Preverbal infants affirm third-party interventions that protect victims from aggressors

• Published in: Nature human behaviour 2017-02, Vol.1 (2), p.0037, Article 0037
• Main Authors: Kanakogi, Yasuhiro, Inoue, Yasuyuki, Matsuda, Goh, Butler, David, Hiraki, Kazuo, Myowa-Yamakoshi, Masako
• Format: Article
• Language: English
• Subjects: 631/477/2811; 706/689/19/2472; Behavioral Sciences; Biomedical and Life Sciences; Experimental Psychology; Humans; Infants; Intervention; letter; Life Sciences; Microeconomics; Morality; Neurosciences; Personality and Social Psychology; Popular culture; Preschool children; Psychological processes; Third party; Victims
• ISSN: 2397-3374; 2397-3374
• DOI: 10.1038/s41562-016-0037

Protective interventions by a third party on the behalf of others are generally admired, and as such are associated with our notions of morality, justice and heroism 1 – 4 . Indeed, stories involving such third-party interventions have pervaded popular culture throughout recorded human history, in myths, books and movies. The current developmental picture is that we begin to engage in this type of intervention by preschool age. For instance, 3-year-old children intervene in harmful interactions to protect victims from bullies 5 , and furthermore, not only punish wrongdoers but also give priority to helping the victim 6 . It remains unknown, however, when we begin to affirm such interventions performed by others. Here we reveal these developmental origins in 6- and 10-month old infants ( N  = 132). After watching aggressive interactions involving a third-party agent who either interfered or did not, 6-month-old infants preferred the former. Subsequent experiments confirmed the psychological processes underlying such choices: 6-month-olds regarded the interfering agent to be protecting the victim from the aggressor, but only older infants affirmed such an intervention after considering the intentions of the interfering agent. These findings shed light upon the developmental trajectory of perceiving, understanding and performing protective third-party interventions, suggesting that our admiration for and emphasis upon such acts — so prevalent in thousands of stories across human cultures — is rooted within the preverbal infant’s mind. Over six experiments, Kanakogi et al. show that infants as young as 6 months support third-party interventions that protect victims from aggressors. This suggests that human emphasis upon such acts is rooted within the preverbal infant’s mind.