Personality is a set of individual differences that are affected by the socio-cultural 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[4] or Eysenck's Personality Questionnaire (EPQ-R).

Temperament vs. personality

The theory of individual differences started from the concept of temperament suggested by Hippocrates and Galen. Hippocrates' four humours gave rise to four temperaments.[5] 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.[6]

Therefore temperament should be kept as an independent concept for further studies and not be conflated with personality. Moreover, temperament refers to dynamical features of behaviour (energetic, tempo, sensitivity and emotionality-related), whereas personality is to be considered a psycho-social construct comprising the content characteristics of human behavior (such as values, attitudes, habits, preferences, personal history, self-image). Temperament researchers point out that the lack of attention to extant temperament research by the developers of the Big Five model led to an overlap between its dimensions and dimensions described in multiple temperament models much earlier. For example, neuroticism reflects the traditional temperament dimension of emotionality, extraversion the temperament dimension of "energy" or "activity", and openness to experience, the temperament dimension of Sensation Seeking.[7]

Five-factor model

Personality is usually broken into components called the Big Five, which are openness to experience, conscientiousness, extraversion, agreeableness, and neuroticism (or emotionality). These components are generally stable over time, and about half of the variance appears to be attributable to a person's genetics rather than the effects of one's environment.[9]

Some research has investigated whether the relationship between happiness and extraversion seen in adults can also be seen in children. The implications of these findings can help identify children that are more likely to experience episodes of depression and develop types of treatment that such children are likely to respond to. In both children and adults, research shows that genetics, as opposed to environmental factors, exert a greater influence on happiness levels. Personality is not believed to become stable until approximately the age of thirty, and personality constructs in children are referred to as temperament. Temperament is regarded as the precursor to personality. Whereas McCrae and Costa's Big Five model assesses personality traits in adults, the EAS (emotionality, activity, and sociability) model is used to assess temperament in children. This model measures levels of emotionality, activity, sociability and shyness in children. The personality theorists consider temperament EAS model similar to the Big Five model in adults; however, this might be due to a conflation of concepts of personality and temperament as described above. Findings show that high degrees of sociability and low degrees of shyness are equivalent to adult extraversion, and also correlate with higher levels of life satisfaction in children.

Another interesting finding has been the link found between acting extraverted and positive affect. Extraverted behaviors include acting talkative, assertive, adventurous and outgoing. For the purposes of this study, positive affect is defined as experiences of happy and enjoyable emotions. This study investigated the effects of acting in a way that is counter to a person's dispositional nature. In other words, the study focused on the benefits and drawbacks of introverts (people who are shy, socially inhibited and non-aggressive) acting extraverted, and of extraverts acting introverted. After acting extraverted, introverts' experience of positive affect increased whereas extraverts seemed to experience lower levels of positive affect and suffered from the phenomenon of ego depletion. Ego depletion, or cognitive fatigue, is the use of one's energy to overtly act in a way that is contrary to one's inner disposition. When people act in a contrary fashion, they divert most, if not all, (cognitive) energy toward regulating this foreign style of behavior and attitudes. Because all available energy is being used to maintain this contrary behavior, the result is an inability to use any energy to make important or difficult decisions, plan for the future, control or regulate emotions, or perform effectively on other cognitive tasks.

One question that has been posed is why extraverts tend to be happier than introverts. The two types of explanations attempt to account for this difference are instrumental theories and temperamental theories. The instrumental theory suggests that extraverts end up making choices that place them in more positive situations and they also react more strongly than introverts to positive situations. The temperamental theory suggests that extraverts have a disposition that generally leads them to experience a higher degree of positive affect. In their study of extraversion, Lucas and Baird found no statistically significant support for the instrumental theory but did, however, find that extraverts generally experience a higher level of positive affect.

Research has also been done to uncover some of the mediators that are responsible for the correlation between extraversion and happiness. Self-esteem and self-efficacy are two such mediators. Self-efficacy has been found to be related to the personality traits of extraversion and subjective well-being. Self-efficacy is one's belief about abilities to perform up to personal standards, the ability to produce desired results, and the feeling of having some ability to make important life decisions. However, the relationship between extraversion (and neuroticism) and subjective happiness is only partially mediated by self-efficacy. This implies that there are most likely other factors that mediate the relationship between subjective happiness and personality traits. Another such factor may be self-esteem. Individuals with a greater degree of confidence about themselves and their abilities seem to have both higher degrees of subjective well-being and higher levels of extraversion.

Other research has examined the phenomenon of mood maintenance as another possible mediator. Mood maintenance, the ability to maintain one's average level of happiness in the face of an ambiguous situation (meaning a situation that has the potential to engender either positive or negative emotions in different individuals), has been found to be a stronger force in extraverts. This means that the happiness levels of extraverted individuals are less susceptible to the influence of external events. Another implication of this finding is that extraverts' positive moods last longer than those of introverts.

Environmental influences

It has been shown that personality traits are more malleable by environmental influences than researchers originally believed.[9][11] Personality differences also predict the occurrence of life experiences.[11]

Cross-cultural studies

There has been some recent debate over the subject of studying personality in a different culture. Some people think that personality comes entirely from culture and therefore there can be no meaningful study in cross-culture study. On the other hand, others believe that some elements are shared by all cultures and an effort is being made to demonstrate the cross-cultural applicability of "the big five".

Historical development of concept

The modern sense of individual personality is a result of the shifts in culture originating in the Renaissance, an essential element in modernity. In contrast the Medieval European's sense of self was linked to a network of social roles: "the household, the kinship network, the guild, the corporation - these were the building blocks of personhood", Stephen Greenblatt observes, in recounting the recovery (1417) and career of Lucretius' poem De rerum natura: "at the core of the poem lay key principles of a modern understanding of the world." "Dependant on the family, the individual alone was nothing," Jacques Gélis observes.


The biological basis of personality is the theory that anatomical structures located in the brain contribute to personality traits. This stems from neuropsychology, which studies how the structure of the brain relates to various psychological processes and behaviors. For instance, in human beings, the frontal lobes are responsible for foresight and anticipation, and the occipital lobes are responsible for processing visual information. In addition, certain physiological functions such as hormone secretion also affect personality. For example, the hormone testosterone is important for sociability, affectivity, aggressiveness, and sexuality.[12] Additionally, studies show that the expression of a personality trait depends on the volume of the brain cortex it is associated with.[14]

There is also a confusion among some psychologists who conflate personality with temperament. Temperament traits that are based on weak neurochemical imbalances within neurotransmitter systems are much more stable, consistent in behavior and show up in early childhood; they can't be changed easily but can be compensated for in behavior. In contrast to that, personality traits and features are the product of the socio-cultural development of humans and can be learned and/or changed.


High neuroticism is an independent prospective predictor for the development of the common mental disorders.[19]


Personology confers a multidimensional, complex, and comprehensive approach to personality. From a holistic perspective, personology studies personality as a whole, as a system, but in the same time through all its components, levels and spheres.