Our work is broadly based on the perceptual and cognitive changes that occur as we accumulate experiences. We examine how people develop expertise when learning to distinguish between complex categories, and the role of awareness in everyday classification and judgment and decision-making. Some questions are more “pure” (e.g., what’s the best way to learn the visual structure of a brand new category?), while others are more “applied” (e.g., how should forensic examiners testify in court?). This work spans many different domains: radiology, rationality, fingerprint identification, face recognition, illusions, insight, and teaching and learning in higher education.