Psychological - Incomplete AJ

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.

• Good predictive validity of the tests, or

• Predictive validity of IQ test is confounded with stability in environment of longitudinal samples

• 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.

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?!

• 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.

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.

• 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.

1. Mother history mental illness

2. Mother didn’t go to high school

3. Mother severs anxiety

4. Mother rigid attitudes

5. Few mother-child interactions

6. Head of household semi-skilled job

7. > 4 siblings

8. Father not living at home

9. Child belongs to a minority group

10. 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.

• 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.

Kaufman et al. (1989)

• Verbal IQ scores remain stable with age (crystallized)

• Non-verbal IQ scores show a decline (fluid intelligence)

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