What parts of my personality are set at birth? Flashcards
(24 cards)
Longitudinal design
- individual interviewed repeatedly
- compare responses
- within individual change
- hard to retain participants (also they could die or refuse)
Lewis Terman- Longevity project
-longitudinal study of intelligence and achievement
offered participants incentives so criticized for this
(continuity) homotypic
- responses to the same instrument at different time points
- structural continuity
- differential/rank-order continuity
- absolute/mean-level continuity
Structural continuity
- correlation between terms
- are the elements the same?
differential/rank order continuity
-is the score likely to stay the same relative to the rest of the group (will high stay high?)
absolute/mean-level continuity
-are you likely to get the same score again?
Julian Morizot
-continuity and change in personality traits from adolescence to midlife
-“representative” and adjudicated boys
-structural continuity: disinhibition, negative emotionality, extraversion/positive emotionality
(elements of personality held across ages and samples)
-rank order continuity: gets stronger
-mean-level:
-all decrease with age
(continuity) Heterotypic
responses to different instruments (but related construct) at different time points
-e.g. measures for kids (you have to adapt the measures for kids)
Moffitt and Caspi (2000)
- Dunedin, NZ (all of the kids)
- assessed age 3-21
- minimal attrition (97% retention)
- age 3:
- well-adjusted, undercontrolled, inhibited, confident, reserved
- age 18: the category of age 3 related to how participants describe themselves at age 18
- age 21: informant report, still see differences measured at age 3, also self-report and life-outcome, still related
childhood self-control compared to life outcomes
- higher self-control as child
- less likely to have adult health problems, financial struggles/problesm, convictions, single parent
- more likely to have higher socioeconomic status
Robert and DelVecchio (2010)
-meta analysis from childhood to age 70
- greater differential continuity with older samples when measured at shorter intervals
- when you are older, you are more selective with your environments, you choose people that lead to stability (so more likely to be same rank relative to others when you are older)
Limitations of longitudinal design
- select samples
- significant attrition
- time, energy, resources
- confounding of age and cohort (are changes due to cultural/societal changes?)
- assumption of comparability across instruments
- reactivity to study
Strengths of longitudinal design
- follow individuals over time
- examine individual change
Francis Galton
- thought genetics made his family smart
- interested in cross-generational continuity within the family
Equation for phenotype
influence of genes + influence of environment + interaction of genes and environment
Genes/heritability
- proportion of observed phenotypic variance that can be explained by common genetic factors
- genes influence personality by shaping biological functioning
- behaviors shaped by functioning of many genes
- characteristic that is linked to genes can be altered by the environment
environment
- all influences other than genetic inheritance
- shared: factors common to members of the same family making them similar (SES, neighborhood, culture)
- nonshared: factors not common to members of the same family making them different
Monozygotic twins
-share 100 percent of genes
dizygotic twins
-share 50% of genes
Heritability coefficient
difference between differences within MZ and DZ twins
= (MZ difference - DZ difference)*2
= (100% shared genes + shared environment) - (50% shared genes + shared environment) *
= 50% shared genes * 2
what have twin studies shown about personality?
- MZ more similar than DZ
- Extraversion = 60% heritability
- neuroticism = 50% heritability
- agreeableness, openness, conscientiousness = 40%
- moderate genetic influence found with peer reports
- extraversion : 45% of variance in self-report is due to genes, only 20% of variance in peer report
Criticism of twin studies
- not good measure of shared and non-shared environmental factors
- difficult to distinguish between shared genes versus shared environments
MZ and DZ twins reared apart
- personality similarities can’t be due to shared environment
- heritability = 50% shared genes * 2
- still come up with same 40% heritability statistic
- shared environmental influnces may be due to shared heredity
- shared environmental influences personality less than shared heredity
Limitations of behvioral genetic studies
- findings from twin/ adoption studies only tell us about those samples
- influenes of environment not measured
- no consideration of trends or common sociocultural factors
- common family enviornments can lead to different behaviors
- don’t know the mechanism by which genetic predispositions to certain personality traits are expressed