Intelligence - The Role of Heredity and Environment in IQ Flashcards
What does IQ stand for?
Intelligence Quotient
What is IQ?
Index of an individual’s intelligence
What are the two tests for IQ?
Verbal
Non-verbal
What are the advantages of non-verbal tests?
Eliminate issues with language, verbal abilities and cultural differences (not 100% of the time)
What did Francis Galton believe?
Reasoned intelligence is a product of natural selection
Genetically determined
Potential in theory of evolution for planned betterment - selective breeding
Intelligence = desirable characteristic
What did Binet and Simon do?
Developed 1st IQ tests to measure student abilities for education purposes
What did Lewis Terman and Maud Merrill do?
Developed Stanford-Binet scale
Studied sample of “gifted” children throughout their lives (longitudinal study)
Highly intelligent individuals not weaklings and misfits but healthy and stable
What did Lewis Terman do?
Military use (alpha, beta test) to assign soldiers to tasks appropriate to their abilities during WW1
Non-verbal test
Eugenics - promote selective breeding to cultivate desirable characteristics (intellectually and physically)
What did Cyril Burt do?
Advised British government to use aptitude tests to determine which children will go on to grammar schools (11+)
Research seemed to suggest occupational levels and social class determined by innate and hereditary levels of intellignece
Problems with his data and analysis - fabricated?
What are the issues with IQ tests?
Cultural bias in test construction and standardisation procedures
Intelligence tests favour groups from more affluent backgrounds and discriminate against less privileged racial, ethnic and social groups
What are the more recent IQ tests?
WISC = Wechsler Intelligence Scale for Children
WASI = Wechsler Adult Scale for Intelligence
Include verbal and non-verbal tests (tap into both crystalised and fluid intelligence)
What is genotype?
Genetic makeup of an organism
What is phenotype?
Observable physical properties or an organism
Include organism’s appearance, development and behaviour
Includes both genotype and environmental influence
Can we measure genotype or phenotype?
Only phenotype
What does performance on IQ tests depend on?
Many factors
Therefore cannot determine how intelligence is determined - cannot isolate genetics
What is degree of genetic relatedness?
Looking at people with various degrees of relatedness can give us an understanding of the genetic basis of a concept
What kind of distribution does IQ have?
Normal distribution
Typically seen in characteristics that are genetically predetermined
What is the atheoretical definition of intelligence?
Intelligence is what IQ tests measure
No theory of intelligence that determines what questions should be included in an IQ test
However IQ tests highly correlate with each other and with other measures (WM, academic performance, problem solving, etc)
What is correlation?
Statistical test and term that examines relationship between 2 or more variables
What does the theory that intelligence is a singe construct believe?
Generalised intelligence
Measures
- Stanford-Binet
- Raven’s Progressive Standard matrices
What is generalised intellignece?
Single construct that influences all cognitive function
Demonstrated through correlations of performances on different tests
What does the theory that intelligence is a multiple construct believe?
Composed of fluid and crystallised intelligence
Supported by correlations between tests of FI and CI respectively
Both interact in some ways
Relatively stable FI but increasing CI across life span
What is fluid intelligence?
Cognitive functioning component not influenced by the environment and fixed throughout lifetime
What is crystalised intelligence?
Stored factual information which benefits from schooling can change throughout life span
How is tested whether intelligence is genetically determined?
Twin studies
- valuable to examine genetic characteristics
- however hard to separate genetic and environmental factors
Degree of genetic relatedness
- examining individuals with varying levels of shared genes can help us pick apart genetic influences
What are the environmental factors of intelligence?
Environment in the womb
Family environment
How does the environment in the womb affect intelligence?
Mother’s health and habits can influence fetus development
How does the family environment affect intelligence?
An enriched and stimulating environment correlates with IQ
What was the method of Elardo et al’s (1975) study into the quality of family environment?
When speaking to children, mother’s voice conveys positive feeling
Mother structures child’s play periods
Mother reads stories at least 3 times weekly
Family provides learning equipment appropriate to age of the child
Child gets out of house at least 4 times a week
Mother shouts at child relatively infrequently
Mother spontaneously vocalises to child relatively frequently
Children observed at 6 months and 24 months
IQ tested at 3 years and 4.5 years
What were the results of Elardo et al’s (1975) study into the quality of family environment?
Rating of family when child was aged 24 months correlated with IQ at 3 years = .70
Rating of family when child was aged 6 months correlated with IQ at 4.5 years = .44
What are the important things to consider when deciding if intelligence is genetically or environmentally determined?
Covariance between inheritance and environment - intelligent children tend to have intelligent parents who provide enriched environment
Transactional process - intelligent children provoke an intelligent response that potentially feeds their development even further
Isn’t possible to specify which part of performance is due to heredity and which is due to environment
Estimates of heritability are based on population data and don’t necessary apply neatly to individual cases
What was the Benton and Roberts (1988) study into whether taking vitamins can make you smarter - boost executive functions?
Study with 6 year old children
50% = vitamin supplement every day for 3 months
50% = placebo
IQ measured before and after study
Children in experimental group had greater IQ increase compared to control
What was the Benton (2001) study into whether taking vitamins can make you smarter - boost executive functions?
Increase only observed in children with really poor nutrition
Children that have healthy lifestyle and rich diet didn’t benefit
What was the Eysenck and Schoenthaler (1997) study into whether taking vitamins can make you smarter - boost executive functions?
Metanalysis
Hard to draw conclusions as different studies use different populations, vitamins and IQ tests
What was the Owen et al (2010) study into whether cognitive (brain) training can make you smarter or increase cognitive abilities?
430 participants
Five cognitive domains (reasoning, memory, planning, visuospatial skills, attention)
6 week training period
Participants become better at cognitive task they trained on
Effects didn’t transfer or generalise to other tasks and to everyday cognition
What is the confluence model (Zajonc, 1976) about why 1st born children may be smarter than their younger siblings?
First born children spend more time with intelligence adults
As number of siblings increases, children spend more time with each other
Interactions between children not as intellectually stimulating as between child and adults
What is the dilution model (Blake, 198176) about why 1st born children may be smarter than their younger siblings?
Parental finite resources
First or alone child spends significant time with adults, gets more attention
As number of siblings increases, time parents spend with each child decreases
Less stimulating environment
What is the Flynn effect?
IQ is increasing with time in the world
IQ maybe 25 points higher for a test designed in 1930s (even fluid intelligence)
Can’t be evolutionary - not enough time
Improvements in education, nutrition and supportive parenting styles
