Pain as social glue: shared pain increases cooperation

Even though painful experiences are employed within social rituals across the world, little is known about the social effects of pain. We examined the possibility that painful experiences can promote cooperation within social groups. In Experiments 1 and 2, we induced pain by asking some participants to insert their hands in ice water and to perform leg squats. In Experiment 3, we induced pain by asking some participants to eat a hot chili pepper. Participants performed these tasks in small groups. We found evidence for a causal link: Sharing painful experiences with other people, compared with a no-pain control treatment, promoted trusting interpersonal relationships by increasing perceived bonding among strangers (Experiment 1) and increased cooperation in an economic game (Experiments 2 and 3). Our findings shed light on the social effects of pain, demonstrating that shared pain may be an important trigger for group formation.