Past research has demonstrated that emotions can accurately be communicated via touch (e.g., Hertenstein, Keltner, App, Bulleit, and Jaskolka, 2006). In stranger female dyads, physiological linkage plays a role in the mechanism whereby this successful communication occurs, as touch strengthens and lengthens linkage (Kissel, 2020). While touch has a direct impact on physiological processes, viewing touch may have similar effects. The current study explored this possibility in regard to physiological linkage. Hertenstein et al., 2006 demonstrated that participants can correctly decode emotions from observing videos of communication via touch to the forearm and hand. The current study replicated this finding with forty-seven female participants, while also determining the levels of physiological linkage between the "live" observers and the video-recorded participants from Kissel (2020) using dynamic linear time series modeling. Results showed that physiological linkage can occur between "live" and recorded participants. Participants demonstrated longer linkage times with the initial dyad they viewed, but linkage with videoed communicators whose communications were correctly perceived by their fellow videoed receiver had a larger influence on emotion word, valence, intensity, and quadrant detection accuracy. Based on these results, physiological linkage may influence empathic accuracy in virtual settings. / Doctor of Philosophy / A common American English slang expression to state that you relate to someone on a deep personal level is "I feel you." This is a verbal expression of empathy, but what if empathy goes deeper than our thoughts or memories of similar experiences? What if our bodies experience the same emotion as the person with whom we are interacting? This is possible through the phenomenon of "physiological linkage." Physiological linkage occurs when physiological signals, such as heart rate, between interaction partners start to sync up—for example, when one person's heart rate speeds up, so does the heart rate of the person with whom they are interacting. The author's thesis study demonstrated that this linkage can occur when people communicate emotions solely through touch. But what happens if you are watching these emotion communications instead of experiencing them? The current study examined if physiological linkage occurs between people watching a video and the people emoting in the video. The results showed that linkage does occur while watching emotional touch interactions and that this can help the observer understand what these emotions are (even if the observer can see no faces and hear no voices). Touch has many health benefits, so the observation that watching recorded touch interactions can have a similar bodily effect has implications for increasing health and connectedness. This is particularly important given the limited face-to-face and touch interactions, as well as the increase in video call interactions, resulting from the COVID-19 pandemic.

Previous research has demonstrated that communication of emotion via touch is possible and occurs well-above chance levels, though the potential mechanism whereby this occurs has yet to be determined. The current study aimed to determine if physiological linkage, or the synchrony between various physiological signals between two interaction partners, played a role in successful communication of emotion via touch. Dynamic linear times series analysis was used to determine the strength and length of synchrony between the inter-beat intervals of fifty-two stranger female-female dyads (n=104, mean age=19.88) during two rounds of an emotion communication task in which they communicated a randomized list emotions to each other via forearm touch alone without being able to see their interaction partner. Results showed the highest magnitude linkage coefficients and the greatest number of consecutive lagged linked seconds during the “touch alone” communication—demonstrating that touch increases physiological linkage. Stronger and longer physiological linkage across tasks predicted emotion word, valence, intensity, and quadrant (from the circumplex model) detection accuracy. Participants serving as the initial communicator in the first round of emotion communication tended to have a greater influence on the physiology of initial receivers. Overall, greater physiological linkage as the result of touch predicted successful communication of emotion via touch and is therefore likely a portion of the mechanism underlying this phenomenon. / M.S. / People often communicate with their friends, family, and acquaintances using touch—when meeting a loved one after a long time, we might give them a particularly tight hug; to congratulate someone, we give a high five; and even in business settings, handshakes are used as a form of greeting or parting. Touch can also be used to communicate distinct emotions, just like a frown or a stern tone can communicate visually and aurally that someone is angry. However, although past research has demonstrated this communicative ability of touch, it is not yet known how touch is able to communicate emotion. The current study hypothesized that physiological linkage might play a role. Physiological linkage occurs when physiological signals, such as heart rate, between interaction partners starts to sync up—for example, when one person’s heart rate speeds up, so does the heart rate of the person with whom they are interacting. Results showed that greater levels of physiological linkage occurred in response to touch and that these increased levels of physiological linkage predicted people’s ability to successfully determine which emotion was communicated to them via touch to their forearm. All the emotions were communicated via touch alone; participants could not see or hear their interaction partner. This demonstrates how powerful communication via touch can be. Future research should examine how touch and physiological linkage can be incorporated into medical and psychological therapies.