Lecture 6 Individual & Group Differences (Catherine Flashcards
To Provide a summary of Lecture 6 to serve as revision content on Individual and group differences
Provide an overview of the key areas related to Intelligence testing & IQ ability
- IQ stability & instability
- Individual differences in intellectual ability & IQ
- Group differences in intellectual ability & IQ
- Age, The Flynn-effect, cross-sectional vs longitudinal studies
- Gender
- SES
- Race/ethnicity/indigene
- Beyond the norms:
- Intellectual ability
- Intellectually gifted
Provide evidence that Group scores in IQ remain stable over time
*Individual’s test scores remains relatively stable after the age of 6 years:
1. 3rd grade school boys (n=613) reassessed 10 years later: r= 0.72
2. 13yr old (n=4500) reassessed at 18 years: r= 0.78
3. 3yr old reassessed at 4 years: r= 0.83 (very good)
3yr old reassessed at 12 years: r= 0.46 (not so good- a lot has changed in the 9 year period)
4. 2-5.5 yr old reassessed 10 years later: r= 0.65, 25 years later: r=0.85 (very good!) overall r=0.59
*By about 16-18 years of age, IQ remains pretty stable
What are the implications that Group scores in IQ remain stable over time?
Implications:
*Good Predictive Validity of the tests
OR
*Predictive Validity of IQ tests is confounded with stability of the environment of longitudinal studies
Why are group IQ scores more stable with age?
Possible explanations are:
- Cumulative nature of intellectual development
- Environmental stability
- Prerequisite learning skills
Provide evidence that Individual IQ scores can be more unstable over time
California Guidance study (n=222)
*6yr vs 18 yr - test-retest correlations were high (around 0.60)
*59% of children IQ increased by up to 15
*37% of children IQ increased by up to 20
*9% of children IQ increased by up to 30!!!
This is incredible!
What are some of the factors affecting a child’s intellectual development?
- Change in family structure/home
- Poor home conditions
- Change in parents SES
- Adoption
- Severe or prolonged illness
- Therapeutic, remedial, educational or counselling intervention programmes
When viewing the correlation between IQ scores compared at different time periods, what is an important consideration?
- The correlation tells us the variance is the same/stable
- The correlation does not tell us that someone with an IQ of 100 still has an IQ of 100 10 years on, merely that the group overall is consistent
What did Capron & Duyme find from their 1989 Adoption study published in Nature?
- Children reared by higher SES parents had a higher IQ
- Change enhances IQ independent of the SES of the biological parent
- SES of biological parent does have some effect
What have been the findings of some longitudinal studies into the effect of SES on IQ score?
- without early intervention in low SES groups, IQ score declines from the baseline over time
- In High SES groups, IQ score increases from the baseline over time
The Rochester Longitudinal Study by Sameroff et al., (1987, 1993) found 10 risk factors associated with decreases in IQ score. What were these?
- mother had history of mental illness
- Mother did not go to high school
- Mother had severe anxiety
- Mother had rigid attitudes
- Few mother-child interactions
- Head of household in semi-skilled job
- > more than 4 siblings
- Father not living at home
- Child belongs to a minority group
- Family had > (more than) 20 stressful events in child’s 1st 4 years (!)
What was the impact for the children in the Rochester Longitudinal Study by Sameroff et al., (1987, 1993) who had 4 or more of the risk factors?
Those children had decreased IQ in the retest phase (1993)
What do we need to bear in mind when considering Group and individual differences of Age, Gender, Culture/Race, Indigene?
Our results should be stratified by age, gender, culture in the standardisation process as a result it is important that we do not compare one group with another, as this can lead to inappropriate interpretations.
*For instance, we recognise & accept gender differences in the sub-sets, but the overall IQ score is standardised according to group norms so should not have differences
How are IQ scores standardised by age?
- IQ scores are standardised by 9 age groups from age 16 through to 74 years old
- The WAIS uses raw scores on the sub-sets but the overall IQ score is standardised according to group norms
What are the standardised scores for IQ tests?
96% range between 70 - 130 68% range between 85 - 115 0.1% have an IQ 55 or below 2% have an IQ 70 or below 14% have an IQ between 71 - 84 34% have an IQ between 85 - 99 34% have an IQ between 100 - 114 14% have an IQ between 115 - 129 2% have an IQ 130 -145 0.1% have an IQ above 146
Why is it inappropriate to compare IQ scores across ages?
- It is not meaningful to compare a 17 year old with a 70 year old because of age related changes in IQ
- The IQ scores must be standardised by cohort not across the age range.
What are the main findings from Cross-Sectional analysis of Age-related changes in IQ?
- Verbal scores (crystallised intelligence) remain stable with age
- NonVerbal scores (fluid intelligence) declines with age
What are the main limitations of Cross-sectional studies?
They are confounded by changes in culture and age
even one generation has seen significant changes in healthcare, diet, technology, media, educational opportunities
What are the strengths and weaknesses of a Longitudinal design?
weakness:
- practice effects
- small IQ increase on retest
- age related (old people = less increase)
- practice effect up to 4 months
- studies have recorded high increase following practice effect
- is practice effect an artefact?
- Selective attrition
- some people more likely to remain
- higher IQ associated with longer life & motivation
Strengths:
continuation of individuals
What was ideal about the Seattle Longitudinal Study?
It was a Cross-Sequential Design, (AKA cohort sequential) which incorporates the best elements of a Cross-sectional and a Longitudinal