From Rats To Humans, A Brain Knows When It Can't Remember

"The human brain knows what it knows. And so, it appears, does a rat brain."

"Rats have shown that they have the ability to monitor the strength of their own memories, researchers from Providence College reported this month in the journal Animal Cognition."

"Brain scientists call this sort of ability metacognition. It's a concept that became famous in 2002, when then Secretary of Defense Donald Rumsfeld explained to reporters:

There are known knowns. There are things we know we know. We also know there are known unknowns; that is to say we know there are some things we do not know.

Rumsfeld wasn't talking about rats. But he could have been, says Michael Beran, a comparative psychologist and associate professor at Georgia State University who was not part of the research."