Emotional primes modulate the responses to others’ pain: an ERP study

Can guilt enhance sensitivity to other's suffering? An EEG investigation into moral emotions and pain empathy

As a unique form of empathy, pain empathy often has a close relationship with society and morality. Research has revealed that moral emotions can influence pain empathy. The underlying physiological mechanism still needs to be further examined to understand how moral emotions affect pain empathy. This study employs EEG and Machine Learning techniques, using a painful image induction paradigm to explore the impact of moral emotion (guilt)-on pain empathy and its neural mechanisms. Participants without pain sensation were instructed to observe and evaluate pictures of an anonymous hand in painful or non-painful pictures under feelings of guilt or neutral emotion. Results found slower reaction times and higher pain ratings for painful pictures. Furthermore, guilt led to higher pain ratings. Under conditions of painful pictures, guilt-induced greater P3(350-450ms) amplitudes and higher α oscillations and enhanced the functional connectivity between the prefrontal cortex, the central frontal region, and the parieto-occipital lobe. K-nearest neighbor can effectively classify high and low-pain empathy under guilt emotion. The result showed that guilt promotes the brain's processing of painful picture, causing individuals to pay high attention and engage in deep cognitive processing. This study provides insights into enhancing empathy and fostering interpersonal relationships.

The Charactertistics and neural mechanisms of trait and state empathy in deaf individuals

Empathy deficiencies are prevalent among deaf individuals. It has yet to be determined whether they exhibit deficiencies in both trait empathy and state empathy, along with the effect of top-down attention. Here, the current study employed the IRI-C scale and physiological pain empathy tasks (A-P task and A-N task) to explore the temporal dynamics of neural activities when deaf individuals were processing second-hand painful/non-painful stimuli. For trait empathy, we found that deaf individuals have deficiencies in both emotional and cognitive empathy compared to their hearing counterparts. For state empathy, we found that deaf individuals showed stronger automatic emotional empathy responses and paid more cognitive evaluation resources. Moreover, the differential processing of empathy between deaf individuals and hearing individuals towards others' pain could be regulated by top-down attention, which occurs both in the early and late processing stages of pain empathy.

Individuals' Food Preferences can be Influenced by the Music Styles: An ERP Study

Studies have shown that a cross-modal association between listening to music and eating. This study aims to explore the influence of music style on individuals' food preferences and provide evidence for understanding multi-sensory research. Twenty-seven participants participated in the experiment which consisted of two parts. First, participants completed basic demographic information, followed by a food choice task after exposure to four different music styles: classical, jazz, rap, and rock, with ERP data recorded simultaneously. The behavioral results showed that participants selected more high-calorie foods after exposure to jazz and rock music compared to low-calorie foods. Additionally, during jazz and rock music, participants selected more high-calorie foods, while they favored low-calorie foods during classical music. The ERP results showed that the N1 amplitudes were smallest during the food choice task following the classical music and greatest during the food choice task following the rock music, while the N450 amplitudes were smallest during the food choice task following the jazz music. P2 amplitudes were smallest during the food choice task following the rock music and greatest during the food choice task following the classical music, and P3 amplitudes during the food choice task following jazz music were the greatest. The aforementioned ERP differences were observed irrespective of food choices. However, we did not find a significant interaction between foods (high and low-calorie) and music. Pearson correlation analysis revealed a positive relationship between body satisfaction and P3 amplitudes for classical, jazz, and rock music, with BMI negatively correlated with body satisfaction. This study provides innovative practical perspectives for healthy eating.

Group empathy for pain is stronger than individual empathy for pain in the auditory modality

Humans live in collective groups and are highly sensitive to perceived emotions of a group, including the pain of a group. However, previous research on empathy for pain mainly focused on the suffering of a single individual ("individual empathy for pain"), with limited understanding of empathy for pain to a group ("group empathy for pain"). Thus, the present study aimed to investigate the cognitive neural mechanisms of group empathy for pain in the auditory modality. The study produced group painful voices to simulate the painful voices made by a group, and recruited 34 participants to explore differences between their responses to group painful voices and individual painful voices using the event-related potential (ERP) techniques. The results revealed that group painful voices were rated with higher pain intensity, more negative affective valence, and larger P2 amplitudes than individual painful voices. Furthermore, trait affective empathy scores of the participants were positively correlated with their P2 amplitudes of group painful voices. The results suggested that the group empathy for pain may facilitate affective empathetic processing in auditory modality.

Emotional contagion and cognitive empathy regulate the effect of depressive symptoms on empathy-related brain functional connectivity in patients with chronic back pain

BACKGROUND

Chronic pain and depression share common neural mechanisms, but their impacts on empathy are different. It is unclear how comorbid depressive symptoms affect empathy-related brain function in patients with chronic pain.

METHODS

A total of 29 healthy participants and 107 patients with chronic back pain (CBP) were included in this study. All subjects underwent a functional MRI scan with concurrent empathic stimulation. Multiple linear regression, moderation analysis, and mediation analysis were used to explore the impacts of chronic pain and comorbid depression on empathy.

RESULTS

The interaction between the pain intensity and the depressive symptoms affected the functional connectivity (FC) of the insula-middle frontal gyrus (MFG), and the severity of the self-rating depression scale (SDS) scores moderated the effect of the pain on the left insula-left MFG FC. Within the CBP group, the emotional contagion (EC) scores served as a mediator in the association between the SDS scores and the FC of the left middle cingulate cortex (MCC)-inferior temporal gyrus (ITG), and the level of cognitive empathy (CE) moderated the effect of the SDS scores on the left MCC-ITG FC.

LIMITATIONS

There is a lack of research on the effects of depressive symptoms on empathy in individuals with different types of chronic pain.

CONCLUSION

Depressive symptoms were strongly associated with the emotional contagion in patients with chronic back pain. Furthermore, the emotional contagion and the cognitive empathy regulated the effect of the comorbid depressive symptoms on the MCC-ITG connectivity in patients with chronic back pain.

Vicarious facilitation of facial responses to pain: Does the others' expression need to be painful?

INTRODUCTION

Prior exposure to others' facial expressions of pain can lead to a facilitation of pain responses, including its corresponding response channel, namely facial responses to pain. It has been questioned, however, whether this vicarious pain facilitation occurs only when observing others' pain or whether the observation of other negative expressions can trigger similar facilitation of facial responses to pain. The study aimed to test this, by comparing the impact of viewing others' facial expressions of pain versus another negative expression (sadness) and two control expressions (neutral, happiness) on facial responses to pain.

METHOD

Participants (N = 56; 31 females), watched short video clips of computer-generated facial expressions (pain, sadness, neutral & happiness) before they received painful and non-painful heat stimuli. Facial responses were analysed using the Facial Action Coding System. In addition, subjective and autonomic responses were assessed.

RESULTS

The prior exposure to others' expressions of pain and sadness versus neutral did not lead to significantly increased facial responses to pain. Likewise, subjective and autonomic pain responses were not facilitated. However, viewing others' expressions of happiness, consistently reduced facial as well as subjective and autonomic responses to pain compared to others' negative or neutral expressions. This dampening effect was not observed for non-painful heat.

DISCUSSION

Facial and other pain responses were most strongly affected by prior exposure to others' facial expressions of happiness, which led to a pain-dampening effect. In contrast, the evidence for vicarious facilitation of pain was rather weak in the present study, with no evidence of pain-specificity.

SIGNIFICANCE STATEMENT

Facial responses to pain - along with subjective and autonomic responses - are reduced when observing others' expressions of happiness, demonstrating pain modulation by positive affective social signals, which may also transfer to clinical contexts.

Do we empathize humanoid robots and humans in the same way? Behavioral and multimodal brain imaging investigations

Humanoid robots have been designed to look more and more like humans to meet social demands. How do people empathize humanoid robots who look the same as but are essentially different from humans? We addressed this issue by examining subjective feelings, electrophysiological activities, and functional magnetic resonance imaging signals during perception of pain and neutral expressions of faces that were recognized as patients or humanoid robots. We found that healthy adults reported deceased feelings of understanding and sharing of humanoid robots' compared to patients' pain. Moreover, humanoid robot (vs. patient) identities reduced long-latency electrophysiological responses and blood oxygenation level-dependent signals in the left temporoparietal junction in response to pain (vs. neutral) expressions. Furthermore, we showed evidence that humanoid robot identities inhibited a causal input from the right ventral lateral prefrontal cortex to the left temporoparietal junction, contrasting the opposite effect produced by patient identities. These results suggest a neural model of modulations of empathy by humanoid robot identity through interactions between the cognitive and affective empathy networks, which provides a neurocognitive basis for understanding human-robot interactions.

The Empathy for Pain Stimuli System (EPSS): Development and preliminary validation

We present the Empathy for Pain Stimuli System (EPSS): a large-scale database of stimuli for studying people's empathy for pain. The EPSS comprises five sub-databases. First, the Empathy for Limb Pain Picture Database (EPSS-Limb) provides 68 painful and 68 non-painful limb pictures, exhibiting people's limbs in painful and non-painful situations, respectively. Second, the Empathy for Face Pain Picture Database (EPSS-Face) provides 80 painful and 80 non-painful pictures of people's faces being penetrated by a syringe or touched by a Q-tip. Third, the Empathy for Voice Pain Database (EPSS-Voice) provides 30 painful and 30 non-painful voices exhibiting either short vocal cries of pain or neutral interjections. Fourth, the Empathy for Action Pain Video Database (EPSS-Action_Video) provides 239 painful and 239 non-painful videos of whole-body actions. Finally, the Empathy for Action Pain Picture Database (EPSS-Action_Picture) provides 239 painful and 239 non-painful pictures of whole-body actions. To validate the stimuli in the EPSS, participants evaluated the stimuli using four different scales, rating pain intensity, affective valence, arousal, and dominance. The EPSS is available to download for free at https://osf.io/muyah/?view_only=33ecf6c574cc4e2bbbaee775b299c6c1 .

Altered neurophysiological responses during empathy for pain in insomnia: evidence from an EEG study in non-clinical samples

BACKGROUND

This study aims to investigate the behavioral and neurophysiological changes accompanying the empathy for pain among individuals with insomnia in nonclinical samples, which has been scarcely explored in the existing literature despite the deleterious effects of sleep disturbance on social behavior, and interactions had been well-documented.

METHODS

Twenty-one individuals with insomnia in nonclinical samples and 20 healthy individuals as normal controls participated in the study. Electroencephalograph (EEG) was continuously recorded, while the participants underwent an empathy for pain task.

RESULTS

Subjective ratings of pain for painful and non-painful images revealed no statistically significant differences between the insomnia and control groups. The painful images induced a smaller P2 compared to non-painful images in the insomnia group, whereas no such difference was revealed for the controls. Moreover, a higher power density of the alpha and theta2 bands in the posterior brain regions was found in the insomnia group compared to the control group.

CONCLUSION

These findings suggest that individuals with insomnia exhibit altered neurophysiological responses to pain stimuli and a lower capacity to share empathy for pain. These alterations may be associated with changes in attentional mechanisms.

"Listen to your heart": A novel interoceptive strategy for real-time fMRI neurofeedback training of anterior insula activity

Real-time fMRI (rt-fMRI) neurofeedback (NF) training is a novel non-invasive technique for volitional brain modulation. Given the important role of the anterior insula (AI) in human cognitive and affective processes, it has become one of the most investigated regions in rt-fMRI studies. Most rt-fMRI insula studies employed emotional recall/imagery as the regulation strategy, which may be less effective for psychiatric disorders characterized by altered emotional processing. The present study thus aimed to examine the feasibility of a novel interoceptive strategy based on heartbeat detection in rt-fMRI guided AI regulation and its associated behavioral changes using a randomized double-blind, sham feedback-controlled between-subject design. 66 participants were recruited and randomly assigned to receive either NF from the left AI (LAI) or sham feedback from a control region while using the interoceptive strategy. N = 57 participants were included in the final data analyses. Empathic and interoceptive pre-post training changes were collected as behavioral measures of NF training effects. Results showed that participants in the NF group exhibited stronger LAI activity than the control group with LAI activity being positively correlated with interoceptive accuracy following NF training, although there were no significant increases of LAI activity over training sessions. Importantly, ability of LAI regulation could be maintained in a transfer session without feedback. Successful LAI regulation was associated with strengthened functional connectivity of the LAI with cognitive control, memory and learning, and salience/interoceptive networks. The present study demonstrated for the first time the efficacy of a novel regulation strategy based on interoceptive processing in up-regulating LAI activity. Our findings also provide proof of concept for the translational potential of this strategy in rt-fMRI AI regulation of psychiatric disorders characterized by altered emotional processing.

Desensitized gamers? Violent video game exposure and empathy for pain in adolescents - an ERP study

This Event-Related Potential (ERP) study aimed to test how habitual and short-term violent video game exposure (VVGE) may affect empathy for pain responses in adolescents. In a within-subjects design, boys (N = 56; aged 12-16 years) performed a pain judgment task before and immediately after playing a violent video game. In this task, participants judged whether photos of hands depicted on their screen were in a painful situation or not. While both the P3 and the LPP components were not related to habitual violent video game exposure, general exposure to antisocial media content predicted lower P3 amplitudes to painful pictures. Further, 40 min of violent gameplay did not affect the P3 responses; however, it temporarily decreased LPP responses to painful pictures, suggesting a modest short-term desensitization effect. However, this latter interpretation is limited by a strong LPP pain effect - a significant amplitude difference between painful and non-painful pictures - that remained present in the post-game condition. Such persistent LPP effect may relate to the notion that adolescents are still learning how to properly regulate their emotional reactions. This study contributes to the limited literature on violent video games' desensitization in adolescents' brains, opening new avenues for media violence research.

Group environment modulates how third parties assess unfairly shared losses and unfairly shared gains: neural signatures from ERPs and EEG oscillations

INTRODUCTION

Through its long-term evolution and development, human society has gradually formed stable and effective norms to maintain normal social production and social activities. Altruistic punishment is indispensable in maintaining social norms. Altruistic punishment includes second-party and third-party punishment, and third-party punishment refers to punishing violators by unbiased bystanders who have not suffered damage to their interests. Cooperation is an important form of human social interaction. Third parties play an essential role in maintaining social cooperation. Third parties' behaviors in maintaining cooperative norms may be related to their social environment.

METHOD

We used the prisoner's dilemma (PD) game and distinguished between the gain and loss contexts of the economy to explore how the group environment modulates the cognitive neural mechanisms and psychological processing of the third-party punishment decision. Twenty-six college students (Mage = 19.88 ± 1.58) participated in the experiment; data from four participants were excluded from analyses of the EEG data due to large artifacts.

RESULTS

The behavioral results show that the degree of punishment from the third party in a loss context was greater than in a gain context. ERP analysis results show that the third party applied a lower P300 in the loss context. The loss context induced a greater N100 than the gain context in the individual environment. At the same time, alpha-band power activated by the individual environment was greater than that activated by the group environment under the gain context.

CONCLUSION

These results suggest that a third party maintaining the norms of social cooperation in different contexts will adjust punishment decisions according to the environment, and this process is mainly dominated by the negative emotions caused by environment.

Mood congruency affects physiological synchrony but not empathic accuracy in a naturalistic empathy task

Empathy is a crucial aspect of our daily lives, as it enhances our wellbeing and is a proxy for prosocial behavior. It encompasses two related but partially distinct components: cognitive and affective empathy. Both are susceptible to context, biases and an individual's physiological state. Few studies have explored the effects of a person's mood on these empathy components, and results are mixed. The current study takes advantage of an ecological, naturalistic empathy task - the empathic accuracy (EA) task - in combination with physiological measurements to examine and differentiate between the effects of one's mood on both empathy components. Participants were induced with positive or negative mood and presented videos of targets narrating autobiographical negative stories, selected from a Chinese empathy dataset that we developed (now publicly available). The stories were conveyed in audio-only, visual-only and full-video formats. Participants rated the target's emotional state while watching or listening to their stories, and physiological measures were taken throughout the process. Importantly, similar measures were taken from the targets when they narrated the stories, allowing a comparison between participants' and targets' measures. We found that in audio-only and visual-only conditions, participants whose moods were congruent with the target showed higher physiological synchrony than those with incongruent mood, implying a mood-congruency effect on affective empathy. However, there was no mood effect on empathic accuracy (reflecting cognitive empathy), suggesting a different influence of mood on the two empathy components.

The influence of aggressive exercise on responses to self-perceived and others' pain

Previous studies have reported relationships between exercise and pain. However, little is known about how aggressive exercise modulates individuals' responses to their own and others' pain. This present study addresses this question by conducting 2 studies employing event-related potential (ERP). Study 1 included 38 participants whose self-perceived pain was assessed after intervention with aggressive or nonaggressive exercises. Study 2 recruited 36 participants whose responses to others' pain were assessed after intervention with aggressive or nonaggressive exercise. Study 1's results showed that P2 amplitudes were smaller, reaction times were longer, and participants' judgments were less accurate in response to self-perceived pain stimuli, especially to high-pain stimuli, after intervention with aggressive exercise compared to nonaggressive exercise. Results of study 2 showed that both P3 and LPP amplitudes to others' pain were larger after intervention with aggressive exercise than with nonaggressive exercise. These results suggest that aggressive exercise decreases individuals' self-perceived pain and increases their empathic responses to others' pain.

Words hurt: common and distinct neural substrates underlying nociceptive and semantic pain

Introduction

Recent studies have shown that processing semantic pain, such as words associated with physical pain, modulates pain perception and enhances activity in regions of the pain matrix. A direct comparison between activations due to noxious stimulation and processing of words conveying physical pain may clarify whether and to what extent the neural substrates of nociceptive pain are shared by semantic pain. Pain is triggered also by experiences of social exclusion, rejection or loss of significant others (the so-called social pain), therefore words expressing social pain may modulate pain perception similarly to what happens with words associated with physical pain. This event-related fMRI study aims to compare the brain activity related to perceiving nociceptive pain and that emerging from processing semantic pain, i.e., words related to either physical or social pain, in order to identify common and distinct neural substrates.

Methods

Thirty-four healthy women underwent two fMRI sessions each. In the Semantic session, participants were presented with positive words, negative pain-unrelated words, physical pain-related words, and social pain-related words. In the Nociceptive session, participants received cutaneous mechanical stimulations that could be either painful or not. During both sessions, participants were asked to rate the unpleasantness of each stimulus. Linguistic stimuli were also rated in terms of valence, arousal, pain relatedness, and pain intensity, immediately after the Semantic session.

Results

In the Nociceptive session, the 'nociceptive stimuli' vs. 'non-nociceptive stimuli' contrast revealed extensive activations in SI, SII, insula, cingulate cortex, thalamus, and dorsolateral prefrontal cortex. In the Semantic session, words associated with social pain, compared to negative pain-unrelated words, showed increased activity in most of the same areas, whereas words associated with physical pain, compared to negative pain-unrelated words, only activated the left supramarginal gyrus and partly the postcentral gyrus.

Discussion

Our results confirm that semantic pain partly shares the neural substrates of nociceptive pain. Specifically, social pain-related words activate a wide network of regions, mostly overlapping with those pertaining to the affective-motivational aspects of nociception, whereas physical pain-related words overlap with a small cluster including regions related to the sensory-discriminative aspects of nociception. However, most regions of overlap are differentially activated in different conditions.

Subliminal perception of others' physical pain induces personal distress rather than empathic concern

BACKGROUND

What is our immediate reaction when we witness someone experiencing pain? The empathy-altruism hypothesis predicts that observers would display empathy and a tendency to approach the person in pain. Alternatively, the threat value of pain hypothesis (TVPH) argues that others' pain serves as a signal of threat and should induce observers' avoidance response.

METHODS

To examine these two hypotheses, three experiments were conducted. The experiments aimed to investigate the impact of subliminal exposure to others' physical pain on participants' emotional and behavioural responses.

RESULTS

The results revealed that subliminal pain priming resulted in faster response and attentional bias to fearful faces compared to sad faces (Experiment 1), faster reaction times in recognizing fear-related words compared to anger-related words during a lexical decision task (Experiment 2), and faster avoidance responses towards anger-related words, as opposed to approaching responses towards positive words (Experiment 3).

CONCLUSIONS

The consistent findings across all experiments revealed that subliminal perception of pain scenes elicited fear emotion and immediate avoidance responses. Therefore, the outcomes of our study provide supportive evidence for the TVPH.

The role of manual gestures in second language comprehension: a simultaneous interpreting experiment

Manual gestures and speech form a single integrated system during native language comprehension. However, it remains unclear whether this hold for second language (L2) comprehension, more specifically for simultaneous interpreting (SI), which involves comprehension in one language and simultaneous production in another. In a combined mismatch and priming paradigm, we presented Swedish speakers fluent in L2 English with multimodal stimuli in which speech was congruent or incongruent with a gesture. A picture prime was displayed before the stimuli. Participants had to decide whether the video was related to the prime, focusing either on the auditory or the visual information. Participants performed the task either during passive viewing or during SI into their L1 Swedish (order counterbalanced). Incongruent stimuli yielded longer reaction times than congruent stimuli, during both viewing and interpreting. Visual and audio targets were processed equally easily in both activities. However, in both activities incongruent speech was more disruptive for gesture processing than incongruent gesture was for speech processing. Thus, the data only partly supports the expected mutual and obligatory interaction of gesture and speech in L2 comprehension. Interestingly, there were no differences between activities suggesting that the language comprehension component in SI shares features with other (L2) comprehension tasks.

Empathy for pain in Individuals influenced by moral identity: Evidence from an ERP study

Both morality and empathy are crucial in the construction of human society. The influence of morality on empathy also deserves researchers' attention. This study used event-related potential techniques to control the degree of moral identity of participants through writing tasks and deeply explored the psychological processes and neural mechanisms of moral identity affecting pain empathy. Behavioral results for picture type showed that the response time to the pain pictures was longer than the nonpain pictures, the accuracy of pain pictures was lower than that of nonpain pictures and ratings of pain pictures were rated higher than non-pain picture. Behavioral results for moral identity showed that there were no significant differences in response time, accuracy, and rating. The interaction between picture type and moral identity was not significant. The ERP results showed that people with high moral identity had higher levels of empathy than those with low moral identity, and pain pictures induced smaller N2 amplitudes and larger Late Positive Component (LPC) amplitudes than nonpain pictures. For people with low moral identity, the pain picture amplitudes were not significantly different from the N2 and LPC amplitudes induced by the nonpain pictures. These results suggest that moral identity affects and moderates the early processing of emotional empathy in the N2 representation and the late processing of cognitive empathy in the LPC representation. Individuals with high moral identity are more likely to induce early automated processing of pain to others when stimulated by pain pictures, automatically sharing the negative emotions of others, which is manifested as having more emotional empathy. Individuals with high moral identity exhibit a more refined analytical evaluation of pain pictures and a conscious, top-down control of processing when stimulated by pain pictures, which is manifested as having more cognitive empathy. Whether in the emotional empathy stage or in the cognitive empathy stage, moral identity has an important impact on pain empathy, and higher moral identity is the premise of empathy for the pain of others.

The relationship between autistic traits and empathy in adolescents: An ERP study

Based on the mind-blindness hypothesis, a large number of studies have shown that individuals with autism-spectrum disorder (ASD) and autistic traits have empathy deficits. However, the recent double empathy theory contradicts the mind-blindness hypothesis and suggests that individuals with ASD and autistic traits do not necessarily lack empathy. Thus, the presence of empathy deficits in individuals with ASD and autistic traits is still controversial. We recruited 56 adolescents (28 high autistic traits, 28 low autistic traits, 14-17 years old) in this study to explore the relationship between empathy and autistic traits. The study participants were required to undertake the pain empathy task, during which the electroencephalograph (EEG) activities were recorded. Our results show that empathy was negatively associated with autistic traits at the questionnaire, behavioral, and EEG levels. Our results also suggested that empathy deficits in adolescents with autistic traits may be manifested mainly in the late stages of cognitive control processing.

The role of empathy in shared intentionality: Contributions from Inter-Processual Self theory

Research in psychology related to the conceptualization of empathy has been on the rise in the last decades. However, we argue that there is still space for further research to help capture the important notion of empathy and its theoretical and conceptual depth. Following a critical review of the current state of the research that conceptualizes and measures empathy, we focus on works that highlight the importance of a shared vision and its relevance in psychology and neuroscience. Considering the state of the art of current neuroscientific and psychological approaches to empathy, we argue for the relevance of shared intention and shared vision in empathy-related actions. Upon review of different models that emphasize a shared vision for informing research on empathy, we suggest that a newly developed theory of self, human growth and action–the so-called Inter-Processual Self theory (IPS)–can significantly and novelly inform the theorization on empathy beyond what the literature has stated to date. Then, we show how an understanding of integrity as a relational act that requires empathy is an essential mechanism for current key research on empathy and its related concepts and models. Ultimately, we aim to present IPS as a distinctive proposal to expand upon the conceptualization of empathy.

Moral transgression modulates empathy for pain: Evidence from ERP and EEG data

Empathy for others' pain plays a critical role in human social interactions; however, the influence of moral transgression remains unclear. We examined the effect of moral transgression on the behavioral and underlying neural processes of empathy for others' pain. Participants performed a pain-empathy task separately in a moral transgression condition and a neutral behavior condition, while an electroencephalogram was recorded. Event-related potential (ERP) results showed that empathic response, as reflected in the late positive component, was smaller when participants performed the task in the moral transgression condition than in the neutral behavior condition. Time-frequency results also showed decreased empathic effect on the beta event-related desynchronization response in the moral transgression as compared to the neutral behavior condition. However, empathic response as reflected in the N2 component was comparable between the moral conditions. These findings demonstrate a moral transgression effect on both cognitive evaluations and sensorimotor processes of empathy for others' pain. Furthermore, spontaneous alpha-oscillation power recorded prior to the onset of empathy-inducing stimuli was significantly higher in the moral transgression condition than in the neutral behavior condition. Consequently, differences in sustained attention may be the physiological foundation of the impact of moral transgression of the observed person on the cognitive and sensorimotor processes of empathy for pain.

Effect of doctor-patient news-induced moral judgments on pain empathy for doctors and patients in China

Objective

Pain empathy's preferential nature tends to trigger prejudice and intergroup conflicts. Given the current degree of proliferation of doctor-patient conflict news in China, this study aims to determine whether readers of doctor-patient news-initiated moral judgments prefer pain empathy for doctors or patients.

Materials and methods

This study utilized localized doctor-patient news with high or low moral performance (based on morality ratings of patients' behaviors) as moral-judgment-eliciting materials, and painful pictures as pain empathy-eliciting materials. The event-related potential (ERP) technique was utilized to assess moral judgment's effect on the cognitive empathy component and to investigate electroencephalogram signals' accuracy in classifying four brain response patterns when facing doctor or patient is experiencing or not experiencing pain.

Results

Under low moral text material, participants exhibited smaller mean wave amplitude of positive 300 (P3) and late positive potential (LPP) to painful pictures than non-painful pictures when facing patients; under high moral text material, participants exhibited larger mean wave amplitude of P3 and LPP to painful pictures than non-painful pictures when facing doctors. Electroencephalogram (EEG) signals' classification accuracy was significant in 0-1,000 ms in both high and low moral judgments, but the classification accuracy was higher in low moral judgments in some cognitive empathy stages (0.51, 0.53-0.55, 0.66-0.79, and 0.88-1 s).

Conclusion

Under low moral judgment, individuals pay less attention to the patient's (perpetrator's) pain; under high moral judgment, individuals empathize with the doctor (the person praised), showing that news-induced moral judgment can sway readers' empathy for different social groups. In cognitive empathy, individuals' brain representations are more discriminatory under low than high moral judgments when confronted with pain by doctors and patients, which provides insight into objectively recognizing group bias.

Listen to my feelings! How prosody and accent drive the empathic relevance of complaining speech

Interpersonal communication often involves sharing our feelings with others; complaining, for example, aims to elicit empathy in listeners by vocally expressing a speaker's suffering. Despite the growing neuroscientific interest in the phenomenon of empathy, few have investigated how it is elicited in real time by vocal signals (prosody), and how this might be affected by interpersonal factors, such as a speaker's cultural background (based on their accent). To investigate the neural processes at play when hearing spoken complaints, twenty-six French participants listened to complaining and neutral utterances produced by in-group French and out-group Québécois (i.e., French-Canadian) speakers. Participants rated how hurt the speaker felt while their cerebral activity was monitored with electroencephalography (EEG). Principal Component Analysis of Event-Related Potentials (ERPs) taken at utterance onset showed culture-dependent time courses of emotive prosody processing. The high motivational relevance of ingroup complaints increased the P200 response compared to all other utterance types; in contrast, outgroup complaints selectively elicited an early posterior negativity in the same time window, followed by an increased N400 (due to ongoing effort to derive affective meaning from outgroup voices). Ingroup neutral utterances evoked a late negativity which may reflect re-analysis of emotively less salient, but culturally relevant ingroup speech. Results highlight the time-course of neurocognitive responses that contribute to emotive speech processing for complaints, establishing the critical role of prosody as well as social-relational factors (i.e., cultural identity) on how listeners are likely to "empathize" with a speaker.

The influence of pride emotion on executive function: Evidence from ERP

BACKGROUND

The current study examined the influence of positive "basic" emotions on executive function; there is limited evidence about the influence of positive "self-conscious"emotions, such as pride, on executive functions processes.

METHODS

Pride is a status-related self-conscious emotion and the present research explored the influence of pride on the subcomponents of executive function, using three experiments that adopted the digit size-parity switching, N-back, and dual choice oddball paradigms.

RESULTS

The behavioral results suggested that cognitive load and behavior inhibition effects in the pride emotion were significantly higher than the neutral emotion. The ERP results showed that the pride emotion elicited smaller P3 difference wave for the switching task and dual choice oddball task. In the N-back task, the pride emotion elicited larger N1 amplitude and smaller P2 difference wave compared to the neutral emotion. A comparison among results from the three experiments indicated that pride emotion restrains all subcomponents of executive function, though with different manifestations of the impact.

CONCLUSION

Experiencing positive emotions is typically viewed as desirable and adaptive in educational settings; however, pride as a unique positive emotion may damage people's cognitive performance, indicating that we need to be cautious when performing cognitive operations in a pride mood.

Skin Color and Attractiveness Modulate Empathy for Pain: An Event-Related Potential Study

Although racial in-group bias in empathy for pain has been reported, empathic responses to others’ pain may be influenced by other characteristics besides race. To explore whether skin color and attractiveness modulate empathy for pain, we recorded 24 participants’ reactions to painful faces from racial in-group members with different skin color (fair, wheatish, or dark) and attractiveness (more or less attractive) using event-related potentials (ERPs). Results showed that, for more attractive painful faces, dark skin faces were judged as less painful and elicited smaller N2 amplitudes than fair- and wheatish-skinned faces. However, for less attractive faces, there were no significant differences among the three skin colors. Our findings suggest that empathy for pain toward racial in-group members may be influenced by skin color and attractiveness.

The influence of social pain experience on empathic neural responses: the moderating role of gender

Empathy for pain, the ability to share and understand the pain of others, plays an important role in the survival and development of individuals. Previous studies have found that social pain experience affects empathy for pain, but potential gender differences have not been considered. The stage of information processing during which gender is most likely to play a moderating role has yet to be clarified. In the current study, we set up two groups (social pain experience priming: social exclusion group; positive social interaction experience priming: social inclusion group) with a Cyberball game paradigm. We recorded the electrophysiological responses when participants were completing an empathy task. An early frontal P2 and N2 differentiation between painful stimuli and neutral stimuli was observed and females showed larger P2 amplitudes than males. At the P3 stage, in the social exclusion group, males showed similar parietal P3 amplitudes for painful and neutral stimuli, while females showed smaller P3 amplitudes for painful stimuli. At the central-parietal late positive potential (LPP) stage, females in the social inclusion group showed larger LPP amplitudes for painful stimuli than males. Our results suggest that gender plays a significant moderating role in how social pain experience affects empathy for pain during the late cognitive processing stage. Experiment 2 was designed to investigate the cognitive mechanism behind the results for the P3 component in females and the results partially confirmed our speculation. This study provides a neurophysiological basis for the dynamic gender differences in the effects of social pain experience on empathy for pain.

Interoceptive attentiveness and autonomic reactivity in pain observation

Aim: This study explores interoceptive attentiveness (IA) influence on autonomic reactivity related to pain and self-regulation during situations evoking physiological mirroring for pain.Methods: 20 participants observed face/hand, painful/non-painful stimuli in an individual versus social condition while the autonomic response was measured [Electrodermal activity, Pulse Volume Amplitude (PVA), and Heart Rate (HR)] was measured. The sample was divided into experimental (EXP) subjects, required to focus on their interoceptive correlates while observing the stimuli, and the control (CNT) group. HR inter-beat interval (IBI), and HR Variability (HRV) were calculated.Results: Results showed high accuracy to painful and non-painful stimuli recognition. Regarding autonomic indices, higher PVA values were detected for hand painful versus non-painful stimuli, whereas for the EXP group a significant activation of IBI was found for face painful vs non-painful stimuli.Conclusion: In the context of observation of pain in others, PVA and IBI could be respectively markers of mirroring mechanisms and autonomic self-regulation mediated by IA.

ERP Indicators of Self-Pain and Other Pain Reductions due to Placebo Analgesia Responding: The Moderating Role of the Fight-Flight-Freeze System

This study evaluates the modulation of phasic pain and empathy for pain induced by placebo analgesia during pain and empathy for pain tasks. Because pain can be conceptualized as a dangerous stimulus that generates avoidance, we evaluated how approach and avoidance personality traits modulate pain and empathy for pain responses. We induced placebo analgesia to test whether this also reduces self-pain and other pain. Amplitude measures of the N1, P2, and P3 ERPs components, elicited by electric stimulations, were obtained during a painful control, as well as during a placebo treatment expected to induce placebo analgesia. The placebo treatment produced a reduction in pain and unpleasantness perceived, whereas we observed a decrease in the empathy unpleasantness alone during the empathy pain condition. The moderator effects of the fight-flight-freeze system (FFFS) in the relationships linking P2 and P3 amplitude changes with pain reduction were both significant among low to moderate FFFS values. These observations are consistent with the idea that lower FFFS (active avoidance) scores can predict placebo-induced pain reduction. Finally, in line with the revised Reinforcement Sensitivity Theory (r-RST), we can assume that phasic pain is an aversive stimulus activating the active-avoidance behavior to bring the system back to homeostasis.

The Effect of Empathy on the Attentional Processing of Painful and Emotional Stimuli

Background

Empathy is shown to affect the attentional processing of painful stimuli and emotional stimuli. However, whether the attentional effects on emotional stimuli depend on emotional valence and the nature of the relationship between the attentional effects on different stimuli are still unknown.

Methods

In the present study, 25 high-empathy (HE) participants and 25 low-empathy (LE) participants were recruited to perform dot-probe tasks on painful stimuli and emotional stimuli.

Results

The results showed that HE individuals had weak attentional disengagement to painful pictures. More importantly, regarding emotional pictures, HE individuals showed attentional avoidance to negative emotion pictures, while LE individuals showed attentional bias to positive emotion pictures. Correlation analysis showed that the attentional bias score and attentional disengagement score were only associated with each other within the same category of stimuli (painful, positive or negative stimuli).

Conclusion

These results revealed that HE individuals mainly showed attentional avoidance to negative stimuli, while LE individuals mainly showed attentional bias to positive stimuli.

The effects of attentional and interpretation biases on later pain outcomes among younger and older adults: A prospective study

BACKGROUND

Studies examining the effect of biased cognitions on later pain outcomes have primarily focused on attentional biases, leaving the role of interpretation biases largely unexplored. Also, few studies have examined pain-related cognitive biases in elderly persons. The current study aims to fill these research gaps.

METHODS

Younger and older adults with and without chronic pain (N = 126) completed an interpretation bias task and a free-viewing task of injury and neutral scenes at baseline. Participants' pain intensity and disability were assessed at baseline and at a 6-month follow-up. A machine-learning data-driven approach to analysing eye movement data was adopted.

RESULTS

Eye movement analyses revealed two common attentional pattern subgroups for scene-viewing: an "explorative" group and a "focused" group. At baseline, participants with chronic pain endorsed more injury-/illness-related interpretations compared to pain-free controls, but they did not differ in eye movements on scene images. Older adults interpreted illness-related scenarios more negatively compared to younger adults, but there was also no difference in eye movements between age groups. Moreover, negative interpretation biases were associated with baseline but not follow-up pain disability, whereas a focused gaze tendency for injury scenes was associated with follow-up but not baseline pain disability. Additionally, there was an indirect effect of interpretation biases on pain disability 6 months later through attentional bias for pain-related images.

CONCLUSIONS

The present study provided evidence for pain status and age group differences in injury-/illness-related interpretation biases. Results also revealed distinct roles of interpretation and attentional biases in pain chronicity.

SIGNIFICANCE

Adults with chronic pain endorsed more injury-/illness-related interpretations than pain-free controls. Older adults endorsed more illness interpretations than younger adults. A more negative interpretation bias indirectly predicted pain disability 6 months later through hypervigilance towards pain.

The effects of long-term menstrual pain on pain empathy in women with primary dysmenorrhea

ABSTRACT

Primary dysmenorrhea (PDM) is not only a painful experience but also affects the psychological and affective states of women. Neuroimaging studies have revealed shared neural substrates for somatic and empathic pains in healthy subjects. However, little is known about the relationship between pain intensity and pain empathy in pain disorders. The cyclic nature of PDM makes it a unique model for investigating this issue during a patients' pain phase. To study how long-term pain modulates empathy for pain, T1-weighted magnetic resonance imaging scans were obtained in 39 PDM patients and 41 matched female healthy controls during menstruation. Subjects viewed static visual stimuli of the limbs submitted to painful and nonpainful stimulation to solicit empathy. The visual analogue scale for pain intensity and the Interpersonal Reactivity Index for empathic ability were also obtained. We found that women with PDM exhibited higher pain empathy compared with controls. The anterior insula and brain regions related to sensory discrimination with decreased gray matter volumes were not only shared but also acted as a mediator between pain intensity and pain empathy in PDM patients. In addition, the general linear modeling analysis revealed that long-term pain experience was a more important factor to pain empathy compared with pain intensity. This indicated that long-term pain may cause maladaptive brain structural plasticity, which may further affect psychological adjustment to bring patients more vivid pain when they witness suffering and distress in others.

Inter-subject phase synchronization differentiates neural networks underlying physical pain empathy

Recent approaches for understanding the neural basis of pain empathy emphasize the dynamic construction of networks underlying this multifaceted social cognitive process. Inter-subject phase synchronization (ISPS) is an approach for exploratory analysis of task-fMRI data that reveals brain networks dynamically synchronized to task-features across participants. We applied ISPS to task-fMRI data assessing vicarious pain empathy in healthy participants (n = 238). The task employed physical (limb) and affective (face) painful and corresponding non-painful visual stimuli. ISPS revealed two distinct networks synchronized during physical pain observation, one encompassing anterior insula and midcingulate regions strongly engaged in (vicarious) pain and another encompassing parietal and inferior frontal regions associated with social cognitive processes which may modulate and support the physical pain empathic response. No robust network synchronization was observed for affective pain, possibly reflecting high inter-individual variation in response to socially transmitted pain experiences. ISPS also revealed networks related to task onset or general processing of physical (limb) or affective (face) stimuli which encompassed networks engaged in object manipulation or face processing, respectively. Together, the ISPS approach permits segregation of networks engaged in different psychological processes, providing additional insight into shared neural mechanisms of empathy for physical pain, but not affective pain, across individuals.

Expressive suppression to pain in others reduces negative emotion but not vicarious pain in the observer

Although there are situations where it may be appropriate to reduce one's emotional response to the pain of others, the impact of an observer's emotional expressivity on their response to pain in others is still not well understood. In the present study, we examined how the emotion regulation strategy expressive suppression influences responses to pain in others. Based on prior research findings on expressive suppression and pain empathy, we hypothesized that expressive suppression to pain expression faces would reduce neural representations of negative emotion, vicarious pain, or both. To test this, we applied two multivariate pattern analysis (MVPA)-derived neural signatures to our data, the Picture Induced Negative Emotion Signature (PINES; Chang, Gianaros, Manuck, Krishnan, and Wager (2015)) and a neural signature of facial expression induced vicarious pain (Zhou et al., 2020). In a sample of 60 healthy individuals, we found that viewing pain expression faces increased neural representations of negative emotion and vicarious pain. However, expressive suppression to pain faces reduced neural representations of negative emotion only. Providing support for a connection between neural representations of negative emotion and pain empathy, PINES responses to pain faces were associated with participants' trait-level empathy and the perceived unpleasantness of pain faces. Findings suggest that a consequence of suppressing one's facial expressions in response to the pain of others may be a reduction in the affective aspect of empathy but not the experience of vicarious pain itself.

EEG based functional connectivity analysis of human pain empathy towards humans and robots

Humans can show emotional reactions toward humanoid robots, such as empathy. Previous neuroimaging studies have indicated that neural responses of empathy for others' pain are modulated by an early automatic emotional sharing and a late controlled cognitive evaluation process. Recent studies about pain empathy for robots found humans present similar empathy process towards humanoid robots under painful stimuli as well as to humans. However, the whole-brain functional connectivity and the spatial dynamics of neural activities underlying empathic processes are still unknown. In the present study, the functional connectivity was investigated for ERPs recorded from 18 healthy adults who were presented with pictures of human hand and robot hand under painful and non-painful situations. Functional brain networks for both early and late empathy responses were constructed and a new parameter, empathy index (EI), was proposed to represent the empathy ability of humans quantitatively. We found that the mutual dependences between early ERP components was significantly decreased, but for the late components, there were no significant changes. The mutual dependences for human hand stimuli were larger than to robot hand stimuli for early components, but not for late components. The connectivity weights for early components were larger than late components. EI value shows significant difference between painful and non-painful stimuli, indicating it is a good indicator to represent the empathy of humans. This study enriches our understanding of the neurological mechanisms implicated in human empathy, and provides evidence of functional connectivity for both early and late responses of pain empathy towards humans and robots.

Dispositional Self-Construal Modulates the Empathy for Others' Pain: An ERP Study

Previous studies have shown that temporal self-construal priming can modulate the empathic neural responses to others' pain. However, little is known about the influences of the dispositional self-construal on empathic neural responses to others' pain. The present study aimed to investigate neural correlates that underlie the modulation effect of dispositional self-construal on perception of others' pain. Event-related potentials were recorded for pictures depicting the hands of strangers in painful or no-painful situations while subjects performed a pain judgment task. The regression analysis on behavioral data showed that the level of interdependent self-construal could positively predict behavioral ratings of perceived pain, but not the self-unpleasantness. The ERP results showed painful stimuli elicited decreased N2 amplitudes and larger P3 amplitudes than those by no-painful stimuli. Moreover, the level of interdependent self-construal (interdependence minus independence scores) could predict the amplitude differences on the P3 component (painful minus neutral stimulus conditions), but not the N2 component: the higher the level of the interdependent self-construal, the larger amplitude differences of P3 to painful stimuli (vs. no-painful stimuli). These findings extended previous studies by showing a clear modulation effect of the dispositional self-construal on empathic neural responses to others' pain, and that this modulation effect occurred at the late cognitive evaluation stage indexed by the P3 component.

Impaired empathy in patients with idiopathic generalized epilepsy: An event-related potentials study

PURPOSE

Epilepsy is a common neurological disorder that may be complicated by neurobehavioral comorbidities. In a previous study, we identified impairment of empathy in patients with idiopathic generalized epilepsy (IGE). However, the temporal processing of empathy in patients with IGE is not well understood.

METHODS

We investigated empathy for pain and self-reported empathy in 21 patients with IGE and 22 healthy control subjects. All study participants were required to complete a pain empathy task involving images of individuals in pain and neutral conditions during recording of event-related potentials.

RESULTS

Compared with the controls, the patients with IGE showed impaired cognitive empathy but intact emotional empathy on the Chinese version of the Interpersonal Reactivity Index; they also had normal N1, N2, and late positive potential (LPP) but lower P3 amplitudes evoked by depictions of pain in others when compared with neutral images during the pain judgment task; the difference in the effects of pain empathy on the pain task between the IGE group and the control group was statistically significant.

CONCLUSION

These results indicate that later processing of pain empathy is impaired but early processing is intact in patients with IGE. The present study extends the findings of our previous behavioral study by providing solid evidence of impaired empathy in patients with IGE at the neural processing level.

Empathic pain evoked by sensory and emotional-communicative cues share common and process-specific neural representations

Pain empathy can be evoked by multiple cues, particularly observation of acute pain inflictions or facial expressions of pain. Previous studies suggest that these cues commonly activate the insula and anterior cingulate, yet vicarious pain encompasses pain-specific responses as well as unspecific processes (e.g. arousal) and overlapping activations are not sufficient to determine process-specific shared neural representations. We employed multivariate pattern analyses to fMRI data acquired during observation of noxious stimulation of body limbs (NS) and painful facial expressions (FE) and found spatially and functionally similar cross-modality (NS versus FE) whole-brain vicarious pain-predictive patterns. Further analyses consistently identified shared neural representations in the bilateral mid-insula. The vicarious pain patterns were not sensitive to respond to non-painful high-arousal negative stimuli but predicted self-experienced thermal pain. Finally, a domain-general vicarious pain pattern predictive of self-experienced pain but not arousal was developed. Our findings demonstrate shared pain-associated neural representations of vicarious pain.

Images depicting human pain increase exercise-induced pain and impair endurance cycling performance

The current study investigated whether viewing images of others in pain influences exercise-induced pain (EIP) and cycling performance. Twenty-one recreational cyclists attended five laboratory visits. The first two visits involved measuring participants' maximal aerobic capacity and familiarized participants to the fixed power (FP) and 16.1 km cycling time trial (TT) tasks. The FP task required participants to cycle at 70% of their maximal aerobic power for 10-minutes. In the subsequent three visits, participants performed the FP and TT tasks after viewing pleasant, ‎painful or neutral images. Participants rated the subset of painful images as more painful than the pleasant and neutral images; with no difference in the pain ratings of the pleasant and neutral images. In the FP task, EIP ratings were higher following painful compared to pleasant images, while no differences in EIP were observed between any other condition . In the TT, performance did not differ between the pleasant and neutral conditions. However, TT performance was reduced after viewing painful images compared to neutral or pleasant images. HR, B[La], perceived exertion and EIP did not differ between the three conditions. These results suggest that viewing painful images decreases TT performance and increases pain during fixed intensity cycling.‎ Abbreviations: EIP: Exercise Induced Pain; FP: Fixed Power; TT: Time Trial; HR:Heart Rate; B[La]: Blood Lactate; RPE: Rating of Perceived Exertion; IAPS: International Affective Picture System; PO: Power Output.

Eye Movements in Response to Pain-Related Feelings in the Presence of Low and High Cognitive Loads

The affective dimension of pain contributes to pain perception. Cognitive load may influence pain-related feelings. Eye tracking has proven useful for detecting cognitive load effects objectively by using relevant eye movement characteristics. In this study, we investigated whether eye movement characteristics differ in response to pain-related feelings in the presence of low and high cognitive loads. A set of validated, control, and pain-related sounds were applied to provoke pain-related feelings. Twelve healthy young participants (six females) performed a cognitive task at two load levels, once with the control and once with pain-related sounds in a randomized order. During the tasks, eye movements and task performance were recorded. Afterwards, the participants were asked to fill out questionnaires on their pain perception in response to the applied cognitive loads. Our findings indicate that an increased cognitive load was associated with a decreased saccade peak velocity, saccade frequency, and fixation frequency, as well as an increased fixation duration and pupil dilation range. Among the oculometrics, pain-related feelings were reflected only in the pupillary responses to a low cognitive load. The performance and perceived cognitive load decreased and increased, respectively, with the task load level and were not influenced by the pain-related sounds. Pain-related feelings were lower when performing the task compared with when no task was being performed in an independent group of participants. This might be due to the cognitive engagement during the task. This study demonstrated that cognitive processing could moderate the feelings associated with pain perception.

Pain and social decision-making: New insights from the social framing effect

This paper focuses on the social function of painful experience as revealed by recent studies on social decision-making. Observing others suffering from physical pain evokes empathic reactions that can lead to prosocial behavior (e.g., helping others at a cost to oneself), which might be regarded as the social value of pain derived from evolution. Feelings of guilt may also be elicited when one takes responsibility for another’s pain. These social emotions play a significant role in various cognitive processes and may affect behavioral preferences. In addition, the influence of others’ pain on decision-making is highly sensitive to social context. Combining neuroimaging techniques with a novel decision paradigm, we found that when asking participants to trade-off personal benefits against providing help to other people, verbally describing the causal relationship between their decision and other people’s pain (i.e., framing) significantly changed participants’ preferences. This social framing effect was associated with neural activation in the temporoparietal junction (TPJ), which is a brain area that is important in social cognition and in social emotions. Further, transcranial direct current stimulation (tDCS) on this region successfully modulated the magnitude of the social framing effect. These findings add to the knowledge about the role of perception of others’ pain in our social life.

Differences between empathy for face and body pain: Cognitive and neural responses

Empathy for pain is a hotspot in the field of empathy research because of its specific cognitive and neural mechanism. Currently, studies of empathy for pain can be classified into two categories based on the body regions receiving the painful stimulus, i.e., empathy for face pain and empathy for body pain, which conveys painful information based on individuals’ faces or body parts, respectively. Although the existing evidence revealed differences between these two kinds of pain empathy regarding the underlying cognitive and neural mechanisms, the current studies tend to confuse these findings. Therefore, we summarized the differences between empathy for face and body pain, mainly regarding the behavioral reactivity tendency, brain activations, and electrophysiological (EEG) signals. These differences probably stem from the fact that the human face contains more emotional information, while other body parts contain more perceptual information. Thus, future studies should identify the distinctions between empathy for face and body pain, to explore further how empathy for face pain is affected by the facial information of others and focus on empathy for face pain in individuals with psychopathological disorders. Furthermore, the specific reasons for these distinctions and their underlying neuromechanisms deserve to be further reviewed.

The interaction between pain and attractiveness perception in others

When considering the “beauty-is-good” stereotype, facial attractiveness should facilitate empathy for pain. On the other hand, having in mind the “threat value of pain” hypothesis, pain cues would be more salient, and thus, its processing would not suffer influence by facial attractiveness. The event-related potential (ERP) allows investigating if one of these theories could predict individuals’ responses regarding the perception of pain or attractiveness in others’ faces. We tracked 35 participants’ reactions to pictures depicting more and less attractive faces displayed in a painful and non-painful condition. Each participant completed the following two tasks when presented the images of faces: (1) the Pain Judgment Task, in which participants should rate the pain levels, and (2) the Attractiveness Judgment Task, in which participants should rate the attractiveness. Results showed that participants exhibited differences rating more and less attractive faces in the non-painful pictures, but not in the painful pictures. These results were observed in P3 and LPC amplitudes in the Pain Judgment Task, as well as in N170 and P2 amplitudes in the Attractive Judgment Task. Our results suggested that both explicit and implicit empathic pain processing inhibited the processing of attractiveness perception. These findings supported the “threat value of pain” hypothesis. Besides, in the Attractive Judgment Task, the N170 and P2 amplitudes for more attractive painful pictures were larger than those for more attractive non-painful pictures. In contrast, no significant difference was found between the amplitudes for painful and non-painful, less attractive pictures. Our findings suggest that explicit facial attractiveness processing for more attractive face images potentiates the implicit empathy for pain processing, therefore partly supporting the “beautiful-is-good” stereotype.

The effect of emotional information from eyes on empathy for pain: A subliminal ERP study

Facial expressions are deeply tied to empathy, which plays an important role during social communication. The eye region is effective at conveying facial expressions, especially fear and sadness emotions. Further, it was proved that subliminal stimuli could impact human behavior. This research aimed to explore the effect of subliminal sad, fearful and neutral emotions conveyed by the eye region on a viewer's empathy for pain using event-related potentials (ERP). The experiment used an emotional priming paradigm of 3 (prime: subliminal neutral, sad, fear eye region information) × 2 (target: painful, nonpainful pictures) within-subject design. Participants were told to judge whether the targets were in pain or not. Results showed that the subliminal sad eye stimulus elicited a larger P2 amplitude than the subliminal fearful eye stimulus when assessing pain. For P3 and late positive component (LPC), the amplitude elicited by the painful pictures was larger than the amplitude elicited by the nonpainful pictures. The behavioral results demonstrated that people reacted to targets depicting pain more slowly after the sad emotion priming. Moreover, the subjective ratings of Personal Distress (PD) (one of the dimensions in Chinese version of Interpersonal Reactivity Index scale) predicted the pain effect in empathic neural responses in the N1 and N2 time window. The current study showed that subliminal eye emotion affected the viewer's empathy for pain. Compared with the subliminal fearful eye stimulus, the subliminal sad eye stimulus had a greater impact on empathy for pain. The perceptual level of pain was deeper in the late controlled processing stage.

The Role of Social Power in Neural Responses to Others' Pain

Recent evidence has demonstrated that empathic responses are modulated by social power. However, there is little consensus regarding how an observer's social power can shape empathic responses. The present study used event-related potentials (ERPs) to explore the role of social power in empathic responses. Specifically, to induce the sense of power, we asked participants to recall a past situation in which they were in a position of power (high power prime) or a situation in which they were lacking power (low power prime). Afterward, we used ERPs to record the responses when participants were viewing pictures depicting other people in painful or non-painful situations. The results revealed that larger amplitudes in the earlier P2 and the later P3 components in response to painful stimuli than to non-painful stimuli. Besides, participants primed with high power only showed larger P1 amplitudes than participants primed with low power. The present study extended previous studies by showing that social power tends to enhance the early sensory processing of both painful and non-painful stimuli, instead of directly decreasing the level of empathic responses to others' pain.

Processing of Painful Pictures in Individuals With High and Low Rejection Sensitivity: Evidence From Event-Related Potentials

An increasing number of studies have investigated the relation between the processing of painful stimuli and rejection. Little was known, however, about the impact of the rejection sensitivity (RS) on the processing of painful pictures. This study addressed this issue using high temporal resolution event-related potential techniques. Thirty high RS (20 women and 10 men who scored in the top 20th percentile of the Rejection Sensitivity Questionnaire scores) and 30 low RS (20 women and 10 men who scored in the bottom 20th percentile) volunteers participated in the experiment. All volunteers performed a discrimination task of painful pictures in which they were asked to judge whether target pictures were painful or not. Behaviorally, participants exhibited shorter reaction times for painful than nonpainful pictures. For the P100 component, low RS participants showed stronger brain activities for painful than nonpainful pictures, suggesting vigilance toward painful pictures. High RS participants, however, exhibited no P100 amplitude differences between painful and nonpainful pictures, indicating an analgesia phenomenon. Furthermore, we found that there were larger amplitudes in the late late positive complex component for painful compared with nonpainful pictures, regardless of participants' RS. This suggested a person's further assessment for painful pictures. In short, our findings demonstrated that the level of RS influenced the pain processing at a very early stage of processing.