Incomplete AJ Flashcards
GROUP SCORES IN IQ STABLE OVER TIME
Individual’s test score remains relatively stable after approx 6 yrs of age
- Evidence: 3rd grade boys reassessed 10yrs later: r = 0.72
- 13yr-olds reassessed at 18yrs: r = 0.78
- 3yr-olds reassessed at 4yrs: r = 0.83
- 3 yr-olds reassessed at 12 yrs: r = 0.46
The longer the time frame, the weaker the relationship.
Shorter time frames hold true.
16-18+ yrs of age: the IQ stays more constant.
IQ’s do vary within individuals BUT as a group, the correlations do remain fairly consistent after about 16-18yr-olds.
Group Scores In IQ Stable Over Time
What are the Implications?
- Good predictive validity of the tests, or
- Predictive validity of IQ test is confounded with stability in environment of longitudinal samples
Why isIQ more stable with age?
- Cumulative nature of intellectual development - It’s easier to build on foundations
- Environmental stability
- Prerequisite learning skills - prior learning supports your ability to continue to learn & gives you flexibility of thought & problem-solve more effectively.
What about individual differences?
Does everyone remain stable?
Individual scores over time can be more unstable.
California Guidance Study (n=222)
- 6y vs 18y (test-retest correlations high) .6
- 59% chn increased > 15 IQ points
- 37% chn Increased >20 IQ points
- 9% chn increased > 30 IQ points
Huge difference.
Why? e.g.an enriched environment
Can we use thst kind of enriched environment to improve everybody’s IQ?!
FACTORS AFFECTING A CHILD’S INTELLECTUAL DEVELOPMENT
- Change in family structure/home/and or change in parent’s economic status
- Adoption
- Severe or prolonged illness, or poor home conditions
- Therapeutic, remedial or counselling programs
- Enriched educational programs
NB Not blanket statements for all children.
INSTABILITY?STBILITY IN INDIVIDUAL’S IQ
Capron & Duyme (1989):
2x2 design for adopted chn.
- High/low SES-biological parents x high/low SES-adopted parents.
- WISC-R
Children reared by high SES parentsIncreased IQ.
Change enhances IQ INDEPENDENT of SES of biological parent
SES of biological still had some effect.
LONGITUDINAL STUDIES AND INDIVIDUAL’S IQ
- In low SES groups, IQ’s decline from the baseline over time without early intervention
- In high SES groups, IQ’s increase from baseline over time.
RISK FACTORS OF INTELLIGENCE
The Rochester Longitudinal Study
Sameroff et al. (1987)
1987 4yr (n=215)
1993 13yr (n=152)
Identified 10 risk factors for lower IQ
- Mother history mental illness
- Mother didn’t go to high school
- Mother severs anxiety
- Mother rigid attitudes
- Few mother-child interactions
- Head of household semi-skilled job
- > 4 siblings
- Father not living at home
- Child belongs to a minority group
- Family > 20 stressful events in child’s first 4 years.
CHILDREN WHO HAD 4 OF THESE RISK FACTORS AT AGE 4 - HAVE AN IMPACT ON IQ.
Intelligence and Age
WAIS FACTS
- WAIS:Raw scores are on subsets - the standardized IQ score according to norms.
- Standardised in 9 age groups between 16 and 74 on adult intelligence scales
- Mean is always 100
- 1 Standard Deviation is always 15
* 96% of all people will fall within 30 points of 100 (b/n 70 & 130)
* 68% of people score within 15 points above or below 100 (85 -115)
* 14% people (115 -130 & 70-85)
* 2% 130 +
* 2% below 70.
Cross-sectional analysis of age-related changes in IQ
Kaufman et al. (1989)
- Verbal IQ scores remain stable with age (crystallized)
- Non-verbal IQ scores show a decline (fluid intelligence)
IQ and Age
Age does not make your IQ drop.
Test results are standardized.
Therefore, these are a refelection of the age group.
You may see a drop in intellect.
Fluid intelligence declines after mid 30’s (standardised)
Crystallized less so but a decline evident (standardised)
Slide 18 graph
