Six- and 10-month-old babies are much more capable judges of character than previously thought. Not only can infants pick out a good Samaritan, they tend to identify with them, according to a Yale University study published in the journal Nature.

The study released last month presented babies with a diorama-like display of an anthropomorphic circle struggling to make it up a hill. Just when it appeared that all hope was lost, a heroic triangle appeared, and pushed the circle to the top. The round climber bounces, clearly elated to have reached the summit. The same scenario is played out again, only this time a square appears at the top of the hill and pushes the circle to the bottom.

The babies were then asked to pick a toy – the helper or the hinderer, as scientists called them. One hundred percent of 6-month-olds and 87.5 percent of 10-month-olds chose the helper. The results were consistent even when the triangle and the square swapped places as good guy and bad guy. In several other iterations of the experiment, the helper, regardless of shape or color, won out.

"Babies are very competent socially," says Kiley Hamlin, lead author of the study. "They can figure this kind of stuff out without people explicitly teaching what's nice and not nice and who's nice and who's not nice."

In another component of the study, researchers showed the circle choosing to sit with the helper or the hinderer. In this instance they found that 10-month-old babies were far more adept at noticing something seemed strange when the circle decided to sit with the hinderer. (They figured this out by how long the baby watched the helper or hinderer pair up with the circle, working under the assumption that babies, like adults, study something that appears out of the ordinary.)

While other research has shown that babies make assessments about people based on their physical appearance – they gravitate toward attractive people – these new findings show more complex levels of judgment.

"In any species that needs to cooperate as much as humans do … we always need to know who might be a good cooperator and who might not," says Ms. Hamlin.