Non-targeted Metabolomics Analysis Reveals Distinct Metabolic Profiles Between Positive and Negative Emotional Tears of Humans: A Preliminary Study

Background Basal, reflex, and emotional tears differ in chemical components. It is not yet known whether chemical differences exist in tears of different emotions. We investigated the biochemical basis of emotional tears by performing non-targeted metabolomics analyses of positive and negative emotional tears of humans. Methods Samples of reflex, negative, and positive emotional tears were obtained from 12 healthy college participants (11 females and one male). Untargeted metabolomics was performed to identify metabolites in different types of tears. The differentially altered metabolites were screened and assessed using univariate and multivariate analyses. Results The orthogonal partial least squares discriminant analysis model showed that reflex, negative, and positive emotional tears were clearly separated. A total of 133 significantly differentially expressed metabolites of electrospray ionization source (ESI-) mode were identified between negative and positive emotional tears. The top 50 differentially expressed metabolites between negative and positive emotional tears were highly correlated. Pathway analysis revealed that secretion of negative emotional tears was associated with some synapses in the brain, regulation of a series of endocrine hormones, including the estrogen signaling pathway, and inflammation activities, while secretion of positive emotional tears was correlated with biotin and caffeine metabolism. Conclusions It is indicated that metabolic profiles of reflex, positive, and negative emotional tears of humans are distinct, and secretion of the tears involves distinct biological activities. Therefore, we present a chemical method for detecting human emotions, which may become a powerful tool for the diagnosis of mental diseases and the identification of fake tears.

When animals cry: The effect of adding tears to animal expressions on human judgment

At a time of growing interest in and awareness about the relationships between humans and animals, it is of relevance to scientifically analyse the intrinsic nature of these interactions. Reactions to emotional tears show our extraordinary capacity for detecting micro-nuances when judging another human’s face. Regarding such behaviour, previous studies carried out in our laboratory have pointed to an adaptive function of emotional tears: i.e. their inhibitory influence on perceived aggressiveness. In the present work we aimed to further explore that hypothesis by extending our investigation from humans to animals, using pictures of five different animal faces (cat, dog, horse, chimpanzee, hamster) to which tears were added digitally. To this end, we conducted an online study of 403 participants recruited from different social networks and academic institutions. We questioned the participants about their perceptions of emotional intensity, aggressiveness and friendliness in the animal faces and analysed the comparisons they made between faces with and without tears. In addition, a latent variable referred to as “passion for animals” was measured using different indicators. By adding the results obtained in each species and breaking them down into different basic emotions, we found that the presence of tears was related to a higher absolute frequency of participants who perceived sadness, which endorsed our previous results obtained using images of humans. Regarding aggressiveness, the presence of tears favoured the perception of less aggressiveness. A structural equation model was also conducted to explore the relations among all the measured variables. The model confirmed that the presence of tears in the animal faces had a significant influence on the perception of higher emotional intensity and friendliness, and of lower aggressiveness.

How Our Gaze Reacts to Another Person's Tears? Experimental Insights Into Eye Tracking Technology

Crying is an ubiquitous human behavior through which an emotion is expressed on the face together with visible tears and constitutes a slippery riddle for researchers. To provide an answer to the question "How our gaze reacts to another person's tears?," we made use of eye tracking technology to study a series of visual stimuli. By presenting an illustrative example through an experimental setting specifically designed to study the "tearing effect," the present work aims to offer methodological insight on how to use eye-tracking technology to study non-verbal cues. A sample of 30 healthy young women with normal visual acuity performed a within-subjects task in which they evaluated images of real faces with and without tears while their eye movements were tracked. Tears were found to be a magnet for visual attention in the task of facial attribution, facilitating a greater perception of emotional intensity. Moreover, the inspection pattern changed qualitatively and quantitatively, with our participants becoming fully focused on the tears when they were visible. The mere presence of a single tear running down a cheek was associated with an increased emotional inference and greater perception of sincerity. Using normalized and validated tools (Reading the Eyes in the Mind Test and the SALAMANCA screening test for personality disorders), we measured the influence of certain characteristics of the participants on their performance of the experimental task. On the one hand, a higher level of cognitive empathy helped to classify tearful faces with higher emotional intensity and tearless faces with less emotional intensity. On the other hand, we observed that less sincerity was attributed to the tearful faces as the SALAMANCA test scores rose in clusters A (strange and extravagant) and B (immature and emotionally unstable) of our sample. The present findings highlight the advantages of using eye tracking technology to study non-verbal cues and draw attention to methodological issues that should be taken into account. Further exploration of the relationship between empathy and tear perception could be a fruitful avenue of future research using eye tracking.

A Call for the Empirical Investigation of Tear Stimuli

Emotional crying is a uniquely human behavior, which typically elicits helping and empathic responses from observers. However, tears can also be used to deceive. "Crocodile tears" are insincere tears used to manipulate the observer and foster prosocial responses. The ability to discriminate between genuine and fabricated emotional displays is critical to social functioning. When insincere emotional displays are detected, they are most often met with backlash. Conversely, genuine displays foster prosocial responses. However, the majority of crying research conducted to date has used posed stimuli featuring artificial tears. As such it is yet to be determined how the artificial nature of these displays impacts person perception. Throughout this article, we discuss the necessity for empirical investigation of the differences (or similarities) in responses to posed and genuine tearful expressions. We will explore the recent adoption of genuine stimuli in emotion research and review the existing research using tear stimuli. We conclude by offering suggestions and considerations for future advancement of the emotional crying field through investigation of both posed and genuine tear stimuli.

Cognitive-Emotional and Inhibitory Deficits as a Window to Moral Decision-Making Difficulties Related to Exposure to Violence

In the present review, we illustrate how exposure to violence results in an increased probability of developing functional impairments of decision mechanisms necessary for moral behavior. We focus in particular on the detrimental effects of exposure to violence on emotional (e.g., Empathy), cognitive (e.g., Theory of Mind), and inhibitory control abilities. Relying on studies that document impaired moral behavior in individuals with deficits in these abilities, we propose a "model" of how exposure to violence can affect moral behavior. We then discuss how impaired moral decision making can also be a factor increasing the likelihood of reiterating violence: agents who lack abilities such as understanding and resonating with others' emotions or inhibitory control, can lead to an increase of violent displays. Thus, if not properly addressed, the noxious effects of exposure to violence on morality can lead to a violence generating cycle. We conclude proposing that interventions targeted at improving moral behavior can maximize their efficacy focusing on mitigating the impact of violence on the basic cognitive, emotional, and inhibitory abilities discussed.

Holding Back the Tears: Individual Differences in Adult Crying Proneness Reflect Attachment Orientation and Attitudes to Crying

Despite being a universal human attachment behavior, little is known about individual differences in crying. To facilitate such examination we first recommend shortened versions of the attitudes and proneness sections of the Adult Crying Inventory using two independent samples. Importantly, we examine attachment orientation differences in crying proneness and test the mediating role of attitudes toward crying in this relationship. Participants (Sample 1 N = 623, Sample 2 N = 781), completed online measures of adult attachment dimensions (avoidance and anxiety), attitudes toward crying, and crying proneness. Exploratory factor analyses in Sample 1 revealed four factors for crying attitudes: crying helps one feel better; crying is healthy; hatred of crying; and crying is controllable; and three factors for crying proneness: threat to self; sadness; and joy. Confirmatory factor analyses in Sample 2 replicated these structures. Theoretically and statistically justified short forms of each scale were created. Multiple mediation analyses revealed similar patterns of results across the two samples, with the attitudes “crying is healthy” and “crying is controllable” consistently mediating the positive links between attachment anxiety and crying proneness, and the negative links between attachment avoidance and crying proneness. Results are discussed in relation to attachment and emotion regulation literature.

Empathy Predicts an Experimental Pain Reduction During Touch

Previous studies have provided evidence for pain-alleviating effects of segmental tactile stimulation, yet the effect of social touch and its underlying mechanism is still unexplored. Considering that the soma affects the way we think, feel, and interact with others, it has been proposed that touch may communicate emotions, including empathy, interacting with the identity of the toucher. Thus, the goal of the current study was to examine the analgesic effects of social touch, and to test the moderating role of the toucher's empathy in analgesia using an ecological paradigm. Tonic heat stimuli were administered to women. Concurrently, their partners either watched or touched their hands, a stranger touched their hands, or no one interacted with them. The results revealed diminished levels of pain during partners' touch compared with all other control conditions. Furthermore, taking into account the dyadic interaction, only during the touch condition we found 1) a significant relationship between the partners' pain ratings, and 2) a significant negative relationship between the male touchers' empathy and the pain experience of their female partners. The findings highlight the powerful analgesic effect of social touch and suggest that empathy between romantic partners may explain the pain-alleviating effects of social touch.

PERSPECTIVE

Pain research mostly concentrates on different factors around a single pain target, without taking into account various social interactions with the observers. Our findings support the idea that pain perception models should be extended, taking into account some psychological characteristics of observers. Our conclusions are on the basis of advanced statistical methods.

Music training and empathy positively impact adults' sensitivity to infant distress

Crying is the most powerful auditory signal of infant need. Adults' ability to perceive and respond to crying is important for infant survival and in the provision of care. This study investigated a number of listener variables that might impact on adults' perception of infant cry distress, namely parental status, musical training, and empathy. Sensitivity to infant distress was tested using a previously validated task, which experimentally manipulated distress by varying the pitch of infant cries. This task required that participants discriminate between pitch differences and interpret these as differences in infant distress. Parents with musical training showed a significant advantage on this task when compared with parents without. The extent of the advantage was correlated with the amount of self-reported musical training. For non-parents, individual differences in empathy were associated with task performance, with higher empathy scores corresponding to greater sensitivity to infant distress. We suggest that sensitivity to infant distress can be impacted by a number of listener variables, and may be amenable to training.