4. Determining Nature, Nurture, & Necessity Flashcards
Behavioural Genetics
The study of genetic and environmental influences on behaviour.
Environmentalist View
The belief that personality is determined by socialization practices, such as parenting style and other agents of society.
Eugenics
From The Textbook: “The notion that the future of the human race can be influenced by fostering the reproduction of people with certain traits and discouraging reproduction among people without those traits or who have undesirable traits.”
Percentage Of Variance
Refers to the fact individuals vary, and this variability can be divided into percentages of different causes of the veriability.
But, typically, not nearly the only thing behavioural geneticists want to figure out, they also want to look at the environment.
Heritability
The proportion of observed variance in a group of individuals that can be accounted for by genetic variance.
In essence/more formally, heritability is the proportion of phenotypic variance that can be attributed to genotypic variance
Phenotypic Variance
Observed individual differences
Genotypic Variants
Individual differences in the total collection of genes in each person
Environmentality
The percentage of observed variance in a group of individuals that can be attributed to environmental/non-genetic differences.
Misunderstood Things About Heritability
- Heritability cannot be applied to a single individual
- Heritability is not constant, it is a statistic that applies only to a population at one point in time and in a particular type of environment
- Hertiability is not a precise tstatistic, it is an estimate of the percentage of phenotypic differences due to genetic differences
These are the FACTS, not the myths
Nature-Nurture Debate
The discussion of whether genes or environment are the more important influence on personality.
Family Studies
Research that correlates the degree of genetic overlap among family members with the degree of personality similarity. Utilizes the fact that there are known degrees of genetic overlap between different members of a family in terms of degree of relationship.
Note a con, it violates equal enviroments assumption as members of a family may be similar on a specific trait based on environment rather than genes.
Twin Studies
Estimate heritability by gauging whether (genetically) identical twins are more similar in personality to fraternal twins (50% shared DNA).
Equal Environments Assumption
Assumption that environments experienced by identical twins are no more similar to each other than environments experienced by fraternal twins.
Studies have consistently supported the equal environments assumption.
From The Textbook: If they are more similar, then the greater similarity of the identical twins could plausibly be due to the fact that they experience more similar environments rather than the fact that they have moregenesin common.
Adoption Studies
Examines correlations between adopted children and their adoptive parents, with whom they share no genes. Compared to correlations between adopted children and genetic parents, who had no influence on the childrens’ environments.
Adoption Studies
Assumption of Representativeness and Selective Placement
Assumption of Representativeness: The assumption that adopted children, birth parents, and their adoptive parents are representative of the general population (confirmed by studies).
Selective Placement: The concern that adopted children are placed with adoptive parents similar to their birth parents (no real evidence of this).
‘Psychopathic’ traits show [answer]
Moderate to high heritability / substantial heritability
According to several studies
Each Big Five trait yields heritability estimates of approximately [answer]
50%
Exactly 48% according to textbook, 49% according to lecture
How heritable is sexual orientation?
Evidence it is moderately heritable
Marriage and Heritability
- The propensity to marry is hertiable
- Hertiable personality characteristics are suggested to play a role in marriage satisfaction (especially for women, husbands’ personality did not explain as much)
Shared Environmental Influences
Features of the environment that siblings share, eg. number of books in the home, whether there is a TV in the house, etc.)
Non-Shared Environmental Influences
Features of the environment siblings do not share. Eg. Different peer groups
Do shared or non-shared environmental influences affect personality more?
By far, non-shared environmental factors affect personality traits more.
However, research is still developing on this, since a lot of these findings have been from self-report, observational studies indicate potential other findings
Molecular Genetics
Techniques designed to identify specific genes associated with specific traits (like personality traits).
Molecular Genetics - The Association Method
Identifies whether individuals with a particular gene/allele score higher or lower on a particular trait measure.
DRD4 Gene
Gene located on short arm of chromosome 11 (not sure if testable) that codes for a dopamine receptor (responds to dopamine, discharges electrical signal, activating other neurons). Associated with novelty seeking, the tendency to seek out new (and often risky) experiences.
Individuals with ‘long repeat’ versions of the gene[’s 7R allele (7R+)] showed higher rates of novelty seeking than individuals with ‘short repeat’ versions of the gene (long DRD4 genes tend to make people relatively unresponsive to dopamine).
DRD4 gene’s 7R+ allele more common in North America than Asia
While this has been replicated several times, there are also studies that fail to replicate. This may be because the DRD4 gene is estimated to only explain 4% of the variation in novelty seeking.
Serotonin transporter gene 5-HTTLPR is linked to…
neuroticism and other depressive and anxiety related traits.
Genome-Wide Association Studies (GWAS)
Rapidly examine the entire genome for links with personality.
Polygenic Risk Scores
Mathematical sums of many genetic variants. Basically, looking at a ton of genes to predict the risk of having certain personality traits/having a low sense of well-being, etc.
Complete understanding of the role genes play in personaliy may be many years away.
Genotype-Environment Interaction
Refers to how the environment has a different impact depending on an individual’s genotype.
Eg. Most introverts need a low-stimulation environment to focus, whereas extraverts do well with stimulation, but make more errors when there is little stimulation
Genotype-Environment Interaction - Abusive Parenting
- Abused children who had a genotype that produced low monoamine oxidase A (MAOA) far more likely to develop conduct disorders than abused children with high levels of MAOA
Genotype-Environmental Correlation
The different exposure of individuals with differing genotypes to different environments/exposure to environmental conditions depends on/is affected by genotype.
Passive genotype-environment correlation
Children exposed to certain environments early on based on parents both giving the child their genes and providing them with an environment based on those genes. It’s not because of anything the child is doing, the parents have the genes as is and thus are providing the environment as such.
Eg. Parents pass on genes for verbal/linguistic ability, and stock their houses with a lot of books
Reactive genotype-environment correlation
Where parents (or others) respond to children differently based on children’s genotypes. (Children who like to be hugged are more likely to be cuddled/hugged by parents than children who don’t)
Similar in principle to evocation.
Active genotype-environment correlation
When a person with a particular genotype creates or seeks a specific environment/the heritable propensity to select environmental exposure.
E.g. High sensation seekers expose themselves to risky environments
Epigenetics
The study of how experience (i.e. environmental influences) can mediate/determine how or whether a gene is expressed in an organism. Epigenetic effects involve changes in an organism’s phenotype, not genotype, as a result of something prominent in the environment.
Epigenetics: How nurture shapes nature.
Some epigenetic changes are hertiable.
Heritability estimates do not factor in epigenetic effects.
Overall, personality characteristics are [percent] heritable and [percent] environmental.
Overall, personality characteristics are 30-50% heritable and 50-70% environmental.
Cleaner Wrasse Fish
Personality Differences
Some fish cheat/steal mucus that they need, some do not, this is consistent over time for individual fish.
Natural Selection
Variants of phenotypes that better allow an organism to survive and reproduce will lead to more descendants.
Natural selection results in gradual changes in a species over time - successful variants increase in frequency and eventually spread throughout the gene pool, replacing less successful variants.
Hostile Forces of Nature
May not be testable
The term used by Darwin describing any event that impedes survival.
Sexual Selection
Definiton + Two Types
Evolution of traits based on mating benefits rather than survival benefits.
Intrasexual competiton: Competition between one sex for mates
Intersexual selection: A mate selecting a mate of the opposite sex
This is more the general definition, not a 1:1 for humans
Differential Gene Reproduction
Reproductive success relative to others.
From the Textbook: The genes of organisms who reproduce more than others get passed down to future generations at a relatively greater frequency than the genes of those who reproduce less.
Inclusive Fitness Theory
Maybe testable?
From The Textbook: Modern evolutionary theory based on differential gene reproduction. The “inclusive” part refers to the fact that the characteristics that affect reproduction need not affect the personal production of offspring; they can affect the survival and reproduction of genetic relatives as well.
Eg. Protecting a sibling may enable them to better survive and reproduce
Note this happens more the closer the relation is. (Happens more with siblings than cousins, for example)
Adaptations
A reliably developing structure in the organism, that causes the solution to an adaptive problem (anything that impedes survival/reproduction).
Hallmark: Special design (features of an adaptation are recognized as components of specialized problem-solving machinery
Byproducts of Adaptations
Evolutionary mechanisms that are not adaptations, but instead byproducts of other adaptations.
Evolutionary Noise
Random genetic/phenotypic variations that are neutral with respect to selection.
Three key premises of Evolutionary Psychology
List them
- Domain Specificity (specific in the sense they solve a particular adaptive problem)
- Numerousness (numerous adaptive mechanisms)
- Functionality (our psychological mechanisms are designed to accomplish particular goals)
More detail for these three on individual flashcards
Domain Specificity
The presumption that adaptations are engineered by the evolutionary process to solve specialized adaptive problems. Implies selection tends to generate specialized mechanisms for each specific adaptive problem.
Numerousness
We have numerous adaptive mechanisms to handle the numerous adaptive problems that humans have faced.
Functionality
Our psychological mechanisms are designed to accomplish particular adaptive goals.
Hierarchy of Evolutionary Analysis
Top: Evolution by Selection (usually skipped by scientists/scientists move onto a different hypothesis, as this has never been disproven).
Middle: Middle-level evolutionary theories (eg. the theory of parental investment and sexual selection [this is one single theory]). From these hypotheses, predictions can be developed and tested empirically.
Bottom: Specific, testable, predictions.
Two ways to approach this hierarchy, top-down and bottom-up. More detail on other cards.
Parental Investment and Sexual Selection Theory: “The sex (female or male) that invests more in offspring is predicted to be more discriminating or “choosy” about its mating partners.”
Hierarchy of Evolutionary Analysis
Deductive Reasoning Approach
The top-down, theory-driven method of empiracle research. Using theories to generate predictions/hypotheses.
Hierarchy of Evolutionary Analysis
Inductive Reasoning Approach
The bottom-up, data driven method of empirical research. Observing a phenomenon, then developing a theory to fit those observations.
Need to Belong - Status and Group Acceptance
A central motive of human nature. Aligns with the human motives of agency and communion.
Origin of Social Anxiety
Theorized to originally have been an adaptation to prevent humans from being socially excluded
What can trigger group cohesion?
- External threats (especially intense ones)
- The opportunity to acquire resources
Evolutionary Psychology
Humans have a propensity to this darker trait.
Aggression, due to a lower expression of a gene that inhibits fight or flight.
Three perspectives on
Three distinct perspectives on the study of emotions
- Examining whether facial expressions are interpreted the same across cultures (universality is a criterion for adaptation)
- Emotions are adaptive psychological mechanisms that signal “fitness affordances” in the social landscape. Emotions guide the person towards goals that would have conferred fitness in ancestral environments or avoided conditions that minimized fitness.
- “Manipulation hypothesis” - emotions are designed to exploit the psychological mechanisms of other people
All of these perspectives depend on the concept that emotions are universal and universally recognized the same way.
Evolutionary Psychology
Empathy facilitates [answer], which offered an evolutionary [answer] for humans.
Empathy facilitates cooperation, which offered an evolutionary advantage for humans.
Evolutionary Psychology
Propensity to [answer] is a negative universal trait in humans.
Remember the gene
Propensity to aggression is a negative universal trait in humans.
Gene - ADRA2C
