In this section, the theoretical background of applied personality theory in presented empirical research will be introduced. Biological bases of personality are thoroughly explored within well-known Eysenck's dimensional personality theory (1967). The main postulations of this theory will be presented with the special accent on biological bases of personality, i.e. extraversion and neuroticism. This will bring light on understanding the arousal theory and Brebner-Cooper's model of extraversion. In addition, Strelau's temperament theory (1983) will be presented, regarding its theoretical postulations, main temperament dimensions and its explanation within the frame of understanding the Central Nervous System functioning.
TopIntroduction To Eysenck’S Dimensional Personality Theory
McAdams and Palls (2006, p. 3) said that: “Theory is at the heart of science.” Although throughout the history of the development of personality psychology it is evident that there is a large number of personality theories, they all have three common elements: emphasis on individual personality characteristics, motivation, and the holistic approach to the study of human personality. The first component seeks to answer the question what and how do people differ from each other, and what is the structure of their personality. It is attempted to provide answers to these questions through correlation-research drafts and the traditional concepts in the context of theories are personality traits, temperament, and personality types. Within the framework of the second elements, it is attempted to answer the questions about why people do what they do, what they want, what directs their behavior, and what are the dynamics of their actions. Traditional concepts within these questions are values, needs, goals, instincts, conflicts, defenses, etc., and laboratory experiments are used in the attempt to test them. The third element is focused on the understanding of the entire person, the meaning of a person’s life, and what integrates it. Traditional concepts are the concept of ego, self-esteem, lifestyle, identity, and structure of life, which are tested by using case studies. One of the most important constructs that has experienced the longest and strongest empirical validation and whose creation is the central function of personality theories refers to extraversion. This construct is also one of those that mostly relate to biological determinants of human functioning, which is evident in biological theories that follow.
The roots of biological personality theories are associated with the first data on the theories of temperament and personality, which sought to establish basic types of personality or temperament, i.e. a limited number of typical patterns by which it would be possible to describe any person, and to find the causes of individual differences (according Tadinac, 1986). Thus, the Greek physician Hippocrates (5/4. C. BC. AD) and the Roman physician Galen (2nd century, AD) considered that the personality characteristics of the individual are the result of the functioning of his body, and the differences between personality characteristics of individual people are the result of differences in the functioning of their organisms. This statement formed the foundation for the understanding of the four temperament types that are associated with the four main types of body fluids (blood, slime, yellow bile, and black bile): sanguine (bright and lively), phlegmatic (hardly exciting and indifferent), choleric (easy exciting, sudden and abrupt), and melancholic (pessimistic and depressed). They are described in Table 1, in which the relation between Hippocratic-Galen’s temperaments and Pavlov’s basic types of nervous system (NS) is also observable. Hippocrates-Galen’s temperament typology was not only interesting to Pavlov, but also to Kant (1912), who provided a detailed description of the four temperaments in terms of behavior and divided them into temperament emotions: melancholic and sanguine, and temperament activities: phlegmatic and choleric.
Unlike him, Wundt’s (1903) interest in this temperament typology resulted in the creation of dimensional systems with orthogonal dimensions: “strength of emotion” and “rate of emotion change.” Their combination forms four types of temperament, which have the following features: melancholic have intense emotions and their slow changes; choleric have also intense emotions but their changes are rapid; phlegmatic have weaker emotions and their changes are slow; and sanguine also have weaker emotions but their changes are quick. In addition, Theophrastus described different characteristics in terms of lines, emphasizing the role of the environment in their formation. N. Wundt also believed that there are four types of temperament, while Shelldon’s, Kretschmer’s and Conrad’s constitutional psychology brought personality traits into connection with the physical characteristics of the individual.