Emotional physiological responses are altered not only by external events, but also by the emotions of the people in front of us. While these interpersonal emotional linkages are considered an important aspect of empathy, it is unclear how they relate to cognitive empathy, that is, how we perceive others' emotions. We investigated the relationship between emotional linkage and emotional cognition in an experiment in which two participants estimate each other's emotions while their heart rates were measured during a thrilling joint task using a block game. We also collected data from the two observers because, in reality, in addition to understanding the emotions of the interacting partner, it is sometimes necessary to understand the emotions of a non-interacting person from a third-person perspective. The results suggest that, for game players, their own heart rate is related to perceived partner emotion, and for observers, the degree of heart rate synchrony between observers is related to perceived player emotion. Capturing emotional cognition in a joint task requires consideration of both individual emotion and interpersonal emotional linkages.

Interpersonal physiological linkage has been shown to play important roles in social activities. Studies have shown thatpeople tend to share heart rate (HR) dynamics through a joint collaborative task. In this study, we investigated whethershared HR dynamics (i.e., HR synchrony) would correlate with excitement during a joint task. Two participants played acollaborative block-stacking game (Jenga), alternating their roles as player and adviser, while their HRs being recorded.The participants evaluated their own excitement for each turn. Additional bystanders watched their playing to evaluatethe players excitement. The results showed that the players excitement increased with individual HR but also with HRsynchrony. HR synchrony also affected the evaluation of players excitement by the bystanders. These results suggestthat physiological linkage between cooperating individuals is related to the evaluation of excitement not only by playerthemselves but also by bystanders.

The automatic contagion of emotion is considered crucial in interpersonal communication. In face-to-face interac-tions, people could be both the receiver and sender of emotional content. Thus, contagion may have bidirectional influenceson the emotional states of individuals. However, many studies have mainly dealt with unidirectional contagion, such that theexpression of pain in a target entails a reaction of pain in the observer. In this study, we demonstrated bidirectional emotionalcontagion in the experience of thermal pain during interaction. Firstly, we showed that the physiological responses of dyadmembers were correlated with each other when they could interact compared to when they were impaired to see each other.Further, we demonstrated that individuals showed higher or lower physiological responses when their partners experiencedstronger or weaker stimuli respectively. Thus, people can develop similar physiological responses through interactions, and thiseffect seems to induce a change in the responsivity to stimuli.

Interpersonal physiological connection is thought to play a crucial role in group activities. A previous study with participants who had little musical experience has shown that the groups with higher heart rate synchronization were better able to perform simple drumming tasks in a coordinated manner. In the present study, we investigated whether heart-rate synchronization is associated with improvement in a complex harmonic performance of an orchestra. The subject of this study was an orchestra composed of several semi-professional and amateur musicians rehearsing a new original piece. The heart rates of sixteen musicians were simultaneously measured during a joint rehearsal. The results indicate that while the average heart rate of the musicians decreased, heart-rate synchronization among the musicians increased over the course of repeated group rehearsals. For a harmonic performance, the musicians may need to have a physiological connection to each other without their physiological arousal being too high.

Our body movements often reflect our inner states. Dance is one of the remarkable movements closely related to the emotional state. Previous studies suggest that the velocity of dance movements changes when dancers are instructed to express joyful or sad feelings through neutral gestures. However, whether a dancer’s emotions can emerge in dance movements remains unclear. We examined changes in dance movements when dancers’ emotions were naturally induced by music. In the experiment, semi-professional dancers were asked to perform the same choreography while listening to joyful or sad music or a metronome. The results revealed that joyful music increased the dancers’ heart rates, pelvic velocity, and range of motion compared to sad music and the metronome. This outcome suggests that naturally induced joyful emotions promote fast, bouncing dance movements. The dance performance could implicitly express the dancers’ inner states, which an audience might feel.

It is known that perspective-taking helps humans recognize anothers emotional state on an individual basis. Here, weinvestigated how perspectives influence emotional sharing, namely the act of understanding mood, or a relationship be-tween other people in a multiparty conversation. In order to capture the effects of perspectives on sensitivity and biasin responses, we introduced condition-specific parameters in a Bayesian item response model. The model revealed thatinterlocutors are more sensitive and biased to emotional incongruency when they give ratings for a pair including them-selves than that excluding them. This relationship holds for observers who did not participate in the conversation and tookthe respective perspectives. The findings support the assimilating effects of perspective-taking through which people canperceive mood as the target does.

Dancers vividly express joy, grief, and other emotions through their body movements, which reflect the deliberate expression of certain emotions and also the unintentional emotions. Research has shown that the speed of performers' movements varies according to the emotions deliberately expressed. However, no study has examined the non-deliberate emotions. Therefore, this study examined dancers' unintentionally exposed emotions through their movements. Seventeen semi-professional dancers performed a neutral choreography to three music types—joy-inducing music, sadness-inducing music, and a metronome—and their performances were compared. Changes in the dancers' body movements were measured using a motion-capture system. Results showed that body movements were generally faster and more dynamic with emotion-inducing music compared to the metronome. While the speed of pelvic movements was more when they danced to joy-inducing music, arm movement was more apparent for sadness-inducing music. These findings help understand the unintentional emotion-expression dynamics in dance.