Erich Adickes, Eduard Spränger, Ernst Kretschmer, and Erich Fromm all theorized on the four temperaments (with different names) and greatly shaped our modern theories of temperament. Hans Eysenck 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. The factors he proposed in his book Dimensions of Personality were Neuroticism (N) which was the tendency to experience negative emotions, and the second was Extraversion (E) which was the tendency to enjoy positive events, especially social ones. By pairing the two dimensions, Eysenck noted how the results were similar to the four ancient temperaments.
Other researchers developed similar systems, many of which did not use the ancient temperament names, and several paired extroversion with a different factor, which would determine relationship/task-orientation. Examples are DiSC assessment, Social Styles, and a theory that adds a fifth temperament. One of the most popular today is the Keirsey Temperament Sorter, whose four temperaments were based largely on the Greek gods Apollo, Dionysus, Epimetheus and Prometheus, and were mapped to the 16 types of the Myers-Briggs Type Indicator (MBTI). They were renamed (SP=Artisan, SJ=Guardian, NF=Idealist, NT=Rational). Rather than using extroversion and introversion (E/I) and task/people focus, like other theories, KTS mapped the temperaments to "Sensing" and "Intuition" (S/N, renamed "concrete" and "abstract") paired with a new category, "Cooperative" and "pragmatic" . When "Role-Informative" and "Role-Directive" (corresponding to people/task-orientation), and finally E/I are factored in, you attain the 16 types. Finally, the Interaction Styles of Linda V. Berens combines Directing and Informing with E/I to form another group of "styles" which greatly resemble the ancient temperaments, and these are mapped together with the Keirsey Temperaments onto the 16 types.
A person described as "bilious" is mean-spirited, suspicious, and angry. This, again, is an adaptation of the old humour theory "choleric."
The disease Cholera gained its name from choler (bile).
While phlegmatics are generally self-content and kind, their shy personality can often inhibit enthusiasm in others and make themselves lazy and resistant to change. They are very consistent, relaxed, rational, curious, and observant, making them good administrators and diplomats. Like the sanguine personality, the phlegmatic has many friends. However the phlegmatic is more reliable and compassionate; these characteristics typically make the phlegmatic a more dependable friend.
One of the most current assessments of the four temperaments, Personality Dimensions was created in 2003 in Canada, utilizing the work of Linda Berens, David Keirsey, et al.
LaHaye believes there are twelve mixtures of the four temperaments, representing people who have the traits of two temperaments, called Mel-Chlor, Chlor-San, San-Phleg, Phleg-Mel, Mel-San, Chlor-Phleg; and the reverse of these: Chlor-Mel, San-Chlor, Phleg-San, Mel-Phleg, San-Mel, and Phleg-Chlor. The order of temperaments in these pairs was based on which temperament was the "dominant" one (this is usually expressed by percentages). A person can also be a blend of three temperaments. Other four-type models, such as Social Styles, also have similar blends q.v., and in the five temperament theory, the blends are defined along the three areas of "Inclusion", "Control", and "Affection". The blends expand the number of types to sixteen (twelve blends of two types, plus the four pure types) or more (for blends of three).