2026-10-06 カリフォルニア大学サンタバーバラ校（UCSB）
Photo Credit:Evolution and Human Behavior
The first study sought to understand whether infants inferred a close relationship between actors who shared food versus sharing a ball
＜関連情報＞
- https://news.ucsb.edu/2026/022855/young-infants-infer-closeness-social-relationships-saliva-sharing-interactions
- https://www.sciencedirect.com/science/article/abs/pii/S109051382600139X
生後4～6ヶ月の乳児は、唾液の共有という相互作用を通して社会的親密さを推測する Four- to 6-month-old infants use saliva-sharing interactions to infer social intimacy
Brandon M. Woo, Elizabeth S. Spelke, Rebecca Saxe c, Ashley J. Thomas
Evolution and Human Behavior Available online: 1 September 2026
DOI:https://doi.org/10.1016/j.evolhumbehav.2026.106960
Abstract
People form distinctive relationships that are close, intimate, or “thick”. Across cultures, these relationships are often characterized by physical intimacy, including actions that involve sharing saliva, such as kissing or sharing foods or utensils. Recent research by Thomas et al. (2022) provides evidence that infants recognize saliva sharing as evidence of a thick relationship: Eight- to 10-month-old infants expect that two characters who share saliva will subsequently respond to each other’s distress. To constrain theories of how knowledge of thick relationships emerges in development, the current studies tested for this expectation in younger infants, who have limited experience sharing food within the family and observing other people doing so. We tested 4- to 6-month-old infants in the same paradigms that Thomas et al. (2022) used to study 8- to 10-month-old infants. We replicated the findings from older infants in this younger sample; when 4- to 6-month-old infants saw a central actor in distress, they looked longer to an actor who had previously shared saliva with the central actor than to another actor who had not. These findings suggest that 4- to 6-month-old infants distinguish thick from other social relationships.
