Facial feedback manipulation influences the automatic detection of unexpected emotional body expressions

Unexpected or changing facial expressions are known to be able to engage more automatic processing than frequently occurring facial expressions, thereby inducing a neural differential wave response known as expression mismatch negativity (EMMN). Recent studies have shown that EMMN can be modulated by the observer's facial feedback (i.e., feedback from their own facial movements). A similar EMMN activity has been discovered for body expressions, but thus far only a few emotion types have been investigated. It is unknown whether the EMMNs evoked by body expressions can be influenced by facial feedback. To explore this question, we recorded EEG activity of 29 participants in the reverse oddball paradigm. Here two unexamined categories of body expressions were presented, happy and sad, placed in two paired stimulus sequences: in one the happy body was presented with a probability of 80% (standards) while the sad body was presented with a probability of 20% (deviants), and in the other the probabilities were reversed. The facial feedback was manipulated by different pen holding conditions (i.e., participants holding the pen with the teeth, lips, or nondominant hand). The nonparametric cluster permutation test revealed significant happy and sad body-related EMMN (bEMMN) activities. The happy-bEMMN were more negative than sad-bEMMN within the range of 100-150 ms. Additionally, the bEMMN amplitude of both emotions is modulated by the facial feedback conditions. These results expand the range of emotional types applicable to bEMMN and provide evidence for the validity of the facial feedback hypothesis across emotional carriers.

Inability to move one's face dampens facial expression perception

Humans rely heavily on facial expressions for social communication to convey their thoughts and emotions and to understand them in others. One prominent but controversial view is that humans learn to recognize the significance of facial expressions by mimicking the expressions of others. This view predicts that an inability to make facial expressions (e.g., facial paralysis) would result in reduced perceptual sensitivity to others' facial expressions. To test this hypothesis, we developed a diverse battery of sensitive emotion recognition tasks to characterize expression perception in individuals with Moebius Syndrome (MBS), a congenital neurological disorder that causes facial palsy. Using computer-based detection tasks we systematically assessed expression perception thresholds for static and dynamic face and body expressions. We found that while MBS individuals were able to perform challenging perceptual control tasks and body expression tasks, they were less efficient at extracting emotion from facial expressions, compared to matched controls. Exploratory analyses of fMRI data from a small group of MBS participants suggested potentially reduced engagement of the amygdala in MBS participants during expression processing relative to matched controls. Collectively, these results suggest a role for facial mimicry and consequent facial feedback and motor experience in the perception of others' facial expressions.

Application of facial neuromuscular electrical stimulation (fNMES) in psychophysiological research: Practical recommendations based on a systematic review of the literature

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.

An Audience Facilitates Facial Feedback: A Social-Context Hypothesis Reconciling Original Study and Nonreplication

Nonreplications of previously undisputed phenomena tend to leave a theoretical vacuum. This theoretical perspective seeks to fill the gap left by the failure to replicate unobtrusive facial feedback. In the emblematic original study, participants who held a pen between the teeth (i.e., requiring activity of the zygomaticus major muscle) rated cartoons more positively than participants who held the pen between the lips. We argue that the same social mechanisms (e.g., the presence of an audience) modulate facial feedback to emotion as are involved in the feed-forward shaping of facial actions by emotions. Differing social contexts could thus help explain the contrast between original findings and failures to obtain unobtrusive facial feedback. An exploratory analysis that included results only from (unobtrusive) facial-feedback studies without explicit reference to emotion in the facial manipulation provided preliminary support for this hypothesis. Studies with a social context (e.g., due to experimenter presence) showed a medium-sized aggregate facial-feedback effect, whereas studies without a social context (e.g., when facial actions were only filmed), revealed a small effect. Video awareness strengthened facial feedback considerably within an engaging social context, but seemed to reduce it without a social context. We provisionally conclude that a (pro-)social interpretation of facial actions facilitates feedback to (primarily positive) emotion, and suggest further research explicitly manipulating this context.

Influence of advisees' facial feedback on subsequent advice-giving by advisors: Evidence from the behavioral and neurophysiological approach

Previous work has demonstrated the interpersonal implications of advisees' decisions (acceptance or rejection) on advisors' advice-giving behavior in subsequent exchanges. Here, using an ERP technique, we investigated how advisees' facial feedback (smiling, neutral, or frowning) accompanying their decisions (acceptance or rejection) influenced advisors' feedback evaluation from advisees and their advice-giving in subsequent exchanges. Behaviorally, regardless of whether the advice was accepted or rejected, advisors who received smiling-expression feedback would show higher willingness rates in subsequent advice-giving decisions, while advisors who received frowning-expression feedback would show lower willingness rates. On the neural level, in the feedback evaluation stage, the FRN and P3 responses were not sensitive to facial feedback. In contrast, frowning-expression feedback elicited a larger LPC amplitude than neutral- and smiling-expression feedback, regardless of whether the advice was accepted or rejected. In the advice decision stage, advisors who received neutral-expression feedback showed a larger N2 in making decisions than advisors who received frowning-expression feedback only after the advice was rejected. Additionally, Advisors who received smiling- and neutral-expression feedback showed a larger P3 in making decisions than advisors who received frowning-expression feedback only after the advice was accepted. In sum, the current findings extended previous research findings by showing that the effect of advisees' facial expressions on the advisors' advice-giving existed in multiple stages, including both the feedback evaluation stage and the advice decision stage.

How the Experience of Emotion is Modulated by Facial Feedback

The facial feedback hypothesis states that facial actions modulate subjective experiences of emotion. Using the voluntary facial action technique, in which the participants react with instruction induced smiles and frowns when exposed to positive and negative emotional pictures and then rate the pleasantness of these stimuli, four questions were addressed in the present study. The results in Experiment 1 demonstrated a feedback effect because participants experienced the stimuli as more pleasant during smiling as compared to when frowning. However, this effect was present only during the critical actions of smiling and frowning, with no remaining effects after 5 min or after 1 day. In Experiment 2, feedback effects were found only when the facial action (smile/frown) was incongruent with the presented emotion (positive/negative), demonstrating attenuating but not enhancing modulation. Finally, no difference in the intensity of produced feedback effect was found between smiling and frowning, and no difference in feedback effect was found between positive and negative emotions. In conclusion, facial feedback appears to occur mainly during actual facial actions, and primarily attenuate ongoing emotional states.

Instructions to mimic improve facial emotion recognition in people with sub-clinical autism traits

People tend to mimic the facial expression of others. It has been suggested that this helps provide social glue between affiliated people but it could also aid recognition of emotions through embodied cognition. The degree of facial mimicry, however, varies between individuals and is limited in people with autism spectrum conditions (ASC). The present study sought to investigate the effect of promoting facial mimicry during a facial-emotion-recognition test. In two experiments, participants without an ASC diagnosis had their autism quotient (AQ) measured. Following a baseline test, they did an emotion-recognition test again but half of the participants were asked to mimic the target face they saw prior to making their responses. Mimicry improved emotion recognition, and further analysis revealed that the largest improvement was for participants who had higher scores on the autism traits. In fact, recognition performance was best overall for people who had high AQ scores but also received the instruction to mimic. Implications for people with ASC are explored.

Emotional proprioception: Treatment of depression with afferent facial feedback

We develop the concept of emotional proprioception, whereby the muscles of facial expression play a central role in encoding and transmitting information to the brain's emotional circuitry, and describe its underlying neuroanatomy. We explore the role of facial expression in both reflecting and influencing depressed mood. The circuitry involved in this latter effect is a logical target for treatment with botulinum toxin, and we review the evidence in support of this strategy. Clinical trial data suggest that botulinum toxin is effective in treating depression. We discuss the clinical and theoretical implications of these data. This novel treatment approach is just one example of the potential importance of the cranial nerves in the treatment of depression.

Facial Feedback and Social Input: Effects on Laughter and Enjoyment in Children with Autism Spectrum Disorders

Both social input and facial feedback appear to be processed differently by individuals with autism spectrum disorder (ASD). We tested the effects of both of these types of input on laughter in children with ASD. Sensitivity to facial feedback was tested in 43 children with ASD, aged 8-14 years, and 43 typically developing children matched for mental age (6-14), in order to examine whether children with ASD use bodily feedback as an implicit source of information. Specifically, children were asked to view cartoons as they normally would (control condition), and while holding a pencil in their mouth forcing their smiling muscles into activation (feedback condition) while rating their enjoyment of the cartoons. The authors also explored the effects of social input in children with ASD by investigating whether the presence of a caregiver or friend (companion condition), or the presence of a laugh track superimposed upon the cartoon (laugh track condition) increased the children's self-rated enjoyment of cartoons or the amount of positive affect they displayed. Results showed that the group with ASD was less affected by all three experimental conditions, but also that group differences seemed to have been driven by one specific symptom of ASD: restricted range of affect. The strong relationship between restricted affect and insensitivity to facial feedback found in this study sheds light on the implications of restricted affect for social development in ASD.

A differing bidirectional impact on the recognition accuracy of facial expression

This study explored a bidirectional impact on the recognition accuracy of various facial expressions deriving from both the observer and sender in a sample of Chinese participants. A facial manipulation task was used to examine the ability of an observer's facial feedback to modulate the recognition of various facial expressions. Furthermore, the effect of a sender's facial expression with an open or closed mouth on recognition accuracy was investigated. The results showed that only recognition accuracy of a sad facial expression was influenced simultaneously by bidirectional sources from a sender and observer. Moreover, the impact of the unidirectional cue of a sender's facial feature (i.e., mouth openness) on happy and neutral faces was found to influence the recognition accuracy of these faces, but not the observer's bodily state. These findings indicate that the bidirectional impact derived from an observer and sender on facial expression recognition accuracy differs for emotional and neutral expressions.

Sniff and mimic - Intranasal oxytocin increases facial mimicry in a sample of men

The neuropeptide oxytocin (OT) has many potential social benefits. For example, intranasal administration of OT appears to trigger caregiving behavior and to improve the recognition of emotional facial expressions. But the mechanism for these effects is not yet clear. Recent findings relating OT to action imitation and to the visual processing of the eye region of faces point to mimicry as a mechanism through which OT improves processing of emotional expression. To test the hypothesis that increased levels of OT in the brain enhance facial mimicry, 60 healthy male participants were administered, in a double-blind between-subjects design, 24 international units (IUs) of OT or placebo (PLA) through nasal spray. Facial mimicry and emotion judgments were recorded in response to movie clips depicting changing facial expressions. As expected, facial mimicry was increased in the OT group, but effects were strongest for angry infant faces. These findings provide further evidence for the importance of OT in social cognitive skills, and suggest that facial mimicry mediates the effects of OT on improved emotion recognition.