From New World Encyclopedia
Revision as of 17:58, 26 March 2023 by Rosie Tanabe (talk | contribs)
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)

Personality is a collection of emotional, thought, and behavioral patterns unique to a person that is consistent over time. The idea that we can understand ourselves and others by categorizing the ways in which we experience, respond, and behave toward the physical and social world has a long tradition. With the advent of psychology as an academic discipline, theories of personality and techniques for measuring personality characteristics and individual differences developed significantly. No single model has been able to describe the totality of human personality. The inherent complexity of human nature, and the infinite diversity among individuals may indeed preclude such a possibility. Even so, those who work to advance our understanding of ourselves and others enable us to build bridges and overcome barriers between people with different personalities. Understanding and appreciating our differences allows us to become one human family, where each person can fulfill his or her own potential and contribute to the whole, according to their unique nature.

What is personality?

In psychology, personality is a collection of emotional, thought, and behavioral patterns unique to a person that is consistent over time. The word originates from the Latin persona, which means "mask," indicating that early theorists regarded the personality as the outward expression of the internal nature of human beings. Personality can also be distinguished from the related concept of temperament, which is the aspect of personality concerned specifically with emotional dispositions and reactions, or the mood pattern of a person.

Brief history of personality theory

The four temperaments as illustrated by Johann Kaspar Lavater.

Greek philosopher/physician Hippocrates recorded the first known personality model, basing his four “types” on the amount of body fluids, or "humors," an individual possessed. Greek physician Galen expounded upon Hippocrates' theory based on the four basic body fluids (humors): blood, phlegm, black bile, and yellow bile. According to their relative predominance in an individual, they would produce, respectively, temperaments designated sanguine (warm, pleasant), phlegmatic (slow-moving, apathetic), melancholic (depressed, sad), and choleric (quick to react, hot-tempered). German philosopher Immanuel Kant popularized these ideas by organizing the constructs along the two axes of feelings and activity.

The advent of the field of psychology led to more formalized categories and tests. Wilhelm Wundt proposed that the four temperaments fall along the axes of changeability and emotionality. As the field of psychology grew and matured, both the theoretical models of personality and the methods designed to assess personality differences have made significant advances.

A typology of personality models

Modern personality models may generally be broken into three types: factorial models, typologies, and circumplexes.

Factorial models posit that there are dimensions along which human personality differs. The main purpose of a personality model is thus to define the dimensions of personality. The statistical technique of factor analysis is a primary tool of theorists composing factorial models. Such models arise directly from a classical individual differences approach to the study of human personality. The "Big Five" model is the best-known example of this type of theory.

Typologies or type models arise naturally from some theories that posit "types" of people. For example, astrological signs represented a well-known, pre-scientific typological model. Typological models posit a relatively small number of modal types and possibly some interaction between the types. The Jungian typology implemented in the MBTI represents the typology approach.

Circumplex models may resemble factorial or type models, but further specify a relationship between the different types or factors. Typically, some types or factors are more related than others and can be presented on a polygon. Correlations of personality scores should resemble a simplex form, where opposing types have low correlation and close types have a high correlation. John L. Holland's RIASEC or "Holland Codes" is a typical example of this type of theory.

Personality theories

There are several theoretical perspectives on personality in psychology, which involve different ideas about the relationship between personality and other psychological constructs, as well as different theories about the way personality develops. Most theories can be grouped into one of the following classes:

The latter two regard the objective measurements of traits as too fragmented to fully capture personality development. Instead, they use global explanations and subjective methods to describe the development of the "whole person."

Behavioral-genetic theories

Behaviorists explain personality in terms of reactions to external stimuli. This school of thought was initiated by B. F. Skinner. According to these theories, people's behavior is formed by processes such as operant conditioning.

Some psychologists take a biological view of personality and research temperaments in children and heritability in adult twins, hoping is to find the genes underlying temperament. Individual differences in temperaments or manner of reacting to the environment emerge early in life and are an influence in later personality development. Behavioral-genetic data from twin and adoption studies show that the heritability of many adult personality traits is between .40 to .60, with the remaining variability accounted for by a person's unique environment and experiences.

Trait theories

According to the Diagnostic and Statistical Manual of the American Psychiatric Association, personality traits are "prominent aspects of personality that are exhibited in a wide range of important social and personal contexts." In other words, persons have certain characteristics which partly determine their behavior. According to the theory, a friendly person is likely to act in a friendly fashion in any situation because of the traits in his personality. One criticism of trait models of personality as a whole is that they lead professionals in clinical psychology and laypeople alike to accept classifications, or worse offer advice, based on a superficial analysis of a person's profile.

The most common models of traits incorporate four or five broad dimensions or factors. The least controversial dimension, observed as far back as the ancient Greeks, is extroversion vs. introversion (outgoing and physical-stimulation-oriented vs. quiet and physical-stimulation-averse).

Gordon Allport delineated different kinds of traits, which he also called dispositions. Central traits are basic to an individual's personality, while secondary traits are more peripheral. Common traits are those recognized within a culture and thus may vary from culture to culture. Cardinal traits are those by which an individual may be strongly recognized.

In 1936, Gordon Allport and H. S. Odbert hypothesized that:

Those individual differences that are most salient and socially relevant in people’s lives will eventually become encoded into their language; the more important such a difference, the more likely is it to become expressed as a single word.

This statement became known as the "Lexical Hypothesis." Allport and Odbert had worked through two of the most comprehensive dictionaries of the English language available at the time, and extracted 18,000 personality-describing words. From this gigantic list they extracted 4,500 personality-describing adjectives which they considered to describe observable and relatively permanent traits.

In 1946, Raymond B. Cattell used the emerging technology of computers to analyze the Allport-Odbert list. He organized the list into 181 clusters, and asked subjects to rate people whom they knew by the adjectives on the list. Using factor analysis Cattell generated twelve factors, and then included four factors which he thought ought to appear. The result was the hypothesis that individuals describe themselves and each other according to 16 different, independent factors.

With these sixteen factors as a basis, Cattell went on to construct the 16 Personality Factors (16PF) questionnaire, which remains in use by universities and businesses for research, personnel selection and the like. Although subsequent research has failed to replicate his results, and it has been shown that he retained too many factors, the current 16PF takes these findings into account and is considered to be a very good test. In 1963, W.T. Norman replicated Cattell’s work and suggested that five factors would be sufficient.

For the next seventeen years, the changing zeitgeist made the publication of personality research difficult. Social psychologists argued that behavior is not stable, but varies with context, so that predicting behavior by personality test was impossible. They further argued that character, or personality, is something humans impose on people in order to maintain an illusion of consistency in the world. Furthermore, Walter Mischel in his 1968 book Psychological Assessment asserted that personality tests could not predict behavior with a correlation of more than 0.3.

Around 1980, three developments brought personality research into the modern era: personal computers, statistical aggregation, and the "Big Five Factors." Before the advent of personal computers, psychologists wishing to conduct large scale statistical analysis needed to rent access to a mainframe. However, once personal computers become widely available, they could do this work on their desktops. Therefore anybody could easily re-examine the Allport-Odbert list. The question remained as to why they would do so, given that it had seemingly already been established that personality was an illusion.

It was argued that personality psychologists had considered behavior from the wrong perspective. Instead of trying to predict single instances of behavior, which was unreliable, it was thought that researchers should try to predict patterns of behavior. As a result correlations soared from .3 to .8 and it seemed that “personality” did in fact exist. Social psychologists still argue that we impose consistency on the world, but with statistical aggregation it could be shown that there was in fact more consistency than was once thought.

The Big Five Factors

In 1981, at a symposium in Honolulu, four prominent researchers (Lewis Goldberg, Naomi Takamoto-Chock, Andrew Comrey, and John M. Digman) reviewed the available personality tests of the day, and decided that most of the tests which held any promise seemed to measure a subset of five common factors, just as Norman had discovered in 1963.

Following the discovery of the convergence of the Lexical Hypothesis with the findings of theoretical research, a model was developed which states that personality can be described in terms of five aggregate-level trait descriptors.

Although many personality researchers have built their own models, when they talk to each other they usually translate their model into the one proposed by Norman in 1963. The following descriptions of the five factors were adapted from the writings of John A. Johnson.


Extroversion (also sometimes "Extraversion") is marked by pronounced engagement with the external world. Extroverts 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 extroverts. They tend to be quiet, low-key, deliberate, and disengaged from the social world. Their lack of social involvement should not be interpreted as shyness or depression; the introvert simply needs less stimulation than an extrovert and prefers to be alone.


Agreeableness reflects individual differences in concern with cooperation and social harmony. Agreeable individuals value getting along with others. They are therefore 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 therefore are unlikely to extend themselves for other people. Sometimes their skepticism about others' motives causes them to be suspicious, unfriendly, and uncooperative.
Agreeableness is obviously advantageous for attaining and maintaining popularity. Agreeable people are better liked than disagreeable people. On the other hand, agreeableness is not useful in situations that require tough or absolute objective decisions. Disagreeable people can make excellent scientists, critics, or soldiers.


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.

Neuroticism or (inversely) Emotional Stability

Neuroticism refers to the tendency to experience negative feelings. 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 Extroversion domain.

Openness to Experience

Openness to Experience describes a dimension of cognitive style 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 tend to think and act in individualistic and nonconforming ways. 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.
Openness is often presented as healthier or more mature by psychologists, who are often themselves open to experience. However, open and closed styles of thinking are useful in different environments. The intellectual style of the open person may serve a professor well, but research has shown that closed thinking is related to superior job performance in police work, sales, and a number of service occupations.

One of the most significant advances of the five factor model was the establishment of a taxonomy that demonstrates order in a previously scattered and disorganized field. For example, as an extremely heterogeneous collection of traits, research had found that "personality" (i.e., any of a large number of hypothesized personality traits) was not predictive of important criteria. However, using the five-factor model as a taxonomy to group the vast numbers of unlike personality traits, meta-analysis of previous research by Barrick and Mount showed that there were many significant correlations between the personality traits of the five-factor model and job performance in many jobs. Their strongest finding was that Conscientiousness was predictive of performance in all the job families studied. This makes perfect sense, insofar as it is very difficult to imagine any job where, all other things equal, being high in Conscientiousness is not an advantage.

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. The existence of each one has been verified by cross-cultural research demonstrating that they exist in individuals outside of Western nations, and all show an influence from both heredity and environment (in roughly equal proportion).

A person's ratings on the five factors has been found to change with time, with Agreeableness and Conscientiousness increasing, while Extroversion, Neuroticism, and Openness generally decrease as a person ages. Sexes show differences in Big Five scores across cultures, with women scoring higher in both the Agreeableness and Neuroticism domains. (The mere fact that sex differences have been found does not by itself demonstrate that the sexes are innately different in personality, although that is a possibility.) Individuals also differ when viewed by the order of their births; Frank J. Sulloway has mounted evidence that birth order is correlated with personality traits: firstborns are statistically more conscientious, more socially dominant, less agreeable, and less open to new ideas compared to later born children.

Relationships have also been discovered between Geert Hofstede's cultural factors (Individualism, Power Distance, Masculinity, and Uncertainty Avoidance) and the average Big Five scores in a country. For instance, the degree to which a country values individualism correlates with its average Extroversion, while people living in cultures which are accepting of large inequalities in their power structures tend to score somewhat higher on Conscientiousness.


There are several weaknesses to the Big Five. The first of these is that 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 Extroversion, for instance, indicating that those who are more prone to experiencing negative emotions tend to be less talkative and outgoing.

Another weakness is that the Big Five do not explain all of human personality. Some psychologists have dissented from the model precisely because they feel it neglects other personality traits, such as:

  • Religiosity
  • Manipulativeness
  • Honesty
  • Sexiness
  • Thriftiness
  • Conservativeness
  • Masculinity/Femininity
  • Snobbishness
  • Sense of humor

Correlations have been found between these factors and the Big Five, such as the well known inverse relationship between political conservatism and Openness, although variation in these traits is not entirely explained by the Five Factors themselves.

Moreover, the methodology used to investigate these phenomena (factor analysis) does not have a well-supported, universally-recognized scientific or statistical basis for choosing among solutions with different numbers of factors. That is, a five factor solution is a choice of the analyst, at least to some degree. A larger number of factors may, in fact, underlie these five factors and a dataset of these variables may be factored into simpler models. This has lead to disputes about the "true" number of factors. Many researchers and practitioners have criticized these five factors as being far too broad for applied work. In unpublished research, Goldberg (who coined the term "Big Five") found that Cattell's 16 factor solution has greater predictive power than five factors, even when the number of predictors is controlled by using a cross-validation sample to assess the prediction of competing regression models (16 versus 5 variables).

Another weakness of the Big Five is that they rely on self report questionnaires to be measured; 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 last weakness of the Big Five, and a criticism which has frequently been leveled at it, is that it 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.

Social-cognitive theories

In cognitivism behavior is explained as guided by cognitions (e.g., expectations) about the world, and especially those about other people. Albert Bandura, a social learning theorist suggested that the forces of memory and emotions worked in conjunction with environmental influences. Social-cognitive theorists emphasize the situation the person is in and the person's expectations, habits, and belief system. This approach claims that the environment, cognitions, and a person's behavior all have an influence on each other in a complex pattern called reciprocal determinism, which shapes one's distinctive personality. We learn ways of reacting to situations in our environment in part because of rewards and punishment. However, once acquired, our habits, behaviors, and cognitions influence how we respond to others and to situations.

A significant personality trait that illustrates reciprocal determinism is "self-efficacy," a sense of one's ability to achieve results and reach goals even in the face of overwhelming obstacles. Self-efficacy is acquired through four factors:

  • having experiences in mastering new skills and overcoming obstacles
  • having successful and competent role models in one's life
  • receiving feedback and encouragement from others
  • self awareness and management of one's inner state (thoughts and emotions).

Another example of how reciprocal determinism shapes personality is called "locus of control." This is the degree to which people believe they have control over their lives. One's expectations of success or failure, control over events, or lack of control, may create a self-fulfilling prophecy; one's expectations can actually lead to behavior that makes the expectation occur. Typically people with an internal locus of control believe they are responsible for what happens in their lives and that they control their own destiny. Those with an external locus of control tend to believe that the control is outside of them - luck, fate, or other people control their life circumstances. Julian Rotter developed an Internal/External Scale which as been used in research extensively. He stated that an internal locus of control typically emerges at a very young age, but can change depending on later life experiences in society and one's perceptions of their life experiences.

Both self-efficacy and an internal locus of control are considered to produce positive results in one's health, achievements, and social activism.

Cultural theories

Many qualities that are treated as personality traits are actually influenced by one's culture. For example, in "cultures of honor" men are more likely to react aggressively to restore their sense of honor than are men from other cultures. In "individualistic cultures" people define themselves in different terms than those in "collectivist cultures", as they see their "selves" as more stable cross-situationally. In "monochronic cultures" individuals stress punctuality and doing things one at a time, whereas those from "polychronic cultures" value relationship above time schedule. The challenge for cultural theorists is to describe cultural influences on personality without stereotyping.

Work by Geert Hofstede in over 64 countries has demonstrated that there are national and regional cultural groupings that affect the behavior of organizations, and that are very persistent across time. He identified five dimensions of culture in his study of national influences:

  • Power Distance
  • Individualism
  • Masculinity versus Femininity
  • Uncertainty Avoidance
  • Long-term versus Short-term Orientation

Hofstede's research revealed that country scores on the five dimensions were statistically correlated with a multitude of other data about the countries, pointing to some of the roots of [cultural differences.

Psychoanalytic theories

Psychoanalytic theories, based on the work of Sigmund Freud, explain human behavior in terms of interaction between the various components of personality. Freud drew on the physics (thermodynamics) of his day to coin the term psychodynamics: based on the popular ideas of conversion of heat into mechanical energy and vice versa, he proposed the conversion of psychic energy into behavior. He broke the human personality down to three significant components: the ego, superego, and id. According to Freud, personality is shaped by the interactions of these three components.

Psychoanalytic theories have been the source of subjective tests of personality called projective tests (including the Rorschach Inkblot Test). These are considered useful for therapy, but are considered to have poor reliability and validity and therefore not used in legal or employment settings.

Psychoanalytic approaches have been criticized for basing theories on the sometimes unreliable memories of patients, rather than on prospective studies. However, ideas about unconscious processes and defense mechanisms have been studied empirically and have made important contributions to psychology.

Jungian typology

Carl Jung taught that the personality includes many archetypes, including the shadow, the anima and the animus. This is based on his theory that all people share a collective unconscious that consists of universal memories and images, which he called archetypes.

Building on the writings and observations of Carl Jung, during World War II Isabel Briggs Myers and her mother Katharine Cook Briggs delineated personality types by constructing the Myers-Briggs Type Indicator (MBTI). This model was later elaborated further by David Keirsey. The model begins by accepting Extroversion vs. Introversion as basic, and adding an additional three dimensions:

  • Extroversion vs. Introversion (preferring the external world of events and people versus finding meaning within one's own thoughts and feelings)
  • Intuition vs. Sensing (trust in conceptual/abstract models of reality versus concrete sensory-oriented facts)
  • Thinking vs. Feeling (thinking as the prime-mover in decision-making vs. feelings as the prime-mover in decision-making)
  • Perceiving vs. Judging (desire to perceive events vs. desire to have things done so judgments can be made)

Although founded in the psychoanalytic approach stressing unconscious motives and memories, this personality typology has some aspects of a trait theory: it explains people's behavior in terms of opposite fixed characteristics. The intuition factor is considered the most basic, dividing people into "N" or "S" personality types. An "N" is further assumed to be guided by the thinking or Objectivation habit, or feelings, and be divided into "NT" (scientist, engineer) or "NF" (author, human-oriented leader) personality. An "S", by contrast, is assumed to be more guided by the perception axis, and thus divided into "SP" (performer, craftsman, artisan) and "SJ" (guardian, accountant, bureaucrat) personality. These four are considered basic, with the other two factors in each case (including always extraversion) less important. Critics of this traditional view have observed that the types are quite strongly stereotyped by professions, and thus may arise more from the need to categorize people for purposes of guiding their career choice.

Humanistic theories

In humanistic psychology it is emphasized that people have free will and that they play an active role in determining how they behave. This approach places less emphasis on genes, past learning, or unconscious conflicts and dwells mostly on the unique human capacity to shape one's own future through freedom of choice and free will. Accordingly, humanistic psychology focuses on subjective experiences of persons instead of factors that determine behavior. This approach explores human potential and the strengths of the human being. Abraham Maslow, with his concept of peak experiences and self actualization, and Carl Rogers, who stressed the importance of unconditional positive regard, were proponents of this view. In addition, Rollo May and Viktor Frankl emphasized the search for meaning in life.

While critics observe that these ideas are subjective and very difficult to measure, these theories add depth and balance to the study of personality, as well as foster a new appreciation of human resilience in the face of adversity.

Personality tests

Personality tests aim to assess aspects of a person's character that remain stable across a variety of situations. Various approaches are taken to this type of assessment, based on the different theoretical models of personality and on various methodologies. Some tests involve long self-assessment questionnaires in which the subjects rate themselves on a series of attitudes or responses to situations. Others, known as projective tests, involve having people respond to ambiguous pictures, revealing their feelings and underlying needs or conflicts.

Brain Research

Around the 1990s, neuroscience entered the domain of personality psychology. Whereas previous efforts for identifying personality differences relied upon simple, direct, human observation, neuroscience introduced powerful brain analysis tools like Electroencephalography (EEG), Positron Emission Tomography (PET), and Functional Magnetic Resonance Imaging (fMRI) to this study.

Research in this area by Richard Davidson at the University of Wisconsin-Madison, has focused on the role of the prefrontal cortex (PFC) and amygdala in manifesting human personality. In particular, this research has looked at hemispheric asymmetry of activity in these regions. A major focus of their research concerns individual differences in affective style: how and why individuals differ in how they respond to emotional challenges.

Research on brain processes has provided substantial support for personality models involving the extroversion-introversion dimension, such as the MBTI model of personality. Research reported by Kahn and Radcliffe (2005) has identified 16 different ways in which people process information and their corresponding brain mechanisms. These 16 processes of the "Human Dimensions Model" (HDM) correspond very closely to the 16 types of the MBTI, lending scientific credibility to the test.


Human personality is a complex area of study. Not only is human nature complex, but also each individual has a unique combination of inherent abilities and preferences and learned responses. Beyond that, any researchers of personality also have certain personalities, which requires them to "bare their soul" in order to understand themselves and others.

Perhaps no single theory will ever account for all the complexities of human personality. All five theories may be integrated by recognizing that personality is multi-dimensional. There is a public personality of our basic traits which are addressed by the biological (genetic), learning and cultural theories; and there is a private personality that reflects the inner sense of self, emotions, dreams and memories, that is addressed by the humanist and psychodynamic theories.

ISBN links support NWE through referral fees

  • Carole, Wade & Tavris Carol. 2005. Psychology. Prentice-Hall, Inc. ISBN 0131926845
  • Kahn, Alan R. & K.A. Radcliffe. 2005. Mind Shapes:Understanding the Differences in Thinking and Communication. St. Paul, MN: Paragon House. ISBN 1557788499
  • Kassin, Saul. 2003. Psychology. Prentice-Hall, Inc. ISBN 013863887X
  • Mischel, W. 2003. Introduction to Personality, Seventh edition. Wiley. ISBN 0471272493

External links

All links retrieved November 23, 2022.


New World Encyclopedia writers and editors rewrote and completed the Wikipedia article in accordance with New World Encyclopedia standards. This article abides by terms of the Creative Commons CC-by-sa 3.0 License (CC-by-sa), which may be used and disseminated with proper attribution. Credit is due under the terms of this license that can reference both the New World Encyclopedia contributors and the selfless volunteer contributors of the Wikimedia Foundation. To cite this article click here for a list of acceptable citing formats.The history of earlier contributions by wikipedians is accessible to researchers here:

The history of this article since it was imported to New World Encyclopedia:

Note: Some restrictions may apply to use of individual images which are separately licensed.