The four tendencies:

During her multibook investigation into human nature, Gretchen Rubin realized that by asking the suspiciously simple question “How do I respond to expectations?” we gain explosive self-knowledge. Rubin discovered that people fit into Four Tendencies: Upholders, Questioners, Obligers, and Rebels. Our Tendency shapes every aspect of our behavior, so understanding this framework lets us make better decisions, meet deadlines, suffer less stress and burnout, and engage more effectively. The Four Tendencies explain why we act and why we don’t act.