Individual Differences


Personality Types

Last updated:
29 Sep 2005


Personality type theory aims to classify people into distinct CATEGORIES. i.e. this type or that.  Personality types are synonymous with "personality styles".

Types refers to categories that are distinct and discontinuous. e.g. you are one or the other.  This is important to understand, because it helps to distinguish a personality type approach from a personality trait approach, which takes a continuous approach.

To clearly understand the difference between types and traits, consider the example of the personality dimension of "introversion".  We can view introversion as:

  • A personality type approach says you are either an introvert or an extravert

  • A personality trait approach says you can be anywhere on a continuum ranging from introversion to extraversion, with most people clustering in the middle, and fewer people towards the extremes

The following sections provide an overview of some of the more popular and commonly known personality type taxonomies.

Allport and Odbert (1936, cited in Funder, 1999) found over 17,000 words in the dictionary which referred to psychological differences between people, e.g., trustworthy, shy, arrogant.  Typically, modern personality taxonomies have emphasized between two, three, four, and five personality types, through to identifying 16 or more subtypes.

The Four Humors - Ancient Greeks (~2000 BC - 0 AD)

Ancient Greek philosophers such as Hippocrates 400 BC and Galen, 140/150 AD classified 4 types of "humors" in people.  Each type was believed to be due to an excess of one of four bodily fluids, corresponding to their character.  The personalities were termed "humors".




Corresponding Trait in the Big 5



yellow bile




black bile





Openness to experience





Somatotypes - William Sheldon, 1940's

William Sheldon (1940, 1942, cited in Phares, 1991) classified personality according to body type. He called this a personís somatotype.

Sheldon identified three main somatotypes:

Sheldon's Somatotype




Endomorph [viscerotonic]

relaxed, sociable, tolerant, comfort-loving, peaceful

plump, buxom, developed visceral structure

Mesomorph [somatotonic]

active, assertive, vigorous, combative


Ectomorph [cerebrotonic]

quiet, fragile, restrained, non-assertive, sensitive

lean, delicate, poor muscles

To further categorize a person's somatotype, an individual is given a rating from 1 to 7 on each of the three body types.  1 = very low; 7 = very high.  For example:

  • a stereotypical basketballer 1-1-7 (ectomorph)

  • Mohammed Ali 1-7-1 (mesomorph)

  • a pear-shaped person 7-1-1 (endomorph)

View drawings of the three extreme somatotypes, with physical descriptors. (Walsh)

More typically, however, the person in the street could be something like:

  • a slightly lanky person 5-2-3 (a bit ecomorphic)

  • a person of average height who is moderately muscular  4-5-3 (a bit mesomorphic)

  • a person who is slightly heavy-set 3-3-5 (a bit endomorphic)

Sheldon measured the proportions of hundreds of juvenile delinquent boys and concluded that they
were generally mesomorphs (Ornstein, 1993).

Body types have been criticized for very weak empirical methodology and are not generally used in
psychology.  The use of somatotyping (using different taxonomies) is used more often in alternative therapies and Eastern psychology and spirituality.

Ayurvedic Body Types (Doshas) (India, ~3000 BC to present)

In Ayurvedic medicine (used in India since ~3000 BC), in which there are three main metabolic body types (doshas) - Vata, Pita, & Kapha.

Ayurvedic Doshas (Sheldon Somatotype)





changeability, unpredictability, variability - in size, shape, mood, and action

moody, enthusiastic, imaginative, and impulsive, quick to grasp ideas and  good at initiating things but poor at finishing them.

energy fluctuates, with jagged peaks and valleysable, tolerant, comfort-loving, peaceful

slender with prominent features, joints, and veins, with cool, dry skin

eat and sleep erratically

prone to anxiety, insomnia, premenstrual syndrome, and constipation.



relatively predictable.

quick, articulate, biting intelligence, and can be critical or passionate with short, explosive tempers.

Efficient and moderate in daily habits, eats and sleeps regularly


medium build, strength, and endurance.

well-proportioned and easily maintains a stable weight. Often fair haired, red or blond, ruddy complexion.

tends to perspire heavily and are warm and often thirsty.

prone to acne, ulcers, hemorrhoids, and stomach ailments.




slow to anger, slow to eat, slow to act. They sleep long and heavily.

tends to procrastinate and be obstinate.

solid, heavy, and strong, with a tendency to be overweight,

slow digestion and somewhat oily hair, and cool, damp, pale skin.

prone to high cholesterol, obesity, allergies, and sinus problems.

(Table constructed from information at; Read more about Ayurveda)

Jungian Types, Myers-Briggs, & the Four Temperaments

Jungian psychological types are probably the most widely used and amongst the best-known in everyday life.  Jung's typology emerges from Jung's deep, holistic philosophy and psychology about the person.  Jung's typology is not, unfortunately, always included in mainstream personality courses, because it wasn't empirically-driven. Jung viewed the ultimate psychological task as the process of individuation, based on the strengths and limitations of one's psychological type.

Myers-Briggs developed the Myers-Briggs Type Indicator, a commercially available questionnaire, which is widely used in business and training, etc. and which provides information and exercises for better understanding one's own personality type and others with who the individual interacts and works.

Keirsey has renamed and reconceptualized the Jungian types, but they relate very closely to the Jungian types.  Keirsey refers to "temperaments" rather than personality.

Underlying all these typologies are four personality traits (functions):

Extroversion (E) --- Introversion (I)
Do you recharge your energy via external contact & activity (Extroversion) or spending time in your inner space (Introversion)?

Intuition (N) --- Sensing (S)
Do you rely on your inner voice (Intuition) or observation (Sensing)?

Thinking (T) --- Feeling (F)
When making decisions, what do you rely most on?  Your thoughts or your feelings?

Judgement (J) --- Perception (P)
Do you tend to set schedules and organize your life (Judgement), or do you tend to leave the options open and see what happens (Perception)?

Using the letters above, it is possible to have a unique 4 letter code to indicate each of the 16 Jungian personality types, e.g., I am an INTJ.

Type A / B Personalities

Meyer Friedman, an American cardiologist, noticed in the 1940's that the chairs in his waiting room got worn out from the edges.  They hypothesized that his patients were driven, impatient people, who sat on the edge of their seats when waiting.  They labelled these people "Type A" personalities.  Type A personalities are work-aholics, always busy, driven, somewhat impatient, and so on.  Type B personalities, on the other hand are laid back and easy going.  "Type A personality" has found its way into general parlance.

Read more....Type A behavior: The poorly recognized and rarely treated major coronary risk factor.

Block's Personality Types

Block (1971) identified 5 personality types among male participants in a study. These types
were found only to exist in mostly white, intelligent and relatively affluent males. A number of
subsequent studies conducted in the 1990s, however seems to bear out three of Blockís 5
identified types:

  • Well-adjusted or Resilient person: adaptable, flexible, resourceful, interpersonally

  • Overcontrolling: this is a maladjusted type; uptight, and difficult to deal with

  • Undercontrolled: another maladjusted type; impulsive, risky, delinquent or even
    criminal behaviour; unsafe sex etc.

Strengths & limitations of personality types

Type theory in general has been criticized as over-simplistic because it overlooks
the multi-dimensional and continuous nature of personality traits.

Also, some would say that Individual Differences may be qualitative not quantitative. That is
that there may be a difference in the qualities that people possess rather than, as trait theory
would have us believe, we all possess certain traits itís just a case of how much or how little
we possess (the quantity).

A key strength of the personality type approach, I think, is its simple applicability and person-centered relevance.  It can be particularly useful to complete personality type profiles for helping improve how people get along in relationships and at work.


Berlin, I. (1953). The Hedgehog and the Fox. New York, Simon & Schuster.

Funder, D. C. (2001). The Personality Puzzle (2nd ed.). New York: W. W. Norton.

Ornstein, R. (1993). The Roots of the Self: Unraveling the mystery of who we are. New York: Harper Collins.

Phares, J. E. (1991). Introduction to Personality (3rd ed.). New York: Harper Collins.

The Psychology of C. G. Jung and the Body and Temperament Types of W. H. Sheldon