Personality and Individual Differences: Lecture 2 Notes

Personality and Individual Differences (PS416) - Lecture 2: Historical Overview of Personality

Lecture Series Overview

• Lecture 2 (Current): Historical overview of personality.
• Lecture 3: Human values, item creation, and intelligence.
• Lecture 4: Creativity.

Introduction to Personality

Why Personality Research?

• Romantic Partner Priorities (YouGov Study, 2017): A survey of American men and women conducted between July 31 and August 1, 2017, investigated personal preferences in romantic partners. Results indicated that "personality" was the top priority for both genders, ranking significantly higher than physical appearance or financial status.
  • American Men (Summary of Rankings):
    • "They have a personality I like": Ranked 1st by $41\%$, Ranked 2nd by $24\%$.
    • "They have a sense of humor I like": Ranked 1st by $17\%$, Ranked 2nd by $18\%$.
    • "They are intelligent": Ranked 1st by $9\%$, Ranked 2nd by $23\%$.
    • "They are good looking": Ranked 1st by $13\%$, Ranked 6th by $54\%$.
    • "They have/make a decent amount of money": Ranked 1st by $2\%$, Ranked 6th by $68\%$.
  • American Women (Summary of Rankings):
    • "They have a personality I like": Ranked 1st by $38\%$, Ranked 2nd by $26\%$.
    • "They have a sense of humor I like": Ranked 1st by $20\%$, Ranked 2nd by $17\%$.
    • "They are intelligent": Ranked 1st by $13\%$, Ranked 2nd by $27\%$.
    • "They are good looking": Ranked 1st by $15\%$, Ranked 6th by $29\%$.
    • "They have/make a decent amount of money": Ranked 1st by $3\%$, Ranked 6th by $49\%$.
  • Conclusion: Both men and women agree that personality matters most, while looks and money land at the bottom of the list.

Purpose of Systematic Research

• People possess implicit personality theories, which are implicit assumptions regarding what personality means.
• Assumptions about others' personalities can often be incorrect. A systematic approach (research) is required to overcome these errors.

Defining Personality

• Gordon Allport (1961): "a dynamic organisation, inside the person, of psychophysical systems that create the person’s characteristic patterns of behaviour, thoughts and feelings."
• Eysenck & Eysenck (1985): Personality consists of temperament and intelligence.
• Motivational Basis: Personality researchers aim to understand the underlying motivations of behavior (e.g., "What keeps you going?").

Historical Development of Personality Research

Brief History I: The Four Temperaments

• Hippocrates (460–370 BC): The Greek physician proposed the four temperament theory comprising four distinct types:
  • Sanguine: e.g., confident, optimistic.
  • Choleric: e.g., easily angered.
  • Melancholic: e.g., depressed, anxious.
  • Phlegmatic: e.g., calm.
• Other Greek philosophers and physicians expanded on this, describing up to $30$ unique personality traits.

Brief History II: Phrenology

• Definition: A pseudoscience claiming that the science of the special functions of several parts of the brain, or the connection between mental faculties and organs in the brain, could be determined by bumps on the skull.
• Origin: Developed by physician Franz Gall in $1796$.
• A Chart of Phrenology (35 Organs):
  1. Amativeness; 2. Philoprogenitiveness; 3. Concentrativeness; 3a. Inhabitiveness; 4. Adhesiveness; 5. Combativeness; 6. Destructiveness; 6a. Alimentiveness; 7. Secretiveness; 8. Acquisitiveness; 9. Constructiveness; 10. Self-esteem; 11. Love of Approbation; 12. Cautiousness; 13. Benevolence; 14. Veneration; 15. Firmness; 16. Conscientiousness; 17. Hope; 18. Wonder; 19. Ideality; 19a. (Not determined); 20. Wit; 21. Imitation; 22. Individuality; 23. Form; 24. Size; 25. Weight; 26. Coloring; 27. Locality; 28. Number; 29. Order; 30. Eventuality; 31. Time; 32. Tune; 33. Language; 34. Comparison; 35. Causality.

The Trait Approach to Personality

Theory and Methodology

• Traits: Stable individual tendencies to think, feel, and act (McCrae & Costa, 2003).
• Historical Context: Inspired by L. L. Thurstone’s work on the multidimensional structure of intelligence. In the $1940\text{s}$, researchers began using factor-analytic methods to investigate personality structure.
• Key Contributors:
  • John P. Guilford ($1897$-$1988$)
  • Raymond B. Cattell ($1905$-$1998$)
  • Hans J. Eysenck ($1916$-$1997$)
  • Ernest C. Tupes & Raymond E. Christal
  • Warren Norman ($1930$-$1998$)

The Lexical Hypothesis (Sedimentation Hypothesis)

• Concept: Socially relevant and salient personality characteristics are encoded in natural language. Dictionaries provide an extensive, finite set of attributes found useful in daily human interaction.
• Allport and Odbert (1936): Using the Webster's Encyclopedic Unabridged Dictionary of the English Language ($500,000$ words), they identified $18,000$ words describing individual differences, categorized into four groups:
  1. Generalised and personal dispositions: Consistent and stable ways of adapting to environment (e.g., sociable, aggressive; $4,504$ terms).
  2. States, moods, and activities: (e.g., happy, sad, enthusiastic; $4,541$ terms).
  3. Highly evaluative judgments of personal reputation: (e.g., excellent, valuable, average; $5,226$ terms).
  4. Physical and unclassifiable characteristics: ($3,682$ terms).

Empirical Development: Norman and Goldberg

• Norman (1963): Replicated factor structure in peer nomination ratings. Male students rated each other on scales such as "talkative - silent" ($1$-$5$ scale).
• Factor Analysis: A statistical method to group observed variables. Includes types like Exploratory Factor Analysis (EFA) and Confirmatory Factor Analysis (CFA).
• Goldberg (1990): Used $1,710$ adjectives with $187$ participants (self-description on an $1$-$8$ scale). Replicated the "Big Five" (Tupes & Christal, 1961):
  1. Surgency (Extraversion)
  2. Agreeableness
  3. Conscientiousness
  4. Emotional Stability (Neuroticism)
  5. Intellect (Openness to New Experience)
• Goldberg (1992) Scale Types:
  • Unipolar Scale: Asking "How extraverted are you?" and "How introverted are you?" separately. Goldberg found unipolar scales work better.
  • Bipolar Scale: Asking participants to choose between pairs (e.g., "Indicate whether you are introverted OR extraverted").

The Big-5 Model (Costa & McCrae, 1992)

Dimensions and Facets (NEO-PI-R)

• Openness to Experience: Fantasy, Aesthetics, Feelings, Actions, Ideas, Values.
• Conscientiousness: Competence, Order, Dutifulness, Achievement Striving, Self-Discipline, Deliberation.
• Extraversion: Warmth, Gregariousness, Assertiveness, Activity, Excitement Seeking, Positive Emotions.
• Agreeableness: Trust, Straight-forwardness, Altruism, Compliance, Modesty, Tender-Mindedness.
• Neuroticism: Worry, Anger, Discouragement, Self-Consciousness, Impulsivity, Vulnerability.

Alternative and Expanded Personality Models

The HEXACO Model (Ashton & Lee, 2004)

• The Sixth Factor: Honesty-Humility. Includes traits like honest, sincere, loyal, and trustworthy. Found across seven samples/languages.
• Debate: Some suggest Honesty-Humility is part of Agreeableness; results may depend on statistical methods. Note: Human-developed structures often outperform AI-proposed structures.

Dark Personality Traits

• The Dark Triad (Paulhus & Williams, 2002): Narcissism, Machiavellianism, and Psychopathy.
• The Dark Pentad (Monteiro et al., 2022): Adds Sadism and Spitefulness. It is debated whether these are distinct or merely lower facets of Agreeableness.

Demographic and Stability Patterns

Age-Group Differences (Srivastava et al., 2003)

• Study: $N = 132,000$, ages $21$-$60$.
• Conscientiousness: Generally increases throughout early and middle adulthood.
• Agreeableness: Increases particularly in middle adulthood.
• Neuroticism: Tends to decrease, especially in women during early adulthood.

Gender Differences (Hofmann et al., 2025)

• Study: $N = 307,000$.
• Gender differences exist across personality nuances, but distributions overlap significantly.
• Example (Neuroticism): Standardized trait scores show overlapping normal distributions with a Cohen's $d = 0.36$.

Stability Over Time

Traits are stable individual tendencies. Testing via 6-year and 5-year intervals yielded high correlation coefficients:

• Neuroticism: $0.83$ (6-yr); $0.78$ (5-yr).
• Extraversion: $0.82$ (6-yr); $0.82$ (5-yr).
• Openness: $0.83$ (6-yr); $0.76$ (5-yr).
• Agreeableness: $0.63$ (6-yr); $0.71$ (5-yr).
• Conscientiousness: $0.79$ (6-yr); $0.80$ (5-yr).

Personality Traits vs. States

• Traits: Stable individual tendencies over time (McCrae & Costa, 2003).
• States: Thoughts, feelings, and behaviors at a particular time (Columbus & Strandsbjerg, 2025).
• Correlation: Traits and states are moderately correlated, typically between $r = 0.42$ and $r = 0.56$ (Fleeson & Gallagher, 2009).

Correlates of the Big Five

• Neuroticism: Positive correlation with mental disorders and negative affect; negative correlation with life and job satisfaction.
• Extraversion: Positive correlation with Narcissism, Psychopathy (but not Machiavellianism), positive affect, life satisfaction (even during lockdowns), and interest in social jobs.
• Openness: Positive correlation with Narcissism, Psychopathy (but not Machiavellianism), intelligence, and creativity.
• Agreeableness: Positive correlation with job satisfaction, helpfulness, and altruism; negative correlation with Dark Triad traits. Essential for romantic partner selection.
• Conscientiousness: Positive correlation with school success (to a similar extent as IQ, suggesting importance of discipline) and professional success; negative correlation with Machiavellianism and Psychopathy (but not Narcissism).

Other Personality Variables

Character Strengths and Virtues (Peterson & Seligman, 2004)

• Morally valued and socially facilitative traits grouped into six virtues.
• Example (Wisdom): The virtue of wisdom is reached through pathways of creativity, curiosity, judgment, love of learning, and perspective.

Moral Foundations (Haidt & Graham)

• Based on the social intuitionist model (Haidt, 2001). Five primary moral values/foundations (Graham et al., 2009; 2011):
  1. Care: Wanting to help others and prevent harm.
  2. Fairness: Wanting justice and equal treatment.
  3. Loyalty: Sticking by one's group, team, or community.
  4. Authority: Respecting rules, leaders, and hierarchy.
  5. Purity: Caring about cleanliness and avoiding things seen as "gross" or wrong.
• Political Implications: Liberals and conservatives rely on different sets of foundations, though substantial similarities between groups remain (Hanel et al., 2019).