Meta-analysis of ERP investigations of pain empathy underlines methodological issues in ERP research

The mutual influences between working memory and empathy for pain: the role of social distance

Understanding the mechanisms behind the interaction of empathy for pain (EfP) and working memory (WM), particularly how they are influenced by social factors like perceived social distance (SD), is vital for comprehending how humans dynamically adapt to the complexities of social life. However, there is very little known about these mechanisms. Accordingly, we recruited 116 healthy participants to investigate the bidirectional influence and electrophysiological responses between WM and EfP, including the role of SD. Our research results revealed that the interaction between WM load and SD significantly influenced the processing of EfP. Specifically, high WM load and distant SD facilitated early processing of EfP. Conversely, low WM load and close SD promoted late processing of EfP. Furthermore, the interaction between EfP and SD significantly influenced the performance of ongoing WM tasks. Specifically, the kin's pain, compared to kin's nonpain, improved the participant's performance on low-load WM tasks; however, it diminished the participant's performance on tasks with high WM load. Overall, these results provide evidence at both behavioral and neural levels for the mutual influence of WM and EfP during the same temporal process, and SD emerged as a crucial moderating factor during these mutual influences.

Threatening an Illusory Limb: An Event-related Potential Study of the Rubber Hand Illusion

BACKGROUND

The rubber hand illusion (RHI) is a well-established method for studying body ownership: Given adequate concordance of visual, sensory, and proprioceptive stimuli, the individual experiences a rubber hand as his or her own.

OBJECTIVE

To study the effects of a threat to the rubber hand.

METHODS

We created a typical RHI paradigm but added threatening pain: Both the real hand of an individual and the rubber hand were stroked with a brush, either synchronously (RHI-inducing condition) or asynchronously (control condition), but only the rubber hand was then pricked with a needle to create a threatening pain condition. Event-related potentials (ERPs) were recorded in a group of 23 typically-developed individuals. ERP effects were source-localized using low-resolution electromagnetic tomography.

RESULTS

The individuals consistently reported experience of the RHI during the experiment when the brush strokes were applied synchronously to both the real hand and the rubber hand. ERP analysis revealed that synchronous brush stroking gave rise to higher amplitude of frontal ERPs in the 100-200 ms range than asynchronous brush stroking, which was interpreted as reflecting the RHI. In the threatening pain condition, ERPs showed a greater positivity at frontocentral electrodes, source localized in the supplementary motor area (SMA).

CONCLUSION

SMA activation could reflect a control mechanism over reflexive motor activity, facilitating a possible threat-related response. Further studies should address ERP effects and the extent of the RHI to standard and threat stimuli in a correlative fashion to further elucidate the functional significance of the neurophysiological findings.

Neural mechanisms of altruistic decision-making: EEG functional connectivity network analysis

Altruism is an enigmatic form of prosocial behavior, characterized by diverse motivations and significant interindividual differences. Studying neural mechanisms of altruism is crucial to identify objective markers of pro- and antisocial tendencies in behavior. This study was designed to delve into the mechanisms of altruism by analyzing EEG-based functional connectivity patterns within the framework of the network approach. To experimentally induce a situation of altruistic decision-making, we employed the Pain versus Gain (PvsG) task, which implies making choices concerning financial self-benefit and pain of the other. Our results reveal that the behavioral measure of altruism in the experiment correlated with emotional empathy, which is in line with the "empathy-altruism" hypothesis. Applying the network approach to EEG functional connectivity analysis, we discovered that the very process of decision-making in the PvsG is characterized by the synchronous activity of structures in the right hemisphere, which are involved in empathy for pain. The prosociality of decisions was reflected in functional connectivity between the rostral ACC and orbital IFG in the left hemisphere and the overall network centrality of the caudal ACC. This finding additionally points to the distinct functional roles of the ACC subregions in altruistic decision-making. The proposed neural mechanisms of altruism can further be used to identify neurophysiological markers of prosociality in behavior.

Dissecting shared pain representations to understand their behavioral and clinical relevance

Accounts of shared representations posit that the experience of pain and pain empathy rely on similar neural mechanisms. Experimental research employing novel analytical and methodological approaches has made significant advances in both the identification and targeted manipulation of such shared experiences and their neural underpinnings. This revealed that painful experiences can be shared on different representational levels, from pain-specific to domain-general features, such as negative affect and its regulation. In view of direct links between such representations and social behaviors such as prosocial behavior, conditions characterized by aberrant pain processing may come along with heavy impairments in the social domain, depending on the affected representational level. This has wide potential implications in light of the high prevalence of pain-related clinical conditions, their management, and the overuse of pain medication. In this review and opinion paper, we aim to chart the path toward a better understanding of the link between shared affect and prosocial behavior.

Psychopathic callousness and perspective taking in pain processing: an ERP study

Psychopathy is a multifaceted personality disorder characterized by distinct affective/interpersonal traits, including callousness-unemotionality/meanness, which are often considered the hallmarks of empathic deficits. It has been posited that the processing of others' pain could play an important role in empathy capabilities. This study aimed to investigate the influence of perspective taking on electrocortical responses during pain processing in relation to psychopathic callousness. The late positive potential (LPP) -a well-established electrophysiological indicator of sustained attention to motivationally significant stimuli- was measured while 100 female undergraduates viewed images depicting bodily injuries while adopting an imagine-self or an imagine-other perspective. Callousness factor scores -computed as regression-based component scores from EFA on three relevant self-report measures of this dimension- predicted reduced LPP amplitudes to pain pictures under the imagine-other (but not imagine-self) perspective, even after controlling for other LPP conditions. This result suggests that high-callous individuals exhibit diminished brain responsiveness to others' distress, potentially contributing to the empathic deficits observed in psychopathy. This finding highlights the usefulness of the LPP and perspective taking in studies on pain processing to refine our understanding of the low empathy characteristics of psychopathy in biobehavioral terms.

An ERP investigation of electrocortical responses in pain empathy from childhood through adolescence into adulthood

Only a few studies investigated the neurodevelopment of pain empathy. Here, the temporal dynamics of electrocortical processes in pain empathy during individual neurodevelopment from childhood through adolescence into adulthood, along with the moderation effect of top-down attention, were investigated using the event-related potential (ERP) technique. To investigate the role of top-down attention in empathy development, both A-P task and A-N task were conducted. In the A-P and A-N task, participants are instructed to judge whether the models in pictures were painful or non-painful and count the number of limbs in pictures, respectively. We found that compared to the adolescent and adult groups, the children group responded significantly worse, along with stronger neural responses in both tasks. Compared to the adolescent and adult groups, the differential amplitudes between painful and non-painful conditions of P2, N2 and P3 were significantly larger in the children group. Moreover, this P3 differential amplitude could only be modulated by age in the A-P task. These results suggest that the capacity to empathize has not yet attained complete development in these children. Significantly more attention resources were involuntarily attracted by the nociceptive cues in these children, which could also reflect the immaturity of empathy ability in these children.

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.

Neural dynamics of vicarious physical pain processing reflect impaired empathy toward sexually objectified versus non-sexually objectified women

Sexually objectified women are perceived as dehumanized. This may affect the behavioral and neural responses underlying the observer's empathic reactions for their physical pain, although this hypothesis still lacks empirical support. In the present study, we measured the electrophysiological activity of 30 participants (14 females and 16 males), in an empathy for physical pain paradigm in which pictures of sexualized and non-sexualized women were presented in painful and non-painful situations. The behavioral results revealed that sexualized women were evaluated as experiencing less pain than non-sexualized women. Neural evidence corroborated this finding showing that the perception of vicarious physical pain is lacking for sexualized women in both event-related potentials (ERPs) and brain oscillation domains. Specifically, the P2 component and the event-related synchronization/desynchronization (ERS/ERD) on the mu frequency band differed between painful and non-painful stimulation exclusively when women were not sexualized. Our results provide the first evidence that the neurophysiological responses to the vicarious experience of physical pain are dampened or even absent for sexualized women. These findings expand our understanding of the neurophysiological signatures of empathic processes and highlight the detrimental effect of a sexual-objectification bias in everyday contexts.

Does the cowl make the monk? The effect of military and Red Cross uniforms on empathy for pain, sense of agency and moral behaviors

According to the embodied cognition framework, cognitive functions are not confined to the brain but are also shaped by the mutual interactions between the brain, body, and external environment. In this regard, a theory developed in 2012, called enclothed cognition, suggests an effect on wearing specific clothing on various psychological processes. However, the neuro-cognitive mechanisms underlying the impact of clothing on behavior have received less systematic investigation. The present study examined the influence of clothing on prosocial behaviors, and focused on sense of agency, and empathy for pain as neuro-cognitive processes of interest. Participants (40 in total) wore civilian, military, and Red Cross uniforms. They were paired up and assigned as either agents or victims. Agents had the option to administer real electric shocks to victims for a monetary reward of +€0.05. They could choose to shock freely (free condition) or follow the experimenter's instructions (coerced condition). We measured prosocial behavior by counting the number of shocks prevented, neural empathic response using electroencephalography with the P3 and the LPP, and sense of agency through an implicit method based on interval estimates. Findings showed that wearing the Red Cross uniform led to more prosocial behavior compared to civilian clothing. The Red Cross uniform also increased neural response to pain when participants witnessed shocks, compared to civilian or military clothing. Moreover, wearing a military uniform increased the sense of agency in the free condition, as compared to civilian clothing. This study broadens our knowledge on the impact of enclothed cognition on cognitive and psychological processes.

Machine learning and EEG can classify passive viewing of discrete categories of visual stimuli but not the observation of pain

Previous studies have demonstrated the potential of machine learning (ML) in classifying physical pain from non-pain states using electroencephalographic (EEG) data. However, the application of ML to EEG data to categorise the observation of pain versus non-pain images of human facial expressions or scenes depicting pain being inflicted has not been explored. The present study aimed to address this by training Random Forest (RF) models on cortical event-related potentials (ERPs) recorded while participants passively viewed faces displaying either pain or neutral expressions, as well as action scenes depicting pain or matched non-pain (neutral) scenarios. Ninety-one participants were recruited across three samples, which included a model development group (n = 40) and a cross-subject validation group (n = 51). Additionally, 25 participants from the model development group completed a second experimental session, providing a within-subject temporal validation sample. The analysis of ERPs revealed an enhanced N170 component in response to faces compared to action scenes. Moreover, an increased late positive potential (LPP) was observed during the viewing of pain scenes compared to neutral scenes. Additionally, an enhanced P3 response was found when participants viewed faces displaying pain expressions compared to neutral expressions. Subsequently, three RF models were developed to classify images into faces and scenes, neutral and pain scenes, and neutral and pain expressions. The RF model achieved classification accuracies of 75%, 64%, and 69% for cross-validation, cross-subject, and within-subject classifications, respectively, along with reasonably calibrated predictions for the classification of face versus scene images. However, the RF model was unable to classify pain versus neutral stimuli above chance levels when presented with subsequent tasks involving images from either category. These results expand upon previous findings by externally validating the use of ML in classifying ERPs related to different categories of visual images, namely faces and scenes. The results also indicate the limitations of ML in distinguishing pain and non-pain connotations using ERP responses to the passive viewing of visually similar images.

Biological postural oscillations during facial expression of pain in virtual characters modulate early and late ERP components associated with empathy: A pilot study

There is a surge in the use of virtual characters in cognitive sciences. However, their behavioural realism remains to be perfected in order to trigger more spontaneous and socially expected reactions in users. It was recently shown that biological postural oscillations (idle motion) were a key ingredient to enhance the empathic response to its facial pain expression. The objective of this study was to examine, using electroencephalography, whether idle motion would modulate the neural response associated with empathy when viewing a pain-expressing virtual character. Twenty healthy young adults were shown video clips of a virtual character displaying a facial expression of pain while its body was either static (Still condition) or animated with pre-recorded human postural oscillations (Idle condition). Participants rated the virtual human's facial expression of pain as significantly more intense in the Idle condition compared to the Still condition. Both the early (N2-N3) and the late (rLPP) event-related potentials (ERPs) associated with distinct dimensions of empathy, affective resonance and perspective-taking, respectively, were greater in the Idle condition compared to the Still condition. These findings confirm the potential of idle motion to increase empathy for pain expressed by virtual characters. They are discussed in line with contemporary empathy models in relation to human-machine interactions.

Do Bad People Deserve Empathy? Selective Empathy Based on Targets' Moral Characteristics

The relation between empathy and morality is a widely discussed topic. However, previous discussions mainly focused on whether and how empathy influences moral cognition and moral behaviors, with limited attention to the reverse influence of morality on empathy. This review summarized how morality influences empathy by drawing together a number of hitherto scattered studies illustrating the influence of targets' moral characteristics on empathy. To explain why empathy is morally selective, we discuss its ultimate cause, to increase survival rates, and five proximate causes based on similarity, affective bonds, the appraisal of deservingness, dehumanization, and potential group membership. To explain how empathy becomes morally selective, we consider three different pathways (automatic, regulative, and mixed) based on previous findings. Finally, we discuss future directions, including the reverse influence of selective empathy on moral cognition, the moral selectivity of positive empathy, and the role of selective empathy in selective helping and third-party punishment.

Understanding racial bias through electroencephalography

Research on racial bias in social and cognitive psychology has focused on automatic cognitive processes such as categorisation or stereotyping. Neuroimaging has revealed differences in the neural circuit when processing social information about one's own or another's ethnicity. This review investigates the influence of racial bias on human behaviour by reviewing studies that examined changes in neural circuitry (i.e. ERP responses) during automatic and controlled processes elicited by specific tasks. This systematic analysis of specific ERP components across different studies provides a greater understanding of how social contexts are perceived and become associated with specific stereotypes and behavioural predictions. Therefore, investigating these related cognitive and neurobiological functions can further our understanding of how racial bias affects our cognition more generally and guide more effective programs and policies aimed at its mitigation.

Scarcity mindset reduces empathic responses to others' pain: the behavioral and neural evidence

Resource scarcity pervades our life. A scarcity mindset triggered by perceiving insufficient resources has been proven to influence our cognition and behaviors, yet it remains unknown whether this mindset specifically influences empathy. The present study induced feelings of scarcity or abundance in separate groups of participants through experimental manipulation and examined the effects of both mindsets on the behavioral and neural responses to others' pain. Behaviorally, pain intensity ratings of others' pain were lower in the scarcity group than in the abundance group. The analysis of event-related potentials revealed that N1 amplitudes for painful and nonpainful stimuli were comparable in the scarcity group but differed significantly in the abundance group. Additionally, while both groups showed larger late positive potential amplitudes for painful stimuli than for nonpainful stimuli, this amplitude differential was significantly smaller in the scarcity group than in the abundance group. Thus, behavioral and neural evidence suggests that inducing a scarcity mindset significantly dampens the ability to empathize with others' pain during both the early and late stages of empathic processing. These findings shed light on our understanding of how a scarcity mindset may influence social emotions and behaviors.

On the cognitive mechanisms supporting prosocial disobedience in a post-genocidal context

The aim of the present study was to offer a first investigation of the neuro-cognitive processes and the temporal dynamics at the neural level, together with cultural, social and psychological dimensions, that may support resistance to orders to harm another person. Using a novel experimental approach to study experimentally disobedience, we recruited individuals from the first generation born after the 1994 genocide in Rwanda. Seventy-two were recruited and tested in Rwanda and 72 were recruited and tested in Belgium. Results indicated that a higher neural response to the pain of others and a higher feeling of responsibility when people obeyed orders were associated with more resistance to immoral orders. We also observed that participants who had a higher processing, as measured through mid-frontal theta activity, when listening to the orders of the experimenter disobeyed less frequently to immoral orders. Further, participants experiencing a higher conflict before administering a shock to the 'victim' also disobeyed more frequently to immoral orders. Finally, a low cultural relationship to authority and a high estimated family suffering during the genocide were also associated with more disobedience to immoral orders. The present study opens new paths for interdisciplinary field research dedicated to the study of obedience.

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.

The Effect of Cognitive Strategies and Facial Attractiveness on Empathic Neural Responses

Empathy is a phenomenon that brings together both emotions and an understanding of another person. Recent studies have disentangled the mechanisms of empathy into emotional and cognitive aspects. Event-related potential (ERP) studies suggest that emotional empathy is related to the modulation of the amplitude of early ERPs, and cognitive empathy is linked to later ERPs. In the current study, we examined the influences of facial attractiveness on empathic response and the effect of cognitive strategies with setting the participants' attention to attractiveness or pain. Participants (N= 19) viewed photos of physically attractive and unattractive men and women receiving painful stimulation. The amplitude of the N2 component measured at the frontal regions was more negative in painful stimulation compared to the non-painful, but only for attractive faces. There were no differences between painful and non-painful stimulation for unattractive faces. The amplitude of the P3 measured at the central-parietal region component was more positive in the painful condition compared to the non-painful one, but only when participants performed a pain judgment task. There were no differences in the attractiveness judgment task. This study showed that the attractiveness of a model and drawing the participants' attention to pain constitute an essential modulator of pain empathy.

Pain processing and antisocial behavior: A multimodal investigation of the roles of boldness and meanness

Antisocial behavior has been linked to an increased tolerance of painful stimuli; however, there is evidence that pain behavior is multidetermined. The current study used pain measures from 3 different modalities (pain tolerance, pain ratings, electrocortical reactivity) and assessed triarchic traits of boldness and meanness to clarify the dispositional basis of associations between pain processing and antisocial behavior. High boldness was significantly associated with blunted early neural response to painful and nonpainful stimuli as well as increased pain tolerance. High meanness was associated with blunted elaborative processing of painful images, lower ratings of perceived pain for self and others, and increased pain tolerance. Meanness also accounted for variance shared between pain processing and antisocial behavior. Findings demonstrate that boldness and meanness contribute to pain processing in different ways and suggest that meanness may uniquely account for the association between blunted pain processing and antisocial behavior. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

A novel approach to measure brain-to-brain spatial and temporal alignment during positive empathy

Empathy is defined as the ability to vicariously experience others' suffering (vicarious pain) or feeling their joy (vicarious reward). While most neuroimaging studies have focused on vicarious pain and describe similar neural responses during the observed and the personal negative affective involvement, only initial evidence has been reported for the neural responses to others' rewards and positive empathy. Here, we propose a novel approach, based on the simultaneous recording of multi-subject EEG signals and exploiting the wavelet coherence decomposition to measure the temporal alignment between ERPs in a dyad of interacting subjects. We used the Third-Party Punishment (TPP) paradigm to elicit the personal and vicarious experiences. During a positive experience, we observed the simultaneous presence in both agents of the Late Positive Potential (LPP), an ERP component related to emotion processing, as well as the existence of an inter-subject ERPs synchronization in the related time window. Moreover, the amplitude of the LPP synchronization was modulated by the presence of a human-agent. Finally, the localized brain circuits subtending the ERP-synchronization correspond to key-regions of personal and vicarious reward. Our findings suggest that the temporal and spatial ERPs alignment might be a novel and direct proxy measure of empathy.

Commanding or Being a Simple Intermediary: How Does It Affect Moral Behavior and Related Brain Mechanisms?

Psychology and neuroscience research have shown that fractioning operations among several individuals along a hierarchical chain allows diffusing responsibility between components of the chain, which has the potential to disinhibit antisocial actions. Here, we present two studies, one using fMRI (Study 1) and one using EEG (Study 2), designed to help understand how commanding or being in an intermediary position impacts the sense of agency and empathy for pain. In the age of military drones, we also explored whether commanding a human or robot agent influences these measures. This was done within a single behavioral paradigm in which participants could freely decide whether or not to send painful shocks to another participant in exchange for money. In Study 1, fMRI reveals that activation in social cognition-related and empathy-related brain regions was equally low when witnessing a victim receive a painful shock while participants were either commander or simple intermediary transmitting an order, compared with being the agent directly delivering the shock. In Study 2, results indicated that the sense of agency did not differ between commanders and intermediary, no matter whether the executing agent was a robot or a human. However, we observed that the neural response over P3 event-related potential was higher when the executing agent was a robot compared with a human. Source reconstruction of the EEG signal revealed that this effect was mediated by areas including the insula and ACC. Results are discussed regarding the interplay between the sense of agency and empathy for pain for decision-making.

Effects of selective attention on the C1 ERP component: A systematic review and meta-analysis

The C1 event-related potential (ERP) captures the earliest stage of feedforward processing in the primary visual cortex (V1). An ongoing debate is whether top-down selective attention can modulate the C1. One side of the debate pointed out that null findings appear to outnumber positive findings; thus, selective attention does not seem to influence the C1. However, this suggestion is not based on a valid approach to summarizing evidence across studies. Therefore, we conducted a systematic review and meta-analysis investigating the effects of selective attention on the C1, involving 47 experiments and 794 subjects in total. Despite heterogeneity across studies, results suggested that attention has a moderate effect on the C1 (Cohen's d z $$ {d}_z $$  = 0.33, p < .0001); that is, C1 amplitude is larger for visual stimuli that are attended than unattended. These results suggest that C1 is affected by top-down selective attention.

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.

Neural mechanisms of modulations of empathy and altruism by beliefs of others' pain

Perceived cues signaling others' pain induce empathy which in turn motivates altruistic behavior toward those who appear suffering. This perception-emotion-behavior reactivity is the core of human altruism but does not always occur in real-life situations. Here, by integrating behavioral and multimodal neuroimaging measures, we investigate neural mechanisms underlying modulations of empathy and altruistic behavior by beliefs of others' pain (BOP). We show evidence that lack of BOP reduces subjective estimation of others' painful feelings and decreases monetary donations to those who show pain expressions. Moreover, lack of BOP attenuates neural responses to their pain expressions within 200 ms after face onset and modulates neural responses to others' pain in the insular, post-central, and frontal cortices. Our findings suggest that BOP provide a cognitive basis of human empathy and altruism and unravel the intermediate neural mechanisms.

Natural human postural oscillations enhance the empathic response to a facial pain expression in a virtual character

Virtual reality platforms producing interactive and highly realistic characters are being used more and more as a research tool in social and affective neuroscience to better capture both the dynamics of emotion communication and the unintentional and automatic nature of emotional processes. While idle motion (i.e., non-communicative movements) is commonly used to create behavioural realism, its use to enhance the perception of emotion expressed by a virtual character is critically lacking. This study examined the influence of naturalistic (i.e., based on human motion capture) idle motion on two aspects (the perception of other’s pain and affective reaction) of an empathic response towards pain expressed by a virtual character. In two experiments, 32 and 34 healthy young adults were presented video clips of a virtual character displaying a facial expression of pain while its body was either static (still condition) or animated with natural postural oscillations (idle condition). The participants in Experiment 1 rated the facial pain expression of the virtual human as more intense, and those in Experiment 2 reported being more touched by its pain expression in the idle condition compared to the still condition, indicating a greater empathic response towards the virtual human’s pain in the presence of natural postural oscillations. These findings are discussed in relation to the models of empathy and biological motion processing. Future investigations will help determine to what extent such naturalistic idle motion could be a key ingredient in enhancing the anthropomorphism of a virtual human and making its emotion appear more genuine.

Social Exclusion Down-Regulates Pain Empathy at the Late Stage of Empathic Responses: Electrophysiological Evidence

Social exclusion has a significant impact on cognition, emotion, and behavior. Some behavioral studies investigated how social exclusion affects pain empathy. Conclusions were inconsistent, and there is a lack of clarity in identifying which component of pain empathy is more likely to be affected. To investigate these issues, we used a Cyberball task to manipulate feelings of social exclusion. Two groups (social exclusion and social inclusion) participated in the same pain empathy task while we recorded event-related potentials (ERP) when participants viewed static images of body parts in painful and neutral situations. The results showed early N2 differentiation between painful and neutral pictures in the central regions in both groups. The pattern at the late controlled processing stage was different. Parietal P3 amplitudes for painful pictures were significantly smaller than those for neutral pictures in the social exclusion group; they did not differ in the social inclusion group. We observed a parietal late positive potential (LPP) differentiation between painful and neutral pictures in both groups. LPP amplitudes were significantly smaller in the social exclusion group than those in the social inclusion group for painful stimuli. Our results indicate that social exclusion does not affect empathic responses during the early emotional sharing stage. However, it down-regulates empathic responses at the late cognitive controlled stage, and this modulation is attenuated gradually. The current study provides neuroscientific evidence of how social exclusion dynamically influences pain empathy.

Enhanced Neural Empathic Responses in Patients with Spino-Bulbar Muscular Atrophy: An Electrophysiological Study

BACKGROUND

Spino-bulbar muscular atrophy is a rare genetic X-linked disease caused by testosterone insensitivity. An inverse correlation has been described between testosterone levels and empathic responses. The present study explored the profile of neural empathic responding in spino-bulbar muscular atrophy patients.

METHODS

Eighteen patients with spino-bulbar muscular atrophy and eighteen healthy male controls were enrolled in the study. Their event-related potentials were recorded during an "Empathy Task" designed to distinguish neural responses linked with experience-sharing (early response) and mentalizing (late response) components of empathy. The task involved the presentation of contextual information (painful vs. neutral sentences) and facial expressions (painful vs. neutral). An explicit dispositional empathy-related questionnaire was also administered to all participants, who were screened via neuropsychological battery tests that did not reveal potential cognitive deficits. Due to electrophysiological artefacts, data from 12 patients and 17 controls were finally included in the analyses.

RESULTS

Although patients and controls did not differ in terms of dispositional, explicit empathic self-ratings, notably conservative event-related potentials analyses (i.e., spatio-temporal permutation cluster analyses) showed a significantly greater experience-sharing neural response in patients compared to healthy controls in the Empathy-task when both contextual information and facial expressions were painful.

CONCLUSION

The present study contributes to the characterization of the psychological profile of patients with spino-bulbar muscular atrophy, highlighting the peculiarities in enhanced neural responses underlying empathic reactions.

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.

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.

He had it Comin': ERPs Reveal a Facilitation for the Processing of Misfortunes to Antisocial Characters

Human sociality and prosociality rely on social and moral feelings of empathy, compassion, envy, schadenfreude, as well as on the preference for prosocial over antisocial others. We examined the neural underpinnings of the processing of lexical input designed to tap into these type of social feelings. Brainwave responses from 20 participants were measured as they read sentences comprising a randomly delivered ending outcome (fortunate or unfortunate) to social agents previously profiled as prosocial or antisocial individuals. Fortunate outcomes delivered to prosocial and antisocial agents aimed to tap into empathy and envy/annoying feelings, respectively, whereas unfortunate ones into compassion for prosocial agents and schadenfreude for antisocial ones. ERP modulations in early attention-capture (100-200 ms), semantic fit (400 ms), and late reanalysis processes (600 ms) were analyzed. According to the functional interpretation of each of these event-related electrophysiological effects, we conclude that: 1) a higher capture of attention is initially obtained in response to any type of outcome delivered to a prosocial versus an antisocial agent (frontal P2); 2) a facilitated semantic processing occurs for unfortunate outcomes delivered to antisocial agents (N400); and 3) regardless of the protagonist's social profile, an increased later reevaluation for overall unfortunate versus fortunate outcomes takes place (Late Positive Potential). Thus, neural online measures capture a stepwise unfolding impact of social factors during language comprehension, which include a facilitated processing of misfortunes when they happen to occur to antisocial peers (i.e., schadenfreude).

The Role of Sensorimotor Processes in Pain Empathy

Pain is a salient, aversive sensation which motivates avoidance, but also has a strong social signaling function. Numerous studies have shown that regions of the nervous system active in association with first-hand pain are also active in response to the pain of others. When witnessing somatic pain, such as seeing bodies in painful situations, significant activations occur not only in areas related to the processing of negative emotions, but also in neuronal structures engaged in somatosensation and the control of skeletal muscles. These empathy-related sensorimotor activations are selectively reviewed in this article, with a focus on studies using electrophysiological methods and paradigms investigating responses to somatic pain. Convergent evidence from these studies shows that these activations (1) occur at multiple levels of the nervous system, from the spinal cord up to the cerebral cortex, (2) are best conceptualized as activations of a defensive system, in line with the role of pain to protect body from injury, and (3) contribute to establishing a matching of psychological states between the sufferer and the observer, which ultimately supports empathic understanding and motivate prosocial action. Future research should thus focus on how these sensorimotor responses are related to higher-order empathic responses, including affective sharing and emotion regulation, and how this motivates approach-related prosocial behaviors aimed at alleviating the pain and suffering of others.

Exploring the effects of visual perspective on the ERP components of empathy for pain

Previous neurophysiological research suggests that there are event-related potential (ERP) components associated with empathy for pain: an early affective component (N2) and two late cognitive components (P3/LPP). The current study investigated whether and how the visual perspective from which a painful event is observed affects these ERP components. Participants viewed images of hands in pain vs. not in pain from a first-person or third-person perspective. We found that visual perspective influences both the early and late components. In the early component (N2), there was a larger mean amplitude during observation of pain vs no-pain exclusively when images were shown from a first-person perspective. We suggest that this effect may be driven by misattributing the on-screen hand to oneself. For the late component (P3), we found a larger effect of pain on mean amplitudes in response to third-person relative to first-person images. We speculate that the P3 may reflect a later process that enables effective recognition of others' pain in the absence of misattribution. We discuss our results in relation to self- vs other-related processing by questioning whether these ERP components are truly indexing empathy (an other-directed process) or a simple misattribution of another's pain as one's own (a self-directed process).

Basic statistical considerations for physiology: The journal Temperature toolbox

The average environmental and occupational physiologist may find statistics are difficult to interpret and use since their formal training in statistics is limited. Unfortunately, poor statistical practices can generate erroneous or at least misleading results and distorts the evidence in the scientific literature. These problems are exacerbated when statistics are used as thoughtless ritual that is performed after the data are collected. The situation is worsened when statistics are then treated as strict judgements about the data (i.e., significant versus non-significant) without a thought given to how these statistics were calculated or their practical meaning. We propose that researchers should consider statistics at every step of the research process whether that be the designing of experiments, collecting data, analysing the data or disseminating the results. When statistics are considered as an integral part of the research process, from start to finish, several problematic practices can be mitigated. Further, proper practices in disseminating the results of a study can greatly improve the quality of the literature. Within this review, we have included a number of reminders and statistical questions researchers should answer throughout the scientific process. Rather than treat statistics as a strict rule following procedure we hope that readers will use this review to stimulate a discussion around their current practices and attempt to improve them. The code to reproduce all analyses and figures within the manuscript can be found at https://doi.org/10.17605/OSF.IO/BQGDH.