Two-factor models of personality

The Two-Factor Model of Personality is the most widely used psychometric factor analysis measurement of personality, behavior and temperament. It most often consists of a matrix measuring the factor of introversion and extroversion with some form of people versus task orientation.

Beginnings
From the beginning, with Galen's ancient Four Temperaments, it was observed:
 * The sanguine temperament showed quick, impulsive and relatively brief reactions.
 * The phlegmatic temperament was characterized by a longer response-delay, but the response was also short-lived.
 * The choleric temperament manifested a short response time-delay, but the response was sustained for a relatively long time.
 * The melancholic temperament (Also called "Melancholy) exhibited a long response time-delay, and the response was sustained at length, if not, seemingly, permanently.

Therefore, it was evident that the sanguine and choleric shared a common trait: quickness of response, while the melancholic and phlegmatic shared the opposite, a longer response. The melancholic and choleric, however, shared a sustained response, and the sanguine and phlegmatic shared a short-lived response. That meant, that the choleric and melancholic both would tend to hang on to emotions like anger, and thus appear more serious and critical than the fun-loving sanguine, and the peaceful phlegmatic. However, the choleric would be characterized by quick expressions of anger (like the sanguine, with the difference being that the sanguine cools off); while the melancholic would build up anger slowly, silently, before exploding. Also, the melancholic and sanguine would be sort of "opposites", as the choleric and phlegmatic, since they have opposite traits. These are the basis of the two factors that would define temperament in the modern theory.

Development
In the last few centuries, various psychologists would begin expressing the four temperaments in terms of pairs behaviors that were held in common by two temperaments each.

Ivan Pavlov (1849-1936), from his work with dogs came up with the factors of Passivity: (Active or Passive) and Extremeness: (Extreme response or Moderate response). His view of the temperaments in dogs was:
 * The Melancholic type (Weak inhibitory): categorized as "weak" dogs;
 * Choleric type (Strong excitatory): strong, unbalanced, EASILY aroused (excitable);
 * Sanguine type (Lively): strong, balanced, mobile;
 * Phlegmatic type (Calm imperturbable): strong, balanced, sluggish.

His theory of course would also be extended to humans.

Alfred Adler (1879-1937) measured "activity" (connected with "energy") against "social interest", yeiding the four "styles of Life:
 * Ruling or Dominant type: high activity, low social interest (Very energetic & aggressive in pursuing their own goals. Can exploit or manipulate others).
 * Getting or Leaning type: low activity, high social interest (Often charming, but use their charm to lean on others. Sensitive people who have developed a shell around themselves which protects them, but they must rely on others to carry them through life's difficulties and become dependent).
 * Avoiding type: low activity, low social interest (Tends to be passive-aggressive).
 * Socially Useful type: high activity, high social interest. (Copes with life's problems within a well-developed framework of social interest. Orients toward success in proper, realistic ways).

These he compared to the choleric, phlegmatic, melancholic and sanguine respectively. 

Eric Fromm's (1900-1980) factors were acquiring and assimilating things ("assimilation"), and reacting to people ("socialization"). These two factors form four types of character, which he calls Receptive, Exploitative, Hoarding and Marketing.

Also deserving mention is a single scale invented in the 1940s by Karen Horney (1885-1952). This one dimension measured "movement" towards, against and away from people. This would result in the coping strategies, in which these three "neurotic" patterns would be paired with a fourth, "healthy" one called "movement with people". These would describe behaviors associated with both extroversion and reacting to people, in which people attempt to avoid getting hurt, by either distancing themselves from others or maintaining self-sufficiency and independence on one hand; or approaching others, attempting to control or exploit them, and otherwise gain power and recognition; or "give in" to them to gain acceptance and approval, on the other.

Factors integrated into modern instruments
As the twentieth century progressed, numerous other instruments were devised measuring not only temperament, but also various individual aspects of personality and behavior, and several began using forms of extroversion and the developing category of people versus task focus as the factors.

In 1928, William Moulton Marston identified four primary emotions, each with an initial feeling tone of either pleasantness or unpleasantness. This led to his viewing people's behavior along two axes, with their attention being either "passive" or "active", depending on the individual's perception of his or her environment as either "favorable" or "antagonistic". By placing the axes at right angles, four quadrants form with each describing a behavioral pattern:
 * Dominance, which produces activity in an antagonistic environment; with a feeling of unpleasantness until stimulus is acted upon
 * Compliance, which produces produces passivity in an antagonistic environment; with a feeling of unpleasantness until stimulus is reconciled
 * Inducement, which produces activity in a favorable environment; with a feeling of pleasantness increasing as interaction increases
 * Submission, which produces passivity in a favorable environment; with a feeling of pleasantness increasing as yielding increases

This would be further developed in the 1970s by John G. Geier into the DiSC assessment System, which grades individual scales of "Dominance", "Influence", "Steadiness", and "Conscientiousness". By now, it would be classified in terms of the two factors; consisting of pairs of Extroverted or "Assertive" aspects (D, I), Introverted or "Passive" aspects (S, C), Task-oriented or "Controlled" aspects (D, C) and social or "Open" aspects (I, S).

David Merrill, an industrial psychologist and university professor in 1964 began researching predictors of success in selling and management careers, which led to the foundation of the  Social Styles model, which also gauges a person on the two dimensions of "Assertiveness" and "Responsiveness" which describe those who are more responsive as emotionally responsive or expressive and those who are less responsive as emotionally controlled. The descriptors of this dimension include people versus task focus. This yielded the styles:
 * Analytical (low Assertive + low Responsive): serious, exacting, logical; values accuracy and facts.
 * Driving (high Assertive + low Responsive): independent, practical, formal; values actions and results.
 * Expressive (high Assertive + high Responsive): animated, forceful, impulsive; values approval and spontaneity.
 * Amiable (low Assertive + high Responsive): dependable, open, supportive; values security and relationships.

In both of these, the four behaviors or styles resembled the key characteristics of the ancient four temperaments: The Choleric's extroversion and seriousness; the Melancholy's introversion and seriousness; the Sanguine's extroversion and sociability, and the Phlegmatic's peacefulness.

Tony Allessandra would follow the Social Styles model with his "Platinum Rule" Personality styles, and the factors of Indirect/Direct and Open/Guarded with the styles Thinker, Director, Socializer, and Relater.

The California Psychological Inventory's CPI 260 Instrument also has similar scales, of Initiates action, Confident in social situations versus Focuses on inner life, Values own privacy; and Rule-favoring, Likes stability, Agrees with others versus Rule-questioning, Has personal, value system, Often disagrees with others and the four "lifestyles" Leader, Supporter, Innovator, and Visualizer.

Dr. Linda V. Berens, building upon David W. Keirsey's work, would take MBTI's "I/E" scale, and pair it with a new people/task orientation scale, called "Informing/Directing" to form four Interaction Styles mapped to the MBTI's 16 types that would resemble the ancient temperaments.
 * Chart the Course (Introvrted, Directing) IST/INJ
 * In Charge (Extroverted, Directing) EST/ENJ
 * Get Things Going (Extroverted, Informing) ESF/ENP
 * Behind the Scenes (Introverted, Informing) ISF/INP

This also implies that the people/task-orientation factor is represented in the MBTI by a combination of the Thinking/Feeling and Judging and Perceiving scales. Berens herself stating "MBTI practitioners have long related task focus to a preference for Thinking and people focus to a preference for Feeling". (Understanding Yourself and Others: An Introduction to Interaction Styles Telos Publications, 2001 ISBN 0971214409)

Based directly on Fromm are LIFO's Four "orientations to life" types: Supporting-Giving, Controlling-Taking, Conserving-Holding, and Adapting-Dealing. It adds a "Leadership-Management Matrix" pairing the scale of "Leadership Skills" (Directing vs. Inspiring) with the scale of "Management Skills" (Planning vs.Doing)

Two-Factors expanded to measure more than four types
Another addition to the two factor models was the creation of a 10 by 10 square grid developed by Robert R. Blake and Jane Mouton in their Managerial Grid Model introduced in 1964. This matrix graded from 0-9, the factors of "Concern for Production" (X-axis) and "Concern for People" (Y-axis), allowing a moderate range of scores, which yielded five "leadership styles":
 * Impoverished (low X, Y)
 * Produce or Perish (high X low Y)
 * Country Club (low X high Y)
 * Team (high X and Y)
 * Middle of the Road (moderate X, Y)

The Thomas Kilmann Conflict Mode Instrument (TKI) used a version of this with "Assertiveness" and "Cooperativeness" as the two factors, also leading to a fifth mode:
 * Competing, (assertive, uncooperative)
 * Avoiding (unassertive, uncooperative)
 * Accommodating (unassertive, cooperative)
 * Collaborating (assertive, cooperative)
 * Compromising (intermediate assertiveness and cooperativeness).

FIRO-B would call the two dimensions Expressed Behavior and Wanted Behavior, and use three separate matrices for the respective areas of Inclusion (social skills) Control (leadership and responsibility-taking) and Affection (deep personal relationships). In 1977, "locator charts" were produced for each area by Dr. Leo Ryan, providing a map of the various scores, following the Managerial Grid model; with unofficial names assigned to different score ranges. They were generally grouped into five main types for each area, in the vein of the Managerial Grid and TKI, except that moderate scores (generally 4, 5) in only one dimension (with the other dimension being high or low) were given separate names, creating nine basic groups for each area (low e/w, low e/high w, low e/moderate w; etc. In the control area, there is a tenth group created by a further division of the low e high w range).

This would form the basis of the Five Temperaments theory by Dr. Richard G. and Phyllis Arno, in which the ancient temperaments were mapped to the FIRO-B scales (in all three areas), with Phlegmatic becoming the moderate e/w instead of low e/high w; which was now taken to constitute a fifth temperament called "Supine", which has many of the "introverted and relationship oriented" traits of the other types defined as such, above. (The "Wanted behavior" scale is generally renamed "'Responsive behavior"). The moderate scores mixed with high or low are designated "Phlegmatic blends" and divided with 4 being a blend of Phlegmatic with the lower adjacent temperament, and 5 being a blend with the higher adjacent temperament. This results in 13 separate ranges in each area.

Other Factor pairs
Other factors devised along the way measured other aspects of personality, mostly cognitive aspects. This would form a second strain of temperament theory; one which enjoys the most popularity today.

Immanual Kant (1724-1804) defined his typology by a duality of the beautiful and  sublime and concluded it was possible to represent the four temperaments with a square of opposition using the presence or absence of the two attributes. He determined that the phlegmatic type has no interest in either the beautiful or the sublime, so there was an absence of both (sb). The melancholic had a feeling for both (SB), and the sanguine had a predominating feeling for the beautiful, (sB) while the choleric he determined after comparing with the melancholic, lacked a sense of beauty and had only a sense of the sublime (Sb)

Hans Eysenck (1916-1997) was one of the first psychologists to analyze personality differences using a psycho-statistical method (factor analysis), and his research led him to believe that temperament is biologically based. In his book Dimensions of Personality (1947) he paired Extraversion (E) which was "the tendency to enjoy positive events", especially social ones with Neuroticism (N) which was the tendency to experience negative emotions, and By pairing the two dimensions, Eysenck noted how the results were similar to the four ancient temperaments.
 * High N, High E = Choleric
 * High N, Low E = Melancholy (also called "Melancholic")
 * Low N, High E = Sanguine
 * Low N, Low E = Phlegmatic

He later added a third dimension psychoticism, resulting in his "P-E-N" three factor model of personality. This has been correlated with two separate factors developed by The Big Five personality traits (Five Factor Model), called "agreeableness" and "conscientiousness"; the former being similar to the people/task orientation scale alaborated above. Neuroticism in Eysenck's case acted like the people/task-orientation scale (except for being inverted as to which temperaments were "high" or "low), but was later separated as a distinct factor in the Big Five.

Carl Jung in the early 20th century introduced the four factors that would become apart of the later MBTI, and these included extroversion/introversion, sensing and intuition, and thinking/feeling, which would be correlated to Agreeableness, with Judging-Perceiving roughly as Conscientiousness.

Ernst Kretschmer (1888-1964) divided personality into two "constitutional groups": Schizothymic, which contain a "Psychaesthetic proportion" between sensitive and cold poles, and Cyclothymic which contain a "Diathetic" proportion between gay and sad. The Schizoids consist of the Hyperesthetic (sensitive) and Anesthetic (Cold) characters, and the Cycloids consist of the Depressive (or "melancholic") and Hypomanic characters.

David W. Keirsey would make the connection of the two groups with Myers' Sensors and iNtuitors, providing the two factors for his four temperaments.. He would rename Sensing to "Observant" or "Concrete", and Intuiting to "Introspection" or "Abstract", and pair it with "Cooperative" versus "Pragmatic" (or "Utilitarian") which would be the "Conscientiousness scale; to form:
 * SP Artisan (Concrete, Pragmatic)
 * SJ Guardian (Concrete, Cooperative)
 * NT Rational (Abstract, Pragmatic)
 * NF Idealist (Abstract, Cooperative)

Keirsey also divided his temperaments by "Role-Informative"/Role Directive" to form eight "intelligence types"; and finally by E/I, to yield the 16 types of the MBTI. It was when his former student Berens, paired the latter two factors separately that she yielded here Interaction Styles, discussed above.

The Enneagram of Personality would map its nine types to a matrix, whose scales are "Surface Direction" and "Deep Direction". These are similar to Extroversion and people/task-orientation, but instead of the types being plotted on a scale of 0-9, Horney's original three grades of "towards", "away", and "against" were retained, and now used in both dimensions (graded respectively, as "+", "0" and "-". This changes the criteria, as the "moderate" (0) grade is considered "away", but this does not necessarily correspond to the moderate extroversion or agreebleness scores of the other instruments.