What Is Personality?
Personality refers to the characteristic patterns of thoughts, feelings, and behaviors that make a person unique and relatively consistent across situations and time.
Personality is partly inherited and partly shaped by environment-neither "nature" nor "nurture" alone explains who we are.
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The Big Five (OCEAN)
The most widely accepted model of personality identifies five broad dimensions. Most people fall somewhere in the middle of each dimension, not at the extremes.
Openness to Experience
High: Creative, curious, open to new ideas, appreciates art and beauty, enjoys variety.
Low: Practical, conventional, prefers routine, concrete thinking, down-to-earth.
Openness is associated with creativity and artistic achievement.
Conscientiousness
High: Organized, disciplined, reliable, goal-oriented, plans ahead, follows rules.
Low: Spontaneous, flexible, easygoing, less focused on achievement, may procrastinate.
Conscientiousness is the best personality predictor of job performance.
Conscientiousness is associated with better health outcomes and longer life.
Extraversion
High: Outgoing, energetic, talkative, seeks stimulation, enjoys social interaction, positive emotions.
Low (Introversion): Reserved, prefers solitude or small groups, less need for excitement, processes internally.
Extraverts are not necessarily "better" at social skills-introverts can be equally socially competent, they just find social interaction more draining.
Agreeableness
High: Cooperative, trusting, helpful, empathetic, values harmony, avoids conflict.
Low: Competitive, skeptical, challenging, prioritizes self-interest, comfortable with conflict.
Agreeableness is associated with relationship satisfaction but can predict lower income-very agreeable people may not negotiate as hard.
Neuroticism (vs Emotional Stability)
High neuroticism: Prone to negative emotions (anxiety, sadness, irritability), reacts strongly to stress, worries frequently.
Low neuroticism (emotional stability): Calm, even-tempered, resilient, less reactive to stress.
Neuroticism is a risk factor for anxiety and depression-but having high neuroticism does not mean you will develop a disorder.
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Measuring Personality
Self-Report Questionnaires
Most personality tests ask you to rate how much statements describe you.
Reliable measures:
- NEO-PI-R (240 items, comprehensive)
- Big Five Inventory (BFI, 44 items)
- IPIP scales (free, online)
Problems with self-report:
- Social desirability bias (wanting to look good)
- Limited self-insight
- Reference group effects (comparing to different standards)
Other Methods
Informant reports: Ask others who know you well.
Self and informant ratings usually agree moderately-but informants may see things you miss.
Behavioral measures: Observe actual behavior.
Behavioral measures often show weaker correlations with self-report than expected-the "personality paradox."
Personality Tests to Be Skeptical of
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Where Does Personality Come From?
Genetic Influences
Twin studies suggest Big Five traits are about 40-60% heritable.
This means:
- Identical twins are more similar in personality than fraternal twins
- But genes do not determine personality completely
- Many genes each contribute small effects-there is no single "extraversion gene"
Environmental Influences
Shared environment (experiences siblings have in common): Surprisingly small effect on personality.
Non-shared environment (unique experiences): Accounts for most environmental influence.
Birth order effects on personality are much smaller than popularly believed.
Gene-Environment Interactions
Genes and environment are not independent:
- Gene-environment correlation: Genes influence the environments we select and create
- Gene-environment interaction: Same environment affects people differently based on genes
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Personality Stability and Change
Stability
Personality becomes more stable with age-by age 30, major changes are less common.
Rank-order stability is high-if you are more extraverted than average at 20, you probably still will be at 50.
Change
Personality can and does change across the lifespan-people generally become:
- More conscientious
- More agreeable
- Less neurotic
- Less open to experience
This pattern is called personality maturation.
Major life events can change personality-but the effects are usually modest.
Therapy can produce meaningful personality change-especially in neuroticism.
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Personality vs Personality Disorders
Personality traits are dimensions everyone has to varying degrees.
Personality disorders are extreme, inflexible patterns that cause significant distress or impairment.
The Dimensional View
Many researchers argue personality disorders are better understood as extreme variants of normal traits:
| Normal Trait | Extreme/Disorder |
|-------------|-----------------|
| Low agreeableness | Antisocial features |
| High neuroticism + low emotional stability | Borderline features |
| Very high conscientiousness | Obsessive-compulsive features |
| Very low extraversion + high neuroticism | Avoidant features |
There is no sharp boundary between "normal personality" and "personality disorder"-it is a matter of degree.
When Traits Become Problems
A trait becomes problematic when it is:
- Extreme (far from average)
- Inflexible (cannot adapt to situations)
- Causes distress (to self or others)
- Impairs functioning (work, relationships)
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Personality in Context
Personality and Situations
Person-situation debate: Is behavior driven more by personality or by situations?
Modern consensus: Both matter, and they interact.
People are most consistent in situations they choose themselves.
Strong situations (clear expectations) override personality-weak situations allow personality to emerge.
Cross-Cultural Differences
The Big Five structure appears across many cultures-suggesting some universality.
But average levels of traits vary across cultures-e.g., some cultures score higher on agreeableness.
Western psychology may over-emphasize individual traits vs relational patterns.
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Applications
Work and Career
Conscientiousness predicts performance across almost all jobs.
Extraversion predicts performance in sales and management roles.
Personality assessment can aid career counseling-but should not be used as sole hiring criterion.
Relationships
Similarity in personality is associated with relationship satisfaction-but complementarity can also work.
High neuroticism in either partner predicts relationship problems.
Agreeableness is important for relationship harmony.
Health
Conscientiousness is associated with better health behaviors and longevity.
High neuroticism is associated with more health complaints-partly due to greater attention to symptoms.
Optimism (related to low neuroticism, high extraversion) is associated with better health outcomes.
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See also: [Psychology](/psychology) for cognitive biases, [Clinical Psychology](/clinical-psychology) for personality disorders, [Relationships](/relationships) for interpersonal dynamics