Personality Psychology: Definition, Examples, & Theories

By Beth Birenbaum, MPH
​Reviewed by Tchiki Davis, M.A., Ph.D.
Personality psychology studies why different personalities develop and how they function. Read on to find out more about this fascinating field.​
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We all have an idea of what personality is. But how do we measure and study it? How do we even define it? These are some things personality psychology aims to do. Not only can this field of psychology provide useful diagnostic tools for mental health professions, but it can also improve self-awareness. ​
In this article, we’ll describe different personality theories and take a look at factors that contribute to individual personality differences. We’ll also look at how these differences affect our functioning.
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What Is Personality Psychology? (A Definition)

Personality psychology studies individual differences in thoughts, feelings, and behaviors that persist over time and place (Roberts & Yoon, 2022). It also attempts to define personality, determine how it develops and operates, and investigate unique variations including personality disorders (APA, 2023a). That is, personality psychology studies individual differences that make us who we are.

Personality Psychology Tests

Most of us have probably taken some kind of personality test—they’re all over the Internet. These are designed to get a better idea of our unique characteristics. They’re used by employers to help with hiring, by mental health professionals as diagnostic tools, and for entertainment. We also use them as a guide to gain self-awareness for things like helping to decide on a career. 

I took one recently, and when I first got the results, I thought, “Yeah, that’s me!” But then as I dove in deeper, some things just didn't fit at all. And then I start to wonder how everyone can fit into one of these categories. 

Researchers continue to debate how accurately these tests reflect individual personalities, and some show more validity than others (Laajaj et al., 2019). So although these personality surveys are popular and can be fun to take, I’d view them with some healthy skepticism.

Below are some widely used tests:

  • Big Five Personality Test - This test measures personality based on the combination of five personality traits: openness, conscientiousness, agreeableness, extroversion, and neuroticism. These traits are seen as being present in everyone to varying degrees. 
  • HEXACO Personality Inventory - This is similar to the Big Five as it consists of a questionnaire to measure personality traits. But in addition to the traits in the big five, it also measures honesty-humility. This test is often used in research.
  • Myers-Briggs Type Indicator - This questionnaire assigns you one of sixteen personality types. Your type is determined based on where you fall on a spectrum for these four categories: introversion/extroversion, sensing/intuition, thinking/feeling, and judging/perceiving. 
  • Minnesota Multiphasic Personality Inventory (MMPI) - This one is used mostly in a clinical setting to diagnose mental health disorders. It consists of 567 true-false questions that are intended to measure nine common mental health and behavioral issues.
  • Sixteen Personality Factor Questionnaire (16PF) - This measures 16 traits with a lengthy questionnaire. It’s considered one of the more reliable personality tests and is used for hiring, counseling, and research (Boyle et al., 2008). ​

Personality Psychology Terms

  • Personality - Defining personality can be more difficult than it seems. Does it include things like attitudes, intelligence, motives, or values? Most psychologists would agree with this definition: the stable patterns of behavior, thinking, and feeling that determine a person’s unique way of adjusting to the environment. (Coaley, 2014)
  • Traits - Traits are defined as “enduring individual characteristics that describe or determine behavior across situations'' (APA, 2023b).
  • The Big Five Traits:
    • Extroversion - This refers to how much your energy is directed outward. People that lean toward extroversion prefer to interact with people and objects rather than internally with thoughts and reflection.
    • Neuroticism - How much you tend toward depression and anxiety or conversely toward emotional stability.
    • Agreeableness - How well you get along with others. Includes characteristics like compassion and respectfulness. 
    • Openness - This refers to openness to new experiences and includes curiosity and imagination.
    • Conscientiousness - The tendency to be organized, responsible, and hardworking.
  • Determinism - The belief that all events, including human behavior, are determined by causes such as biology, environment, or experience, and that we don’t have much control over these forces.
  • Free will - “The power or capacity of a human being for self-direction” (APA, 2023c).
  • Person-situation debate - Controversy about whether personal traits or the situation has a greater influence over behavior.

Personality Psychology Theories

There are a lot of personality theories—too many to cover them all here. Some of the most prominent theories include psychodynamic, trait/type theories, behaviorism, social-learning, humanistic, and biological. 

Each of these theories offers explanations for behavior related to personality. Unfortunately, there isn’t a theory that explains all aspects of personality. Each offers strengths, drawbacks, and criticisms. 

Psychoanalysis
​
Psychodynamic theories focus on the interactions between the conscious and unconscious processes of the mind (Coaley, 2014). Also, these theories claim that our personalities develop in childhood and remain stable.

The first (and most well-known) psychodynamic theory is psychoanalysis. It was developed by psychologist Sigmund Freud in the 1890s and is considered both a theory and a treatment. Freud believed that the mind is made up of three components, and our personalities are a reflection of how these components interact with each other. He also believed that many causes of behavior, and thus our personality, come from the subconscious. 

The three components of the mind are the id, our instincts and impulses that operate beneath awareness; the superego, which is our conscience and guides morality; and the ego, which is the rational part of the mind. The ego acts as a moderator between the instinctual impulses of the id and the moralistic influence of the superego (Coaly, 2014). Psychoanalysis also includes “psychosexual” stages that we go through in childhood. Freud believed that the way we go through these stages determines personality. This brief video explains this in more detail.​

Video: Psychoanalytic Theory - What Freud Thought of Personality

A major criticism of psychodynamic theories is that there is very little scientific evidence to back them up. Another criticism is that these theories are deterministic, meaning that we have little free will over our personalities and our future. In addition, they ignore cognitive processes as a contributing factor to personality.

Trait Theories 
We tend to describe people based on characteristics. It’s natural to see one person as outgoing, charismatic, and a leader or another person as quiet and hard-working. Categorizing people in this way helps us to make sense of our complex social world (Coaley, 2014).

Trait theories “explain personality in terms of internal characteristics that are presumed to determine behavior” (APA, 2023d). They usually measure personality characteristics through questionnaires that place people on a continuum of specific traits. The Big Five personality test does this. For example, one part of the survey aims to measure how extroverted you are. According to your answers, you’re placed somewhere on the spectrum between completely extroverted to completely introverted. Most of us fall somewhere in the middle.  

Another example is the Briggs-Myers Type Indicator. This personality test evolved from a concept developed by psychologist Carl Jung, a student of Freud’s. Jung believed in the importance of interactions between the conscious and unconscious mind. But he added the idea that personality is made up of four distinct categories of observable traits (Coaley, 2014). People are placed in one of sixteen categories, which is intended to give information about your nature and act as a guide for relationships and careers. (Coaley, 2014). 

One criticism of trait theory is that people are complex, and there are just too many traits to consider. Also, trait theories describe personality, but they don’t address how or why different personalities come about.

Video: The Big Five Personality Traits

Behaviorism

​Behaviorism is based on the principle that behavior, and therefore personality, is exclusively determined by the environment. It doesn’t take into account internal processes such as thoughts and feelings. It states that behaviors are either reinforced by rewards or discouraged by punishments. Some researchers even asserted that if they could completely control someone’s environment, they could also control their thoughts and feelings. Unlike psychodynamic theories, behaviorists believe that personality develops and changes over your lifetime and adapts to your situation. 

For example, when you’re young and single, you might be super outgoing and have a busy social life. But then when you're older and have a family, your interests and behaviors might change. You prefer to be home, enjoy quiet time, and become less interested in meeting new people. Your personality changed due to your situation. 

Social-Learning Theory
​
The social-learning theory grew out of behaviorism and was developed by Albert Bandura in the 1960s. In addition to considering rewards and punishments that shape our behavior, the social-learning theory also considers the effect of cognitive processes, or mental functions, as a major driver of personality. Cognitive processes such as perception and judging interact with the environment to influence behavior. Bandura even thought that how we interpret our environment has a greater effect than the reality of the environment itself. 

Social learning theory also says that observing and then imitating others' behavior is a primary way we learn behaviors. Especially when watching others receive rewards or punishment. Check out this video on Bandura’s famous Bobo Doll experiment.​

Video: Social Learning Theory: Bandura’s Bobo Beatdown Experiments

Humanistic Theories

Humanistic theory sees people as inherently good and able to change and control their futures to obtain positive outcomes. 
​
These theories stress subjective experiences and free will in determining our personality. In opposition to behavioral theory, humanistic theories assert that free will plays a big role in creating personality despite inherent traits or our environment (Hersen et al., 2006). They also stress the influence of phenomenology, which is how our minds create our reality based on our experiences and how we interpret the world. Self-actualization, or the need to reach your full potential, is seen as another important driver of human behavior.  

Biological 

Biological theories emphasize physiological and genetic influences on personality (Khatabi & Khormaee, 2016). Although we can’t point to specific genes that cause a personality trait, researchers believe that genetics plays a significant role in personality development. Your DNA controls how your brain is structured, which is related to physiological processes such as chemicals and hormones that influence personality. For example, studies suggest that testosterone contributes to sociability (Khatibi & Khormaee, 2016). Other researchers claim that introverts have higher cortisol levels which leads them to avoid too much stimulation (Khatibi & Khormaee, 2016).  ​

Personality Psychology History

Ancient Greece

The Greeks were the first to classify personality characteristics. They conceived of four “humors”, or bodily fluids, that correspond to temperaments. The temperaments are sanguine, phlegmatics, choleric, and melancholic. They hypothesized that personality and disease were influenced by different balances of these four humors. While this concept sounds rather silly today, it did contribute to modern theories of biological causes of personality as well as the classification of personality traits and types.

The 1890s - Psyhcoanalysis

Sigmund Freud developed the first modern theory of how individual differences in character drive behavior. Psychoanalysis is both a theory and a treatment. Freud believed that we can only see the “tip of the iceberg” of how our minds work, so we need to explore the unconscious to understand ourselves (Dumont, 2012). Much of the theory examines mental illness and attempts treatment. 

Several other theories arose from psychoanalysis. Carl Jung, a student of Freud, developed the first type-based personality theory. It emerged from psychoanalysis but is less concerned with sickness and is more about describing personality based on observable characteristics. Several personality tests came out of his concepts. 

Early 1900s - Behaviorism

Behaviorism came partly from a rejection of unscientific psychodynamic theories. It catalogs behaviors as a reflection of personality, and behaviors are controlled by our environment. This theory is built on observable behaviors rather than internal processes in the subconscious. So an advantage of this theory is that it can be tested. However, behaviorists disregard internal processes like thoughts and feelings or unconscious motivations which most researchers agree also influence personality. 

Mid 1900s -  Humanism

Humanism came about as a reaction to psychodynamic and behavior theories which were viewed as too pessimistic and too deterministic. This theory of personality psychology rejects determinism and stresses subjective experiences. Expanding on original humanistic theory, in 1943 Abraham Maslow created the hierarchy of needs. This model posits that people have an innate drive to make themselves better, with the ultimate goal of self-actualization. However, these concepts are rather vague and difficult to test.

Person-Situation Debate
​
​In the 1970s, some researchers moved further away from the view that entrenched personality traits dictate behavior. They began to see the environment as the primary shaper of behavior which is also a primary concept in social psychology. This sparked the person-situation debate. This debate centered around whether behavior and personality are determined more by the characteristics of the individual or by characteristics of the situation (Roberts & Yoon, 2022). Trait theorists believed a person’s personality was consistent across situations. But others, like behaviorists, believed the situation was most important. During this time period, situation seemed to be winning the debate, and social psychology was becoming more prominent.

Now

​In the last 20 years personality psychology is having a resurgence (Roberts & Yoon, 2022) due to the popularity of new trait theories and tests that came about from the Big Five. Newer theories also address evidence about both the crucial role of biology and the environment, setting aside the person-situation debate (McCrae, 2011).

Personality Psychology vs Social Psychology

These two disciplines have a lot of overlap. Both study the way people interact with each other. They both explore reasons for individuals’ social behavior. But, personality psychology focuses on how individual characteristics affect behavior while social psychology focuses on how specific situations and society influence behavior. Personality psychology emphasizes behavior that stems from individual characteristics and internal mental processes. Social psychology is more attuned to how the environment influences personality. This is what sparked the person-situation debate (Coaley, 2014).

For example, if studying aggression, a personality psychologist might look at a trait that someone is born with. But a social psychologist might see it as a natural result of the specific situation the person is in. 

In addition, personality psychology is more correlational. It uses things like surveys to draw correlations between characteristics and behaviors. But social psychology conducts structured experiments. They compare an experimental group that received some kind of “treatment” with a control group that did not.​

Personality Psychology Facts

  • Some personality traits can predict well-being and mental health (Coaley, 2014)
  • Birth order and family size can influence personality, but maybe not in the ways that show up in popular culture (Rohrer et al., 2015). In one study, firstborns did tend to score higher on intelligence tests. But, there was no difference in things such as extroversion or conscientiousness. 
  • Some personality traits stay stable throughout life, but others change. Extraversion and openness are highest when we’re younger and decline as we age. But neuroticism and conscientiousness increase as we age. ​

Personality Psychology Topics

  • How personality develops.
  • Can personality traits be changed? 
  • Why do some traits predict well-being and mental health?
  • Free will vs determinism.
  • Are personality traits unique or universal?

How Does Personality Psychology Benefit Society? ​

Having a better understanding of what drives personality, especially characteristics that are associated with unhealthy or destructive behavior, can help psychologists develop better treatments. This makes it possible to help people make better life choices, thus supporting people to live happier, more fulfilling lives. If a greater proportion of people are leading happier, healthier lives, society as a whole benefits. ​

Personality Psychology Quotes

  • “Personality is, in fact, only a free being emphasizing and recognizing itself as such. Every man makes his own personality, he is to that extent his own creator.” - Sabine Baring-Gould
  • “The curious paradox is that when I accept myself just as I am, then I can change.” - Carl R. Rogers
  • “The human mind is generative, creative, proactive, and reflective—not just reactive.” Albert Bandura
  • “I am not what happened to me, I am what I choose to become.” - Carl G. Jung
  • “We continue to shape our own personality all our life. If we knew ourselves perfectly, we should die.” Albert Camus
  • “Personality is only ripe when a man has made the truth his own.” - Soren Kierkegaard
  • “The more you know yourself, the more patience you have for what you see in others.” - Erik Erikson

Articles Related to Personality Psychology

​Want to learn more? Check out these articles:

Books Related to Personality Psychology

If you’d like to keep learning more, here are a few books that you might be interested in.

Final Thoughts on Personality Psychology

Personality psychology is an interesting and evolving field with many theories and differing viewpoints. People are complex. Although no single theory gives a full explanation of personality differences and how it affects behavior, they all have something to offer, and each raises thought-provoking perspectives. Ultimately, personality psychology can help us understand ourselves better. This can lead to better decisions about relationships and careers, and therefore more fulfilling lives. ​

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