Problem 5 Flashcards
Heritability
Is a descriptive statistic that indicates the degree of population variation of a trait, that is due to genetic differences
Complement of heritability (1-h2)
Indicates the degree of population variation of a trait, that is due to environmental influences
What kind of studies are used to measure/ estimate the heritability of various traits ?
Twin + adoption studies
Nuisance variables
Refer to variables that are assumed to be causes of group/individual differences, but seemingly irrelevant to the theory of the investigator
–> closely related to heritability
How much does genetic vs environment influence personality traits ?
Increased genetic influence with age + decreasing shared environmental influence
–> environmental factors often decrease to 0 after adolescence
Why have personality + individual differences been neglected ?
- Cogent evolutionary theories existed for predicting + explaining sex differences
ex. : sexual selection - Assumption that natural selection has reduced/eliminated heritable individual difference because traits that are advantageous tend to spread over tome to fixation
Which theories are able to explain personality and individual differences (variation) ?
- Life history theory
- Costly signaling theory
- Environmental heterogeneity
- Frequency dependent selection
- Mutation load
- Contingent shift
Life history theory
States that we have a certain amount of energy throughout our life, that we try to allocate over the course of our life
–> some put more emphasis on kinship, some on multiple mating partners
e.g.: reproductive development and behaviors, post-reproductive behaviors, and lifespan
Costly signaling theory
States that people compete with one another by sending costly signals to others about their qualities
–> might explain conscientiousness, agreeableness, generosity etc
e.g.: to be able to be generous, one has to first have the ressources/affordances
Balancing selection
Occurs when genetic variation is maintained by selection
ex.: heterozygote advantage, where both alleles are maintained, as Aa will have a better chance of survival than AA or aa
Frequency dependent selection
Occurs when 2 or more strategies are maintained within a population at a particular frequency relative to each other, such that the fitness of each strategy decreases as it becomes increasingly common
ex.: Psychopathy, if only a few have these traits than those will consequently have an advantage, as opposed to when this is common
Role of Mutation load in heritability ?
Heritability of some traits originates from individual differences in mutation load
–> explains some harmful mental disorders
Environmental heterogeneity/ Flucturating optima
Environmental conditions can vary from time and place therefore, the traits favored by natural selection can change/fuctuate as well
–> variation in personality traits
Contingent shift
Refers the the ability to adapt psychological mechanisms in response to changes in environmental conditions
- selection favors those that are adaptive
- can occur in response to individual phenotypic qualities + environmental conditions
ex.: chef vs angestellt personality anpassen können
Stabilizing selection
Exists when selection favors a trait that is intermediate within the range represented within a population
–> most common trait is selected + continues to dominate
Adoption studies
Assessing differences in personality between pairs of genetically related individuals who don’t share a common environment
–> to assess the degree of genetic impact by looking at their similarities
Intraclass correlation coefficient
Assesses the correlation between relatives
–> variance between families, as when the variance is high between families then the similarities are high within families
Twin studies
Assesses differences in personality between twins that shared the same environment
–> to assess the degree of environmental impact by looking at the differences