Personality

Personality is a set of individual differences that are affected by the development of an individual: values, attitudes, personal memories, social relationships, habits, and skills. Different personality theorists present their own definitions of the word based on their theoretical positions. The term "personality trait" refers to enduring personal characteristics that are revealed in a particular pattern of behaviour in a variety of situations.

Personality can be determined through a variety of tests. However, dimensions of personality and scales of personality tests vary and often are poorly defined. Examples of such tests are the Minnesota Multiphasic Personality Inventory (MMPI-2), Rorschach Inkblot test, Neurotic Personality Questionnaire KON-2006, or Eysenck's Personality Questionnaire (EPQ-R).

The theory of individual differences started from the concept of temperament suggested by Hippocrates and Galen. Hippocrates' four humours gave rise to four temperaments. The explanation was further refined by his successor Galen during the second century CE. The "Four Humours" theory held that a person's temperament was based on the balance of bodily humours; yellow bile, black bile, phlegm, and blood. Choleric people were characterized as having an excess of yellow bile, making them irascible. High levels of black bile were held to induce melancholy, signified by a sombre, gloomy, pessimistic outlook. Phlegmatic people were thought to have an excess of phlegm, leading to their sluggish, calm temperaments. Finally, people thought to have high levels of blood were said to be sanguine and were characterized by their cheerful, passionate dispositions.

There are debates between researchers of temperament and researchers of personality as to whether or not biologically-based differences define a concept of temperament or a part of personality. The presence of such differences in pre-cultural individuals (such as animals or young infants) suggests that they belong to temperament since personality is a socio-cultural concept. Researchers of adult temperament point out that, similarly to sex, age, and mental illness, temperament is based on biochemical systems whereas personality is a product of socialization of an individual possessing these four types of features. Temperament interacts with social-cultural factors, but still cannot be controlled or easily changed by these factors. Modern theories of temperament converge to 12 components, all based on ensemble interaction between brain neurotransmitters.

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