Successful social behavior includes learning to accurately assess those with whom we come into contact so we can identify friends and foes, and express approval and disapproval of others’ actions. When do these skills emerge and how do they develop? Are babies aware of social nuances in human interactions? How can we find out what babies and young children think about people’s behavior?

At five months, infants saw things in black and white: giving was good; taking away was bad. But when they were eight months old, the response was different.

A recent study, published in the Proceedings of the National Academy of Science, sheds some light on the complex subject of moral awareness and social judgment. It appears to develop very early in life.

The study used puppets to act out different social situations to test infants’ responses. One scenario featured a puppet that was trying to get a ball out of a box while other puppets were either helpful to or obstructive towards that effort. The helpful puppets helped open the box while the obstructive puppet tried to keep it closed.

A second group of puppets was then introduced. These either took away or gave toys to the helpful or obstructive puppets from the first scene. The researchers wondered whether the infants would prefer the puppets that “acted kindly” and gave the puppets toys or would they prefer the puppets that were “mean” and took toys away. At age five months, the infants preferred the puppets who gave toys, regardless of whether toys were given to helpers or obstructers. At five months, infants saw things in black and white: giving was good; taking away was bad.

But when they were eight months old, the response was different. These older infants also liked the puppets that acted helpfully; but they responded more favorably towards the helpful puppets who took toys away from the puppets that had been obstructive to the original target puppet.

Giving and taking was no longer black and white. The infants were influenced by the way the puppets had treated the target and seemed to be aware of the larger context of the situation. They supported negative behavior toward puppets who had acted negatively towards the target. The researchers, from the University of British Columbia and Yale University, concluded that the older babies were able to make a socially-sophisticated connection between rewarding positive social behavior and punishing antisocial behavior.

This both supports and extends previous research which has shown that in the first six months of life, infants' social evaluations are based on simple rules that are rigidly applied: giving is good, taking away is bad. But by the second half of the first year of life infants are able to understand and factor in the context for others' behavior.

In another scenario, 21-month-old toddlers took away or gave treats to the puppets that had been either helpful or obstructive to the target puppet. These toddlers chose to give treats to the helpful puppets and to take them from the obstructive puppets. The researchers concluded that babies' ability to judge behavior in terms of who was the perpetrator and who the target continued to develop into toddlerhood, where it influenced the way infants chose to act towards the puppets.

This social ability may be culturally learned or developmentally acquired, but the researchers believe, “it may [also] stem from processes of natural selection that shaped an evolved system of social judgment that supports the stable existence of cooperation in our species.” Thus these behaviors, which begin to emerge in infancy, are critical for successful interpersonal and intra-population relationships that can help people form beneficial alliances and avoid harmful. They may also increase the likelihood of survival of the species.

The study was published online ahead of print in the November 28 issue of Proceedings of the National Academy of Sciences published on line.