Why do we do what we do? What factors play a role in shaping our personality? What biological and social elements help configure a person's moral and emotional character? In this course, we examine landmark studies that shook standard beliefs about human nature in their time. We analyze those studies in their historical context and discuss their relevance to social, ethical, and policy debates. The studies may include research on mother love, obedience, conformity, bystander intervention in emergencies, deception, race, and gender stereotypes.