nature and nurture of cognitive development Flashcards
(23 cards)
What contributes more to differences in intelligence — individual or national differences?
Individual differences are larger than differences between countries on the PISA mathematics scale.
What does the term “heritability of intelligence” mean?
It refers to the proportion of variance in intelligence among individuals that can be attributed to genetic differences.
What are genetically informative research designs used to study nature and nurture?
Twin studies, adoption studies, MZ vs DZ twins, twins reared apart and together.
What does a twin design allow researchers to estimate?
The separate genetic (A), shared environment (C), and nonshared environment (E) contributions to traits like IQ.
What is the basic formula for phenotypic variation in twin studies?
P = A + C + E (or P = h² + c² + e²)
How is heritability (A) calculated in twin studies?
A = 2(rMZ – rDZ)
What are the average twin correlations for IQ?
MZ twins: r = .86, DZ twins: r = .60
How much of childhood cognitive ability variance is due to genetics, shared, and non-shared environments?
52% genetic, 34% shared environment, 14% non-shared environment.
How does heritability of IQ change with age?
Increases from ~40% in childhood to ~80% in adulthood.
What is passive gene-environment correlation?
When children inherit genes and environments from parents that match (e.g., intelligent parents provide stimulating environments).
What is evocative gene-environment correlation?
When an individual’s genetic traits evoke certain responses from their environment.
What is active gene-environment correlation?
When individuals seek environments that match their genetic propensities.
What is the “One Gene, One Difficulty” (OGOD) hypothesis?
The idea that single genes are responsible for specific learning difficulties.
What is the Quantitative Trait Loci (QTL) hypothesis?
That many genes of small effect influence cognitive traits (i.e., polygenic model)
What does the polygenic model suggest about intelligence?
Intelligence is influenced by many genes, each contributing a small effect, resulting in a bell curve distribution.
How does the HOME inventory relate to intelligence?
It positively correlates with IQ and school achievement.
What is the significance of non-shared family environment?
It explains why siblings differ cognitively despite being raised in the same home.
What did Cahan & Cohen (1989) find about schooling and IQ?
Schooling significantly affects IQ test performance; schooling matters more than age.
What did Alexander et al. (2007) find about SES and learning during summer?
Low-SES children made no gains over summer; high-SES children did — highlighting the importance of educational interventions.
What is the Flynn effect?
A steady rise in IQ scores over generations, about 3 points per decade.
How do social class and poverty affect IQ?
Children from low-SES backgrounds score 10–15 IQ points lower; effects of poverty are profound but may be mediated by home environment.
What is cumulative risk in cognitive development?
The presence of multiple risk factors (e.g., poverty, poor maternal health) increases the risk of poor cognitive outcomes.
What are the key takeaways about genes, environment, and intelligence?
Intelligence is highly heritable, but environment, especially in extreme conditions, plays a critical role.
