Hilary Barth is a psychological scientist working in the broad area of human cognition and development. Primary areas of interest are the development of thinking and learning about number, space, time, and probability; mathematical cognition; social cognitive development; and the development of decision making. Dr. Barth’s research program draws upon work in many disciplines, with connections to perceptual psychophysics, social psychology, comparative psychology, neuroscience, behavioral economics, philosophy, and education. Most projects in her lab involve behavioral studies of preschool children, school-aged children, and adults. Undergraduates play key roles in nearly all lab projects. Currently, the lab is supported by a grant from the National Science Foundation, awarded in 2016.