“This is some of the first evidence that young infants are tracking other people’s social relationships,” said study coauthor Amanda L. Woodward, Ph.D., a William S. Gray Professor of Psychology at the University of Chicago.
The research offers a glimpse into humans’ earliest perceptions of the social world. The findings suggest that even nine-month-old infants — before they develop language skills or knowledge of social structures — can engage in reasoning regarding the friendliness of people toward one another.
For the study, 64 nine-month-old infants were randomly placed into groups and watched videos showing two adults. Each of the adults ate two foods and then reacted in either a positive or a negative way to each one. In some videos the adults shared the same reactions, while in others they reacted differently.
“We depicted evaluations of food because food may provide particularly salient social information,” noted co-author Katherine D. Kinzler, Ph.D, Neubauer Family Assistant Professor of Psychology at the University of Chicago.
“Eating with family and friends is inherently social, and so infants might be particularly inclined to use eating behaviors to make inferences about social relationships.”
To investigate whether babies associated food reactions with social relationships, the researchers examined how the infants responded to later videos, which showed the same adults acting either positively or negatively toward each other.
For example, in the video showing a positive interaction, the adults greeted each other with smiles and said “Hi!” in a friendly tone of voice. In the other video, the adults turned away from each other, crossed their arms and said “Hmph” in an unfriendly manner.
The researchers evaluated the babies’ reactions to the videos by measuring the amount of time the infants focused on the paused screen at the end of each video. Two sets of trained observers coded the infants’ attention.
In previous studies, researchers found that the duration of a baby’s gaze is linked to how familiar or unexpected a situation seems to them.
“When babies see something unexpected, they look longer, “explained Woodward. ”It’s out of place for them and they have to make sense of it.”
The infants’ responses to the videos suggested that they were surprised when adults who liked the same foods behaved negatively toward each other. They were also surprised when adults who disagreed about the foods behaved like friends.
“I was surprised to find that babies at this age showed such strong responses,” Woodward said.
The study suggests that even at the early age of nine months, infants know that adults who agree with each other tend to act in a friendly way in other contexts. The babies predicted that people who reacted similarly to the two foods were likely to be friends and were surprised when the videos showed something else.
“This study raises questions on how babies think about who gets along and who doesn’t,” said lead author Zoe Liberman, a doctoral student in the University of Chicago Department of Psychology.
“Parents will be interested to know that babies are keeping track of what’s going on in the world around them and are making inferences about social interactions that we previously were not aware of before this study.”