Personality: Theories, Biology and Assessment
3. Humanistic theories
The humanistic approach, a reaction against both psychoanalysis and behaviourism, centres on conscious experience, free will and the drive toward growth. Rogers's person-centred theory builds on an actualising tendency and makes the self-concept central: well-being depends on congruence between the real self and the ideal self. Children need unconditional positive regard; when love is made conditional, they internalise conditions of worth and distort experience to keep approval. The goal is the fully functioning person, open to experience and self-directed.
Maslow arranged motives in a hierarchy of needs, from physiological needs and safety through belonging and esteem to self-actualisation, the realisation of one's full potential, at the top. Lower needs generally take priority, and the self-actualised are marked by acceptance, autonomy, deep relationships and occasional peak experiences. The humanistic approach is praised for restoring the whole person and criticised for concepts that are hard to test and measure.
4. Trait and type theories
Trait theories describe personality as a profile of stable dispositions. Allport ranked traits by reach: a rare cardinal trait that dominates a whole life, a handful of central traits that describe a person, and many situation-specific secondary traits; he also distinguished the idiographic study of the individual from the nomothetic search for general laws. Cattell used factor analysis to reduce the surface of behaviour to 16 source traits, measured by his 16PF questionnaire. Eysenck argued for a few broad, biologically grounded dimensions, his mature PEN model naming Extraversion, Neuroticism and Psychoticism. Allport also held that mature motives achieve functional autonomy: they become independent of the origins in which they began.
The modern consensus is the Big Five (OCEAN): Openness, Conscientiousness, Extraversion, Agreeableness and Neuroticism, five dimensions recovered repeatedly from the natural-language vocabulary of description (the lexical hypothesis) and across cultures. Type theories, older and cruder, sort people into categories rather than placing them on continua: the four classical temperaments (sanguine, choleric, melancholic, phlegmatic) of Hippocrates and Galen, Sheldon's body-based somatotypes (endomorph, mesomorph, ectomorph), and the Type A / Type B distinction.
5. The biology of personality
Eysenck gave his dimensions a biological engine. On his arousal theory, introverts have a higher baseline level of cortical arousal (via the ascending reticular activating system), so they are easily over-stimulated and seek quiet, while extraverts are chronically under-aroused and seek stimulation to reach a comfortable level — which is why a noisy party energises one and drains the other. Gray's reinforcement sensitivity theory reframed this around two systems: a behavioural inhibition system (BIS), sensitive to punishment and tied to anxiety, and a behavioural activation system (BAS), sensitive to reward and tied to impulsivity. Eysenck tied neuroticism to the reactivity of the limbic system and autonomic nervous system, so high scorers are quick to become anxious and slow to calm.
Behaviour genetics uses twin and adoption studies to separate heredity from environment. Identical (monozygotic) twins resemble each other on the major traits more than fraternal (dizygotic) twins do, and the standard Falconer estimate doubles that gap: heritability h² = 2(r_MZ − r_DZ). Most Big Five traits come out with heritability near 0.40–0.60, meaning genes account for roughly half the variation between people, with the rest owing to environment — notably the non-shared environment unique to each sibling rather than the family they share. Infant temperament (easy, difficult, slow-to-warm-up, in the classification of Thomas and Chess) shows such inherited differences early.
6. Assessment of personality
Personality is assessed by several methods that trade richness against rigour. Self-report inventories present many standardised items scored against norms — the MMPI (empirically keyed for clinical use), Cattell's 16PF, the NEO-PI-R for the Big Five and Eysenck's EPQ. They are objective and reliable, but open to social desirability and deliberate faking, which validity scales try to catch. The MMPI carries built-in validity scales (L, F and K) that flag lying, careless answering and defensiveness.
Projective tests rest on the projective hypothesis: shown an ambiguous stimulus, a person reads their own unconscious content into it. The Rorschach inkblots (Hermann Rorschach) and the Thematic Apperception Test (TAT) (Morgan and Murray), in which the respondent tells stories about ambiguous pictures, are the classics. They are rich and hard to fake but score poorly on reliability and validity. Behavioural assessment (direct observation and rating of behaviour in situ) and the interview complete the toolkit; the best practice combines methods.
7. Theorists at a glance
| Theorist | Family | Signature idea |
|---|---|---|
| Freud | Psychoanalytic | Id, ego, superego; defence mechanisms; psychosexual stages |
| Jung | Analytical (neo-Freudian) | Collective unconscious, archetypes |
| Adler | Individual psychology | Inferiority and striving; style of life |
| Horney | Neo-Freudian | Basic anxiety |
| Skinner | Behaviourist | Personality as a history of reinforcement |
| Bandura | Social-cognitive | Reciprocal determinism; self-efficacy |
| Rotter | Social learning | Locus of control (internal, external) |
| Kelly | Cognitive | Personal constructs |
| Rogers | Humanistic | Self-concept, congruence, unconditional positive regard |
| Maslow | Humanistic | Hierarchy of needs; self-actualisation |
| Allport | Trait | Cardinal, central, secondary traits; idiographic approach |
| Cattell | Trait (factor-analytic) | 16 source traits; 16PF |
| Eysenck | Trait (biological) | PEN dimensions; cortical arousal theory |
Key takeaways
- Freud's psychoanalytic theory makes personality a conflict among id (pleasure principle), ego (reality principle) and superego (morality), managed by defence mechanisms; the neo-Freudians Jung (collective unconscious), Adler (inferiority and striving) and Horney (basic anxiety) kept the unconscious but stressed social forces.
- Behaviourists (Skinner; Dollard and Miller) reduce personality to learned responses; the social-cognitive theorists add thought — Bandura's reciprocal determinism and self-efficacy, Rotter's locus of control, Mischel's person–situation debate — and Kelly's cognitive theory builds personality from personal constructs.
- The humanistic theories centre on growth: Rogers on the self-concept, congruence, conditions of worth and unconditional positive regard, and Maslow on the hierarchy of needs rising to self-actualisation.
- Trait theories profile stable dispositions: Allport's cardinal/central/secondary traits, Cattell's 16 source traits (16PF), Eysenck's PEN and the Big Five (OCEAN). Type theories sort into categories (the four temperaments, Sheldon's somatotypes), but traits as continua fit the data better.
- Biologically, Eysenck tied introversion to higher cortical arousal and Gray to the BIS and BAS; twin studies give most traits a heritability near 0.40–0.60 via the Falconer estimate h² = 2(r_MZ − r_DZ), with much of the remaining variance from the non-shared environment.
- Personality is assessed by self-report inventories (MMPI, 16PF, NEO-PI-R), which are reliable but open to faking, and projective tests (Rorschach, TAT), which are rich but weaker on reliability and validity — and no measure can be more valid than it is reliable.
Practice questions (16)
Attempt each one before opening the answer. Every explanation names the tempting wrong option as well as the right one, because that is where marks are lost.
In Freud's structural model, which component operates on the reality principle, finding realistic ways to satisfy desires?
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Answer: A — The ego
The ego works on the reality principle, mediating between the id's demands and the outside world. The id works on the pleasure principle (immediate gratification), the superego embodies internalised morality, and the collective unconscious is Jung's concept, not part of Freud's structural model.A man who is furious at his boss comes home and shouts at his family instead. In Freudian terms this redirection of an impulse from a threatening target to a safer one is which defence mechanism?
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Answer: C — Displacement, redirecting an impulse onto a less threatening target
Shifting anger from the boss to the family is displacement — the impulse is redirected onto a safer substitute target. Projection attributes the impulse to someone else, reaction formation expresses the opposite impulse, and sublimation channels it into something constructive, none of which is a mere change of target.Which of the following statements about the neo-Freudian theorists are correct?
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Answer: A — Jung proposed a collective unconscious containing inherited archetypes; B — Adler made striving to overcome inferiority the central human motive; C — Horney traced neurosis to a basic anxiety rooted in childhood insecurity
Jung's collective unconscious with archetypes, Adler's striving against inferiority, and Horney's basic anxiety are all accurate. The claim that the neo-Freudians made sexuality the single dominant force is false — their whole departure from Freud was to demote sexuality and emphasise social and cultural forces instead.In Bandura's social-cognitive theory, a person's belief in their own capacity to carry out the actions needed to succeed at a specific task is called:
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Answer: B — Self-efficacy
Self-efficacy is Bandura's term for the belief in one's capacity to succeed at a task. Locus of control is Rotter's concept about where a person locates the causes of outcomes, functional autonomy is Allport's idea that motives become independent of their origins, and unconditional positive regard is Rogers's humanistic concept.A worker consistently believes that promotions and setbacks at her job are the results of her own effort and choices rather than of luck or office politics. Within the standard theories this belief is best described as:
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Answer: D — an internal locus of control, in Rotter's sense
Seeing outcomes as flowing from one's own effort and choices is an internal locus of control. An external locus would attribute them to luck or powerful others — the opposite belief. A cardinal trait is a dominating disposition, not a belief about causation, and reaction formation is a defence mechanism, neither of which describes this attribution.In Rogers's person-centred theory, accepting and valuing a person without any conditions attached is termed:
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Answer: A — Unconditional positive regard
Unconditional positive regard is acceptance with no strings attached, which Rogers held is needed for healthy development. Conditions of worth are the opposite — valuing a person only when they meet certain standards; a peak experience is Maslow's term, and reciprocal determinism is Bandura's, neither of which is this kind of acceptance.At the top of Maslow's standard five-level hierarchy of needs sits:
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Answer: B — Self-actualisation
Self-actualisation, the realisation of one's full potential, sits at the top of Maslow's hierarchy. Physiological needs are at the base, followed by safety, then belongingness and esteem, with self-actualisation reached only once the lower needs are largely met.Allport distinguished a rare trait that so dominates a person that almost every act can be traced to it. He called this a:
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Answer: C — cardinal trait
A cardinal trait is Allport's term for a single ruling disposition that pervades a whole life, and it is rare. Central traits are the handful that broadly describe a person, secondary traits are narrow and situation-specific, and source trait is Cattell's term, not Allport's.Eysenck's mature PEN model describes personality using which set of broad dimensions?
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Answer: D — Psychoticism, Extraversion and Neuroticism
PEN stands for Psychoticism, Extraversion and Neuroticism, the three broad biologically grounded dimensions in Eysenck's mature model. Openness, conscientiousness and agreeableness belong to the Big Five; fluid and crystallised are Cattell's intelligence constructs; and oral, anal and phallic are Freud's psychosexual stages.Which pairing of a theorist with their account of personality structure is correct?
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Answer: A — Cattell — sixteen source traits derived by factor analysis, measured by the 16PF
Cattell derived sixteen source traits by factor analysis and measured them with the 16PF. The five lexical factors are the Big Five, not Allport's own model; the hierarchy of needs is Maslow's, not Eysenck's; and the collective unconscious with archetypes is Jung's, not Rogers's.Which of the following statements about the Big Five (OCEAN) model are correct?
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Answer: A — The five factors are Openness, Conscientiousness, Extraversion, Agreeableness and Neuroticism; B — The factors emerged partly from the lexical hypothesis, analysing trait words in natural language; C — Each Big Five factor is a continuous dimension on which people vary by degree
The OCEAN factors, their lexical origin, and their nature as continuous dimensions are all correct. The claim that the Big Five sorts people into mutually exclusive types is false: the Big Five is a trait model of five largely independent continua, not a type model of discrete categories.In a factor analysis of a personality questionnaire, an item loads 0.70 on the Extraversion factor. The proportion of that item's variance accounted for by the factor equals the square of its loading. What is that proportion? Give the answer as a decimal to two places.
Numerical answer — type the value.
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Answer: 0.49
The variance explained by a single factor is the square of its loading: 0.70² = 0.49. Reporting the loading itself (0.70) rather than its square is the common error, since a loading is a correlation and the variance accounted for is its square.According to Eysenck's arousal theory, why do introverts tend to avoid highly stimulating environments such as loud parties?
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Answer: B — They have a higher baseline cortical arousal and are easily over-stimulated
On Eysenck's theory introverts already have a high baseline cortical arousal, so additional stimulation pushes them past their comfortable level and they withdraw. The reversed statement describes extraverts (under-aroused, seeking stimulation). The behavioural activation system is Gray's, not Eysenck's, and archetypes are Jung's concept, unrelated to arousal.In a twin study, a personality trait correlates r = 0.50 for identical (monozygotic) twins and r = 0.25 for fraternal (dizygotic) twins. Falconer's formula estimates heritability as h² = 2(r_MZ − r_DZ). What is the estimated heritability? Give the answer as a decimal to two places.
Numerical answer — type the value.
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Answer: 0.50
Applying the formula, h² = 2(0.50 − 0.25) = 2 × 0.25 = 0.50. Forgetting to double the difference gives 0.25, the usual slip; the factor of two is the core of the Falconer estimate.The Rorschach inkblot test and the Thematic Apperception Test (TAT) are examples of which kind of personality assessment?
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Answer: B — Projective tests based on responses to ambiguous stimuli
Both present ambiguous stimuli and ask the respondent to impose meaning, which is the defining feature of projective tests. Self-report inventories use fixed, scored items; physiological recordings measure bodily arousal; and behavioural observation records overt behaviour directly — none of which is the projective method of reading into an ambiguous stimulus.Which of the following statements about personality assessment methods are correct?
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Answer: A — Self-report inventories are vulnerable to social desirability and deliberate faking; B — Projective tests generally show lower reliability and validity than self-report inventories; C — The MMPI is a self-report inventory developed for clinical assessment
Self-report vulnerability to faking, the weaker reliability and validity of projective tests, and the MMPI as a clinical self-report inventory are all correct. The claim that a measure can be highly valid with very low reliability is false: validity is bounded by reliability, so an unreliable measure cannot be highly valid.