Personality Psychology
An open access textbook
Welcome
As the name implies, this is an open access textbook on personality psychology. I wrote it because I wanted a free resource for my students and couldn’t find one I liked. The goal is to give an up-to-date introduction to personality research from a scientific perspective.
I start with a chapter on frameworks I think are useful for orienting our questions about personality (Ch. 1). Then I pay some lip service to historical figures like Freud and Jung, who had a lot to say about personality without much data to back it up (Ch. 2). With that out of the way, we turn to the perspectives that largely inform contemporary approaches—and to current models like the Big Five and HEXACO, which we use as a reference point for the rest of the book (Ch. 3). After working through some matters of measurement (Ch. 4), and glossing over a debate that wasted literal decades in psychology (Ch. 5), we shift to a more topical approach.
From there we examine how evolutionary theory can be applied to help us understand personality (Ch. 6), because personality — like most things in biology — probably can’t be fully understood without thinking about evolution. Then we can see what cutting-edge genetics (Ch. 7) and neuroscience (Ch. 8) research can (and can’t) tell us about personality. We look at how personality relates to other psychological phenomena like emotions (Ch. 9) and motivations (Ch. 10), how personality develops (Ch. 11), and the interplay between personality and culture (Ch. 12). Finally, we ask whether and how personality can be voluntarily changed (Ch. 13).
This is meant to be a living document. I plan to update it every so often as new research advances or changes our understanding of these topics.
Corrections and suggestions are welcome by email, or you can suggest a change directly: every chapter has an Edit this page link that opens the text on GitHub, where you can fix a typo, reword something, or add a study you think belongs. It takes a free GitHub account and nothing else, and GitHub walks you through sending it to me. If you would rather flag something than fix it, Report an issue does that.
I hope you find it useful!
Contents
- Foundational Frameworks
- Past Perspectives
- Contemporary Perspectives
- Measurement Matters
- Personality Power
- Evolution and Personality
- Genetics and Personality
- Physiology and Personality
- Emotions and Personality
- Motivation and Personality
- Development and Personality
- Culture and Personality
- Personality Change
Acknowledgements
Several colleagues have improved this book by reading chapters and sending feedback:
- Dr. Andrew Grotzinger, University of Colorado Boulder, for extensive feedback on Genetics and Personality.
- Dr. Chris Miller, Fresno State, whose comments and additions greatly improved Physiology and Personality.
- Dr. Ted Schwaba for feedback on the interpretation of his 2025 study in Genetics and Personality.
Anyone who sends a correction or suggests an improvement from here on will be added to this list. If you would rather contribute without being named, that is fine too—just say so.
A note on AI
I drafted and revised these chapters myself over a couple of semesters in 2023 and 2024. I occasionally used large language models to get past writer’s block, or to rephrase something more clearly for students. I did the research and organization myself, and I take responsibility for any omissions or inaccuracies.
Three of the later chapters—Development, Culture, and Personality Change—had more AI involvement than the rest, mostly building out earlier incomplete drafts of mine. I revised all three myself.
More recently I used AI tools to convert my Word chapters and figures into the HTML, PDF, and EPUB versions here, and to publish them on this site. During that process I also accepted some suggested edits for clarity and consistency, each of which I reviewed before keeping.
License
Except where otherwise noted, this work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.
You are free to read, share, and adapt this book for noncommercial purposes, as long as you give credit and indicate any changes. Commercial rights are reserved.
Last updated October 2026.