Core - Chapter 2 - Intelligence Flashcards
What is the “g-factor”?
A creation of an early intelligence theorist Charles Spearman, the g-factor is the general intelligence factor that is the basis of all intelligence.
A modern version focus on testing spatial ability, reasoning, divergent thinking and verbal fluency.
Describe a meta-analysis on intelligence
Bouchard and McGue (1981)
Describe the largest twin study ever carried out
Bouchard et al. (1990) Minnesota Twin Study
Describe a study on intelligence and adoptive families
Scarr and Weinberg (1977) and Horn et al. (1979)
Describe a study on intelligence and infant adoption
Wahlsten (1977)
Describe a study on the amount of energy required for problem solving
Hainer et al. (1988)
Describe a study on increasing correlation of intelligence
Plomin and Petrill (1997)
What is the Flynn Effect and what might cause it?
It refers to the rise of average scores on intelligence tests in most parts of the world over the last century, James R. Flynn tried to document this in order to create awareness of its implications.
According to Ulric Neisser who wrote an article on the phenomenon in The American Scientist in 1997, the average mean scores on standard IQ tests have been going up by about three points every 10 years, and the increase is even higher in measures of abstract-reasoning ability.
Real intelligence increase or increase in ability to crack tests? Could be attributed to better nutrition, improved schooling, different child-rearing practices, increased use of technology in modern life. (Neisser argues for that living in a highly visual environment may play an important role in the rise in IQ scores.)
Bouchard and McGue (1981)
Reviewed 111 studies of IQ correlations between siblings from research studies on intelligence around the world (a meta-analysis). The closer the kinship, the higher correlation for IQ.
Bouchard et al. (1990)
Minnesota Twin Study
Longitudinal study that has been going on from 1979. MZAs are compared to MZTs all over the world (the most cross-cultural study up to date). Mean age was 41 years old, compared to other studies mainly focusing on adolescents.
Each twin completed aprox. 50 hours of testing and interviews.
Same person tested twice - 87%
Identical twins reared together - 86%
Identical twins reared apart - 76%
Fraternal twins reared together - 55%
Biological siblings reared together - 47%
Bouchard et al. determined a heritability estimate of 70%, meaning 30% of intelligence can be attributed to other factors.
Limitations: Bouchard relied on media coverage to recruit participants, there are ethical concerns of how he reunited the twins, no adequate control was done to establish the frequency of contact between the twins prior to the study, “equal environment assumption”
Palomino and Petril (1997)
Correlations between parents and children change over time.
Age 4 to 6 - 40% correlation
Early adulthood - 60%
Older adults - 80%
It is possible that our genetic disposition pushes us towards environments that accentuate that disposition, this leading to increased heritability throughout the lifespan. Socio-economic class appears to be one of the most important environmental factors in the development of intelligence.
Haines et al. (1988)
PET scan study which indicated that when solving a reasoning problem, individuals with a high IQ had lower metabolic rates than those with a low IQ. Only seen in problem solving and not data recall. Could mean that those with higher IQs use less energy to think than those with lower IQ, known as the less effort hypothesis.
Wahlsten (1977)
Claimed that well-controlled adoption studies conducted in France have found that transferring an infant from a family with a low socio-economic status to a home where parents have high socio-economic status improved childhood IQ scores by 12-16 points, or about one standard deviation.
Seems to suggest that intelligence has a lot to do with environment as well as genetics. An enriched environment may raise IQ in children.
Scarr and Weinberg (1977) and Horn et al. (1979)
Parents who had raised both adoptive and natural children, assumption being that the children had the same upbringing. Any significant differences between parent-child IQ should be attributed to genes. Researchers found no significant difference in IQ correlations. Very interesting as the adoption families were wealthy, white, and middle class with high IQs, and the adopted children were from poor, lower-class backgrounds with lower IQs.
