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what could be an issue if intelligence is inherited?

This could lead to those on top believing their intellectual birthright justifies their social positions

Do people who share the same genes also share comparable mental abilities?

yes

The intelligence test scores of identical twins reared together are virtually as similar as those of the same person taking the same test twice

Brain scans reveal that identical twins have very similar gray matter volume, and that their brains (unlike those of fraternal twins) are virtually the same in areas associated with verbal and spatial intelligence

researchers have identified chromosomal regions important to intelligence, and they have pinpointed specific genes that seemingly influence variations in intelligence and learning disabilities

Seeking to disentangle genes and environment, researchers have compared the intelligence test scores of adopted children with those of their _____________ and with those of what two sets?

adoptive siblings

(a) their biological parents, the providers of their genes, and
(b) their adoptive parents, the providers of their home environment

"virtual twins"

same age, biologically unrelated siblings reared together from infancy

for intelligence, ___________,not _____________, become more apparent as we accumulate life experience

Genetic influences
environmental ones

adopted children's intelligence scores over time become more like what set of parents?

those of their biological parents

estimates of the heritability of intelligence—the variation in intelligence test scores attributable to genetic factors—put it at about _____%

50 percent

So researchers estimate that heritability of intelligence—the variation in intelligence test scores attributable to genetic factors—put it at about 50 percent. Does this mean your genes are responsible for 50 percent of your intelligence and your environment for the rest?

NO NO NO NO

It means we credit heredity with 50 percent of the variation in intelligence among people being studied. This point is so often misunderstood that I repeat: Heritability never pertains to an individual, only to why people differ from one another.

Heritability never pertains to ___________, only to...

an individual
why people differ from one another

if boys were raised in barrels until age 12, their heritability for their differences would be...

heritability for their differences would be nearly 100 percent

if we raise people with similar heredities in drastically different environments heritability would be...

heritability would be lower

If environments become more equal, the heritability of intelligence would

increase.

decrease.

be unchanged.

Heritability—variation explained by genetic influences—will increase as environmental variation decreases.

tutored human enrichment

J. McVicker Hunt trained caregivers to play language-fostering games with 11 infants, imitating the babies' babbling, then engaging them in vocal follow-the-leader, and finally teaching them sounds from the Persian language

results of Hunt's program

By 22 months of age, the infants could name more than 50 objects and body parts and so charmed visitors that most were adopted—an unprecedented success for the orphanage

Do studies of such early interventions indicate that providing an "enriched" environment can "give your child a superior intellect," as some popular books claim?

Most experts are doubtfu

"Mozart effect"

suggested that listening to classical music boosted cognitive ability

________ and ________ together weave the intelligence fabric

Genes and experience

which sex are better spellers

Females are better spellers

which sex excel at verbal fluency and remembering words

Females excel at verbal fluency and remembering words

which sex have an edge in remembering and locating objects

Females have an edge in remembering and locating objects

which sex are more sensitive to touch, taste, and odor

Females are more sensitive to touch, taste, and odor

which sex are better emotion detectors

Females are better emotion detectors

On math tests given to more than 3 million representatively sampled people in 100 independent studies, which sex obtained nearly higher scores

males and females obtained nearly identical average scores

which sex is most reliable in spatial ability tests that involve speedily rotating three-dimensional objects in one's mind

The average male

intelligence research consistently reports a peculiar tendency for ________ mental ability scores to vary more than __________

males'
females'

Fueling the group-differences debate, what are two other disturbing but agreed-upon facts

Racial groups differ in their average intelligence test scores.

High-scoring people (and groups) are more likely to attain high levels of education and income.

Individual differences within a race are much greater than differences...

between races

polygenetic

traits influenced by more than one gene

Given twin studies what conclusions have been reached regarding how much intelligence is impacted via nature versus nurture?

Clearly nature plays a large part given the high coorelations (Addison, study figure 10.11 in section 10.4.1)

Likewise, the test scores of identical twins reared separately are similar enough to have led twin researcher Thomas Bouchard (1996a) to estimate that "about _____ percent" of intelligence test score variation "can be attributed to genetic variation."

70

So would you expect the family environment effect to grow with age and the genetic legacy effect to shrink?

That is...Who do adopted children resemble? Their adoptive siblings/parents or their biological parents?

As the years went by in their adoptive families, children's verbal ability scores became modestly more like their biological parents' scores.

GENETICS WINS OVER ENVIRONMENT

As the years went by in their adoptive families, children's verbal ability scores became modestly more like their biological parents' scores.

ADDISON STUDY FIGURE 10.12 IN SECTION 10.4.1

Can you guess the coorelations on intelligence on the following:

Same person (tested twice) ______
Identical twins—Reared together _____
Identical twins—Reared apart ______
Fraternal twins—Reared together _____
Fraternal twins—Reared apart ______
Biological siblings—Reared together ______
Biological siblings—Reared apart ______
Unrelated children—Reared together _______
Parent-child—Living together ._______
Parent-child—Living apart_______
Adoptive parent-child—Living together _______

Another summary:
Same person (tested twice) .95
Identical twins—Reared together .86
Identical twins—Reared apart .76
Fraternal twins—Reared together .55
Fraternal twins—Reared apart .35
Biological siblings—Reared together .47
Biological siblings—Reared apart .24
Unrelated children—Reared together .30
Parent-child—Living together .42
Parent-child—Living apart .22
Adoptive parent-child—Living together .19

heritability

the proportion of variation among individuals that we can attribute to genes

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