In this chapter, you learned about the four main theories that have guided research in the psychology of personality. As you look back on them, you may ask yourself, “Why four? Couldn’t psychology settle on just one?”

There may be benefits to four, rather than “just one.” Theories are intellectual tools that help scientists explain events. Each of the theories you learned about provides a unique explanation; each, in other words, covers some aspects of personality that the other theories do not address thoroughly. In combination, then, the four theories give psychology a wide array of tools for explaining the life of individuals and the differences among them.

Psychologists in other fields have put these tools to work, as shown elsewhere in this book. Emotion researchers use the insights of personality psychology to understand why different people may have different emotional reactions in response to the same event (Chapter 10). Researchers studying nature, nurture, and genetics (Chapter 4) employ personality assessments when studying the interplay of inheritance and experience. Clinical psychologists draw on personality theories when formulating therapy strategies (Chapter 15). Motivation researchers draw on them to understand the forces that impel, and impede, human behavior (Chapter 11). “Psychology,” as Hans Eysenck (1972) put it, “is about people.” It’s no surprise, then, that the branch of the field that focuses most explicitly on the individual person—the study of personality—has such wide-ranging implications for psychology as a whole.

Chapter Review Now that you have completed this chapter, be sure to turn to Appendix B, where you will find a Chapter Summary that is useful for reviewing what you have learned about personality.