Big Five personality traits
In psychology, the "Big Five" personality traits are five broad factors or dimensions of personality discovered through empirical research. The first public mention of the model was in 1933, by L. L. Thurstone in his presidential address to the American Psychological Association. Thurstone's comments were published in Psychological Review the next year.
The five factors are Openness, Conscientiousness, Extraversion, Agreeableness, and Neuroticism (OCEAN, or CANOE if rearranged). They are also referred to as the "Five Factor Model" (FFM). However, some discussion remains about how to interpret the Openness factor, which is sometimes called "Intellect."  Each factor consists of a cluster of more specific traits that correlate together. For example, extraversion includes such related qualities as sociability, excitement seeking, impulsiveness, and positive emotions.
The Five Factor Model is a purely descriptive model of personality, but psychologists have developed a number of theories to account for the Big Five.

# Overview
The Big Five factors and their constituent traits can be summarized as follows:
- Openness - appreciation for art, emotion, adventure, unusual ideas, imagination, curiosity, and variety of experience.
- Conscientiousness - a tendency to show self-discipline, act dutifully, and aim for achievement; planned rather than spontaneous behaviour.
- Extraversion - energy, positive emotions, surgency, and the tendency to seek stimulation and the company of others.
- Agreeableness - a tendency to be compassionate and cooperative rather than suspicious and antagonistic towards others.
- Neuroticism - a tendency to experience unpleasant emotions easily, such as anger, anxiety, depression, or vulnerability; sometimes called emotional instability.
When scored for individual feedback, these traits are frequently presented as percentile scores. For example, a Conscientiousness rating in the 80th percentile indicates a relatively strong sense of responsibility and orderliness, whereas an Extraversion rating in the fifth percentile indicates an exceptional need for solitude and quiet.
Although these trait clusters are statistical aggregates, exceptions may exist on individual personality profiles. On average, people who register high in Openness are intellectually curious, open to emotion, interested in art, and willing to try new things. A particular individual, however, may have a high overall Openness score and be interested in learning and exploring new cultures. Yet he or she might have no great interest in art or poetry. Situational influences also exist, as even extraverts may occasionally need time away from people.

# History

## Early trait research
Sir Francis Galton was the first scientist to recognize what is now known as the Lexical Hypothesis. This is the idea that the most salient and socially relevant personality differences in peoples lives will eventually become encoded into their language. The hypothesis further suggests that by sampling language, it is possible to derive a comprehensive taxonomy of human personality traits.
Carl Jung explicated the concepts of extraversion and introversion in his book "Psychological Types" the 1920's.
In 1936, Gordon Allport and H. S. Odbert expanded on the hypothesis. They worked through two of the most comprehensive dictionaries of the English language available at the time and extracted 17,953 personality-describing words. They then reduced this gigantic list to 4500 adjectives which they considered to describe observable and relatively permanent traits.
Raymond Cattell obtained the Allport-Odbert list and eliminated synonyms to reduce the total to 171. He then asked subjects to rate people whom they knew by the adjectives on the list and analyzed their ratings. Cattell identified 35 major clusters of personality traits, and then added ten more traits obtained from a review of the psychiatric literature. Cattell and his associates constructed personality tests for these 45 traits, and the data they obtained from these tests was analyzed with the emerging technology of computers combined with the statistical method of factor analysis. This resulted in sixteen major personality factors, which led to the development of the 16PF Personality Questionnaire.
In 1961, two Air Force researchers, Tupes and Christal analyzed personality data from eight large samples. Using Cattell's trait measures, they found five recurring factors. This work was replicated by Norman, who also found that five major factors were sufficient to account for a large set of personality data. Norman named these factors Surgency, Agreeableness, Conscientiousness, Emotional Stability, and Culture.

## Hiatus in research
For the next two decades, the changing zeitgeist made publication of personality research difficult. In his 1968 book Psychological Assessment, Walter Mischel asserted that personality tests could not predict behavior with a correlation of more than 0.3. Social psychologists like Mischel argued that attitudes and behavior were not stable, but varied with context. Predicting behavior by personality tests was considered to be impossible. Radical situationists in the 1970s went so far as to argue that personality is merely a perceived construct that people impose on others in order to maintain an illusion of consistency in the world.
Emerging methodologies challenged this point of view during the 1980s. Instead of trying to predict single instances of behavior, which was unreliable, researchers found that they could predict patterns of behavior by aggregating large numbers of observations. As a result correlations between personality and behavior increased substantially, and it was clear that personality did in fact exist. Personality and social psychologists now generally agree that both personal and situational variables are needed to account for human behavior. Trait theories became justified, and there was a resurgence of interest in this area.
By 1980, the pioneering research by Tupes, Christal, and Norman had been largely forgotten by psychologists. Goldberg started his own lexical project with a new set of adjectives from the dictionary and independently found the five factors once again.

## Consensus on the Big Five
In a 1981 symposium in Honolulu, four prominent researchers, Lewis Goldberg, Naomi Takemoto-Chock, Andrew Comrey, and John M. Digman, reviewed the available personality tests of the day. They concluded that the tests which held the most promise measured a subset of five common factors, just as Norman had discovered in 1963. This event was followed by widespread acceptance of the five factor model among personality researchers during the 1980s, as well as the publication of the NEO PI-R five-factor personality inventory by Costa and McCrae in 1985.
One of the most significant advances of the five-factor model was the establishment of a common taxonomy that demonstrates order in a previously scattered and disorganized field. What separates the five-factor model of personality from all others is that it is not based on the theory of any one particular psychologist, but rather on language, the natural system that people use to understand one another.
A number of meta-analyses have confirmed the predictive value of the Big Five across a wide range of behaviors. Saulsman and Page examined the relationships between the Big Five personality dimensions and each of the 10 personality disorder categories in the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV). Across 15 independent samples, the researchers found that each disorder displayed a unique and predictable five-factor profile. The most prominent and consistent personality predictors underlying the disorders were positive associations with Neuroticism and negative associations with Agreeableness.
In the area of job performance, Barrick and Mount reviewed 117 studies utilizing 162 samples with 23,994 participants. They found that conscientiousness showed consistent relations with all performance criteria for all occupational groups. Extraversion was a valid predictor for occupations involving social interaction (e.g. management and sales). Furthermore, extraversion and openness to experience were valid predictors of training proficiency criteria. 

# Agreeableness
Main article: Agreeableness
Agreeableness - a tendency to be compassionate and cooperative rather than suspicious and antagonistic towards others.
Agreeableness reflects individual differences in concern with cooperation and social harmony. Agreeable individuals value getting along with others. They are generally considerate, friendly, generous, helpful, and willing to compromise their interests with others. Agreeable people also have an optimistic view of human nature. They believe people are basically honest, decent, and trustworthy.
Disagreeable individuals place self-interest above getting along with others. They are generally unconcerned with others well-being, and are less likely to extend themselves for other people. Sometimes their skepticism about others motives causes them to be suspicious, unfriendly, and uncooperative.

## Sample Agreeableness items
- I am interested in people.
- I feel others emotions.
- I have a soft heart.
- I make people feel at ease.
- I sympathize with others feelings.
- I take time out for others.
- I am not interested in other peoples problems. (reversed)
- I am not really interested in others. (reversed)
- I feel little concern for others. (reversed)
- I insult people. (reversed) 

# Conscientiousness
Main article: Conscientiousness
Conscientiousness - a tendency to show self-discipline, act dutifully, and aim for achievement; planned rather than spontaneous behaviour.
Conscientiousness concerns the way in which we control, regulate, and direct our impulses. Impulses are not inherently bad; occasionally time constraints require a snap decision, and acting on our first impulse can be an effective response. Also, in times of play rather than work, acting spontaneously and impulsively can be fun. Impulsive individuals can be seen by others as colorful, fun-to-be-with, and zany. Conscientiousness includes the factor known as Need for Achievement (NAch).
The benefits of high conscientiousness are obvious. Conscientious individuals avoid trouble and achieve high levels of success through purposeful planning and persistence. They are also positively regarded by others as intelligent and reliable. On the negative side, they can be compulsive perfectionists and workaholics. Furthermore, extremely conscientious individuals might be regarded as stuffy and boring. Unconscientious people may be criticized for their unreliability, lack of ambition, and failure to stay within the lines, but they will experience many short-lived pleasures and they will never be called stuffy (i.e. dull, boring, unimaginative).

## Sample Conscientiousness items
- I am always prepared.
- I am exacting in my work.
- I follow a schedule.
- I get chores done right away.
- I like order.
- I pay attention to details.
- I leave my belongings around. (reversed)
- I make a mess of things. (reversed)
- I often forget to put things back in their proper place. (reversed)
- I shirk my duties. (reversed) 

# Extraversion
Main article: Extraversion and introversion
Extraversion - energy, positive emotions, surgency, and the tendency to seek stimulation and the company of others.
Extraversion, also called "extroversion," is marked by pronounced engagement with the external world. Extraverts enjoy being with people, are full of energy, and often experience positive emotions. They tend to be enthusiastic, action-oriented individuals who are likely to say "Yes!" or "Let's go!" to opportunities for excitement. In groups they like to talk, assert themselves, and draw attention to themselves.
Introverts lack the exuberance, energy, and activity levels of extraverts. They tend to be quiet, low-key, deliberate, and less dependent on the social world. Their lack of social involvement should not be interpreted as shyness or depression; the introvert simply needs less stimulation than an extravert and more time alone.
A simple explanation is that an extravert gains energy by associating with others and loses energy when alone for any period of time.  An introvert is the opposite, as they gain energy from doing individual activities such as watching movies or reading and lose energy, sometimes to the point of exhaustion, from social activities.

## Sample Extraversion items
- I am the life of the party.
- I don't mind being the center of attention.
- I feel comfortable around people.
- I start conversations.
- I talk to a lot of different people at parties.
- I am quiet around strangers. (reversed)
- I don't like to draw attention to myself. (reversed)
- I don't talk a lot.  (reversed)
- I have little to say. (reversed)

## Biology of Extraversion
Extraversion has been linked to higher sensitivity of the mesolimbic dopamine system to potentially rewarding stimuli. This in part explains the high levels of positive affect found in Extraverts, since they will more intensely feel the excitement of a potential reward. One consequence of this is that Extraverts can more easily learn the contingencies for positive reinforcement, since the reward itself is experienced as greater.

# Neuroticism
Main article: Neuroticism
Neuroticism - a tendency to experience unpleasant emotions easily, such as anger, anxiety, depression, or vulnerability; sometimes called emotional instability.
Neuroticism, also known inversely as Emotional Stability, refers to the tendency to experience negative emotions. Those who score high on Neuroticism may experience primarily one specific negative feeling such as anxiety, anger, or depression, but are likely to experience several of these emotions. People high in Neuroticism are emotionally reactive. They respond emotionally to events that would not affect most people, and their reactions tend to be more intense than normal. They are more likely to interpret ordinary situations as threatening, and minor frustrations as hopelessly difficult. Their negative emotional reactions tend to persist for unusually long periods of time, which means they are often in a bad mood. These problems in emotional regulation can diminish a neurotic's ability to think clearly, make decisions, and cope effectively with stress.
At the other end of the scale, individuals who score low in Neuroticism are less easily upset and are less emotionally reactive. They tend to be calm, emotionally stable, and free from persistent negative feelings. Freedom from negative feelings does not mean that low scorers experience a lot of positive feelings; frequency of positive emotions is a component of the Extraversion domain.

## Sample Neuroticism items
- I am easily disturbed.
- I change my mood a lot.
- I get irritated easily.
- I get stressed out easily.
- I get upset easily.
- I have frequent mood swings.
- I often feel blue.
- I worry about things.
- I am relaxed most of the time. (reversed)
- I seldom feel blue. (reversed) 

# Openness to Experience
Main article: Openness to experience
Openness - appreciation for art, emotion, adventure, unusual ideas, imagination, curiosity, and variety of experience.
Openness to Experience describes a dimension of personality that distinguishes imaginative, creative people from down-to-earth, conventional people. Open people are intellectually curious, appreciative of art, and sensitive to beauty. They tend to be, compared to closed people, more aware of their feelings. They therefore tend to hold unconventional and individualistic beliefs, although their actions may be conforming (see agreeableness). 
People with low scores on openness to experience tend to have narrow, common interests. They prefer the plain, straightforward, and obvious over the complex, ambiguous, and subtle. They may regard the arts and sciences with suspicion, regarding these endeavors as abstruse or of no practical use. Closed people prefer familiarity over novelty; they are conservative and resistant to change.

## Sample Openness items
- I am full of ideas.
- I am quick to understand things.
- I have a rich vocabulary.
- I have a vivid imagination.
- I have excellent ideas.
- I spend time reflecting on things.
- I use difficult words.
- I am not interested in abstract ideas. (reversed)
- I do not have a good imagination. (reversed)
- I have difficulty understanding abstract ideas. (reversed) 

# Selected scientific findings
Ever since the 1990s when the consensus of psychologists gradually came to support the Big Five, there has been a growing body of research surrounding these personality traits (see for instance, Robert Hogan's edited book "Handbook of Personality Psychology" (Academic Press, 1997).

## Heritability studies
All five factors show an influence from both heredity and environment. Twin studies suggest that these effects contribute in roughly equal proportion. An analysis of the available studies found overall heritabilities for the Big Five traits as follows:

## Change and development
During young adulthood, a person's ratings on the five factors may change, with average levels of Agreeableness and Conscientiousness typically increasing, and with Extraversion, Neuroticism, and Openness generally decreasing. However, after age 30, researchers have found that stability, not change is the general rule. Both longitudinal data, which correlate people's test scores over time, and cross-sectional data, which compare personality levels across different age groups, show remarkable stability in adulthood. This is not to say that personality as measured on the Big Five cannot change, given life altering circumstances or efforts to do so. It does indicate, however, that after age 30, people generally do not change their personalities very much.

## Sex differences
Cross cultural research from 26 nations (N = 23,031 subjects) and again in 55 nations (N = 17,637 subjects) has shown a universal pattern of sex differences on responses to the Big Five Inventory. Women consistently report higher levels of Neuroticism and Agreeableness than men across nations; higher Extraversion and Conscientiousness are also often reported in women. Surprisingly, sex differences in personality traits are larger in prosperous, healthy, and egalitarian cultures in which women have more opportunities that are equal to those of men.

## Birth order
The suggestion has often been made that individuals differ by the order of their births. Frank J. Sulloway argues that birth order is correlated with personality traits. He claims that firstborns are more conscientious, more socially dominant, less agreeable, and less open to new ideas compared to laterborns.
However, Sulloways case has been discredited because his data confound family size with birth order. Subsequent analyses have shown that birth order effects are only found in studies where the subjects personality traits are rated by family members (such as siblings or parents) or by acquaintances familiar with the subjects birth order. Large scale studies using random samples and self-report personality tests like the NEO PI-R have found no significant effect of birth order on personality. 

## Cultural differences
Recent work has also found relationships between Geert Hofstedes cultural factors, Individualism, Power Distance, Masculinity, and Uncertainty Avoidance, with the average Big Five scores in a country. For instance, the degree to which a country values individualism correlates with its average Extraversion, while people living in cultures which are accepting of large inequalities in their power structures tend to score somewhat higher on Conscientiousness. The reasons for these differences are as yet unknown; this is an active area of research.

# Criticisms
Much research has been conducted on the Big Five. This has resulted in both criticism. and support for the model.

## Limited scope
One common criticism is that the Big Five does not explain all of human personality. Some psychologists have dissented from the model precisely because they feel it neglects other domains of personality, such as Religiosity, Manipulativeness/Machiavellianism, Honesty, Thriftiness, Conservativeness, Masculinity/Femininity, Snobbishness, Sense of humour, Identity, Self-concept, and Motivation. Correlations have been found between some of these variables and the Big Five, such as the inverse relationship between political conservatism and Openness, although variation in these traits is not well explained by the Five Factors themselves. McAdams has called the Big Five a "psychology of the stranger," because they refer to traits that are relatively easy to observe in a stranger; other aspects of personality that are more privately held or more context-dependent are excluded from the Big Five.
In many studies, the five factors are not fully orthogonal to one another; that is, the five factors are not independent. Negative correlations often appear between Neuroticism and Extraversion, for instance, indicating that those who are more prone to experiencing negative emotions tend to be less talkative and outgoing. Orthogonality is viewed as desirable by some researchers because it minimizes redundancy between the dimensions. This is particularly important when the goal of a study is to provide a comprehensive description of personality with as few variables as possible.

## Methodological issues
The methodology used to identify the dimensional structure of personality traits, factor analysis, is often challenged for not having a universally-recognized basis for choosing among solutions with different numbers of factors.  That is, a five factor solution depends on some degree of interpretation by the analyst. A larger number of factors may, in fact, underlie these five factors.  This has led to disputes about the "true" number of factors. Big Five proponents have responded that although other solutions may be viable in a single dataset, only the five factor structure consistently replicates across different studies.
A methodological criticism often directed at the Big Five is that much of the evidence relies on self report questionnaires; self report bias and falsification of responses is impossible to deal with completely. This becomes especially important when considering why scores may differ between individuals or groups of people - differences in scores may represent genuine underlying personality differences, or they may simply be an artifact of the way the subjects answered the questions. The five factor structure has been replicated in peer reports. However, many of the substantive findings rely on self-reports.

## Theoretical status
A frequent criticism is that the Big Five is not based on any underlying theory; it is merely an empirical finding that certain descriptors cluster together under factor analysis. While this does not mean that these five factors don't exist, the underlying causes behind them are unknown. Sensation seeking and cheerfulness are not linked to Extraversion because of an underlying theory; this relationship is an empirical finding to be explained. Several overarching theoretical models have been proposed to cover all of the Big Five, such as Five-Factor Theory and Social Investment Theory. Temperament Theory may prove to provide a theoretical foundation for the Big Five, and provide a longitudinal (life-span) model in which the Big Five could be grounded.

# Further research
Current research concentrates on a number of areas. One important question is: are the five factors the right ones? Attempts to replicate the Big Five in other countries with local dictionaries have succeeded in some countries but not in others. Apparently, for instance, Hungarians dont appear to have a single Agreeableness factor. Proponents state that the problem is that the language does not provide enough variance of the related terms for proper statistical analysis (CITE).  Other researchers find evidence for Agreeableness but not for other factors.
In an attempt to explain variance in personality traits more fully, some have found seven factors, some eighteen, and some only three. What determines the eventual number of factors is essentially the kind of information that is put into the factor analysis in the first place (i.e. the "Garbage in, Garbage out" principle). Since theory often implicitly precedes empirical science (such as factor analysis), the Big Five and other proposed factor structures should always be judged according to the items that went into the factor analytic algorithm. Recent studies show that seven- or eighteen-factor models have their relative strengths and weaknesses in explaining variance in DSM-based symptom counts in non-clinical samples and in psychiatric patients. and do not seem to be clearly outperformed by the Big Five.
A second question is, which factors predict what? Job outcomes for leaders and salespeople have already been measured, and research is currently being done in expanding the list of careers. There are also a variety of life outcomes which preliminary research indicates are affected by personality, such as smoking (predicted by high scores in Neuroticism and low scores in Agreeableness and Conscientiousness) and interest in different kinds of music (largely mediated by Openness).
A validation study, in 1992, conducted by Paul Sinclair and Steve Barrow, involved 202 Branch Managers from the then TSB Bank. It found several significant correlations with job performance across 3 of the Big Five scales.  The correlations ranged from .21 - .33 and were noted across 3 scales:  High Extraversion, Low Neuroticism and High Openness to Experience.
A third area of investigation is to make a model of personality. The Big Five personality traits are empirical observations, not a theory; the observations of personality research remain to be explained. Costa and McCrae have built what they call the Five Factor Theory of Personality as an attempt to explain personality from the cradle to the grave. They don't follow the lexical hypothesis, though, but favor a theory-driven approach inspired by the same sources as the sources of the Big Five.
A fourth area of investigation is the downward extension of Big Five theory, or the Five Factor Model, into childhood. Studies have found Big Five personality traits to correlate with children's social and emotional adjustment and academic achievement. More recently, the Five Factor Personality Inventory - Children was published extending assessment between the ages of 9-0 to 18-11. Perhaps the reason for this recent publication was the controversy over the application of the Five Factor Model to children. Studies by Oliver P. John et al with adolescent boys brought two new factors to the table: "Irritability" and "Activity." In studies of Dutch children, those same two new factors also became apparent. These new additions "suggest that the structure of personality traits may be more differentiated in childhood than in adulthood" which would explain the recent research in this particular area.
Related investigation is on principle motivators. One study suggests eight motivational domains of values:
- enjoyment
- security
- social power
- achievement
- self-direction
- prosocial
- restrictive conformity (per  the  study authors, "Markers in the Rokeach lists are obedient, polite, clean, and self-controlled")
- maturity