Synchronized arousal between performers and related spectators in a fire-walking ritual

Abstract

Collective rituals are present in all known societies, but their function is a matter of long-standing debates. Field observations suggest that they may enhance social cohesion and that their effects are not limited to those actively performing but affect the audience as well. Here we show physiological effects of synchronized arousal in a Spanish fire-walking ritual, between active participants and related spectators, but not participants and other members of the audience. We assessed arousal by heart rate dynamics and applied nonlinear mathematical analysis to heart rate data obtained from 38 participants. We compared synchronized arousal between fire-walkers and spectators. For this comparison, we used recurrence quantification analysis on individual data and cross-recurrence quantification analysis on pairs of participants' data. These methods identified fine-grained commonalities of arousal during the 30-min ritual between fire-walkers and related spectators but not unrelated spectators. This indicates that the mediating mechanism may be informational, because participants and related observers had very different bodily behavior. This study demonstrates that a collective ritual may evoke synchronized arousal over time between active participants and bystanders. It links field observations to a physiological basis and offers a unique approach for the quantification of social effects on human physiology during real-world interactions.

Fig. 1.

(A) Heart rates (beats per minute) recorded during the procession and the ritual from a representative fire-walker (blue), related spouse-spectator (red), and unrelated spectator (green). The red, blue, and pink lines mark the beginning of the ritual and the times this fire-walker and his brother cross the fire, respectively. (B) Recurrence plots for a (i) fire-walker, (ii) related spectator, and (iii) unrelated spectator just before the ritual and during the ritual at 2% recurrence rate. The red and blue lines mark the beginning of ritual and the time of shown fire-walker's walk, respectively. The x and y axes of the recurrence plots are the time axes of the shown participant's heart rate. Note: The epoch shown before the ritual was part of the procession and thus not used as the baseline.

Fig. 2.

Cross-recurrence plots of a (A) fire-walker and related spectator, (B) fire-walker and tangentially related spectator, and (C) fire-walker and unrelated spectator, at 2% recurrence rate, with the fire-walkers’ time series along the x axis and the spectators’ along the y axis. The red and blue lines mark the beginning of ritual and the time of shown fire-walker's walk, respectively. The green line marks the time of the related fire-walker's walk.

Fig. 3.

Average CRQA metrics (%DET, MAXLine, Entropy, and Laminarity) during baseline (black) and ritual (white), across three different groups of paired participants: 1, fire-walkers and related spectators; 2, fire-walkers and tangentially related spectators; and 3, fire-walkers and unrelated spectators.