During development, children must learn both broad facts about the world (that dogs have four legs, for example) and information that is more specific (that the family dog is scared of snow). The study, which appeared in the journal Developmental Psychology , found that kids learn general facts so effortlessly that they often cannot tell that they learned anything new at all.
"This fact - that children thought they knew the information about categories all along - provides an interesting window into how their cognitive systems are eager to absorb general facts," said one of the researchers, Andrei Cimpian, psychology professor at the University of Illinois in the US.
The researchers said much of the previous work suggests that young children are better able to reason about concrete things in the moment.
The study shows that children are also capable of learning about broad, abstract ideas, and that learning at this level might in fact be more efficient for them. "The fact that kids' minds are especially attuned to this information is important," said Cimpian.
"If you learn about dogs as a category, then that information also applies to this dog and the dog you see tomorrow and the dog you will see in a month. Broad facts about the world provide kids with general information that helps them navigate their world."
Upon learning a previously unknown, categorical fact ("opossums make their homes in foliage," for example), the four- to seven-year-old children in the study often felt that they already knew that fact.
But when researchers gave them more specific information ("this opossum makes his home in foliage"), the children were better able to recognize that this was something they had not known before.
This difference between general, category-wide facts and specific facts was present even in the youngest children in the study, and its magnitude did not decrease with age.
Overall, though, children's ability to realize when they learned something new improved with age.