The study of personality has been successfully done through various avenues. These avenues include genetics, chemicals, evolution, and the study of the brain structure. Biologically, the personality of every individual is generally the net effect of numerous coordinated systems. The resulting behavior of persons gives a clear view of how the brains function. This study is rather limited to the outside since it is difficult to observe the brains internally. The first limitation to this study is thus experienced through the fact that touching a living brain is practically impossible. Thus, the brain can be observed through lesion study, brain stimulation and imaging to avoid damage.
It is essential to note that personality is not realized as a result of an individual brain part. Thus, the interaction between diverse brain structures yields to personality. According to previously done researches, psychodynamic ideas and personality traits have been closely linked with biological constructs. In this case, therefore, personality can hardly be fully understood by merely studying the brain structure. It will require knowledge in some key areas such as social aspects, developmental effects and psychodynamic.
An analysis of the structure of the brain shows the role played by every part in personality either directly or indirectly. The interaction between different parts of the brain is very important in personality. If the brain is thus divided in different ways, it would be easier to study its functions in relation to personality. The brain, for instance, can be divided according to the different lobes it contains. The lobes work hand in hand to make up an individual’s personality.
The frontal lobe, for instance, is responsible for mental flexibility, judgment and reasoning. The frontal lobe has a close link with Antisocial PD, which is known to have less inhibition. It has two hemispheres: the right, which is concerned with negative emotions such as fear, anxiety and depression, and the left, which is linked with positive emotions such as joy and happiness. The case of Phineas Gage, who was less emotional, is known to have damaged his frontal lobe when an iron rod went through his cheek and frontal lobes. Other lobes also play key roles in personality. The parietal lobe is associated with linking sensory information; the temporal lobe is responsible for language while the occipital lobe is linked with visual processing.
Emotional responses based on a specific environment are generated by amygdala. Thoughts and perception are linked to their emotional meanings through the amygdala. It activates the autonomic nervous system – fight or flight after assessing the present situation. A case of Charles Whitman who had a nasty tumor on the right side near his amygdala was known to shoot individuals at the University of Texas from the clock tower. This was a clear indicator that amygdala can stimulate the urge to kill. When structural MRIs show reduced volume in amygdala, it is very likely to report a case of Borderline Personality Disorder in an individual.
The main theory of the biological approaches to personality is the three-trait personality (PEN) by Hans Eysenck. He analyses three traits in his theory. These include psychoticism (constraint), extraversion (positive emotionality), and neuroticism (negative emotionality). Eysenck ensured comprehensiveness in his personality factor model. He creates precise biological underpinnings that allow personality to vary in its major dimensions.
Eysenck referred to personality as the combination of both the actual and potential patterns of organism’s behavior as dictated by the environment and heredity. The interaction of the four sectors that facilitates the organization of behavior patterns is the origin of personality that also enhances its development. These four main sectors are identified as the cognitive sector (intelligence), the affective sector (temperament), the conative sector (character), and the somatic sector (constitution).
His inclusion of heredity and environment makes his theory more acceptable and very likely to gain support of many individuals. This is because it describes people as creatures whose characters are dictated by both their inheritance and experiences. He relates the behavioral feature personality to fundamental physiological composition and function through his inclusion of the somatic sector. However, he tries to relate physique and personality and thus strays a bit from his heredity aspect. It is important to note that his main concentration was relating the observable human behavior and the functioning of different parts of the brain.
A close analysis of Eysenck traits gives clear explanations to the personality characteristic attached. Extraversion, for instance, is an attribute of individuals who always want people to be in their company and other stimulations such as noise. Such individuals are not overwhelmed by intense stimuli unlike the introverts who prefer the opposite. The introverts are only comfortable around few close people, in quieter settings and sometimes in solitary seclusions.
Unstable emotionality in individual personality is linked with neuroticism. People associated with trait are mostly found to be upset easily by simple situation and worries. These individuals have a below average emotional control, they are rather slow in thought and taking actions, they are not persistent and are also not social. They also have sensory acuity that is below average although they possess a high level of activation.
Psychoticism turns out to be very interesting as it is not related to actual psychosis. It is a combination of creativity, aggressiveness and impulsiveness. Individuals with this aspect tend to have poor memory, poor concentration, they are insensitive and do not care for others, and disregard danger and convention. They are also linked with creativity, rather unusual things and most often they are considered peculiar by other people.
According to a previous research on Eysenck’s personality traits, three main factors can be drawn. These factors are constraint, positive emotionality and negative emotionality. Based on Eysenck’s findings, the pathway to arousal is the ascending reticular activating systems of the brain (ARAS). It also regulates sleep and wake transitions and also connects the brainstem and the cortex through its neuronal circuits. He observed that the upper brainstem reticular core is the origin of the pathways and that they project through the cortex.
He believed in the existence of biological differences between extraverts and introverts. The brain is aroused by the ARAS, and its activities and mechanisms aimed at calming it down. Eysenck came up with a hypothesis that proposed that the ARAS is responsible for regulating the amount of stimulation and information that gets into the brain. The functioning of the ARAS in individuals is however different and is probably the reason why there exist distinctions in introverts and extroverts. Excitement is avoided while stimulation is reduced by the chronic arousal-introverts. However, the chronic under arousal-extroverts increase the stimulation of an individual by seeking out excitement. He used a simple lemon test to prove difference in the functioning of the introverts and the extroverts besides the inconclusiveness of other complicated tests such as EEG and FMRI.
There are some issues raised by Eysenck however that one can argue out as not convincing. His personality system, for instance, excludes the issue of openness to experience. This is a very essential aspect that is analyzed by the Big Five personality aspect which includes conscientiousness, agreeableness, neuroticism, openness to experience, and extraversion. It is thus an important aspect that has been omitted hence indicating some certain levels of flaw in Eysenck’s argument despite claiming that his approach offered a better description to personality. Therefore, the Big Five can be attributed to giving a comprehensive interpretation of Eysenck’s interpretation of the psychological and biological study.
According to the theorist, there are a number of basic traits that create human personality. Many people agree that individuals can be described under various personality traits. However, several weaknesses can be drawn from this argument. Personality theory, for instance, lacks objectivity that is comprised in the trait theory. Additionally, traits theory faces criticism particularly due to the fact that traits are not good predictors of behavior. This is because people do not always behave the same way in the occurrence of situations. The reason behind different personalities in people is also not mentioned by the trait theory aspect and thus lacks credibility to a certain extent.
Eysenck’s theory also raises some aspects that make his theory not completely agreeable with. He neglects mentioning the aspect of gender and how it affects individual personality. Gender is very essential and according to the cross-cultural research, different genders exhibit varied personality behavior. Women, for instance, have been reported to posses higher neuroticism, agreeableness, the extraversion facet of warmth, and openness to feelings. Men, on the other hand, have reported openness to ideas and also the extraversion facet of assertiveness according to the NEO-PI-R and the Big Five aspect. Eysenck should have accounted for the differences that gender brings to biological personality to display more competent and accurate information for approval by a large number in the society.
Generally, women report higher cases of extraversion, neuroticism, conscientiousness and agreeableness than men according to a study done using the Big Five Inventory. The most prominent and consistent difference between men and women is the neuroticism. However, women, on the other hand, differ in personality across various regions. It is also important that Eysenck should have included the fact that gender inequalities are major contributors of the differences that exist in personality.
Eysenck also generalized most aspects of his findings and did not specify as in the case of Frank Sulloway, who drew a conclusion that birth orders dictate individuality. This generalization by Eysenck is rather not agreeable since clear-cut specifications need to be drawn. The firstborns are reported to be more socially dominant, more conscientious and less open to new ideas, and are generally less agreeable as compared to the lastborns.