Infants judge social relationships via saliva sharing interactions

New research reveals that young infants, as young as four to six months old, can infer the closeness of social relationships by observing saliva sharing interactions. This finding, published in the journal Evolution and Human Behavior, sheds new light on how infants make sense of the social world around them. According to Brandon Woo, a researcher at the University of California, Santa Barbara's psychological and brain sciences department, infants are born into a highly social environment and must map out these social networks.

The researchers observed that infants look longer at the individual who shared saliva with another person when that person later expressed distress, suggesting an understanding of relationship thickness based on saliva sharing. This ability to infer relationship closeness through saliva sharing appears to be abstract knowledge that babies apply across different actions, even when the behavior is less common in their everyday lives.

The study not only debunks the notion that babies are blank slates with no prior knowledge but also contributes to understanding the foundations of children's social knowledge.