Traits and Traits Taxonomies

Formulations and Conceptualizations of Personality Traits

Personality traits are considered the fundamental building blocks of personality, serving as universal dimensions that account for individual differences. There are two primary formulations of traits. The first views traits as internal causal properties. In this view, a trait such as neuroticism is an internal state that causes specific thoughts and emotions within the individual. The second formulation treats traits as purely descriptive summaries. For example, extraversion in this context refers to how socially a person behaves rather than how social they feel or how drawn they are to social situations. This descriptive view often utilizes the act frequency approach, which organizes traits as categories of acts.

The act frequency approach involves three distinct steps: act nomination, prototypicality judgment, and recording of act performance. Act nomination is the process of identifying which specific acts belong to which trait categories. For example, to identify the trait of impulsivity, researchers might look for behaviors such as deciding to go out even when there is studying to be done, or accepting a dare to do something dangerous without thinking about the consequences. Prototypicality judgment involves identifying which acts are most central or typical of a trait. In the case of dominance, an act like "controlled the outcome of a meeting" is considered prototypically dominant, whereas "deliberately arrived late for a meeting" is not. The final step, recording of act performance, involves securing information on how frequently these acts are performed through self-reports or reports from close friends and partners. However, the act frequency approach faces criticisms for technical implementation issues, such as not specifying how much context is applicable and being restricted only to overt actions.

Identification and Taxonomy of Important Traits

There are three main approaches to identifying the most important personality traits: the lexical approach, the statistical approach, and the theoretical approach. The lexical approach is based on the lexical hypothesis, which posits that all important individual differences have become encoded within natural language over time. Therefore, the most essential traits should have a high synonym frequency (many words describing them, such as dominance having terms like bossy, assertive, powerful, and pushy) and cross-cultural universality (people everywhere will have a word for the trait).

The statistical approach often follows the lexical approach by taking personality items and organizing them based on covariance, where items that go together are categorized together. The most common procedure is factor analysis, which identifies groups of items that correlate with each other but not with other groups. Factor loadings indicate how much of the variation in an item is explained by a factor. For instance, an extraversion factor would show high loadings on items like humorous, amusing, and popular. The theoretical approach determines which variables are important based on a specific theory. An example is Maslow’s study of the key personality traits of self-actualizers. Often, researchers use a multifaceted approach where results from lexical studies are analyzed statistically, and theory informs one or more stages of the research, such as in the study of sociosexual orientation involving two alternative sexual strategies.

Eysenck’s Hierarchical Model of Personality

Hans Eysenck proposed a taxonomy based on three broad traits, often referred to as the PEN model: Extraversion ($E$), Neuroticism ($N$), and Psychoticism ($P$). This model is hierarchical, moving from broad traits to narrow traits, then to habitual actions, and finally to specific actions. For example, the broad trait of Extraversion includes the narrow trait of being sociable, which leads to the habitual action of starting conversations frequently. The model emphasizes that being high in one trait does not necessarily mean being high in the others.

Eysenck established specific biological criteria for his traits, including moderate heritability for $P$, $E$, and $N$. He also sought psychophysiological foundations, presuming traits are part of a causal chain rooted in the brain and central nervous system ($CNS$). Extraversion is associated with $CNS$ arousal or reactivity; extraverts seek stimulation while introverts are easily overstimulated. Extraversion is also linked to higher blood flow and reward-seeking behavior. Neuroticism is associated with greater reactivity to stress, involving physiological responses like increased heart rates and the release of cortisol, as well as psychological responses where individuals describe situations as more stressful. Neuroticism also has a small correlation with introversion. Psychoticism is associated with higher levels of testosterone and lower levels of monoamine oxidase ($MAO$), a neurotransmitter regulator. Low $MAO$ allows for high optimal arousal to be achieved through impulsive or tough-minded behavior. An identified example of a high psychoticism individual is Steve Jobs, characterized as unempathetic and manipulative of others' perceptions, though not necessarily highly aggressive or antisocial.

Wiggins’ Interpersonal Circumplex and Social Exchange

Jerry Wiggins developed the Interpersonal Circumplex to specifically map interpersonal traits, which are defined as interactions in social exchange. He identified two primary modes of existence, known as "the Big Two": Agency and Communion. Agency (Status) involves getting ahead, competence, and assertiveness, representing the organism as an individual. This is associated with individual agency and can be detrimental if unmitigated, as it may lead to losing communion. Politically, this aligns with the conservative party. Communion (Love) involves getting along, warmth, and morality, representing the organism as a social being. This aligns with the liberal party. Other dimensions mentioned in this context include femininity/masculinity and individualism/collectivism.

The Interpersonal Circumplex describes three types of relationships between traits based on their geometric position. Adjacency occurs when traits are next to each other on the circle, indicating they are positively correlated (e.g., gregarious-extraverted and warm-agreeable). Bipolarity occurs when traits are located at opposite sides, indicating they are negatively correlated (e.g., dominant and submissive). Orthogonality occurs when traits are separated by $90$ degrees, indicating they are entirely unrelated or have zero correlation. Orthogonality allows for greater precision in describing behavior. For example, dominance expressed in a quarrelsome way might involve yelling to get one's way, while dominance expressed in an agreeable way might involve organizing a group to seek help.

The Five-Factor Model (Big Five) and NEO-PI-R

The Five-Factor Model is the leading taxonomy in personality psychology, having been replicated in numerous countries, cultures, and languages since $1949$. It consists of five broad traits, each with six narrow facets: Surgety/Extraversion, Agreeableness (the opposite of aggressiveness), Conscientiousness, Emotional Instability/Neuroticism, and Openness to Experience (also called Intellect-Openness). High conscientiousness is associated with performing well in school and work, avoiding rule-breaking, and secure romantic relationships, while low conscientiousness is linked to risky sexual behavior and frequent arrests. Neuroticism determines how people cope with stress. Openness to Experience is linked to remembering dreams and trying new foods.

The Big Five is measured through self-ratings of single-word trait adjectives (e.g., talkative, organized) or self-ratings of sentences. The NEO-PI-R (Revised Neuroticism-Extraversion-Openness Personality Inventory) uses sentence-length formats. Examples of items include: "I have frequent mood swings" (Neuroticism), "I don't find it easy to take charge of a situation" (Extraversion, reversed score), "I enjoy trying new foreign food" (Openness), "Most people I know like me" (Agreeableness), and "I keep my belongings neat and clean" (Conscientiousness). Research using the Big Five shows that good grades are predicted by high conscientiousness and high emotional stability. Academic dishonesty is linked to low conscientiousness and low agreeableness. Educational attainment and earnings are predicted by high conscientiousness, high emotional stability, and high openness.

The HEXACO Model and the Dark Tetrad

The HEXACO model adds a sixth factor to the Big Five: Honesty-Humility ($H$). This factor was identified through lexical approaches across various languages. High Honesty-Humility is associated with pro-environmental attitudes and sincere apologies. Low Honesty-Humility is linked to egotistical behavior, sabotaging others at work, and antisocial or criminal activity. Low Honesty-Humility is a core component of the Dark Triad, which consists of Machiavellianism, Narcissism, and Subclinical Psychopathy. These traits are socially harmful and may be expressed more freely in unregulated or loosely structured environments, where they might have served as adaptive traits for survival.

Machiavellianism involves being cunning, deceptive, and exploitative; it is often overrepresented in business environments. Narcissism is characterized by entitlement, superiority, and attention-seeking behavior. Subclinical psychopathy involves high impulsivity, thrill-seeking, and low empathy or anxiety. The Dark Tetrad adds a fourth trait: Dispositional Sadism, where individuals gain enjoyment from hurting others. This can manifest as bug killing, internet trolling, belief in conspiracy theories, and low-empathy responses during global events like pandemics. Within the interpersonal framework, extraversion is seen as a combination of warmth and dominance, while introversion is viewed as cold and submissive. Those who leave a cold social impression are often categorized as arrogant-calculating (dark traits), whereas those who are unassuming-ingenuous are seen as innocent.