Humans are not the only animals capable of meta-cognition: the ability to think about their thinking. A recent article in Science Daily demonstrates that chimpanzees are capable of meta-cognition:

[C]himpanzees named items immediately and directly when they knew what was there, but they sought out more information before naming when they did not already know.

The research team said, “This pattern of behavior reflects a controlled information-seeking capacity that serves to support intelligent responding, and it strongly suggests that our closest living relative has metacognitive abilities closely related to those of humans.”