Babies Can Tell Friend From Foe

Researchers say infants make distinctions based on behaviors

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HealthDay Reporter

WEDNESDAY, Nov. 21, 2007 (HealthDay News) -- New research reveals that infants who have not yet learned language can still judge who is friend and who is foe.

Babies as young as 6 months old prefer people who cooperate versus people who hurt, and this ability could be the foundation for moral thought and action later in life, say the Yale researchers. Their study is published in the Nov. 22 issue of Nature.

"I think it is the first study that demonstrated that very young infants show some understanding of social cooperation," said Tracy Dennis, an expert on child development and assistant professor of psychology at Hunter College in New York City. "This is an important study."

Previous studies had showed that babies prefer physically attractive people, but there has been no data on whether babies judge people based on how they behave.

"We know babies evaluate others based on outside stuff, not necessarily inside stuff," said study author Kiley Hamlin, a doctoral candidate in development psychology at Yale University in New Haven, Conn. "We wanted to see whether or not babies, like adults, have evaluative mechanisms for other people based on behavior."

Kiley and her co-authors (also her advisers) conducted a series of simple experiments to gauge whether 6- and 10-month-old infants preferred social individuals ("helpers") or anti-social individuals ("hinderers").

In one experiment, the infant watched a "climber" (basically a wood puppet with large eyes glued on to it) repeatedly try to climb a hill. On the third try, the climber was either given help or was pushed back down by a puppet.

The babies were then given the chance to choose (reach out and grasp) either the helper or hinderer puppet.

"Basically, we found very high rates of choosing of the helping character," Hamlin said.

One question is whether the babies are learning the behavior, or if it's something innate. The authors argue for the latter.

"Our results suggest that infants have a pretty advanced evaluating system that doesn't need much outside input to develop. It develops at a very early age, by 6 months," Hamlin said. "They are learning lots of stuff by 6 months, however, we know that it's incredibly unlikely that parents are explicitly teaching them anything about this. The fact that they can pick up on it by 6 months suggests that it's an important skill."

In fact, being able to distinguish between friend or foe could be an important survival skill. "It's important to tell who is going to be helpful, who is going to be threatening," Hamlin noted.

But that's the evolutionary argument, and not one everyone would agree with it, Dennis pointed out.

"Even though these authors make a good argument that very young infants don't have a lot of time to learn, even some basic observation of people cooperating might be enough to make some learning take place," Dennis said. "It's important, but it's a study that people are going to debate about."

More information

Read up on child development at the U.S. Centers for Disease Control and Prevention.

SOURCES: Kiley Hamlin, doctoral student, development psychology, Yale University, New Haven, Conn.; Tracy Dennis, Ph.D., assistant professor, psychology, Hunter College, New York City; Nov. 22, 2007, Nature

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