Rats can reflect on their own knowledge, according to scientists at the University of Georgia. This study is the first to show that a non-primate species has metacognition — a proposal that may well be controversial. "This kind of research may change how we think about cognition and memory in animals," said Associate Professor Jonathon Crystal.

The study involved what is called a "duration-discrimination" test. The rats were offered rewards for classifying a signal as short or long. The right answer led to a large food reward, while a wrong answer led to no reward at all. The twist was that the rats were given the chance to decline the test completely. If they made that choice, they got a small reward anyway.

"If rats have knowledge about whether they know or don’t know the answer to the test, we would expect them to decline most frequently on difficult tests," said Crystal. "They would also show the lowest accuracy on difficult tests that they can’t decline. Our data showed both to be true, suggesting the rats have knowledge of their own cognitive states."

The research will also open new lines of inquiry about the differences between humans and animals. "Does it mean, for example, that rats are ‘conscious’, and could that also be true of other non- primates?" ask the researchers.