What Is Personality Psychology?

(Last Updated On: March 6, 2023)

Personality psychology is a branch of psychology that focuses on understanding different aspects of human personality.

The field of personality psychology seeks to understand what causes different personality traits. It also works to understand, diagnose, and treat problems with personality, which are known as personality disorders.

What Is Personality?

Personality is the characteristic pattern of behaviors, feelings, thoughts, and attitudes that influence how we interact with the world around us. Some things are innate, while others are influenced by factors such as upbringing and environment.

Simply put, your personality is what makes you you

Your personality plays a role in every aspect of your life, from how you spend your time to how you relate to other people. Learning more about your personality can be a helpful way to increase self-awareness.

Why Is Personality Psychology Important?

Personality psychology helps people better understand the factors that play a role in personality. It also allows us to know more about how certain personality characteristics affect behavior. 

For example, some traits are linked to higher levels of happiness and well-being. Some traits are connected to greater longevity, while others have been linked to an increased risk of illness.

According to the American Psychological Association, the study of personality focuses on two main areas.

  • The first involves studying how individuals differ in terms of different personality characteristics.
  • The second focuses on understanding how the many different aspects of personality function together to create a cohesive whole.

Personality psychology also helps mental health professionals understand disorders related to personality, such as borderline personality disorder and narcissistic personality disorder.

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Theories of Personality

Some of the best-known theories in psychology are devoted to understanding and explaining how personality develops. 

Psychosexual Theory

Sigmund Freud suggested that personality develops through a series of five psychosexual stages. At each stage, the energy of the id—the primal, instinctual part of personality—is focused on a specific area of the body. 

Freud believed that early childhood experiences play a pivotal role in the formation of personality, and believed that personality was largely completely established by the age of five. 

Psychosocial Theory

Erik Erikson was a theorist who suggested that personality develops through a series of eight psychosocial stages. At each stage, people face a developmental conflict that plays a role in developing psychological virtues. Successfully navigating these stages and conflicts leads to forming a healthy personality.

While Freud’s theory stressed that personality is formed mostly in early childhood, Erikson that a person’s personality continues to develop throughout life.

Humanistic Theory

Humanistic psychology is a perspective that stresses the positive side of human nature. One humanist theory, Maslow’s hierarchy of needs, suggests that humans are motivated to reach a state of self-actualization marked by a coherent, cohesive personality. 

Carl Rogers, another humanist psychologist, believed that when a person’s perceived self and ideal self are aligned, it is a sign of a healthy personality.

Trait Theory

Trait theories of personality suggest that personality comprises several different traits or broad dispositions. There have been many different trait theories, but one of the most widely accepted today is the big 5 theory

The big 5 theory suggests that personality is made up of five broad dimensions—agreeableness, conscientiousness, extroversion, neuroticism, and openness. Each of these traits is a continuum, so you can be either high, low, or somewhere in the middle on each trait.

What’s Your Personality Type?

There are a number of different ways to measure and assess personality. Some of these measurements are tests, inventories, and assessments that may be used for a variety of purposes. Sometimes these tests are used to help assess psychological disorders or for pre-employment screening. 

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In other instances, these inventories are used to tell people more about what is known as their personality type. The idea of personality types is popular, but also somewhat controversial. Many of these personality typologies lack scientific support, while others are too simplistic to fully describe personality. 

Some of the most popular personality typologies include:

Personality tests can be fun and interesting, but you should use caution and not take your results too seriously. Most of the online tests you encounter are not formal assessments, so you should not use the results to diagnose yourself. 

Personality Disorders

Personality psychology also seeks to understand personality disorders. These personality disorders create problems relating to others and problems with thinking and behavior. 

The Diagnostic and Statistical Manual of Mental Disorders (DSM-5-TR) recognizes 10 different personality disorders: 

  • Antisocial personality disorder
  • Avoidant personality disorder
  • Borderline personality disorder
  • Dependent personality disorder
  • Histrionic personality disorder
  • Narcissistic personality disorder
  • Obsessive-compulsive personality disorder
  • Paranoid personality disorder
  • Schizoid personality disorder
  • Schizotypal personality disorder

Treatments for these conditions vary depending on the specific diagnosis but may involve medication, psychotherapy, psychoeducation, and skills training.

The National Institute of Mental Health (NIHM) suggests that just over 9% of adults in the U.S. experience symptoms of one or more personality disorders each year.

Frequently Asked Questions

What are the four personality types?

A large-scale study published in 2018 in the journal Nature Human Behavior found evidence that there are at least four main personality types, which are based on how much they display the big 5 traits.

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These four personality types are: 

  • Average: Fairly conscientious and agreeable, high on extroversion and neuroticism, and low on openness.
  • Reserved: Average in most domains, but low on openness and neuroticism.
  • Self-centered: High on extroversion and low on openness, agreeableness, and conscientiousness.
  • Role model: High on extroversion, conscientiousness, and agreeableness, and low on neuroticism.

What is the rarest personality type?

Of the 16 MBTI personality types, the INFJ type is considered the rarest, with just 1.5% of the population having the type. The INFJ, which stands for introverted, intuitive, feeling, and sensing, is thoughtful and tends to seek meaning in life. They are also described as imaginative, sensitive, and deeply compassionate.


American Psychological Association. Personality.

Fajkowska M, Kreitler S. Status of the trait concept in contemporary personality psychology: are the old questions still the burning questions?. J Pers. 2018;86(1):5-11.doi:10.1111/jopy.12335

National Institute of Mental Health. Personality disorders.

Gerlach M, Farb B, Revelle W, Nunes Amaral LA. A robust data-driven approach identifies four personality types across four large data sets. Nat Hum Behav. 2018;2(10):735-742. doi:10.1038/s41562-018-0419-z

16 Personalities. Advocate personality: INFJ-A/INFJ-T