Chapter 4: Heritability and IQ Flashcards
A new, unique chromosome is produced by which process?
Cross Over
Which type of twinning is heritable?
Dizygotic
The fallacy of exclusive determinism explains
our tendency to identify a single cause of an event
Heritability is not…
- the relative contribution of genetic information
- an estimate of malleability
- whether something is inherited
Asking if a snowflake is a result of temperature or humidity is like asking if…
a trait is a result of genes or environment
The Heritability Statistic and what it tells us
H=
[V(genes) / V(genes) + V(environment) + V(g*e)]
It tells us, for a given population, how much of the variance in the population can be attributed to variance in genes
Some things about the Heritability Statistic
- applies to a large population
- applies only to a particular group at a particular time
- can differ b/t people in different environments
- cannot be measured if there is no variance
- *differences are key
Define intelligence
cognitive capacities such as knowledge, memory and problem-solving as measured by standardized tests
What are the different Weschler Intelligence Scales?
WPPSI-IV (preschool and primary) age 2-7
WISC-V (for children, general knowledge, working memory etc.)
WAIS-V (adults)
Why do we have newer models of intelligent scales?
the Flynn Effect: intelligence test performance has been rising. Biggest improvement in lowest range of scores (access to nutrition and healthcare)
Bayley Scales
An Infant IQ test, a clinical evaluation to identify those with developmental delay. Focus on cognitive, language, and motor skills.
Explain the stability of IQ
Strong positive correlation between scores at age 3 and 6. Diminishes as age interval increases.
Stability seems to start at age 5. Infant measures do not predict adult IQ
What factors positively contribute to IQ?
- breastfeeding
- SES
- better health, schooling, nutrition
- HOME (home observation for measurement of the environment) this includes emotion towards parents, maternal involvement, restrictions/freedom, play materials.
- high IQ also related to longevity
Risk factors related to IQ (list 6)
- poor nutrition/schooling
- low SES
- bigger family (more kids=less mean IQ)
- strict rules
- toxins
- bad parent/child relationship
What do twin studies tell us about IQ and relatedness?
MZ twins living together have the strongest concordance. Even when apart, MZ twins have more concordance than DZ living together.
Explain the elusive heritability of IQ
- If you can standardize the environment, you get a higher heritability statistic.
- Less variance among those with higher education than among those without
- If you have a lot of variance in the environment without a change in genes, you get a smaller estimate of heritability.
Heritability of IQ increases with…
age. Until about 45.
- This means that IQ of adopted kids increasingly correlated with birth parents instead of adopted.
In addition to the 3 main points, what else is heritability not?
fixed. It can change across populations or historical periods.
An example of how heritability can be manipulated artificially
Plants in good soil = tall = high heritability
Plants in bad soil = short = still high heritability
Plants in good and bad soil = mix = low heritability
Francis Galton
- inspired the heritability statistic
- the first person to use the terms “nature” and “nurture”
- psychological traits, not just physical ones, might be heritable
Examples of the non-shared environment
- birth order
- gender
- different friends or teachers
Who first inspired intelligence testing and why?
- Binet and Simon.
- began with public education in France. Need to identify children who require special help.
- The Binet-Simon test was successful in predicting success in school.
7 intelligence constructs that allow more predictive power than “g”
- perceptual speed
- word comprehension
- word fluency
- space competence
- number competence
- memory
- induction
IQ predicts academic and occupational success but an even better predictor is…
self-discipline
The only part of the heritability statistic that can be directly measured is…
the variance in the expressed trait (variance in phenotype)
Adaptations are ______ but are not highly _______
inherited; heritable
