Far from being something young children learn on the playground, from pop culture, or in lessons from parents, babies as young as 10 months old appear to have fundamental expectations when two individuals face off, suggesting that the importance of size in social hierarchies may be innate or develop very early in life, just as in apes and other animals.
In the study published today in the journal Science, babies watched animated cartoons showing big and small blocks bound toward one another, bump against each other, and bow deferentially. If the big block bowed to the small one, the infants stared for a long time, indicating that this bit of social choreography defied their expectations. The new work adds to a growing body of research revealing the powerful social tool kit that babies use to make sense of the world, well before most people thought they could.
"In a sense, one of the most important tasks any infant has to solve is to figure out, what is the structure of the social world," said Lotte Thomsen, a postdoctoral researcher at Harvard and assistant professor of psychology at the University of Copenhagen who led the study. "Who is friend and foe, who is superior, who is a peer."
Research into how people first perceive social hierarchies is more than just a fascinating question about early childhood. Our ability to navigate complex social situations is crucial for success in life, and also shapes people's behavior, attitudes, and opinions.
Preschoolers, researchers have found, calibrate their social interactions with a playmate depending on whether the other child is of higher or lower social rank. There has been growing concern about the role social hierarchy plays in adolescence, because of bullying in schools. Even in adulthood, people who say they prefer an abstract symbol that is a hierarchical pyramid -- instead of one that shows more egalitarian overlapping circles -- are more likely to be racist, ethnocentric, or tolerant of the persecution of others.
In the animal kingdom and across human culture, size is an important factor in establishing social hierarchies -- from an animal that puffs up to show its dominance, to kings or popes who wear big hats or sit up high.
"From my evolutionary perspective, this is an aspect of human social organization that is fundamentally important. And if it's fundamentally important, than very young children should have some predilection to be tuned into these cues from very early on," said Patricia Hawley, a professor of psychology at the University of Kansas who was not involved in the study and praised it for the way researchers systematically ruled out other possible explanations for the babies' behavior.
Since infants who are still learning their first words can't describe their thoughts, Thomsen, working with Harvard psychology professor Susan Carey, used a "looking time" experiment. Such experiments are well-established in developmental psychology, taking advantage of the fact that even young babies can formulate expectations about situations. If a scenario violates that prediction, they will stare for much longer at a screen, as if they are trying to understand what went wrong.
In the experiment, babies from 8 to 16 months old sat on a parent's lap and watched animations. A big blue block with an eye and mouth bounced from left to right. Then, a similar but smaller green block bounded in the opposite direction. Then, researchers showed the two blocks were in conflict: both started at opposite corners, and when they met in the center, they bumped into each other and reversed direction.
Two different scenarios were shown. In one, the blocks bounded toward one another, bumped, and then the small green block bowed and moved out of the way so the big blue block could continue on its way. In another, the large blue block prostrated itself in front of the small green one before moving out of the way so the little block could continue.
Researchers froze the screen after each scenario for one minute, and found that babies consistently stared longer at the unexpected scenario than the expected one -- for 20 seconds on average, instead of 12. The difference was noted in 10-month-olds, but not in the 8-month-olds.
Such experiments may sound incredibly simple, but researchers tested 144 babies and painstakingly designed a number of experiments to ensure their interpretation was correct. They determined that infants weren't staring longer at the animation because when the bigger block fell there was more mass in motion, or because babies expected that small creatures were more likely to fall down.
Such experimental techniques have fostered burgeoning interest in exploring the social abilites of babies. In 2007, J. Kiley Hamlin, now an assistant professor of psychology at the University of British Columbia, showed that infants as young as six months old prefer characters that are helpful over ones that hinder. Her lab is presently working on other social questions, such as how babies make character judgments about who deserves what.
"The idea I'm starting to come to myself is that these things are maybe fundamental to how a baby would interpret an interaction they did experience," Hamlin said. "We're really finding amazing competence across the board ... The more we test them, the more they surprise us."
For Thomsen, these questions about social hierarchies extend into school and even into adulthood. As part of her doctoral thesis, she found that adults' preference for a hierarchical pyramid symbol predicted racist and ethnocentric views. Now, she is finding that preschoolers also intuit hierarchy from looking at the abstract symbols, guessing that the top part of the pyramid represents the strongest, oldest, or most popular.
Preschoolers' preference for the overlapping icon is turning out to be a predictor of how well they share when given stickers, and how secure they feel about friendships.
"The more we understand about how social hierarchy and dominance hierarchies work and how
we recognize them and how we manipulate them -- that should ultimately also make us able to intervene and shape them in ways that are less harmful," Thomsen said.
E-mail Carolyn Y. Johnson.
About white coat notes
|White Coat Notes covers the latest from the health care industry, hospitals, doctors offices, labs, insurers, and the corridors of government. Chelsea Conaboy previously covered health care for The Philadelphia Inquirer. Write her at email@example.com. Follow her on Twitter: @cconaboy.|
Gideon Gil, Health and Science Editor
Elizabeth Comeau, Senior Health Producer