Two hearts in one room

Sit two people facing each other and ask them to talk for half an hour. During that time, their two hearts each do their own work, independently. They share no physical connection, no common signal, no mechanical reason to coordinate.

And yet researchers have been measuring, for more than forty years, that their rhythms resemble each other more during the conversation than before it. The phenomenon has a name, a literature, and limits worth knowing before getting carried away.

The study that launched the field

It is Robert Levenson and John Gottman’s, published in 1983 in the Journal of Personality and Social Psychology under the title “Marital interaction: physiological linkage and affective exchange”. Thirty married couples were recorded while they talked, sometimes about a point of disagreement, sometimes about the ordinary events of their day.

Several measures were taken from both people at once: heart rate, skin conductance, bodily movement. The degree of coupling between them accounted, on its own, for sixty percent of the differences in reported marital satisfaction. For a single physiological measure, that is a great deal.

The result surprised people by its direction: it was the couples in most difficulty who showed the strongest coupling, and the gap widened during the conflict conversation. A shared rhythm is therefore not a sign of harmony. It is a sign of intensity, which is not the same thing at all.

What has been measured since

The field has widened well beyond couples. A systematic review published in 2017 in Personality and Social Psychology Review by Palumbo and colleagues gathers the work on what the literature calls interpersonal autonomic physiology. It finds that coupling shows up in new relationships as much as in established ones, across a wide range of settings.

Other work has observed it in far less peaceful situations. Konvalinka and colleagues published in 2011, in the Proceedings of the National Academy of Sciences, the recording of a fire-walking ritual in Spain: thirty-eight people, walkers and spectators, followed through the thirty minutes of the ceremony. The rhythms of the walkers’ relatives tracked those of the walkers; those of unrelated spectators did not.

Goldstein, Weissman-Fogel and Shamay-Tsoory examined, in 2017 in Scientific Reports, what touch changes about that coupling. Twenty-two couples, one of the two in pain: the other’s physical contact increased the coordination of heart and breathing rhythms between them.

The caveats, which matter as much as the results

Reviews of this field are candid about its weaknesses, and it would be dishonest to leave them out.

• Methods vary enormously from one study to the next: what is measured, the time window considered, the way coupling is computed. Two studies can both say “synchrony” while meaning different things.
• Two curves can resemble each other without either influencing the other. Two people sitting in the same room breathe the same air, hear the same sounds, stand up at the same time. Part of the resemblance comes from the shared situation, not from the bond between them.
• The direction of the finding is not stable. Depending on the study, strong coupling accompanies sometimes a solid relationship, sometimes a struggling one. It is not a quality indicator.

In other words: the phenomenon is real and documented, its interpretation is not. Nobody knows how to read a feeling in two curves that look alike.

What it changes for an artwork

Arsentis does not measure synchrony and draws no conclusion from it. What is recorded during a capture is the variation in two people’s heartbeats, and nothing else: no sound, no image, no content of what is said.

What this body of work does provide is a reason to compose the two traces together rather than side by side. Two people in the same room for half an hour do not produce two independent recordings: something happens between them, and it is that something the composition makes visible, without claiming to name it.

A heartbeat says something happened. It never says what.

That is the limit of the medium, and it is also what makes it bearable. A work claiming to reveal what two people feel for each other would be unbearable on a wall. A work that only shows that half an hour took place, and resembled no other, can be looked at for a long time.

References

Levenson, R. W., & Gottman, J. M. (1983). Marital interaction: Physiological linkage and affective exchange. Journal of Personality and Social Psychology, 45(3), 587–597. https://doi.org/10.1037/0022-3514.45.3.587

Palumbo, R. V., Marraccini, M. E., Weyandt, L. L., Wilder-Smith, O., McGee, H. A., Liu, S., & Goodwin, M. S. (2017). Interpersonal autonomic physiology: A systematic review of the literature. Personality and Social Psychology Review, 21(2), 99–141. https://doi.org/10.1177/1088868316628405

Konvalinka, I., Xygalatas, D., Bulbulia, J., Schjødt, U., Jegindø, E.-M., Wallot, S., Van Orden, G., & Roepstorff, A. (2011). Synchronized arousal between performers and related spectators in a fire-walking ritual. Proceedings of the National Academy of Sciences, 108(20), 8514–8519. https://doi.org/10.1073/pnas.1016955108

Goldstein, P., Weissman-Fogel, I., & Shamay-Tsoory, S. G. (2017). The role of touch in regulating inter-partner physiological coupling during empathy for pain. Scientific Reports, 7(1), 3252. https://doi.org/10.1038/s41598-017-03627-7