ROMANIAN JOURNAL OF EXPERIMENTAL APPLIED PSYCHOLOGY VOL. 5, ISSUE 3 – www.rjeap.ro EDITORIAL: PERSONALITY - THE BIOLOGICAL PERSPECTIVES MIHAI ANIȚEI, PHD. University of Bucharest, Faculty of Psychology and Educational Sciences, Department of Doctoral School Since ancient times, the Greek philosophers attempted to explain human personality. They believed that the human behavior types are caused by the fluids in the human body. Philosophers believed that excess blood determines sanguine temperament, excess black bile causes melancholic temperament, excess yellow bile determines hot temper while excess phlegm leads to a phlegmatic temperament. Of course this is a purely theoretical approach, this perspective never having been empirically tested (Canli, 2006). Temperament refers to a person's characteristic emotional nature, including sensitivity to emotional stimulating, specific reaction speed, prevailing mood condition, and all peculiarities of fluctuation and intensity of dispositional state, all of which are considered to be dependent on the person's physical structure and hereditary determined "(Allport, 1937, as cited in Ryckman, 2008). Ivan Pavlov, one of the greatest psychologists, a physiologist at base, investigated stimulus-response type simple classical conditioning. Pavlov identified three properties (strength, mobility, balance) that determine the structure of the central nervous system (Ryckman, 2008). Strength reflects the energetic capacity of the neuron, being genetically determined, mobility refers to the dynamics of fundamental mental processes, the need to shift from a mental process to another, and balance is the ratio of excitation and inhibition. After studying canine behavior, Pavlov developed four temperament types which are specific to humans as well: 1) weak type characterized by anxiety, inhibition, low tolerance to stress; 2) highly-unbalanced type characterized by excitability, hyperactivity and irritability; 3) strong-balanced-inert type characterized by steadiness, calm, high tolerance to stress and frustration; 4) strong-balanced-mobile type characterized by liveliness, motivation, energy oriented outwards (Ryckman, 2008). Another psychophysiological mechanisms perspective is that of Enrst Kretschmer who, by studying psychiatric patients, determined that these disorders arerelated to physical constitution. Thus, he concluded that there are three main types: 1) picnic - bulky abdomen, overweight, stretched skin, horizontal constitution, 2) asthenic- flat rib cage, small, round head, long, sharp nose, feminine features on men and masculine features on women; 3) athletic- welldeveloped, muscular, broad shoulders, balanced physical constitution (Ashton, 2013). William Sheldon continued the study of these types calling them somatosensory types using different names for each type. Picnic type is called endomorph, the term ectomorph is used for the asthenic type and mesomorphs describes the athletic type (Ashton, 2013). Robert Cloninger developed a model that tests the neurotransmitters influence on personality traits. More broadly, the neurotransmitters are biochemical substances that are involved in communication between nerve cells called neurons (Ashton, 2013). Considering how neurons communicate, we can say that neurons are the basis of thoughts, emotions and human behavior and the substances in the body can influence human behavior (Ashton, 2013). The major neurotransmitters are found in the central nervous system and in the bone marrow and they are serotonin, dopamine and norephinephrine. (Ashton, 2013). Dopamine helps neurons transmit impulses about the existence of things that people consider to be good or are seen as rewards. Individuals characterized by high levels of dopamine are those who seek excitability, excitement, everything new. This dimension of personality has features like extravagance, opulence, lack of organization, excitability, impulsiveness. In contrast, there are people who do not seek excitement or fun (Larsen & Buss, 2008). The second neurotransmitter is serotonin, a neurotransmitter that inhibits signal transmission on punishment, with the purpose to stop the neurons from sending impulses when there are stimuli that represent punishment. Serotonin is related to states like anxiety, tension or pain (Larsen & Buss, 2008). The third neurotransmitter is norepinephrine. Norepinephrine is known as having a role in inhibiting responses to conditioned stimuli, the stimuli that have been associated with rewards. Norepinephrine has a strong relationship with behaviors that generate pleasure (Larsen & Buss, 2008). Another important model is that of Jeffrey Gray, in which he argued that the brain has different regions, and certain functions involving interactions between multiple brain regions and personality traits influence human behavior (Canli , 2006). The two systems described by Jeffrey Gray are The Behavioral Activation System and The Behavioral Inhibition System. The Behavioral Activation System is composed of brain regions that are responsible for receiving signals from the nervous system side which indicates a situation in which reward may be experienced (Canli, 2006). The Behavioral Activation System is related to Cloninger's model in terms of dopamine. Gray argued that the behavioral activation system is different for each person, being more or less sensitive to stimuli showing reward. The behavioral inhibition system is composed of brain regions that are responsible with the reception of signals from the nervous system, which indicates the existence of situations in which punishment or suffering are experienced (Canli, 2006). This system serves to stop behaviors that denote avoidance of punishment and suffering. Another biological model of personality is that of Hans Eysenck. He developed three major personality factors (Extraversion, Neuroticism and 6 Psychoticism) and claimed that human behavior is based on the variation of the central nervous system excitability (Burger, 2007; Ryckman, 2008). Another view of the biological model is the alternative model with five factors of personality of Marvin Zuckerman in which he tried to observe the biological perspective of a number of personality factors using factor analysis. Thus, he developed factors such as: activity, sociability, impulsivity thrill-seeking, aggressiveness and neuroticism-anxiety. According to Zuckerman each personality trait is determined by a unique combination of neurotransmitters between brain structures (Larsen & Buss, 2008). REFERENCES Ashton, M.C., (2013). Individual Differences and Personality, second edition.London: Elsevier. Burger, J.M., (2007). Personality, 7th edition. Belmont: Thomson Wadsworth. Canli, T., (2006). Biology of Personality and Individual Differences. New York: Guilford Press Larsen, R.J., & Buss,D.M., (2008). Personality Psychology. Domains of Knowledge about human nature ,3th edition. New York: McGraw Hill. Ryckman, R.M., (2008). Theories of personality. Belmont: Thomson Wadsworth. 7
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