Discuss research into genetic and/or environmental factors associated with intelligence test performance? 8+16 marks
Individual differences in intelligence tests can be linked to either heredity or environment. Heredity consists of each person’s genetic inheritance, the instructions that tell your body to produce hair of a particular colour, in this context it is the impact on performance in intelligence tests. Environment consists of the situations and experiences encountered by people during their lives which impact the performance on intelligence tests
Many psychologists have studied the relative contributions of genetics versus environment and this leads to the conclusion that individual differences in intelligence depend on differences in genetic endowment or differences in the environment.
Twin studies are a useful way of assessing the relative importance of genetic factors and environment by comparing monozygotic twins (100% same genes) and dizygotic (also known as fraternal) twins (approximately 50% of the same genes). If genetic factors influence individual differences in intelligence, identical twins should be more alike in intelligence than fraternal twins. Bouchard et al studied more than 40 adult identical twin pairs separated at a mean age of 5 months, and found their IQs correlated +.75. The similarity of the correlations supports the reliability and validity of the genetic basis of intelligence.
Further research support would be Horn (1983) who reported findings from the Texas Adoption Project, which involved almost 500 adopted children. The correlation between the adopted children and their biological mothers was +.28, and between the adopted children and their adoptive mothers was even lower at +.15. Both of these correlations although very low but they do suggest a greater role for heredity as the correlation between biological relatives was higher than between adopted relatives.
However, one can question the validity of IQ tests. Intelligence tests are not necessarily a valid measure of intelligence. They are culturally biased and narrow in scope because
Many psychologists have studied the relative contributions of genetics versus environment and this leads to the conclusion that individual differences in intelligence depend on differences in genetic endowment or differences in the environment.
Twin studies are a useful way of assessing the relative importance of genetic factors and environment by comparing monozygotic twins (100% same genes) and dizygotic (also known as fraternal) twins (approximately 50% of the same genes). If genetic factors influence individual differences in intelligence, identical twins should be more alike in intelligence than fraternal twins. Bouchard et al studied more than 40 adult identical twin pairs separated at a mean age of 5 months, and found their IQs correlated +.75. The similarity of the correlations supports the reliability and validity of the genetic basis of intelligence.
Further research support would be Horn (1983) who reported findings from the Texas Adoption Project, which involved almost 500 adopted children. The correlation between the adopted children and their biological mothers was +.28, and between the adopted children and their adoptive mothers was even lower at +.15. Both of these correlations although very low but they do suggest a greater role for heredity as the correlation between biological relatives was higher than between adopted relatives.
However, one can question the validity of IQ tests. Intelligence tests are not necessarily a valid measure of intelligence. They are culturally biased and narrow in scope because