intelligence tests

intelligence tests

1. psychometric tests

   • IQ tests
   • measure intelligence or specific skills/ abilities
     • assumes intelligence can be evaluated using tests
   • standardised assessment
   • objective & scientific
     • systematic, replicable, reliable

2. measuring intelligence

   • Francis Galton discussed intelligence in scientific terms
     • Hereditary genius
     • look at family history, genetic inheritance not environment, twin/adoption studies looked at to measure genetic contribution
     • physical markers of intelligence (skull structure, fingerprints)
     • Anthropometric lab- report personal & fam history. Height, head length, strength, vision, hearing & reaction time measured
       • first attempt at objective measurement of intelligence
   • Alfred Binet & Theodore Simon devised first test in 1904 with the aim to identify mentally handicapped children
     • tasks of increasing difficulty to represent cog.development in children 3-10 yrs- follow light with eyes, shake hands, name object, fill missing word (sample of 50)
       • recognised developmental changes in intelligence
     • mental age= level of test passed compared with actual age
       • first link of intelligence with age
   • Stanford-Binet test (terman)- adapted to americans, bigger & more representative sample (1,000)
     • IQ (Stern)= mental age/actual age X 100. mental=actual= IQ 100. Mental less than actual= IQ<100. Mental more than actual= iq>100
     • single index of intelligence
   • Army Alpha & Beta tests- verbal and non-verbal intelligence of army recruits during WW1
   • Wechsler Adult intelligence scale- comprehensive test. 17-90 yrs. Several indices of intelligence
   • Raven's progressive matrices- non verbal

3. Verbal/general knowledge/ vocab/arithmetic

4. IQ

   • modern batteries use same test for all p's irrespective of age (IQ cannot be calculated by dividing mental age by actual age)
   • IQ looks at how much a score differs from the mean age group (mean is 100 and SD is 15)
   • assumes a normal distribution in population

5. features

   • use variety of tasks to examine abilities - test more abilities= closer to g
   • standardised administration- same procedure
   • norm referencing- individual performance compared to that of a sample of age-matched people
   • internal reliability- measure same concept/ability
   • test-retest reliability- same person taking same test should produce same result
   • validity
     • face/construct- measure what they should do (correspond to implicit and explicit theories)
     • concurrent- correlate with external measures taken at same time or in fute (predictive)
     • same person should receive similar scores and IQ scores should correlate with other tests measuring intelligence

6. issues affecting reliability and validity

   • test-retest- IQ scores can fluctuate by 15 points & practice effects
   • validity- lack of accepted definition of intelligence
   • concurrent/predictive- important to show IQ tests are in agreement with other measures

7. development of intelligence

   • increase in intellectual growth coincides with rapid brain development especially in pre-frontal cortex
     • increases in intelligence mirror increases in abilities measured by IQ
   • expansion of general knowledge
     • vocab- 2yrs= 50-300. 16 yrs= 40,000
   • better performance in GF tests
     • processing speed
     • STM capacity- 5yrs= 4 adults= 7
   • elderly IQ changes- verbal IQ (crystallised)= gradual increase & decrease. procedural (fluid) shows steep drop from 30yrs

8. stability of intelligence

   • Scottish IQ- test mental deficiency and intelligence distribution. Correlated with Binet test
     • IQ scores showed stability from late childhood to adolescence & adulthood.
     • IQ differences at old age can be predicted by IQ differences at 11rs
     • relative to age group- average at 11yrs is likely to be average at 90
     • large individual differences

9. intelligence as a predictor

   • IQ & education
     • IQ scores highly correlate with school atainment & other educational indices (years in education & qualifications)
     • strong predictive validity- IQ scores at 11yrs predict GCSE exams at 16. IQ at 9yrs predicted achievement at 12, but achievement at 9 didn't predict IQ at 12 (Watkins)
     • other contributors
       • personality, motivation, experience, teaching qulaity & structure
   • IQ & occupation
     • scores correlate with job status & performance
     • better predictors than other indicators (CV had 0.37, interview had 0.14)
     • more complex job= better prediction (manager= 0.69, accountant= 0.74)
   • IQ & health
     • IQ correlates with mortality rates
     • IQ predicts death by CHD, accidents, suicide and other causes
     • IQ & mental health
       • SZ patients= decrease in IQ scores. Intelligence is long impaired before SZ. low iq can be used as a predictor of SZ
         • SZ affects those with low grades, bipolar influences those at both ends of spectrum
       • bipolar- liklihood of intellectual impairment is linked to severity of disorder
         • of 900,000 p's 280 had developed bipolar by 2003- low and high acheivers were more likely to develop disorder compared to more average performers
           • other factors may be responsible- attendance, motivation, creativity, attention
           • another study found that high performance on a reasoning task was correlated with an increased risk of the disorder while high performance on a visuo-spatial task was correlated with a reduced risk of the disorder
     • higher IQ= better education= better job= more money= better health care
     • higher iq= better education= better disease and injury prevention
     • genetics influence IQ and susceptibility to disease

10. heritability

    • proportion of individual differences in aa trait that can be explained by genetic factors in a specific environment
      • not proportion of trait attributed to genetic influence
    • supportive and impoverished environments affect heritability- affect expression of trait
    • parents & children have similar IQ regardless of living together or not- environment still impacts

11. genetic & environmental factors

    • family studies
      • environment relatively constant- 50% genetic similarity
    • twin studies
      • control environmental factors & genetic similarity
      • MZ = 100% similar. DZ= 50% similar
    • adoption studies
      • environment relatively constant, no genetic similirity
      • issues- over/under estimate genetic influence. MZ environment is more similar than DZ, adoption agenices dont randomly allocate
    • assortive mating- partner isn;t random- choose similar people (positive) or dissimilar (negative). postivie= increases genetic similarity, negative= decreases similarity

12. environmental influences

    • bio factors
      • nutrition- breastfeeding.
      • iodine- deficiency= retardation
      • iron-cognitive development issues
      • lead- poisonous
    • prenatal
      • alcohol- affects brain
      • tobacco- intellect deficits
    • education- attendance
      • socioeconomic status- high SES= prepare for school (resources, better attitude), low= lack ability to assist children at school (unable to afford tuition, worse performance to attendance and performance)
      • interventions
        • head start- gains disappeared but less likely to drop out
        • abecedarian- encouraging results
        • criticised methodology- sampling errors