Insensitivity to Suffering: Psychopathic Traits and Perception of Others' Pain.

Despite growing evidence that psychopathy entails reduced emotional processing, the relationship between psychopathic traits and third-person pain perception is poorly understood. This study directly examined perception of others' pain in a sample of male and female students (N = 105) who completed the Self-Report Psychopathy scale (SRP-III) and the Toronto Empathy Questionnaire (TEQ). Participants watched a video of 60 one-second clips of other people experiencing pain. Following each clip, participants rated the perceived level of pain intensity and pain unpleasantness. Psychopathic traits were unrelated to response bias, suggesting that individuals high in psychopathic traits were no more or less likely to impute pain to others. However, higher levels of psychopathic traits, particularly callous affect and antisocial behavior, were associated with a decreased ability to discriminate others' pain. Sensitivity and response bias were unrelated to TEQ scores. These findings provide novel insights into the influence of psychopathic traits on emotional processing.

Corrigendum: Computer Mediated Automatic Detection of Pain-Related Behavior: Prospect, Progress, Perils.

[This corrects the article DOI: 10.3389/fpain.2021.788606.].

Unobtrusive Pain Monitoring in Older Adults With Dementia Using Pairwise and Contrastive Training.

Although pain is frequent in old age, older adults are often undertreated for pain. This is especially the case for long-term care residents with moderate to severe dementia who cannot report their pain because of cognitive impairments that accompany dementia. Nursing staff acknowledge the challenges of effectively recognizing and managing pain in long-term care facilities due to lack of human resources and, sometimes, expertise to use validated pain assessment approaches on a regular basis. Vision-based ambient monitoring will allow for frequent automated assessments so care staff could be automatically notified when signs of pain are displayed. However, existing computer vision techniques for pain detection are not validated on faces of older adults or people with dementia, and this population is not represented in existing facial expression datasets of pain. We present the first fully automated vision-based technique validated on a dementia cohort. Our contributions are threefold. First, we develop a deep learning-based computer vision system for detecting painful facial expressions on a video dataset that is collected unobtrusively from older adult participants with and without dementia. Second, we introduce a pairwise comparative inference method that calibrates to each person and is sensitive to changes in facial expression while using training data more efficiently than sequence models. Third, we introduce a fast contrastive training method that improves cross-dataset performance. Our pain estimation model outperforms baselines by a wide margin, especially when evaluated on faces of people with dementia. Pre-trained model and demo code available at https://github.com/TaatiTeam/pain_detection_demo.

Computer mediated automatic detection of pain-related behavior: prospect, progress, perils.

Pain is often characterized as a fundamentally subjective phenomenon; however, all pain assessment reduces the experience to observables, with strengths and limitations. Most evidence about pain derives from observations of pain-related behavior. There has been considerable progress in articulating the properties of behavioral indices of pain; especially, but not exclusively those based on facial expression. An abundant literature shows that a limited subset of facial actions, with homologues in several non-human species, encode pain intensity across the lifespan. Unfortunately, acquiring such measures remains prohibitively impractical in many settings because it requires trained human observers and is laborious. The advent of the field of affective computing, which applies computer vision and machine learning (CVML) techniques to the recognition of behavior, raised the prospect that advanced technology might overcome some of the constraints limiting behavioral pain assessment in clinical and research settings. Studies have shown that it is indeed possible, through CVML, to develop systems that track facial expressions of pain. There has since been an explosion of research testing models for automated pain assessment. More recently, researchers have explored the feasibility of multimodal measurement of pain-related behaviors. Commercial products that purport to enable automatic, real-time measurement of pain expression have also appeared. Though progress has been made, this field remains in its infancy and there is risk of overpromising on what can be delivered. Insufficient adherence to conventional principles for developing valid measures and drawing appropriate generalizations to identifiable populations could lead to scientifically dubious and clinically risky claims. There is a particular need for the development of databases containing samples from various settings in which pain may or may not occur, meticulously annotated according to standards that would permit sharing, subject to international privacy standards. Researchers and users need to be sensitive to the limitations of the technology (for example, the potential reification of biases that are irrelevant to the assessment of pain) and its potentially problematic social implications.

Automated vs. manual pain coding and heart rate estimations based on videos of older adults with and without dementia.

INTRODUCTION: Technological advances have allowed for the estimation of physiological indicators from video data. FaceReader™ is an automated facial analysis software that has been used widely in studies of facial expressions of emotion and was recently updated to allow for the estimation of heart rate (HR) using remote photoplethysmography (rPPG). We investigated FaceReader™-based heart rate and pain expression estimations in older adults in relation to manual coding by experts. METHODS: Using a video dataset of older adult patients with and without dementia, we assessed the relationship between FaceReader's™ HR estimations against a well-established Video Magnification (VM) algorithm during baseline and pain conditions. Furthermore, we examined the correspondence between the Facial Action Coding System (FACS)-based pain scores obtained through FaceReader™ and manual coding. RESULTS: FaceReader's™ HR estimations were correlated with VM algorithm in baseline and pain conditions. Non-verbal FaceReader™ pain scores and manual coding were also highly correlated despite discrepancies between the FaceReader™ and manual coding in the absolute value of scores based on pain-related facial action coding of the events preceding and following the pain response. CONCLUSIONS: Compared to expert manual FACS coding and optimized VM algorithm, FaceReader™ showed good results in estimating HR values and non-verbal pain scores.

Assessing the efficacy of a manual-based intervention for improving the detection of facial pain expression.

BACKGROUND: This article presents the results of a parallel-group, non-randomized, controlled study that evaluated the feasibility of an online training program for improving observer detection of facial pain expression. METHOD: Fifty-four undergraduate students attended two laboratory sessions interspersed by an intervention period where they were assigned to complete the Index of Facial Pain Expression (IFPE)-an online training environment designed to teach observers to code facial muscle movements associated with pain-or a no-contact control. Participants completed questionnaires during the first session and watched parallel versions of the Sensitivity to Expression of Pain (STEP) test during laboratory sessions. STEP tests contained excerpts of facial expressions taken from patients with shoulder pain. Reliability of coding following the IFPE was measured. Signal detection methods were applied to pain ratings to the STEP tests to calculate measures of sensitivity and response bias to facial pain expression. RESULTS: Participants took 3.5 hr to complete the IFPE. Training resulted in reliable coding of facial muscle movements associated with pain and improvements in sensitivity (from 0.75 to 0.87 in experimental relative to 0.75 to 0.80 in control), but not response bias, to facial expressions of clinical pain. Training was influenced by observer traits, including empathy, emotional intelligence (EI), and prior experience with individuals who experience chronic pain. CONCLUSIONS: The IFPE represents a brief measurement system for facial pain expression with research applicability and potential clinical utility. The IFPE could help clinicians be more sensitive to expressions of clinical pain. SIGNIFICANCE: The index of facial pain expression (IFPE) is an online training program that can improve an observer's ability to reliably detect expressions of clinical pain after as few as 3.5-hr of training.

Effect of visual stimuli of pain on empathy brain network in people with and without Autism Spectrum Disorder.

The extent to which affective empathy is impaired in Autism Spectrum Disorder (ASD) remains unclear, as some-but not all-previous neuroimaging studies investigating empathy for pain in ASD have shown similar activation levels to those of neurotypicals individuals. These inconsistent results could be due to the use of different empathy-eliciting stimuli. While some studies used pictures of faces exhibiting a painful expression, others used pictures of limbs in painful situations. In this study, we used fMRI to compare activation in areas associated with empathy processing (empathy network) for these two types of stimuli in 31 participants (16 with ASD, 15 controls). We found a group difference in the inferior frontal gyrus (IFG) and the thalamus when participants viewed stimuli of limbs in painful situations, but not when they viewed face stimuli with a painful expression. Both groups of participants activated their empathy network more when viewing pictures of limbs in painful situations than when viewing pictures of faces with a painful expression; this increased activation for limbs versus faces was significantly enhanced in controls relative to ASD participants, especially in the secondary somatosensory cortex (SII). Our findings suggest that empathy defect of people with ASD is contingent upon the type of stimuli used, and may be related to the level of Mirror Neuron System involvement, as brain regions showing group differences (IFG, SII) underlie embodiment. We discuss the potential clinical implications of our findings in terms of developing interventions boosting the empathetic abilities of people with ASD.

Typical pain experience but underestimation of others' pain: Emotion perception in self and others in autism spectrum disorder.

Difficulties in emotion perception are commonly observed in autism spectrum disorder. However, it is unclear whether these difficulties can be attributed to a general problem of relating to emotional states, or whether they specifically concern the perception of others' expressions. This study addressed this question in the context of pain, a sensory and emotional state with strong social relevance. We investigated pain evaluation in self and others in 16 male individuals with autism spectrum disorder and 16 age- and gender-matched individuals without autism spectrum disorder. Both groups had at least average intelligence and comparable levels of alexithymia and pain catastrophizing. We assessed pain reactivity by administering suprathreshold electrical pain stimulation at four intensity levels. Pain evaluation in others was investigated using dynamic facial expressions of shoulder patients experiencing pain at the same four intensity levels. Participants with autism spectrum disorder evaluated their own pain as being more intense than the pain of others, showing an underestimation bias for others' pain at all intensity levels. Conversely, in the control group, self- and other evaluations of pain intensity were comparable and positively associated. Results indicate that emotion perception difficulties in autism spectrum disorder concern the evaluation of others' emotional expressions, with no evidence for atypical experience of own emotional states.

Empathy in paediatric intensive care nurses part 1: Behavioural and psychological correlates.

AIM: To determine if differences exist between paediatric intensive care nurses and allied health professionals in empathy, secondary trauma, burnout, pain exposure and pain ratings of self and others. Early and late career differences were also examined. BACKGROUND: Nurses are routinely exposed to patient pain expression. This work context may make them vulnerable to adverse outcomes such as desensitization to patient pain or a compromise in personal well-being. DESIGN: Cross-sectional study. METHODS: Data were collected from a convenience sample of paediatric intensive care nurses (n = 27) and allied health professionals (n = 24), from September 2014-June 2015, at a Canadian health centre. Both groups completed one demographic and three behavioural scales. Participants underwent fMRI while rating the pain of infant and adult patients in a series of video clips. Data were analyzed using parametric and non-parametric methods. fMRI results are reported in a second paper. RESULTS: Nurses were significantly more likely to be exposed to pain at work than allied health professionals and scored significantly higher on dimensions of empathy, secondary trauma and burnout. Nurses scored their own pain and the pain of infant and adult patients, higher than allied health participants. Less experienced nurses had higher secondary trauma and burnout scores than more experienced nurses. CONCLUSIONS: Paediatric intensive care work demands, such as patient pain exposure, may be associated with nurse's higher report of empathy and pain in self and others, but also with higher levels of secondary trauma and burnout, when compared with allied health professionals.

Empathy in paediatric intensive care nurses part 2: Neural correlates.

AIMS: To determine if there are brain activity differences between paediatric intensive care nurses and allied health professionals during pain intensity rating tasks and test whether these differences are related to the population observed (infant or adult) and professional experience. BACKGROUND: The underestimation of patients' pain by healthcare professionals has generally been associated with patterns of change in neural response to vicarious pain, notably reduced activation in regions associated with affective sharing and increased activation in regions associated with regulation, compared with controls. Paediatric nurses, however, have recently been found to provide higher estimates of infants' pain in comparison to allied health controls, suggesting that changes in neural response of this population might be different than other health professionals. DESIGN: Cross-sectional study. METHODS: Functional MRI data were acquired from September 2014-June 2015 and used to compare changes in brain activity in 27 female paediatric care nurses and 24 allied health professionals while rating the pain of infants and adults in a series of video clips. RESULTS: Paediatric nurses rated infant and adult pain higher than allied health professionals, but the two groups' neural response only differed during observation of infant pain; paediatric nurses mainly showed significantly less activation in the medial prefrontal cortex (linked to cognitive empathy) and in the left anterior insula and inferior frontal cortex (linked to affective sharing). CONCLUSIONS: Patterns of neural activity to vicarious pain may vary across healthcare professions and patient populations and the amount of professional experience might explain part of these differences.

Repeated exposure to vicarious pain alters electrocortical processing of pain expressions.

Repeated exposure to others in pain has been shown to bias vicarious pain perception, but the neural correlates of this effect are currently not known. The current study therefore aimed at measuring electrocortical responses to facial expressions of pain following exposure to expressions of pain. To this end, a between-subject design was adopted. Participants in the Exposure group were exposed to facial expressions of intense pain, while the participants in the Control group were exposed to neutral expressions before performing the same pain detection task. As in previous studies, participants in the Exposure group showed a significantly more conservative bias when judging facial expressions pain, meaning that they were less inclined to judge moderate pain expressions as painful compared to participants in the Control group. Event-related potential analyses in response to pain or neutral expressions indicated that this effect was related to a relative decrease in the central late positive potential responses to pain expressions. Furthermore, while the early N170 response was not influenced by repeated exposure to pain expressions, the P100 component showed an adaptation effect in the Control group only. These results suggest that repeated exposure to vicarious pain do not influence early event-related potential responses to pain expressions but decreases the late central positive potential. These results are discussed in terms of changes in the perceived saliency of pain expressions following repeated exposure.

Health care providers' judgments in chronic pain: the influence of gender and trustworthiness.

Estimates of patients' pain, and judgments of their pain expression, are affected by characteristics of the observer and of the patient. In this study, we investigated the impact of high or low trustworthiness, a rapid and automatic decision made about another, and of gender and depression history on judgments made by pain clinicians and by medical students. Judges viewed a video of a patient in pain presented with a brief history and rated his or her pain, and the likelihood that it was being exaggerated, minimized, or hidden. Judges also recommended various medical and treatment options. Contrary to expectations, trustworthiness had no main effect on pain estimates or judgments, but interacted with gender producing pervasive bias. Women, particularly those rated of low trustworthiness, were estimated to have less pain and to be more likely to exaggerate it. Unexpectedly, judgments of exaggeration and pain estimates were independent. Consistent with those judgments, men were more likely to be recommended analgesics, and women to be recommended psychological treatment. Effects of depression history were inconsistent and hard to interpret. Contrary to expectations, clinicians' pain estimates were higher than medical students', and indicated less scepticism. Empathy was unrelated to these judgments. Trustworthiness merits further exploration in healthcare providers' judgments of pain authenticity and how it interacts with other characteristics of patients. Furthermore, systematic disadvantage to women showing pain is of serious concern in healthcare settings.

Preserved emotional awareness of pain in a patient with extensive bilateral damage to the insula, anterior cingulate, and amygdala.

Functional neuroimaging investigations of pain have discovered a reliable pattern of activation within limbic regions of a putative "pain matrix" that has been theorized to reflect the affective dimension of pain. To test this theory, we evaluated the experience of pain in a rare neurological patient with extensive bilateral lesions encompassing core limbic structures of the pain matrix, including the insula, anterior cingulate, and amygdala. Despite widespread damage to these regions, the patient's expression and experience of pain was intact, and at times excessive in nature. This finding was consistent across multiple pain measures including self-report, facial expression, vocalization, withdrawal reaction, and autonomic response. These results challenge the notion of a "pain matrix" and provide direct evidence that the insula, anterior cingulate, and amygdala are not necessary for feeling the suffering inherent to pain. The patient's heightened degree of pain affect further suggests that these regions may be more important for the regulation of pain rather than providing the decisive substrate for pain's conscious experience.

Observer trait anxiety is associated with response bias to patient facial pain expression independent of pain catastrophizing.

BACKGROUND: Top-down characteristics of an observer influence the detection and estimation of a sufferer's pain. A comprehensive understanding of these characteristics is important because they influence observer helping behaviours and the sufferer's experience of pain. OBJECTIVES: To examine the hypothesis that individuals who score high in trait anxiety would perceive more intense pain in others, as indicated by a larger negative response bias, and that this association would persist after adjusting for pain catastrophizing. METHODS: Healthy young adult participants (n=99; 50 male) watched videos containing excerpts of facial expressions taken from patients with shoulder pain and were asked to rate how much pain the patient was experiencing using an 11-point numerical rating scale. Sensitivity and response bias were calculated using signal detection methods. RESULTS: Trait anxiety was a predictor of response bias after statistically adjusting for pain catastrophizing and observer sex. More anxious individuals had a proclivity toward imputing greater pain to a sufferer. CONCLUSIONS: Individuals scoring higher on trait anxiety were more likely to impute pain to a sufferer. Anxious caregivers may be better able to respond with appropriate intervention once pain behaviour is detected, or they may exacerbate symptoms by engaging in excessive palliative care and solicitous behaviour.

Pain assessment in elderly adults with dementia.

Chronic pain is highly prevalent in the ageing population. Individuals with neurological disorders such as dementia are susceptible patient groups in which pain is frequently under-recognised, underestimated, and undertreated. Results from neurophysiological and neuroimaging studies showing that elderly adults are particularly susceptible to the negative effects of pain are of additional concern. The inability to successfully communicate pain in severe dementia is a major barrier to effective treatment. The systematic study of facial expressions through a computerised system has identified core features that are highly specific to the experience of pain, with potential future effects on assessment practices in people with dementia. Various observational-behavioural pain assessment instruments have been reported to be both reliable and valid in individuals with dementia. These techniques need to be interpreted in the context of observer bias, contextual variables, and the overall state of the individual's health and wellbeing.

Attentional processing of other's facial display of pain: an eye tracking study.

The present study investigated the role of observer pain catastrophizing and personal pain experience as possible moderators of attention to varying levels of facial pain expression in others. Eye movements were recorded as a direct and continuous index of attention allocation in a sample of 35 undergraduate students while viewing slides presenting picture pairs consisting of a neutral face combined with either a low, moderate, or high expressive pain face. Initial orienting of attention was measured as latency and duration of first fixation to 1 of 2 target images (i.e., neutral face vs pain face). Attentional maintenance was measured by gaze duration. With respect to initial orienting to pain, findings indicated that participants reporting low catastrophizing directed their attention more quickly to pain faces than to neutral faces, with fixation becoming increasingly faster with increasing levels of facial pain expression. In comparison, participants reporting high levels of catastrophizing showed decreased tendency to initially orient to pain faces, fixating equally quickly on neutral and pain faces. Duration of the first fixation revealed no significant effects. With respect to attentional maintenance, participants reporting high catastrophizing and pain intensity demonstrated significantly longer gaze duration for all face types (neutral and pain expression), relative to low catastrophizing counterparts. Finally, independent of catastrophizing, higher reported pain intensity contributed to decreased attentional maintenance to pain faces vs neutral faces. Theoretical implications and further research directions are discussed.

Cardiac vagal reactivity during relived sadness is predicted by affect intensity and emotional intelligence.

BACKGROUND: The induction of one particular emotion - sadness - has shown two different profiles of autonomic nervous system (ANS) response that are characterized by activation, or withdrawal in cardiac parasympathetic activation. We tested whether individual differences in emotion expression predict cardiac vagal reactivity from baseline to autobiographical sadness induction. METHODS: Respiration sinus arrhythmia (RSA(c)) was measured in 56 adults (28 men) asked to relive an episode of sadness. Participants completed an emotional intelligence (EI) test, and a measure of trait affect intensity. RESULTS: Sadness resulted in cardiac vagal activation with concomitant increase in HR suggestive of parasympathetic and sympathetic co-activation. Individual differences were observed in autonomic reactivity during sadness. Higher scores on the affect intensity measure and the emotional intelligence test predicted greater change in RSA(c) during sadness and recovery. CONCLUSION: The tendency to experience affect intensely and the ability to perceive emotions predict adaptive physiological regulation during sadness.

Racial differences in pain treatment and empathy in a Canadian sample.

BACKGROUND: Evidence of inadequate pain treatment as a result of patient race has been extensively documented, yet remains poorly understood. Previous research has indicated that nonwhite patients are significantly more likely to be undertreated for pain. OBJECTIVE: To determine whether previous findings of racial biases in pain treatment recommendations and empathy are generalizable to a sample of Canadian observers and, if so, to determine whether empathy biases mediate the pain treatment disparity. METHODS: Fifty Canadian undergraduate students (24 men and 26 women) watched videos of black and white patients exhibiting facial expressions of pain. Participants provided pain treatment decisions and reported their feelings of empathy for each patient. RESULTS: Participants demonstrated both a prowhite treatment bias and a prowhite empathy bias, reporting more empathy for white patients than black patients and prescribing more pain treatment for white patients than black patients. Empathy was found to mediate the effect of race on pain treatment. CONCLUSIONS: The results of the present study closely replicate those from a previous study of American observers, providing evidence that a prowhite bias is not a peculiar feature of the American population. These results also add support to the claim that empathy plays a crucial role in racial pain treatment disparity.