Personality Psychology

Mike Battista, M.Sc.

Personality is the pattern of thoughts, feelings, and behaviors that make a person unique.  While most of psychology deals with general principles of thought and behavior that all people have in common, personality psychology examines what makes people different from each other.  This can take the form of studying individual people, developing theories of how unique personalities develop, studying the structure of existing individual differences, and more.

A person’s personality generally develops early and remains stable throughout their lives.  Since personality affects thoughts and behaviors, it is possible for psychologists to study personality with several different methods.  However, no psychologists claim to be able to completely summarize everything about any individual.  Humans are such complex creatures, with such a variety of life experiences, that it is not currently possible to fully explain what makes each person unique.  Nonetheless, personality psychologists have discovered many properties and categories of personality that can help us understand general ways in which people differ from each other.

Personality Theories

Many theories have been proposed over the years to explain how personality develops and is expressed.  Some major approaches include:

Psychodynamic Theories

Sigmund Freud emphasized the role of unconscious desires on the development and maintenance of personality differences.  He believed that people go through different "psychosexual stages", and that people who get through all of them successfully have a healthy personality.  Those who fail to resolve issues at a certain stage can become stuck there, developing problems with their personality.  For example, problems with potty training in the Anal stage can, according to Freud, lead to an "anal retentive" personality.

Freud’s theory, as well as other psychodynamic theories, are generally hard to test scientifically.  The aspects that are testable usually fail to gain evidential support.  Therefore, psychodynamic theories are not taken seriously by most personality psychologists, and are probably not an accurate depiction of how personality develops or how people can be categorized.

Type Theories

Type theories state that people can be categorized down into a limited number of different types.  For example, people can be either introverts or extroverts, or can have Type A or Type B personalities.  The popular Myers-Briggs Type Indicator (MBTI) also categorizes people into 16 different types, based on 4 different dimensions.  People within a given type are hypothesized to be similar to each other in many important ways.  Type theories are often criticized as being overly simplistic.  Although some scales, like the MBTI, have shown some reliability and usefulness in predicting real-world outcomes, other theories have more support, or have been built from the ground up from actual observations rather than theory alone.  The Type A / B distinction has also been heavily criticized and refuted, and is considered obsolete by most personality psychologists.  The introversion / extraversion distinction certainly exists, but is now incorporated into more nuanced and accurate theories of personality (e.g., see trait theories, below).

Behavioral Theories

Behaviorist theories of personality focus on individual differences that have been learned from a person’s environment.  They propose that a person’s behavioral tendencies are formed through principles such as classical and operant conditioning.  For example, if a child is frequently rewarded for crying, they will develop an emotional personality.  Behaviorist theories of personality (and behaviorism in general) have been criticized for only paying attention to observable behavior, while ignoring internal thoughts, feelings, and unconscious factors.  While learning and conditioning certainly play a role in personality, it has become apparent that examining the inner workings of the human mind, and not behavior alone, is necessary to fully understand personality.

Biological Theories

With advancing technology, it has become possible to examine the underlying biological reasons for why people differ.  For example, it has been found that people described as extroverted are usually less aroused than introverts.  While this may seem counterintuitive, the explanation is that extroverts seek stimulation through social contact to be at a comfortable level of arousal.  Introverts, however, are already comfortably aroused, and need no further social stimulation.  Genetic studies also fall under the heading of biological theories of personality.  It has been found that almost all personality differences have a large genetic component.  That is, one’s genes cause biological differences that are expressed as personality differences (but of course, life experiences also play a large role).  Neuroscience has also made progress in personality research, determining which parts of the brain are responsible for which individual differences.  However, at this point, biology alone is not enough to understand personality.  Knowing which parts of the brain differ between people, or how much of a personality trait is genetically determined, is useless without reference to how the behavioral and cognitive consequences of personality differences are expressed in everyday life.

Trait Theories

According to trait theories, there are a number of traits that people can differ on.  Traits are habits or patterns of behavior, perception, and thoughts that tend to endure in a wide variety of situations.  For example, being outgoing (vs. shy) is a trait that could affect a person’s thoughts and reactions in any social situation.  Trait theories usually categorize a large number of traits into a smaller number of broad dimensions or factors.  Thus, people can be described on several different levels; in rough factor terms, or in more fine-grained trait terms.

The Big Five

Currently, one of the most popular and agreed-upon findings in psychology is that many traits can be grouped under about five overarching factors.  These "Big Five"[1] were discovered using an empirical approach from the start.  A nearly exhaustive list of traits was compiled, and psychologists observed which traits tended
to occur together.  Those that occur together are grouped under the same Big Five factor.  For example, people who talk a lot also tend to attend a lot of parties, and both of these traits fall under the Extraversion factor.  A rough idea of the most common and/or important dimensions that separate one person from another can be gained from scoring a person on each of the Big Five factors.
The most common labeling for the Big Five follows.  A helpful way to remember them is the acronym OCEAN.  CANOE also works.

  • Openness to Experience: Being imaginative, versus conservative and down-to-earth.  People high in Openness generally appreciate art, emotion, adventure, unusual ideas, imagination, curiosity, and variety.
  • Conscientiousness: The ability to plan behavior and control impulses versus being disorganized and spontaneous.  People high in Conscientiousness generally show self-discipline, act dutifully, and aim for achievement.
  • Extraversion: Being outgoing versus being shy.  People high in Extraversion tend to be enthusiastic in their emotions, enjoy attention from others, and seek out social activities.
  • Agreeableness: Being compassionate and cooperative versus suspicious and antagonistic.  People high in Agreeableness are generally helpful, friendly, willing to sacrifice for others, and optimistic.  People low in Agreeableness are jerks.
  • Neuroticism: Being emotional and reactive to stress versus calm and stable.  People high in Neuroticism tend to experience anger, anxiety and depression, which may affect their ability to think clearly and deal with difficult situations.

Although the discovery of the Big Five is an important advance in personality psychology, and they certainly represent some important ways in which people can differ, some researchers (e.g., Paunonen, 2000) warn that the Big Five do not fully describe human personality.  There may be dimensions and traits that do not fall into the Big Five framework, but are important when describing people in everyday life.  For example, masculinity (versus femininity) is not included in the Big Five, yet is often used to describe people.


As the above summaries should make clear, no theory of personality is completely accurate on its own.  A full understanding of how and why people are different requires consideration of biology, behavior, learning, cognition, and the relations between them.  Personality psychologists have made good progress in separating personality fact from personality fiction, but there is still much work to do.

Measuring Your Personality

    Supposed personality tests can be found everywhere, from magazines to forwarded emails to web sites to Facebook.  However, it is rare to find a free personality test that has been fully studied by personality psychologists, and if it has not, then there is no reason to believe that the test measures any actual underlying aspects of personality (other than being a sucker for crappy personality tests), or corresponds to any real-world behaviors.  Tests found outside of academic settings can be fun, but should be taken with a grain of salt.
    Some popular tests that enjoy empirical support include the Myers-Briggs Type Indicator, which categorizes people into 16 types, and the Revised NEO Personality Inventory (NEO-PI-R), which measures standing on each of the Big Five factors.  The NEO-PI-R, especially, has been shown to be a reliable instrument, and to be valid in predicting some real-world criteria (e.g., Conscientiousness predicts school performance; Conard, 2006).
    If you wish to have your own personality assessed, there are several ways to do so.  Although there are companies that will charge money to have a valid test performed and scored, most universities are always in need of volunteers for psychology research.  Personality psychology is obviously the best area to focus on, but areas like social psychology, clinical psychology, and cognitive psychology also frequently employ personality tests.  Some researchers will offer to divulge personality test results in exchange for volunteering.  Even if this is not offered, it can never hurt to ask for your results.  Studies can often be found, even if you are not a student, by contacting the psychology department directly, but psychologists also often advertise in newspapers, or in signs posted around university campuses.

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External Resources


  • Conard, M. A. (2006). Aptitude is not enough: How personality and behavior predict academic performance. Journal of Research in Personality, 40, 339-346.
  • Paunonen, S. V., & Jackson, D. N. (2000). What is beyond the Big Five? Plenty! Journal of Personality, 68, 821-835.

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