Figure 1. Effects of ritual participation on self-reported affect and heart rates.

Upper left panel: Effects of ritual involvement on physiological arousal (z-transformed heart rates measured in beats-per-minute). Lower left panel: Effects of ritual involvement and time on happiness. Upper right panel: Effect of ritual involvement and time on fatigue. Lower right panel: A female fire-walker stepping onto the fire. The individual pictured has given written informed consent (as outlined in PLOS consent form) to publish this picture.