We marvel as babies develop. Today on A Moment of Science, we're going to discuss the fascinating things researchers have discovered about infants.

It's time for another round of Baby Skills, that fun and wacky guessing game that shows your baby is up to more than crying and napping. Today's question is: What can six-month-olds do better than nine- month-olds?

It turns out that six-month-olds are better than nine-month-olds at recognizing certain faces. In a recent study, scientists observed that six-month-olds are equally good at distinguishing between non-human faces, as they are at distinguishing between human faces.

Six-month-olds apparently have no trouble telling apart animal faces, but then they lose that ability by the time they turn nine months old. In contrast, as they get older, they just get better at distinguishing between human faces.

It doesn't take babies long to learn that it's more important to pay attention to human faces than to animal faces. Scientists call this phenomenon cognitive narrowing. The more human faces babies look at, the better they get at noticing individual features. At the same time, as they grow older, and their knowledge becomes more specialized, babies lose the ability to recognize animal faces, because they don't see nearly as many. As you might expect, when scientists tested this on monkeys, the opposite was true. The monkey babies got better at recognizing monkey faces.