9 - Intelligence and its Measurement Flashcards
Neisser et al., (1996)
Environmental influences on IQ (3)
- Biological variables and maternal effects
- School and education
- Family environment
Influence of Biological variables and Maternal effects on IQ
- Nutrition:
> children given vitamin-mineral supplement showed an increase in IQ scores
+ Benton and Roberts (1988) - Lead exposure
- Prenatal Factors
> women who smoked 20+ cigarettes daily in late pregnancy were likely to have sons with lower IQ at 18-19y
+ Mortensen et al., (2005) - Prenatal conditions may account for 20% of the variance between twins
+ Delvin et al., (1997)
Influence of Family Environment on IQ
Socioeconomic status
|»_space;> SEMINAR DISCUSSION
Influence of School and Education on IQ
Neisser et al., (1996)
- intelligence as a dependent variable
> going to school is likely to increase your abilities, especially those relating to intelligence - intelligence as an independent variable
> intelligence is likely to influence your attendance at school and your length of schooling
Wilson effect (heritability)
Shows that the heritability of IQ increases with age
- MZ twins became increasingly concordant with age and paralleled each other in spurts and lags in development
- DZ twins became less concordant with age, and eventually matched to their singleton siblings
- Overall results suggested that the course of mental development is guided by genetic and environmental factors
- As an individual becomes a more independent age, the experiences they have (environment) become self-selected
> as you start to select the environment, your genes will have more of an influence on your phenotype, because the genes begin to influence the environment that you’re choosing to move into
What does the Wilson Effect show?
Heritability of intelligence depends entirely on the age that it’s measured
shows that heritability is dynamic
- due to the increasing ability of genes to influence environment
Flynn Effect
The average IQ score has increased at a remarkable rate in most industrialised societies throughout the 20th Century
Flynn (1994)
- we have not seen an increase in intelligence itself, but in some kind of abstract problem-solving ability
Must focus on environmental influences, because the change is far too rapid for genetic influence:
- Length of schooling has increased
> However, length of schooling predicts larger rises in verbal tests and lower rises in non-verbal tests…whereas the Flynn effect has found the reverse
+ Flynn effect found larger rises in non-verbal tests than in verbal tests - Test taking sophistication
> more time practicing, more tests generally - Child-rearing practices
> (sesame street) more engaging television
> Head Start Program (support in early years) - Culture and the age of technology
- Improvement in nutrition
If the observed variance in environment accounts for so little variance in adult IQ, how could environmental factors cause large differences?
Reciprocal causation between phenotypic IQ and environment produces gene x environment correlation
- a positive correlation between environment and genotype masks the potency of environment
> judging the size of environmental effects by the fraction of variance not explained by the genotype will understate its full magnitude
+ when measuring heritability, if the effect of the environment acts in the same direction as the genes, then we will not see the effect in the correlations
> in twin studies, we’re saying that the similarities must be due to genes, and the rest must be due to environment - There is a multiplier effect
> genes and environment can interact to inflate their effect
+ having a higher IQ may lead you into better environments which cause your IQ to grow further - Social multipliers can play an important role in determining the impact of society-wide changes
> if some external factor causes the IQ of some individuals to rise, this will improve the environment of others and cause their IQ to rise
Limitations of using IQ to predict achievement
Whalley and Deary (2001)
Found:
- people with a standard-deviation (15-point) disadvantage in IQ relative to others at age 11, were only 79% as likely to like to age 76
Possible explanations:
- High IQ is associated with more optimal health behaviours
- High IQ is predictive of educational qualifications
- High IQ may be associated with jobs with safer environments
Klemp and McCelland (1986) found that scores on standard ability tests tend to be uncorrelated with actual proficiency in managerial jobs and with performance on simulated business problems, why might this be?
Problems in IQ tests are too well-defined:
- in real life, problems are rarely so clear-cut, before figuring out a solution, one must first figure out the problem - only then can one know what kind of information to seek out in order to solve it
Deliberate Practice
Practice that gets you feedback
