Sam Harris speaks with Barbara Tversky about how our senses of space and motion underlie our capacity for thought. They discuss the evolution of mind prior to language, the importance of imitation and gesture, the sensory and motor homunculi, the information communicated by motion, the role of “mirror neurons,” sense of direction, natural and unnatural categories, cognitive trade-offs, and other topics. Barbara Tversky is a professor emerita of Psychology at Stanford University and a Professor of Psychology and Education at Teachers College, Columbia University. She was elected to the American Academy of Arts and Sciences and is a fellow of the Cognitive Science Society, the Association for Psychological Science, and the Society for Experimental Psychology. Barbara has published more than 200 scholarly articles about memory, spatial thinking, design, and creativity. She is the author of Mind in Motion: How Action Shapes Thought.