Humans have feelings of doubt and confidence, and of certainty and uncertainty. You know if you do not know or remember -- a perfect example of this is when something is on the tip of your tongue. This ability to evaluate and predict one’s own mental performance is known as metacognition. It is one of our most sophisticated cognitive capacities and has even been thought to be uniquely human. Metacognition rivals language and tool use in its potential to reveal similarities and differences between human and animal minds. This session presents this rapidly developing area and is convened by the European Science Foundation. It will explore how newly devised experimental paradigms, testing metacognition in dolphins and monkeys, show that it is not a uniquely human talent. Moreover, the same simple, nonverbal, and perceptual tasks used to gauge animals can also be used to explore young children’s earliest metacognitive achievements -- something that has often been underestimated in existing verbal and introspective assessments. The cutting-edge transfer of experimental paradigm from comparative to developmental psychology offers surprising insight into the nature of metacognition in humans and what this means for children’s development and learning. The session will also expand on how this innovative research is profoundly affecting philosophers involved in the current debate on the theory of mind.