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.