Simulated proximity enhances perceptual and physiological responses to emotional facial expressions

Physical proximity is important in social interactions. Here, we assessed whether simulated physical proximity modulates the perceived intensity of facial emotional expressions and their associated physiological signatures during observation or imitation of these expressions. Forty-four healthy volunteers rated intensities of dynamic angry or happy facial expressions, presented at two simulated locations, proximal (0.5 m) and distant (3 m) from the participants. We tested whether simulated physical proximity affected the spontaneous (in the observation task) and voluntary (in the imitation task) physiological responses (activity of the corrugator supercilii face muscle and pupil diameter) as well as subsequent ratings of emotional intensity. Angry expressions provoked relative activation of the corrugator supercilii muscle and pupil dilation, whereas happy expressions induced a decrease in corrugator supercilii muscle activity. In proximal condition, these responses were enhanced during both observation and imitation of the facial expressions, and were accompanied by an increase in subsequent affective ratings. In addition, individual variations in condition related EMG activation during imitation of angry expressions predicted increase in subsequent emotional ratings. In sum, our results reveal novel insights about the impact of physical proximity in the perception of emotional expressions, with early proximity-induced enhancements of physiological responses followed by an increased intensity rating of facial emotional expressions.

Creation and validation of the Picture-Set of Young Children’s Affective Facial Expressions (PSYCAFE)

The immediate detection and correct processing of affective facial expressions are one of the most important competences in social interaction and thus a main subject in emotion and affect research. Generally, studies in these research domains, use pictures of adults who display affective facial expressions as experimental stimuli. However, for studies investigating developmental psychology and attachment behaviour it is necessary to use age-matched stimuli, where it is children that display affective expressions. PSYCAFE represents a newly developed picture-set of children’s faces. It includes reference portraits of girls and boys aged 4 to 6 years averaged digitally from different individual pictures, that were categorized to six basic affects (fear, disgust, happiness, sadness, anger and surprise) plus a neutral facial expression by cluster analysis. This procedure led to deindividualized and affect prototypical portraits. Individual affect expressive portraits of adults from an already validated picture-set (KDEF) were used in a similar way to create affect prototypical images also of adults. The stimulus set has been validated on human observers and entail emotion recognition accuracy rates and scores for intensity, authenticity and likeability ratings of the specific affect displayed. Moreover, the stimuli have also been characterized by the iMotions Facial Expression Analysis Module, providing additional data on probability values representing the likelihood that the stimuli depict the expected affect. Finally, the validation data from human observers and iMotions are compared to data on facial mimicry of healthy adults in response to these portraits, measured by facial EMG (m. zygomaticus major and m. corrugator supercilii).

Brow and Masticatory Muscle Activity Senses Subjective Hedonic Experiences during Food Consumption

Sensing subjective hedonic or emotional experiences during eating using physiological activity is practically and theoretically important. A recent psychophysiological study has reported that facial electromyography (EMG) measured from the corrugator supercilii muscles was negatively associated with hedonic ratings, including liking, wanting, and valence, during the consumption of solid foods. However, the study protocol prevented participants from natural mastication (crushing of food between the teeth) during physiological data acquisition, which could hide associations between hedonic experiences and masticatory muscle activity during natural eating. We investigated this issue by assessing participants’ subjective ratings (liking, wanting, valence, and arousal) and recording physiological measures, including EMG of the corrugator supercilii, zygomatic major, masseter, and suprahyoid muscles while they consumed gel-type solid foods (water-based gellan gum jellies) of diverse flavors. Ratings of liking, wanting, and valence were negatively correlated with corrugator supercilii EMG and positively correlated with masseter and suprahyoid EMG. These findings imply that subjective hedonic experiences during food consumption can be sensed using EMG signals from the brow and masticatory muscles.

Heightened facial muscle reactivity in preadolescent girls with pathological anxiety

Anticipatory anxiety and heightened responses to uncertainty are central features of anxiety disorders (ADs). We examined facial emotional responding in a sample of preadolescent girls with a range of anxiety symptoms: no/low anxiety (controls) to subthreshold anxiety (subthreshold-AD) to DSM-5 diagnoses of separation, social, and/or generalized ADs. Using a threat anticipation paradigm, we assessed how variations in image valence (negative vs. neutral) and image anticipation (uncertain vs. certain timing) impacted activity of the corrugator supercilii, a forehead muscle implicated in the ‘frown’ response that modulates to emotional stimuli (negative>neutral). Average corrugator magnitude and corrugator time-course were compared between groups. Findings demonstrate greater corrugator activity during anticipation and viewing of negative stimuli, with overall increased corrugator reactivity in subthreshold-AD and AD girls. Time-course analyses revealed anxiety-related sustained corrugator activity during uncertain anticipation of negative images. Results extend the physiological characterization of childhood pathological anxiety, highlighting the impact of subthreshold-AD symptoms.

Analysis of Facial Muscle Depths to Guide Botulinum Toxin Therapy of the Periocular Region

Purpose: Botulinum toxin (BTX) injections are used in cosmetic surgery to efface facial wrinkles. Botulinum toxin relaxes the muscle by preventing the release of the neurotransmitter acetylcholine at the neuromuscular junction located at the posterior muscle surface causing local muscle paralysis. The purpose of this study is to provide anatomic knowledge of muscle belly depths of the frontalis, corrugator supercilii, procerus, and orbicularis oculi muscles in an attempt to improve the efficacy of BTX treatment of glabellar, forehead, and lateral eyelid rhytides. Methods: Six-millimeter punch biopsies were obtained from 7 fresh cadavers. Biopsies were taken from the corrugator supercilii, frontalis, procerus, and orbicularis oculi muscles at the sites of routine BTX injection. Specimens were fixed in formalin, and representative H&E-stained sections were used to measure muscle surface depths by light microscopy equipped with digital camera that includes a digital micrometer. One-way analysis of variance test analyses were used to identify statistical differences between measured muscle depths. Results: The measured anterior muscle depth of the corrugator supercilii, frontalis, procerus, and orbicularis oculi was found to be 4.2 ± 0.6, 3.9 ± 0.6, 2.9 ± 0.4, and 2.3 ± 0.7 mm, respectively. The anterior muscle surface of the corrugator supercilii and frontalis was found to be deeper than that of the procerus and orbicularis oculi ( P < .001). The posterior surface depth of the corrugator supercilii, frontalis, procerus, and orbicularis oculi was found to be 6.6 ± 0.8, 5.1 ± 0.7, 4.9 ± 0.7, and 3.8 ± 1.0 mm, respectively. The posterior surface depth of the corrugator supercilii was found to be significantly deeper than that of the frontalis, procerus, and orbicularis oculi ( P < .001); the posterior surface depth of the frontalis and procerus was deeper than that of the orbicularis oculi ( P < .001). The muscle belly width of the corrugator supercilii, frontalis, procerus, and orbicularis oculi measured 2.5 ± 0.9, 1.1 ± 0.4, 2.0 ± 0.6, and 1.5 ± 0.5 mm, respectively. The corrugator supercilii was found to be thicker than the frontalis and orbicularis oculi, while the procerus was found to be thicker than the frontalis ( P < .001). Conclusion: The findings above demonstrate statistical differences in the posterior muscle surface depth of the corrugator supercilii, frontalis, procerus, and orbicularis oculi which can be used clinically to improve BTX injection efficacy when used to efface facial rhytides.

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

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

Reliving emotional memories: Episodic recollection elicits affective psychophysiological responses

Episodic recollection allows people to vividly re-experience past events. The remembered information can then inform and guide behavior in the present, especially in the case of emotional events. One way to fulfill this adaptive memory function might be through psychophysiological responses that signal desirable and undesirable outcomes and thereby motivate behavior. However, it remains unknown whether the recollection of past emotional experiences can indeed re-elicit corresponding affective psychophysiological responses. We addressed this question in two experiments (N1 = 48, N2 = 41). Young adults watched positive, negative, and neutral movie clips. One day later, they were instructed to remember these episodes. To index the psychophysiological expression of positive and negative affect, we measured smiling (zygomaticus major) and frowning (corrugator supercilii) responses, respectively. Results revealed that participants smiled more when remembering positive compared to neutral and negative memories. Moreover, they frowned more when remembering negative compared to positive but not neutral memories. Interestingly, the intensity of smiling or frowning during remembering was not related to the intensity during the original experience. Our results suggest that affective psychophysiological responses might play a crucial role in the adaptive function of episodic memories. Therefore, future studies on emotional episodic memory could benefit from incorporating psychophysiological indices.

Microsurgical decompression of the supraorbital nerve in the treatment of chronic neuropathic pain in the frontal-temporal area

Chronic headache is common. One of the causes of frontal-temporal pain may be compression of sensory nerves from the trigeminal nerve system, for example, the supraorbital nerve. Our study involved 12 women with symptoms of supraorbital nerve neuralgia resistant to drug correction. He underwent microsurgical decompression of the supraorbital nerve. The results of the operation were assessed by the change in the level of neuropathic pain using the PainDetect questionnaire and the degree of psychosocial maladjustment of the patient according to the MIDAS questionnaire, before and after the operation. The data obtained indicate a significant decrease in the level of neuropathic pain in patients 1 month after surgery and a significant minimization of the effect of headache on the quality of life in patients 3 months after surgery. Two out of 12 women did not notice any improvement, which required repeated delayed revision and extended proximal decompression of the supraorbital nerve with dissection of m. corrugator supercilii fibers. After the myotomy, pain regression was achieved and the patients noted that they were satisfied with the result.

Intolerance of uncertainty and physiological responses during instructed uncertain threat: a multi-lab investigation

Individuals with high self-reported Intolerance of uncertainty (IU) tend to interpret uncertainty negatively. Recent research has been inconclusive on evidence of an association between IU and physiological responses during instructed uncertain threat. To address this gap, we conducted secondary analyses of IU and physiology data recorded during instructed uncertain threat tasks from two lab sites (Wisconsin-Madison; n = 128; Yale, n = 103). Higher IU was associated with: (1) greater corrugator supercilii activity to predictable and unpredictable threat of shock, compared to the safety from shock, and (2) poorer discriminatory skin conductance response between the unpredictable threat of shock, relative to the safety from shock. No IU-related effects were observed for the orbicularis oculi. These findings suggest that IU-related biases may be captured differently depending on the physiological measure during instructed uncertain threat. Implications of these findings for neurobiological models of uncertainty and anticipation in anxiety are discussed.

Alexithymia and Facial Mimicry in Response to Infant and Adult Affect-Expressive Faces

Facial mimicry is the automatic tendency to imitate facial expressions of emotions. Alexithymia is associated with a reduced facial mimicry ability to affect expressions of adults. There is evidence that the baby schema may influence this process. In this study it was tested experimentally whether facial mimicry of the alexithymic group (AG) is different from the control group (CG) in response to dynamic facial affect expressions of children and adults. A multi-method approach (20-point Toronto Alexithymia Scale and Toronto Structured Interview for Alexithymia) was used for assessing levels of alexithymia. From 3503 initial data sets, two groups of 38 high and low alexithymic individuals without relevant mental or physical diseases were matched regarding age, gender, and education. Facial mimicry was induced by presentation of naturalistic affect-expressive video sequences (fear, sadness, disgust, anger, and joy) taken from validated sets of faces from adults (Averaged Karolinska Directed Emotional Faces) and children (Picture-Set of Young Children’s Affective Facial Expressions). The videos started with a neutral face and reached maximum affect expression within 2 s. The responses of the groups were measured by facial electromyographic activity (fEMG) of corrugator supercilii and zygomaticus major muscles. Differences in fEMG response (4000 ms) were tested in a variance analytical model. There was one significant main effect for the factor emotion and four interaction effects for the factors group × age, muscle × age, muscle × emotion, and for the triple interaction muscle × age × emotion. The participants of AG showed a decreased fEMG activity in response to the presented faces of adults compared to the CG but not for the faces of children. The affect-expressive faces of children induced enhanced zygomatic and reduced corrugator muscle activity in both groups. Despite existing deficits in the facial mimicry of alexithymic persons, affect-expressive faces of children seem to trigger a stronger positive emotional involvement even in the AG.