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Flashcards in Incomplete AJ Deck (11):
1

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.

2

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

3

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.

4

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?!

 

5

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.

 

6

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.

 

 

7

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.

8

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

  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.

9

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.

10

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)

 

11

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)

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