Intelligence and Psychological Testing: Nature vs. Nurture

Vocabulary practice cards covering the environmental and genetic influences on intelligence, including key studies, statistical estimates, and cultural factors.

Behavior genetic approaches

Methods such as twin studies and adoption studies used to determine the relative contributions of environment and genetics to particular traits like IQ scores.

Twin studies

A research method comparing the resemblance of identical twins and fraternal twins on a respective trait to determine how related they are.

Identical twins

Siblings who share $100\%$ of their genes; their correlations on IQ tests are approximately $0.85$ when reared together.

Fraternal twins

Siblings who share $50\%$ of their genes and are raised in the same environment, showing an IQ correlation of approximately $0.60$.

Adoption studies

Research comparing identical twins reared together versus identical twins reared apart to vary the environment while controlling for genetic contributions.

Heritability ratio (estimates)

A group-level statistic and percentage score that estimates the proportion of trait variability in a population determined by genetic inheritance.

$40$ to $80\%$

The estimated range of heritability for intelligence, suggesting that genes contribute significantly to IQ scores regardless of the group.

Cumulative deprivation hypothesis

The theory that growing up in a deprived environment can lead to the erosion of IQ test scores, whereas enriched environments can lead to increases.

Flynn effect

The observation that IQ test scores have generally increased over successive generations due to environmental factors like nutrition, healthcare, and technology.

Genes by environment interactions

The concept that genetic factors provide a potential ceiling and floor (limit) for IQ, while environmental factors determine where an individual falls within that range.

Stereotyped vulnerability

A phenomenon where stigmatized groups perform less well on tests because they internalize and manifest negative stereotypes about their abilities.

Cultural bias

The argument that IQ tests are 'white man constructions' and applying them to other cultural groups may be inappropriate and lead to underperformance.

Low SES (Socio-Economic Status)

An environmental factor associated with deprived conditions that tends to decrease the influence of genetic factors on intelligence scores.