Personality Psychology Brent W. Roberts University of Illinois at Urbana-Champaign

What is Personality? Broadly speaking it has to do with how each of us is: Different from everyone else Similar to some people The same as all humanity Specifically….

Reputation: Observations Unconscious processes Roles: Status Affiliation Intimacy Identity: Self-reports Conscious, subjective experience Traits Big Five Positive & Negative Affect Attachment Styles Motives & Values Goals Interests Life tasks Abilities g Verbal, Spatial, Quantitative Narratives Stories Significant memories Scripts Ideological settings Society/ Culture Units of Analysis Gene s Physio- Logical Mechanisms Fulcrum of assessmentDistal causes

How did you get your personality? Genes? Experience? Both?

Heritability of Personality Traits 1. Most personality traits have a heritability between.3 to.5 2. Personality is only weakly influenced by “shared” family environment (social class, child-rearing styles, religion, etc.) 3. Personality is more strongly affected by nonshared environment (accidents, sibling interaction, influences outside of family). a. Effects replicate for Monozygotic twins raised apart. b. Average personality trait correlation among adopted siblings is near zero. c. Average personality trait correlation between parents and adoptive children is often near zero. d. Average personality trait correlation between parents and biological offspring is very small.

Moving from behavior genetics to the genome. 1. Are there specific genes that affect personality? a. Wrong question. 2. Correct question: How do genes interact with environments to determine personality (Caspi et al., 2002 & 2003)? 3. Are you a delinquent? a. Don’t conform to social norms b. Break laws c. Dishonest d. Violent & aggressive e. Consistent irresponsibility f. Low agreeableness and conscientiousness

What are the genetic and environmental links? 1. MAOA gene. Encodes the MAOA enzyme which metabolizes neurotransmitters such as norepinephrine, serotonin, and dopamine. 2. Low MAOA activity is associated with elevated aggression. 3. Childhood maltreatment is associated with delinquency in adolescence.

Caspi et al., (2002). 1. Examined interaction between genetic variation in MAOA gene (low and high activity) and childhood maltreatment on delinquency. a. MAOA gene was unrelated to delinquency. b. Boys who had the low activity gene who were severely maltreated committed more delinquent acts in adolescence (violent offenses, antisocial personality disorder). c. Boys who had high activity gene who were severely maltreated committed no more delinquent acts than boys who were not maltreated.

Percent diagnosed with conduct disorder as an adolescent

Why should we care? Because who we are determines what we do….  Children who were rated as more conscientious when they were 8 lived longer than their counterparts (Friedman et al., 2003).  People who are more conscientious as adolescents experience higher levels of occupational success by age 50 (Judge et al., 1999).  People who are more conscientious in college have more children and fewer divorces at age 40 (Roberts & Bogg, 2004).  People who are more anxious at age 18 had lower relationship satisfaction across different relationships at age 21 and age 26 (Robins et al., 2002).  People who are more creative in college experience higher levels of success in creative occupations 30 years later (Helson, Roberts, & Agronick, 1995).

Now that you have a personality are you done developing? No.

Roberts & Walton (under review) 98 longitudinal studies that tracked mean-level changes in personality traits in 104 different samples. 47,340 participants that ranged in age from 10 to 101. d-scores were used to estimate change.  M 2 -M 1 /SD p How much mean-level change do personality traits demonstrate across the life course?

Meta-Analytic Estimates of Change in Social Vitality * Roberts & Walton (under review) *

Meta-Analytic Estimates of Change in Social Dominance * * Roberts & Walton (under review) * *

Meta-Analytic Estimates of Change in Agreeableness *

Meta-Analytic Estimates of Change in Conscientiousness * * * Roberts & Walton (under review) *

Meta-Analytic Estimates of Change in Emotional Stability * * * * Roberts & Walton (under review)

Meta-Analytic Estimates of Change in Openness to Experience * * Roberts & Walton (under review) *

Aggregate Change in Personality Traits Across the Life Course

Why should we care about this? In a follow-up to their earlier work, Friedman et al., found that childhood conscientiousness and adult conscientiousness predicted longevity independent of one another. The changes we experience in adulthood may have significant consequences for our health and well-being.

What causes us to change in adulthood? Social Investment Hypothesis:  Personality changes arise through experiences in universal tasks of social living, such as establishing one’s social position in society through one’s work or forming long-term bonds through the creation of a family unit in young adulthood (Helson, Kwan, John, & Jones, 2002).

The Social Investment Hypothesis Involvement In work at age 26 Increases in Constraint From 18 to 26.25* Percentage of Time married From 43 to 52 Increases in Responsibility From 43 to 52.18* Smoking Marijuana at Age 43 Decreases in Responsibility From 21 to 43.34*

Personality is an exciting, complex, and dynamic field  Behavior genetics  Genomics  Development  Health & Longevity Conclusions