Big Five vs Eysenck's PEN Model: How the Personality Models Differ

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Author: Ukrainian Psychological Hub · Published: October 9, 2026 · Editorial Policy

The Big Five and Hans Eysenck's PEN model describe broad patterns of personality, but they divide the personality domain differently. The Big Five identifies five major dimensions: Openness to Experience, Conscientiousness, Extraversion, Agreeableness, and Neuroticism. Eysenck's PEN framework identifies three broad dimensions: Psychoticism, Extraversion, and Neuroticism. Their shared labels conceal important differences in what is included within each dimension, how the frameworks developed, and what their questionnaires measure.

The closest correspondence is between the two Extraversion dimensions and between the two Neuroticism dimensions. Eysenck's Psychoticism relates most consistently to the lower ends of Big Five Agreeableness and Conscientiousness; it is neither simply equivalent to either trait nor a substitute for Big Five Openness. This pattern emerged directly in McCrae and Costa's 1985 comparison of Eysenck scales and five-factor measures. For a full introduction to the five-factor framework itself, see the Big Five personality traits guide.

Big Five vs PEN model: the essential differences

Number and names of broad dimensions: the Big Five organizes personality into five continuous domains; PEN uses three broad dimensions, abbreviated P for Psychoticism, E for Extraversion, and N for Neuroticism. Neither acronym denotes a set of discrete human personality types. A respondent is described by a position along dimensions, and the meaning of the position depends on the particular scale.

Coverage of personality characteristics: the Big Five treats interpersonal cooperativeness, goal-directed self-regulation, and intellectual or experiential openness as separate major domains. The PEN approach places more weight on three dimensions selected partly for their hypothesized biological and theoretical importance. In the original debates, the central question was which hierarchical level should count as fundamental, rather than a simple contest between three and five questionnaire scores.

Historical tradition: the Big Five draws heavily on the study of personality-descriptive words and later converged with questionnaire-based five-factor approaches. Eysenck developed PEN through psychometric research and a program seeking physiological, genetic, learning-theory, and other explanatory connections. Goldberg's lexical study and Eysenck's discussion of taxonomic criteria make that contrast especially clear.

Practical measurement: a five-factor inventory and an Eysenck questionnaire produce scores for the specific traits and item content they were built to assess. A Big Five score cannot be converted into an EPQ-R score through a universal formula, and two instruments sharing the word Extraversion do not automatically have identical item coverage, norms, or interpretation rules.

What is the Big Five personality model?

The Big Five is a broad descriptive taxonomy of recurring individual differences. Openness describes tendencies involving ideas, imagination, aesthetics, and receptivity to experience; Conscientiousness includes organization, persistence, and responsibility; Extraversion includes sociability, assertiveness, activity, and positive emotional engagement; Agreeableness includes cooperation, trust, compassion, and interpersonal consideration; Neuroticism concerns tendencies toward more frequent or intense negative emotional experiences. These are rough domain summaries; exact item meanings depend on the inventory.

The lexical research tradition asks whether the distinctions that people regularly make in everyday descriptions of personality can be summarized by a smaller number of broad factors. In a major study, Goldberg (1990) found a replicable five-factor solution across comprehensive sets of English trait terms. The modern five-factor framework also rests on questionnaire studies, observer ratings, longitudinal evidence, and research on behavioral correlates. Costa and McCrae (1992) summarized several lines of evidence used to defend the five-factor level.

The Big Five's five domains occupy the broadest familiar level of a hierarchy. More specific characteristics can be organized below them, although the exact aspect and facet structure changes across instruments. The NEO family, the BFI-2, and the Big Five Aspect Scales use their own validated subscale arrangements. The Big Five domains, aspects, and facets guide addresses that internal structure without treating a single questionnaire's facets as universal.

Big Five and Five-Factor Model are often used interchangeably in contemporary writing, although the lexical history, inventory traditions, and some theoretical commitments differ. Those distinctions have their own canonical article, Big Five vs Five-Factor Model. Here the subject is the relationship between the broad five-factor family and Eysenck's PEN system.

What is Eysenck's PEN model?

Hans J. Eysenck's three-factor personality framework proposes three broad, partly heritable dimensions. Its labels form PEN: Psychoticism, Extraversion, and Neuroticism. Eysenck regarded broad factors as parts of a hierarchy running from individual responses and habits toward more general traits and superordinate dimensions. He also wanted a personality taxonomy capable of generating and evaluating explanations involving biological and behavioral processes.

Psychoticism, the P dimension, includes a heterogeneous set of tendencies that Eysenck's measures associated with tough-mindedness, impulsiveness, hostility, low conformity, and reduced interpersonal consideration. A high P scale score is a result on a particular research or personality questionnaire; it is not a diagnosis of psychosis, schizophrenia, or a personality disorder. The provocative historical name has generated lasting conceptual confusion, and the validity of its connection with clinical psychosis was challenged in the peer-reviewed critique by Bishop (1977).

Extraversion, the E dimension, describes differences in sociability, liveliness, activity, and related tendencies, although the emphasis has varied across questionnaires and revisions. Neuroticism, the N dimension, broadly concerns negative emotional reactivity and related vulnerability. These two labels overlap substantially with Big Five Extraversion and Neuroticism, but questionnaire scores remain instrument-specific. For the N-related boundary, the dedicated Neuroticism vs Psychoticism comparison provides the narrower treatment.

Eysenck also investigated biological explanations, including theories linking Extraversion with cortical arousal and Neuroticism with emotional reactivity. These ideas supplied testable hypotheses and guided research; historical theoretical mechanisms should not be presented as universally confirmed explanations for an individual's score. His own 1991 theoretical comparison emphasized criteria such as biological grounding and theoretical integration when selecting fundamental factors.

PEN and Big Five traits side by side

Extraversion: substantial overlap, different emphases

Both models recognize a broad Extraversion dimension. In one classic head-to-head study, Eysenck and five-factor Extraversion measures aligned well, providing unusually direct evidence of overlap across traditions. McCrae and Costa (1985) also found that sociability and impulsivity were distinguishable traits even though both contributed to the wider Extraversion territory in their analysis. This qualification matters because the content of the measured trait can change when researchers revise items.

A person who reports enjoying frequent interaction may score relatively high on Extraversion measures in either family. But the EPQ-R and a particular Big Five inventory do not necessarily weight assertiveness, positive affect, talkativeness, sensation seeking, or activity in the same manner. Thus the comparison is strongest at the level of broad statistical association and weaker when it is treated as a promise of numerically equivalent individual scores.

Neuroticism: shared core, separate measurement histories

The Neuroticism domains also correspond comparatively well. Both broadly concern stable differences in negative emotional experiences, sensitivity to threat or distress, and related patterns. McCrae and Costa's empirical comparison supports the similarity between the factors. However, the term denotes a continuous trait dimension within a model of individual differences; a person's high or low score is not a clinical diagnosis or a determination of whether they will develop a mental disorder.

Modern inventories may name or organize emotionality constructs differently. For example, the BFI-2 uses the label Negative Emotionality for its relevant domain. The original BFI-2 development and validation study describes that instrument's particular hierarchy. Such naming differences require attention to actual scale definitions rather than mechanically substituting one instrument's label for another. The N-specific clinical and measurement details remain with the site's established Neuroticism coverage.

Psychoticism: the most important mismatch

P is the key point of divergence. Eysenck proposed Psychoticism as one broad personality dimension, whereas the Big Five separates a substantial part of its item content across Agreeableness and Conscientiousness. In their original comparative analysis, McCrae and Costa (1985) found P most closely aligned with low Agreeableness and low Conscientiousness. That pattern supports a relationship between constructs; it does not establish that P is precisely their sum or that those two Big Five domains should always collapse.

This distinction has a practical meaning. Agreeableness includes qualities of interpersonal warmth, consideration, and conflict style; Conscientiousness covers planning, persistence, self-control, and order. These characteristics can vary independently. A person may be orderly and self-disciplined while remaining blunt or confrontational, or unusually compassionate while being disorganized. Compressing such combinations into a single P score loses distinctions that a five-domain description can preserve.

The reverse problem also exists: the P score may contain information or item emphases that are not perfectly captured by a simplistic subtraction from Agreeableness and Conscientiousness. Scale content, sample characteristics, and statistical methods influence the relationship. A study comparing EPQ-R with a Big Five Questionnaire in Italian samples found substantial shared variance while reporting only partial support for Eysenck's hierarchical claim. That is why overlapping scales cannot settle the structure of all personality characteristics on their own.

Openness: a broad Big Five domain without a direct PEN equivalent

Openness to Experience describes tendencies such as curiosity, imagination, engagement with ideas, receptivity to art, and interest in alternative perspectives. It appears as an independent broad domain in familiar five-factor systems. McCrae and Costa's 1985 comparison explicitly reported that Openness was not well represented by the Eysenck measures they examined.

Occasional associations between curiosity, unconventionality, or unusual experiences and P-related indicators should not be used to equate Openness with Psychoticism or with clinical psychosis. Different instruments may include very different content under similarly suggestive labels. A five-factor measure of Openness primarily assesses the construct specified by that measure; it is not a test for hallucinations, psychotic symptoms, or diagnostic risk.

Agreeableness and Conscientiousness: distinct domains in Big Five

The five-factor model's major structural advantage for this comparison is its ability to report Agreeableness and Conscientiousness separately. This is especially informative when an investigation requires distinctions between interpersonal tendencies and goal-oriented regulation. The fact that both domains can correlate negatively with Eysenck's P does not make them interchangeable. Factor correlations are sample-level estimates, and factor granularity depends partly on the level of analysis.

Eysenck argued that some five-factor dimensions should be treated as more specific components within a larger, higher-order P-related structure. His 1992 response to Costa and McCrae made that case explicitly. Costa and McCrae, in turn, defended the five-factor structure as a set of enduring basic dispositions with evidence spanning methods and populations. Their 1992 paper documents that competing position. The dispute therefore concerns the most defensible hierarchy, not simply whether relationships between scales exist.

Why do the models have three versus five factors?

The number of factors depends on the psychological domain sampled, how items are written, who responds, which measures are analyzed together, and the criteria researchers adopt for extracting and interpreting factors. Factors summarize covariance in observations. A three-factor solution can represent broader combinations of characteristics that a five-factor solution separates; neither result, in isolation, proves that human personality contains exactly three or exactly five natural kinds.

The lexical approach searches for recurrent patterns among trait-descriptive terms and judgments. Eysenck's tradition prioritized biologically and theoretically meaningful higher-order dimensions. These programs ask related yet partly different questions. The five-factor literature sought broad coverage of everyday trait differences, while PEN placed special value on parsimony and possible causal or physiological grounding. Eysenck's 1991 analysis states the taxonomic issue directly.

A useful empirical caution comes from Saggino's 2000 replication study comparing EPQ-R and a Big Five Questionnaire: substantial shared variance did not reduce to a simple winner-takes-all solution, and a four-factor account fit the scale-level relations studied. Results from a particular sample and battery can support some structural interpretations more than others without deciding every theoretical question.

There is also a difference between recovering three broad factors from one dataset and validating the specific content of PEN's Psychoticism construct. Independent lexical research has sometimes recovered fewer than five highly reproducible dimensions across languages, but the recovered three are not automatically Eysenck's P, E, and N. De Raad and colleagues' 2010 comparison of lexical taxonomies illustrates cross-language structural constraints; it does not validate an equivalence between any three-factor solution and the PEN inventory.

The historical debate: Eysenck, Costa, McCrae, and the factor hierarchy

Personality research had multiple overlapping traditions long before today's popular OCEAN summaries. Eysenck developed broad-factor explanations during decades of psychometric and biological research. The Big Five emerged through independent programs studying personality descriptions, and Costa and McCrae's five-factor inventories provided a major questionnaire-based account. This background explains why the same broad traits can appear in different systems while their theories and scales remain distinct. The complete chronology belongs to the history of the Big Five model.

A particularly valuable moment came in 1985, when McCrae and Costa directly compared Eysenck scales with five-factor measures. Their findings did not suggest that the models were unrelated. They found clear correspondence for N and E, incomplete coverage of Openness in Eysenck's system, and a P relationship concentrated at the low ends of A and C. The empirical pattern made the dispute about hierarchy more precise.

In 1991, Eysenck asked whether personality should be organized into 16, five, or three broad dimensions, proposing standards by which competing taxonomies could be judged. In 1992, Costa and McCrae argued for five basic factors and Eysenck replied with arguments for a three-factor interpretation. Reading these studies together shows a genuine theoretical disagreement about evidence, explanatory mechanisms, and how broadly to define a fundamental personality dimension.

The debate remains instructive because one statistical solution cannot answer every question. Researchers may ask whether a model describes individual differences efficiently, predicts external criteria, supports measurement across groups, yields replicable fine-grained facets, or supplies convincing causal explanations. The appropriate answer can vary with the research question, instrument, and level of inference.

What does Psychoticism mean in the PEN framework?

The word Psychoticism is historically specific to Eysenck's theory. His P scale was intended to index ordinary-range variation in characteristics linked to his broader hypothesis. The clinical sound of the term makes it unusually important to distinguish a personality dimension from symptoms and formal diagnoses. Being high on an EPQ-R P scale does not establish that someone has schizophrenia, psychotic depression, a psychotic episode, or a personality disorder.

The debate about P also concerns measurement quality. The authors of a 1985 revision of the Psychoticism scale identified weaknesses of the original P measure, including reliability and skewed scores, and introduced revised items in an effort to improve it. A later item-response-theory study of a revised short EPQ-R form evaluated a specific 48-item instrument. These results should be understood as evidence about particular test forms and samples, not as a final proof that every version has identical properties.

Scholarly criticism of the psychosis connection was present early. Bishop's 1977 article questioned assumptions behind interpreting P as a continuum connecting ordinary personality and psychosis. Contemporary readers should therefore be particularly cautious when secondary sites equate 'high psychoticism' with being psychotic, dangerous, or inherently antisocial. Those statements exceed what a normal-range questionnaire result can establish.

Low Agreeableness, low Conscientiousness, and high P also must remain descriptive rather than moral labels. Behavioral expressions depend on context, specific subtraits, the instrument used, and many other individual and situational influences. Treating a scale as a judgment about human worth both misrepresents its scientific function and weakens interpretation.

What personality tests measure the Big Five and PEN?

Five-factor instruments

Big Five scores are obtained from questionnaires and rating instruments built around five broad dimensions. Examples include the NEO inventory family, the Big Five Inventory and its BFI-2 revision, and lexical adjective-based instruments. These tools differ in length, item pools, subscales, scoring rules, and populations used for validation. A Big Five framework names a structure; it is not itself a single test with universal scoring thresholds.

The BFI-2 development study describes five domains with three instrument-specific facets each. The NEO-PI-R uses its own facet system, while other questionnaires may report only domains or different intermediate levels. It would be incorrect to claim that every Big Five test has the same number or identity of facets. For this comparison, the useful question is whether an instrument provides separate valid information about Openness, Agreeableness, and Conscientiousness that a PEN-only battery does not report in the same way.

Eysenck questionnaires and the P, E, N, and L scales

Eysenck's questionnaire family includes instruments and revisions that should be distinguished by name and version. The Eysenck Personality Inventory and the Eysenck Personality Questionnaire-Revised are not identical measures; the EPQ-R assesses P, E, N, and a Lie or L scale. The L scale is part of questionnaire scoring and interpretation; it is not generally counted as a fourth major PEN personality dimension. A 2018 EPQ-R short-form study specifies four 12-item scales in its proposed 48-item version.

The L scale should not be treated as a perfect, context-free dishonesty detector. In the early model comparison, McCrae and Costa found that the EPI L scale reflected aspects of several substantive traits rather than merely a response bias. The precise role and interpretation of validity-related scales require evidence specific to the actual instrument. Modern assessment also considers how response style, item reading level, and social context affect answers.

Can scores from one model be converted to the other?

A direct score conversion is not justified merely because domain labels resemble one another. Scales use different items, weights, norms, and measurement error. A research team can estimate statistical relations or design a validated linking study in a defined sample, but such crosswalks need evidence of adequate reliability, construct overlap, and performance in relevant populations before they are applied elsewhere.

In particular, the common summary 'P = low A + low C' is too crude for score interpretation. Correlation with two Big Five domains does not provide a universally accurate formula for an individual's P score. Nor can a Big Five Openness score fill an empty PEN column simply because both models describe personality.

Do the Big Five and PEN describe personality traits or personality types?

Both frameworks are principally dimensional: individual differences are expressed as relatively continuous positions rather than all-or-nothing membership in fixed categories. Eysenck sometimes used typological language when discussing higher-order dimensions, but scores on P, E, and N still vary along scales. Likewise, OCEAN profiles consist of multiple scores, not one of five 'types.'

A trait reflects a relatively enduring tendency across situations and time, while a state refers to what a person is experiencing or doing in a particular context. Neither model predicts that every behavior must match an overall trait score at every moment. A relatively introverted person may enjoy a crowded party; a conscientious person may miss an appointment; a person high in Negative Emotionality may feel calm throughout a particular day.

Any high or low label requires the scoring conventions of the specific validated instrument and reference population. There is no universal clinical cutoff separating high and low Extraversion, or 'normal' from 'abnormal' levels of a broad trait. The same caution applies especially strongly to Psychoticism, given the historical and measurement issues already described.

Which model is scientifically better supported?

The five-factor framework has a very substantial descriptive research tradition encompassing lexical studies, questionnaires, informant reports, and studies across varied populations. Goldberg's 1990 research and Costa and McCrae's 1992 synthesis document important foundations. It is reasonable to use the Big Five as a widely researched broad taxonomy when the task is to summarize general personality characteristics.

The PEN framework remains historically significant and scientifically useful for investigating its three broad constructs, their measurement, and hypotheses associated with Eysenck's psychobiological program. Its explanatory ambition is a distinctive feature. However, the existence of testable biological hypotheses does not mean that all proposed physiological mechanisms have been confirmed or that the P scale measures psychosis reliably. The evidence must be assessed one hypothesis and one instrument at a time.

The comparison becomes sharper when separating descriptive breadth from explanatory depth. A taxonomy can summarize observed differences without supplying a complete causal theory. An explanatory theory can propose mechanisms even where its taxonomy is disputed. Researchers therefore evaluate factor recovery, independent replication, convergent and discriminant validity, criterion associations, measurement precision, and theoretical predictions as separate considerations.

Neither framework alone is an adequate basis for predicting the choices, clinical status, professional outcomes, or character of a specific individual. Group-level relationships between trait scores and outcomes are probabilistic and depend on measurement, opportunity, environment, and context. The scientific literature supports meaningful regularities, but it does not authorize personality score determinism.

What do cross-cultural studies tell us?

Broad Big Five patterns have been documented in research from multiple cultures and languages, but cross-cultural support should be described at the level supported by the particular study. Lexical studies sample different vocabularies, translation choices, and culturally salient distinctions. De Raad and colleagues (2010) reported that only three broad factors of personality description were fully replicable under the methods they used across fourteen lexical taxonomies. That finding qualifies overly simple universal claims.

Crucially, the three lexical factors identified across languages cannot automatically be renamed Psychoticism, Extraversion, and Neuroticism. A factor's number does not determine its substantive identity. Comparisons require evidence about item content, factor loadings, measurement invariance, and criterion relations. Likewise, finding five factors within imported questionnaire items is a different research question from deriving a factor system afresh from independent local personality lexicons.

These issues affect practical scoring. Before comparing two individuals from different language communities—or comparing PEN with a translated Big Five inventory—a researcher must consider whether the questionnaire adequately measures the same constructs across groups. The existence of a recognizable model supplies a starting hypothesis, and instrument-specific validation supplies the more immediate basis for interpretation.

Are the models useful for predicting behavior or life outcomes?

A model can be evaluated by how well its measured traits relate to independently assessed behaviors or outcomes in relevant samples. Five-factor inventories provide broad trait distinctions that many research programs use when studying relationships, work, learning, and well-being. PEN instruments offer a different arrangement, and specific studies may find useful associations for their scales. The direction and strength of relationships depend on the outcome, measure, sample, and analytic design.

Associations at the group level do not establish that a given person will behave in a particular way. A conscientiousness score, for example, can summarize tendencies relevant to organization without fixing a person's job performance, grades, or future decisions. Likewise, low Agreeableness is not proof of hostility in any particular interaction, and a high P score is not a diagnosis or a forecast of violence.

Researchers comparing the two models may ask whether five separate domains explain variation beyond PEN's three, or whether a broader PEN configuration provides a sufficiently parsimonious description for a defined purpose. The EPQ-R and BFQ replication study illustrates this type of structural comparison. Valid prediction requires out-of-sample evidence, attention to base rates and practical effect sizes, and a clear distinction between statistical prediction and causal explanation.

How should a researcher choose between Big Five and PEN?

For a broad, accessible description of personality that preserves separate information about interpersonal style, self-regulation, and openness to experience, a validated five-factor inventory is often a practical choice. The Big Five vocabulary is also useful when a project needs to communicate findings with a large contemporary personality-research literature. Selection should still depend on the specific instrument's evidence in the intended population, language, and setting.

For research focused on Eysenck's historical theory, a particular P–E–N construct hypothesis, or the development and evaluation of Eysenck questionnaires, an appropriately validated PEN instrument may fit the question. That decision requires direct engagement with the measurement record, including the documented concerns about P. The original P-scale revision and a modern EPQ-R short-form analysis are useful starting points.

For an explicit head-to-head investigation, researchers should predefine the intended outcomes and compare instruments using the same sample where possible. They should examine dimensional coverage, reliability, statistical associations between nominally corresponding scales, incremental validity, sample generalizability, and missing dimensions. Factor counts alone do not tell an investigator whether information essential to the research question has been retained.

For clinical or high-stakes applications, neither a PEN questionnaire nor a Big Five test should be mistaken for a diagnostic interview or a complete clinical assessment. Decisions affecting health, employment, and other consequential outcomes demand purpose-specific validation, appropriate professional standards, and attention to fairness, privacy, and interpretation limits.

Common misconceptions about Big Five and Eysenck's PEN model

Misconception: PEN is just a shorter Big Five

PEN is a substantive three-factor theoretical tradition, not a Big Five questionnaire with two columns deleted. It differs in how its constructs are organized and in the explanatory program attached to them. The empirically observed E and N overlap is meaningful, but the P–A–C relationship and missing independent Openness dimension prevent a simple one-to-one mapping.

Misconception: high Psychoticism means a person has psychosis

Eysenck's P is a historically named personality measure, whereas psychosis is a clinical phenomenon assessed using clinical criteria and appropriate evaluation. The early P-scale criticism by Bishop and later efforts to improve the P scale show why the distinction is essential. No ordinary personality-test result establishes a psychiatric diagnosis.

Misconception: three-factor findings prove PEN is universal

A result containing three factors says how variables grouped under the methods used. To identify PEN specifically, those factors must also have relevant content and validated relations. The cross-language lexical comparison does not establish that Eysenck's Psychoticism appears as an identical basic factor in every language.

Misconception: low Agreeableness and low Conscientiousness always equal Psychoticism

The correlations documented by McCrae and Costa are relationships among measured variables. They do not supply a universal mathematical identity, and a particular person can combine high and low scores in many ways. Instrument wording and population characteristics matter.

Misconception: any Big Five or PEN score reveals a personality type

Trait measures report positions along dimensions. They become meaningful through scale definitions, data quality, and appropriate norms. Neither OCEAN nor PEN assigns a single fixed type or a reliable individual destiny.

Frequently asked questions

What is the main difference between the Big Five and Eysenck's PEN?

The Big Five reports five broad domains—Openness, Conscientiousness, Extraversion, Agreeableness, and Neuroticism—while PEN reports three—Psychoticism, Extraversion, and Neuroticism. E and N overlap substantially, whereas P combines characteristics that the Big Five largely distributes across low Agreeableness and low Conscientiousness. Independent Openness is prominent in the Big Five.

Is PEN a five-factor personality model?

No. PEN is the three-dimensional Psychoticism–Extraversion–Neuroticism framework. Some Eysenck questionnaires include an additional L scale, but that response-related scale is not a fourth PEN domain. The Big Five is a separate five-domain family of descriptive models and instruments.

What Big Five trait is Eysenck's Psychoticism closest to?

The strongest classic comparison relates P to lower Agreeableness and lower Conscientiousness, with variation by instrument and sample. It is not simply a relabeling of one Big Five trait. See the original comparative study for the direct evidence.

Are Neuroticism and Extraversion the same in both models?

They are closely corresponding broad constructs, and comparative studies report substantial convergence. Their exact item content, facet coverage, scoring, and norms can differ, so individual questionnaire results should not be equated automatically.

Does high Psychoticism mean schizophrenia?

No. An EPQ or EPQ-R Psychoticism score is not a diagnostic assessment of schizophrenia or any psychotic disorder. Symptoms and clinical diagnoses require an appropriate clinical assessment; the historical P construct has a contested relationship with psychosis.

Does the Big Five replace Eysenck's theory?

The Big Five is widely used to summarize broad personality dimensions, while Eysenck's model remains part of the scientific history and research on personality structure and proposed mechanisms. The frameworks can be compared and tested without treating the three-factor tradition as merely an incomplete Big Five test.

Why do some studies find three, four, or five factors?

Different item sets, samples, languages, analytic decisions, and levels of abstraction can yield different structures. A factor solution should be interpreted with its measurement design and criterion evidence. A three-factor solution is not necessarily PEN, and a five-factor questionnaire result does not by itself establish lexical universality.

Which test should I take?

Choose a specific validated instrument for a clearly defined purpose. For broad five-domain self-understanding, an appropriately validated Big Five measure generally gives more differentiated coverage. If the aim is to study a PEN hypothesis, use a validated Eysenck instrument and interpret the P scale especially carefully. Avoid applying arbitrary online cutoffs, making diagnoses, or treating a result as a fixed label.

Conclusion: two influential maps of personality

Big Five and PEN share an empirical core around Extraversion and Neuroticism but organize the remaining personality territory differently. The strongest comparative evidence relates Eysenck's Psychoticism to the lower poles of Big Five Agreeableness and Conscientiousness and shows that Openness is incompletely represented within the Eysenck scales examined. The two systems also emerged from partly different research programs: broad descriptive taxonomy and a more explicitly psychobiological theory. McCrae and Costa's direct comparison remains an especially clear account of these overlaps and divergences.

For a reader, the practical rule is to distinguish the model from the test, the dimension from a type, the statistical association from an individual prediction, and a questionnaire score from a diagnosis. For a researcher, the right model is the one whose specified constructs, measures, and evidence answer the actual question. The Big Five master guide and the history of its development provide the surrounding context.