A volunteer in psychologist Lotte Thomsen's social understanding study.
Credit: Lotte Thomsen.
Babies understand that might makes right by the time they're 10 months old, according to a new study. The findings suggest infants have a sophisticated understanding of social interactions even before they learn to walk.
The study, reported this week in the journal Science, found that babies expect a larger individual will get his or her way in a conflict. To make that prediction, the babies have to understand on some level that individuals have goals, that they can conflict with each other, and that these conflicts have winners and losers. That's a lot of thinking for someone who can't talk much yet, but according to study researcher Lotte Thomsen, understanding social relationships is a top priority for very young children.
"Social hierarchies are everywhere in the human world," Thomsen, a professor of psychology at the University of Copenhagen, told LiveScience. "So it would make a lot of sense if infants were able to understand this aspect of their world."
Earlier research has shown that infants are savvier than one might expect. Within their first year of life, babies prefer a helpful individual to a hinderer, according to a study published in 2007 in the journal Nature. They understand other people's point of view as early as 7 months of age. By the time they're 6 months old, babies can even tell the difference between an angry dog and a playful dog.
Size is an important marker of dominance among both animals and people, Thomsen said. Mammals puff up their hair to look larger in a fight. Humans, meanwhile, bow down before kings, who are often placed on pedestals wearing crowns and clothes designed to make them look more formidable. The question, Thomsen said, was whether babies might come into the world knowing to look for size cues in social interactions.
Because you can't get a baby to verbally answer questions or fill out a survey, infant cognition researchers use a method called "violation of expectation." Babies are shown photos or videos of situations that proceed as expected, as well as images that break everyday rules. If the baby understands the rules, he or she will be bored by the expected situation and look away. But like a circus clown on the subway, the weird situation will catch the baby's eye, and he or she will stare longer.
In this case, the babies saw two blocks onscreen, both with an eye and a mouth. First, the blocks moved across the screen individually but in opposite directions, to establish that they each had a goal of crossing to the other side. Next, the babies saw the blocks try to cross simultaneously and bump into one another. After a pause, one block would bow down and scoot to the side, letting the other pass. In some cases, the subservient block was the large one, and in others, the smaller one yielded.
"Infants actually think this is really interesting," Thomsen said.
By the time they were 9 or 10 months old, the babies stared longest when the big block yielded to the little block, suggesting they knew the big block was supposed to win. Thomsen found that 8-month-olds didn't understand the interaction, while 10-month-olds were social dominance whiz kids, suggesting babies develop this social understanding between 8 and 10 months of age.
To rule out alternate explanations, such as the babies being intrigued by the relative increase in motion when the big block moved aside, the researchers conducted additional experiments. A big block that bowed and scooted away behind the little block's back elicited a collective baby yawn, suggesting the infants understood the social nature of the interaction and weren't reacting to the motion, Thomsen said.
"They showed again and again that it wasn't these potential alternative explanations," said Kiley Hamlin, an infant cognition researcher from the University of British Columbia. Hamlin, who was not involved in the study, told LiveScience the study was "really incredible."
"It's just one more example of babies showing incredible competence in an area in which we'd never imagined that they would show such competence early on," Hamlin said.
Winners and losers
The research doesn't prove that humans are born with the knowledge that size rules, Thomsen said, but babies this young are unlikely to have had many dominance struggles.
"It's very hard to see how they could learn to understand about social hierarchy from scratch before they have a language," Thomsen said. She suspects infants are born not with ingrained knowledge of hierarchy, but with a predisposition to look for relevant clues about who is in charge. As a dominance cue shared throughout the animal kingdom, size is a good candidate for this type of core concept.
Alan Fiske, an anthropologist at the University of California, Los Angeles who was not involved in the study, has long theorized that an understanding of authority is built into the human brain. The idea, Fiske told LiveScience, is that children innately understand hierarchical structures, but they have to learn how those structures work in their particular culture.
"This is really the first solid test that very, very young infants do understand," Fiske said.
The next step, Thomsen said, is to see if babies remember who is in charge from situation to situation. For example, if they saw a red block bow down to a green block, would they also expect the red block to lose a fight over a cookie?
The researchers also want to know if babies are more likely to prefer associating with winners more than losers, Thomsen said. They like helpers more than hinderers, but it's not as clear whether babies want to ingratiate themselves with whomever's in charge, or whether they identify with the underdog. It's a growing research area, Thomsen said.
"When we started the work, nobody was working on it," she said. "Now quite a lot of people are getting interested in it, so I think there's going to be a lot of interesting work coming out."
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You can follow LiveScience Senior Writer Stephanie Pappas on Twitter @sipappas.