The you drink of just four months identify the exchange of saliva as a sign of emotional ties narrowaccording to a new study from the University of California, Santa Barbara (UCSB) published in the magazine Evolution and human behavior.
The research, led by Brandon Woo researcher from the Department of Psychological and Brain Sciences at UCSB in collaboration with scientists from the Harvard University and the Massachusetts Institute of Technology (MIT) reveals that infants between 4 and 6 months of age are already able to infer the closeness of a relationship from behaviors that involve saliva contact, such as sharing food or putting a finger in another’s mouth.
Scientists from UCSB, Harvard and MIT led research on social perception in early childhood (Illustrative Image Infobae)
“Children are born into a very social world. Because it is so important for children to work and collaborate with others, they need to map those social networks,” Woo said in statements reported by UCSB.
The theoretical starting point of the study is an already documented cross-cultural finding: People with close ties—family, partners, close friends—tend to be more comfortable sharing saliva with each other.. The question that guided this research was whether babies, even before having accumulated sufficient observational experience, could use this logic to interpret human relationships.
Previous work by the same team had established that, by 8 months of age, babies already use the exchange of saliva to predict that two people will respond to mutual discomfort, a sign of emotional bonding. The new study sought to determine whether that ability appears even earlier.
The first experiment compared babies’ attention to the action of sharing food versus the delivery of a ball (Illustrative Image Infobae)
The team designed of experiments with babies between 4 and 6 months. In the first, a human protagonist placed a piece of orange in his own mouth, removed it, and then inserted it into the mouth of a puppet, while another simply handed him a ball. When the puppet expressed discomfort, the researchers recorded which of the two protagonists they looked at for the longest time.
In the second experiment, a protagonist put a finger in his mouth, then touched the mouth of a puppet and put it back in his own. With another puppet he performed a similar sequence, but touching the foreheads instead of the mouths. When the protagonist “cried,” the researchers observed which of the two puppets the babies looked at for the longest, as an indicator of who they expected to respond to the discomfort.
In both cases, the babies looked longer at the individual who had shared saliva which, according to the researchers, indicates that they anticipated a supportive response from that figure to the discomfort of others.
Woo highlighted the importance of the results being consistent in both situations, including the finger in the mouth, a behavior that babies of that age rarely observe in their daily lives. “It is fascinating that they seem to have this abstract knowledge about relationships that is applied to different actions,” said the researcher in statements collected by UCSB.
The infants looked longer at the subject who shared saliva because they anticipated a supportive response to the discomfort (Illustrative Image Infobae)
The finger experiment also had a specific methodological function: to rule out that the babies were responding to the presence of food and not to the exchange of saliva itself. When the same inference is reproduced with a gesture that does not involve food, the data suggest that what infants track is saliva contact as an abstract category, not the shared object.
The findings fit into a long-standing discussion within the field of human development about the degree of innate knowledge that babies are born with. “Some academics maintain that babies are blank slates that know nothing. This work aims to understand how they begin to make sense of the social world, social relationships, and what the role of experience is,” Woo explained.
According to the team, the research also contributes to identifying what are the foundations of social knowledge in early childhood and to what extent that knowledge may precede babies’ own direct experience with the behaviors they observe.
