"Are you sure?"

Whether in a court room, a doctor’s office, a gameshow’s hot seat, or a student’s desk, we are always trying to answer that question. Should we accept eyewitness testimony or a physician’s diagnosis? Do we really want to risk it all on a final question? And what should we be studying in order to do as well as possible on a test? In short, how do we know what we and others know—or as importantly, don’t know?

As cognitive neuroscientist Stephen Fleming shows in Know Thyself, we do this with metacognition. Metacognition, or thinking about thinking, is the most important tool we have for understanding our own mind. Metacognition is an awesome power: It is what enables self-awareness as well as what lets us think about the minds of others. It is the ultimate human trait, and in its most rarefied forms is a power that neither other animals, nor our current artificial intelligences, have. Metacognition teaches us the limits of our own knowledge. Once we understand what it is and how it works, we can improve our performance and make better decisions.

Know Thyself, like the metacognition itself, is equal parts scientific, philosophical, and practical. And that means, like Thinking, Fast and Slow and Predictably Irrational, it’s that rarest of books: one that can both expand our minds and change our lives.
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Stephen M. Fleming is a Sir Henry Dale Wellcome Trust/Royal Society fellow at the department of experimental psychology and principal investigator at the Wellcome Centre for Human Neuroimaging, University College London, where he leads the Metacognition Group. He lives in London.

Elizabeth Phelps is the Pershing Square Professor of Human Neuroscience at Harvard University in the Department of Psychology. She is a cognitive neuroscientist known for her research at the intersection of memory, learning, and emotion.

For more information and videos of Harvard Science Book Talks, see https://science.fas.harvard.edu/book-talks.