Why does a simple incident like a traffic jam affect you the way it does? What makes you act the way you do around your friends and family? Why do you often see the world so differently from the way other people see it? The answer to these questions and more really comes down to one thing: your personality.

Wherever you go in life, you carry with you a large, complex set of traits, beliefs, emotional tendencies, motivations, and values that predispose you to respond to the world in certain ways. Some of these you share with virtually all other human beings; they’re part of human nature. Others, however, differ greatly between one person and another, and they help create the kind of person you are—and the kind of life you lead.

Are you outgoing and highly social, or quiet and more inclined to spend time alone?

Do you consider yourself organized or disorganized?

Do you have more energy in the mornings or in the evenings?

How much self-control would you say you have?

To understand the roots of personality is to understand motivations and influences that shape behavior, which in turn reflect how you deal with the opportunities and challenges of everyday life. Exploring the science of personality is also a chance to gain new insights that might help you better understand both yourself and the other people around you.

According to award-winning Professor Mark R. Leary of Duke University, “the quality of our lives depends in part on how well we can figure out what’s going on with other people.” And that’s the focus of his intriguing 24-lecture course, Why You Are Who You Are: Investigations into Human Personality, in which you examine the differences in people’s personalities, where these differences come from, and how they shape our everyday lives. Drawing on research in psychology, neuroscience, and genetics, Professor Leary opens the door to understanding how personality works and why. Designed as a fascinating, accessible scientific inquiry, these lectures will have you thinking about personality—your own, and that of the people around you—in a way that’s more informed and that reveals what makes you the kind of person that you are.

What Makes a Personality?

We currently understand more about how our brains work than we ever have before. But understanding personality requires more than knowing what goes on in the brain. Combining information gleaned from psychology, neuroscience, and genetics, Why You Are Who You Are will open your eyes to the myriad ways our traits, emotions, beliefs, values, and behaviors are shaped by many different influences, including the genes were inherited, how we were raised, our environment, early evolutionary processes, and more.

Professor Leary has two overarching goals for Why You Are Who You Are:

Understanding personality characteristics. You’ll learn about the most important personality variables that make people different from one another. These characteristics help to account for the variability we see among people—those traits, motives, values, beliefs, and emotional tendencies that make you, you.

Exploring the roots of personality. Why do people end up with the personalities they have? To answer this question, multiple lectures reveal where these personality characteristics come from. You’ll start with the basic biological processes that underlie personality, then go on to the roles played by culture, learning, environment, and personal experiences.

Throughout Professor Leary’s illuminating lectures, five important personality traits come into focus, traits that form the foundation of how psychologists and neuroscientists approach the topic of personality:

Extraversion. The central characteristic of this trait is sociability. People high in extraversion tend to be more gregarious and enjoy large social gatherings. (They also find it difficult to go for a long time without other people to talk to.)

Neuroticism. People higher in neuroticism tend to experience negative emotions that are more intense and long-lasting, including anxiety, sadness, anger, guilt, and regret. Some researchers call this trait “negative emotionality.”

Agreeableness. This trait involves the degree to which people generally have a positive or negative orientation toward others. At the low end are people who are unpleasant and hostile; at the high end are people who tend to be kind and sympathetic.

Conscientiousness. To what degree are you responsible and dependable? Conscientiousness comes down to whether or not you usually do what you should. Conscientious people are organized and hard-working, and exercise good self-control.

Openness. The last of the “big five” personality traits, openness reflects the degree to which people are open to new experiences and receptive to new ideas.

Why Do You Act the Way You Do?

Professor Leary expands on notions you may be familiar with (such as the nature-versus-nurture debate), shatters some commonly held myths (that self-esteem causes people to be successful and happy), and introduces you to some of the problems psychologists and other behavioral scientists obsess over as they try to understand personality (such as disentangling the vast variety of biological, social, and psychological processes that affect personality).

Here are just a few of the many ideas and topics you’ll probe throughout the lectures:

Some aspects of your personality are situation-specific, meaning you consistently behave the same way in the same sorts of situations—but you don’t necessarily behave consistently across different situations.

The fact that much of our personality operates outside our awareness, and that we can never be privy to these nonconscious influences, explains why it’s often so hard to change our behavior.

Two foundations of moral judgments—whether or not an action helps or harms another person and whether or not an action involves fairness—are nearly universal across cultures.

While people can change throughout their lives, in general, personality becomes more stable as people get older (with stability peaking somewhere between age 55 and 65).

An Engaging, Accessible Investigation

Throughout his career, Professor Leary has studied and explored the science behind our emotions, behaviors, and self-views. The author of 14 books and more than 200 scholarly articles and chapters, he has a breadth of experience he brings to every minute of Why You Are Who You Are. Throughout this course, you’ll find yourself in the company of an expert who doesn’t just know the complex science about personality—but who knows how to explain it to you in a way that makes sense.

“Sometimes, it’s really hard to see a difficult person’s redeeming qualities, no matter how hard we try,” Professor Leary says. “But the fact is, whether or not it really ‘takes all kinds,’ they’re all here anyway—us included. And the more we know about all these different kinds of people, including ourselves, the better off we’ll all be.”

The overarching goal of Why You Are Who You Are is to present the concept of personality as a vast, fascinating spectrum that offers a host of different perspectives on the nature and causes of our individual experiences of the world.