By 20 months of age, many infants are capable of a wide range of skills, from throwing a ball and using a toilet to stringing words together and finding objects. But researchers report in the Proceedings of the National Academy of Sciences that they now have evidence of babies doing more than gathering skills and knowledge—they're capable of something called metacognition, or as Donald Rumsfeld famously put it, they're aware that there are "known unknowns." What's more, they turn to caregivers when they realize they don't have an answer for something—as the researchers write, "They consciously experience their own uncertainty."
To study this, researchers at the Ecole Normal Superieure in Paris developed a non-verbal memory test to get around the fact that most infants aren't yet verbalizing the inner workings of their minds. Gathering 80 Parisian parents and their 20-month-olds, the researchers prompted the babies to remember the location of a toy hidden beneath one of two boxes after a three- to 12-second delay, reports the Atlantic. Turns out they turned to their parents for help as the problem got harder—e.g., after a longer delay, or if hidden behind a curtain. And in doing so, they guessed correctly more often. "Children are capable of learning and questioning from an extremely young age," reports Time. "This means engaging the child, not just plonking him in front of a screen. It means that even when you're playing with your baby, he or she is learning about learning." (Check out why babies smile.)