Mary Bates in Wired:
Humans are masters of metacognition: thinking about thinking. We can evaluate what we know and what we don’t know. If you don’t know how to get somewhere, you Google directions. When studying for a test, you have an idea of which material you’re most unsure of and devote more time to it. Psychologists studying human metacognition usually rely on self-reports. Their subjects are able to simply tell the experimenter what they think. Studying metacognition in non-human animals is not as straightforward. How do you get an animal to “tell” you that it doesn’t know something? Instead of verbal reports, scientists interpret behavioral indicators of metacognition in animals. One such behavioral indicator is information seeking: If an animal doesn’t know the correct response, will it take appropriate action to seek out the information that it needs?
In studies with rhesus monkeys, apes, and two-year-old children, experimenters placed several opaque tubes horizontally in front of the subjects. Their job was to choose the one tube that contained a piece of food. When the experimenter placed the food into one of the tubes in full view of the subjects, they all chose the correct tube. But on some trials, a barrier was placed in front of the tubes so they couldn’t see which tube the experimenter loaded with food. On these trials, children, apes, and rhesus monkeys bent down to look through the tubes until they found the one with food and then chose it. This seems to indicate that they knew they were uninformed about the correct choice and thus took appropriate action to gather the information they needed.