectric changes that accompany blinking. In each experiment, lead stimuli altered blink amplitude in a similar manner regardless of measurement technique (i.e., no significant measure by condition interaction emerged). Furthermore, the direction and magnitude of blink amplitude change for the two measurement techniques correlated highly and significantly. These results support the implicit assumptions of researchers that the bioelectric and potentiometric measures provide equivalent information about blink amplitude in reflex modification situations and that reflex-modification findings can be generalized across measurement techniques.
Integrated electromyographic (IEMG) activity was recorded using surface mini-electrodes placed over the corrugator supercilii, zygomatic major, levator labii superioris, masseter, obicularis oris and superficial forearm flexors muscle regions while subjects imagined or performed simple physical or attitudinal tasks. In the physical tasks, subjects either imagined they lifted or actually lifted a 16 gram or 35 gram weight. In the attitudinal tasks, subjects adopted either an agreeable or disagreeable attitudinal set as they silently read neutral text or imagined reading an editorial. Each task was performed for 12 sec on five separate occasions, and tasks were ordered randomly across the experimental trials. Following each trial, subjects provided self-reports regarding the extent to which the task was stressful, arousing and vivid. Multivariate analyses of the topographical features of each IEMG response were performed to determine the effects of the tasks on changes in IEMG response waveforms, and univariate analyses were conducted to assess the features of the waveform that were altered by tasks. Results support the efficacy of electromyographic studies of covert affective processing given that subjects are generally quiescent, unobtrusively observed, unaware that somatic activity is being recorded and involved in the task. The implications of these data for the somatic representation of affect are discussed.
Eight normal subjects were trained with the aid of EMG feedback to successively increase and decrease the activity of the frontalis muscle on 5 consecutive days. Along with the activity of the frontalis, sternomastoid EMG was recorded from 4 subjects and EMG from both the semispinalis and splenius capitus was recorded from the other 4 subjects. Estimates of the degree of subjective tension or relaxation were obtained following Baseline, Increase Frontalis, and Decrease Frontalis periods on each treatment day. Frontalis EMG activity showed significant increases and decreases relative to baseline levels during appropriate periods. Sternomastoid EMG did not change significantly during either Increase Frontalis or Decrease Frontalis periods. Semispinalis/splenius EMG activity also did not change during Increase Frontalis periods, but increased significantly during Decrease Frontalis periods. Subjects’estimates of subjective tension increased above baseline during increases in frontalis EMG activity, but did not change significantly during decreases in frontalis EMG. These data support the findings of Alexander that changes in frontalis EMG neither generalize to other somatic muscles nor correlate with verbal reports of cognitive tension or relaxation.
Biomedical data, such as EEG, EMG and neural impulse sequences, are regarded as the stochastic phenomena of biological systems, and the statistical properties of such time series are often examined. Most of the statistical analysis processed in the frequency and the time domain are based on the assumption that the time series is weakly stationary and normally distributed. Therefore, as the basis of the statistical analysis of the biomedical data, it is necessary to know whether they satisfy the conditions of weak stationarity and normality. However, impulse response and evoked potential biomedical data, are not regarded as the stationary time series. Therefore, other analysis is required. In this paper, the authors present four programs, TEST1, TEST2, TEST3 and TEST4, to examine above conditions. Furthermore, in order to clarify the characteristic of each program, the time series were generated by the computer and examined by the test programs.
A circuit is described which provides a varying DC voltage proportional to the envelope of a raw electromyographic waveform. The design is inexpensive, employs readily available integrated circuitry, and includes selectable gain and integration time constants.
Reflex blinking is primarily controlled by fast fibers of the palpebral portion of the orbicularis oculi but it is difficult to record EMG from these fibers with standard surface electrodes. To solve this problem, a small, easily-prepared, silver/silver chloride electrode embedded in a dental cement casing was developed. Using this electrode, recordings could be obtained from the palpebral component which were of high quality and were many times larger than those recorded from the slow or mixed fibers in the orbital portion.
The integrated electromyogram (IEMG)--force relationships were studied in 26 physically active young men across the entire domain of forces in the elbow flexor group. All possible error factors (fatigue, muscle length, and co-contraction) were controlled to the greatest extent possible. The experimental conditions were more clearly defined than in previous experiments. The results confirm earlier observations of a linear relationship between IEMG and isometric force, under these experimental conditions and using a unipolar lead system. Highly significant correlations were found. Possible methodological error factors were studied. Bipolar recording produced a curvilinear, relationship which may explain some of the discrepancies of results reported in the literature.
The use of digital inverse filtering for modifying the properties of physiological signals is discussed. Particular reference is made to phase correction of signals distorted by recording with analog filters having nonlinear phase properties. Some practical considerations in implementing digital filtering and inverse filtering are presented, especially problems of time-domain and frequency-domain resolution, inverse filter definition, and the effects of digitization errors.
Achilles tendon (T) reflexes were evoked simultaneously in both legs during a fixed foreperiod of 1 sec. Volunteers were instructed to react as quickly as possible by one of four responses (in blocks): a plantar flexion of the left or right foot and a flexion of the left or right index finger. Prior to a foot response one leg was always involved in the response, prior to a finger response neither leg. Reflexes were evoked at 13 different points in time, from 100 msec prior to the warning signal (WS) to 100 msec after the response signal (RS). Amplitudes were expressed in percentages of control (intertrial interval) reflex amplitudes. In all conditions, amplitudes in both legs reached a peak 100 msec after the WS. After this non-selective increment, reflex amplitudes preceding a finger response decreased but remained larger than the baseline. Prior to a foot movement, amplitudes in uninvolved muscles remained larger than the baseline as well, whereas amplitudes in the involved muscle were no longer different from the baseline. This differential effect was independent of the response side. It was concluded that preparation for a response is characterized by a selective lack of activation in the reflex arc of the agonist, and a non-selective activation of the uninvolved spinal motor structures.
An analytic study was initiated to investigate whether the normalized surface myoelectric signal vs. normalized force relationship varies in different human muscles and whether it is dependent on training level and rate of force production. The data were obtained from experiments that involved the biceps, deltoid, and first dorsal interosseous of three pianists, four long-distance swimmers, three power lifters, and six normal subjects. The elite performers (among the world's best) were chosen because they exhibited varying degrees of fine motor control, endurance training, and power training in different muscles. Approximately 200 isometric linearly force-varying contractions peaking at 80% of the maximal voluntary contraction level were processed. The results indicated that the myoelectric signal-force relationship was primarily determined by the muscle under investigation and was generally independent of the subject group and the force rate. Whereas this relationship was quasilinear for the first dorsal interosseous, it was nonlinear for the biceps and deltoid. Several possible physiological causes of the observed behavior of the myoelectric signal-force relationship are discussed.
A partial replication of research by Balshan (1962) was undertaken in order to investigate the existence of a general tension factor operating during rest and during auditory stimulation. Thirty female subjects were each exposed to one 20-min session consisting of 15 min of quiet rest followed by 5 min of binaural white noise stimulation. A computer-controlled scanning electromyograph sampled integrated surface EMG activity from a total of eight muscle sites on the head, neck and limbs. Tensional profiles for all eight EMG sites were assembled every 1.84 sec, resulting in an 8×650 data array for each subject. Statistical analyses revealed overall EMG increments at stimulus onset. R-factor analyses on principal components for group data, as in Balshan (1962), revealed group general factors for both prestimulus and stimulus periods. However, P-factoring on principal components of the within-subject data arrays demonstrated that few subjects met minimal loading criteria for a general factor operating in individuals. Such within-subject EMG-site covariations as were observed were reduced considerably when startle responses at stimulus onset were excluded from the principal-component analyses. It is concluded that the group factors obtained in the present experiment and by Balshan (1962) were artifacts of two influences: the erroneous assumption of across-subject equivalence of EMG-site levels, and the summation of uncorrelated EMG activity which biased the group component solutions toward artifactual generality.
Nonspecific factors such as placebo or expectancy effects may materially influence therapeutic outcome in EMG relaxation training. Yet, controlling for the expectations of experimenters has received little attention even though Rosenthal's Experimenter Expectancy Effect is well-documented. This study examined the effects of experimenter expectancy on frontal EMG conditioning. During training, experimenters were given either no expectancy or led to believe that EMG conditioning would he either difficult (low expectancy) or easy (high expectancy) to achieve. Then, the three groups of experimenters collected data from subjects undergoing 20 min of either contingent or noncontingent reinforcement for frontal EMG decreases. Postexperimental credibility checks indicated that experimenters were unaware they were being studied but could identify their expectancy condition when informed of the three conditions. Differential EMG behavior was observed between groups conditioned by experimenters with no expectancies, with contingent subjects achieving significantly lower EMG levels than noncontingent subjects. Differences were not exhibited, however, between contingent and noncontingent subjects trained by experimenters with either low or high expectancies. These findings suggest that experimenters with prior expectations may covertly communicate to subjects response sets that interfere with acquisition of differential EMG behavior.
A low-noise preamplifier for electromyographic applications is presented. The design features modifiable gain and bandpass characteristics, driven input shielding for high common-mode rejection, and integral optical isolation for participant safety.
The paper recommends an acceptable methodology for recording electrodermal activity which reflects a consensus of experts in the field. These recommendations are presented with a minimum of technical discussion in order to maximize their usefulness to investigators who are not specialists in this area. For most purposes, skin conductance (SC) is to be preferred over skin potential (SP). It is recommended that SC be recorded from palmar sites with silver-silver chloride electrodes and an electrode paste consisting of a sodium chloride electrolyte in a neutral ointment cream medium. The area of contact with the skin should be controlled and time allowed for stabilization of the skin-electrode paste interface. Electrode bias potentials and polarization should be monitored during use. Signal conditioning is achieved by the application of a constant 0.5 volt across the electrodes and measurement of the resultant current flow by amplifying the voltage developed across a small resistor in series with the skin. The measurement of the amplitude - or even the detection - of small responses requires some form of tonic level control, permitting an adjustment of the tonic level. A circuit is provided for signal conditioning and tonic level control. SP can be recorded with the same electrodes and electrode paste, unless the results are to be related to the British work on SP level, in which case the original potassium chloride electrolyte in an agar medium should be used. SP recordings require that one of the electrodes be placed over an inactive reference site, preferably over the ulnar bone near the elbow. No external voltage is applied, but some form of tonic level control may be needed. Electrodes need to be checked for bias potentials but not polarization.
Publication quidelines are provided for the collection, quantification, and analysis of heart rate data. These guidelines are for the preparation of manuscripts describing research in which heart rate is a dependent measure. The primary aim of any data representation is, however, to accurately answer the question posed by the research. The guidelines should assist in this goal; but as implied previously, blind aplication of fixed guidelines cannot substitute for a clear concept of the relationship of data to the question asked of them.
Frontal EMG was concurrently measured using two different electrode placements for each of 12 subjects. One electrode placement was the standard placement of one electrode above each eyebrow (referred to as the horizontal placement). For the other placement, electrodes were positioned vertically above only the left eyebrow (referred to as the vertical placement). Comparisons between the measures of EMG using the two placements were assessed for three different levels of biofeedback-influenced EMG activity.
The horizontal and vertical EMG measures were found to be positively correlated both for the entire group and for individual subjects. Also, the two measures of EMG were positively correlated at three different levels of EMG, i.e., high, medium, and low. Comparisons of horizontal and vertical EMG indicated that horizontal EMG was consistently higher than vertical EMG at all levels of EMG. These findings suggest that placement of EMG electrodes is a very important variable in accurately measuring the magnitude of muscular electrical activity. However, if repeated measures of EMG are used to evaluate changes in muscle tension, and electrode placement is consistent across conditions, electrode placement is of only marginal importance.
Physiological tests support the thesis that prejudicial attitudes are attended by relatively strong emotion.