9. Intelligence

9. Intelligence

1. Testing

   • Raven's progressive matrices (1988) test free of cultural bias, matrix with rules
   • Wechsler-Bellevue Scale (1939) WAIS and WISC on a 1:1 basis for all ages
   • Spearman (1904) suggested 'g' general intelligence and 's' specific abilities. Positive manifold theory
   • Yerkes (1921) suggested the army alpha test for able individuals and beta army test for individuals not able.
   • Inferred process to explain degrees of individuals adaptive success, including the ability to reason, judge
   • Binet (1904) measured educational abilities of French children to determine mental age of child compared to actual age
   • Stern (1922) developed IQ. IQ = mental age/ chronological age x 100
   • Galton (1869) suggested intelligence is quantifiable and normally distributed
   • Terman (1916) Developed the idea of IQ, considering culture and time aspects. Applied Binet scale to califorinian children and found it didnt work, so added elements and created the Standford-Binet scale

2. Multi-factor theorists

   • Thurstone (1988) disagreed with 'g', suggested IQ is heirarchical and there are mutliple intellgiences, suggested 7 abilities
   • Cattell (1941) suggested 'g' is compromised of 2 components = 'gc' crystallised intelligence and 'gf' fluid intelligence
   • Vernon (1950) hierarchical model = highest level 'g', then verbal/spatial, then mirnor factors, then specific abilites, e.g. reading
   • Carrol (1993) Stratum model: factor analysis of 461 data, stratum 1 = specific levels, stratum 2 = 8 broad factors and stratum 3 = 3 general
   • Guilford (1970) structure of intellect (SI) rejected 'g'. Intelligence is comprised of 150 individual abilities = operation, contents and prodcuts = broadens view

3. More to intelligence than 'g'

   • Gardner (1996) educational / neuropsychology. Argued against intelligence being a single faculty. Its a sum of 9 categories = linguistic, muscial, logical, spatial, bodily, inter-personal and intrapersonal, natureal and existential. Suggested these are independent theories, but interact
   • Sternberg (1985;1988) triarchic theory = 3 types of intelligence. componential (mental mechanisms) experimental (experience) and contextual (external, adaption, shaping and selection)

4. Use of tests

   • Das et al (1979) cognitive assessment system (CAS), tests IQ with a PASS system = plan, attention, simultaneous and successive. Can be used to evalutae ADHD
   • Luria (1932) combined motor method = diagnosing thought processes, by doing 3 tasks simultaneously. 1973 = left-hemisphere has cognitive power and conscious control = simultaneous processing
   • Sattler (2002) 3 aspects of tests = variety of tasks, standardisation of administration and norm referencing
   • Validity = face, concurrent, predictive = no tests are fully valid
   • Reliability = internal, test, retest, IQ scores tesn to be stable
   • Jenson (1998) elementary cognitive tasks = simple tasks measure cognition, response times to times, correlations 0.1-0.5
   • Kaufmans ability test = aimed to address children referred for evaluation with learning problems.
   • Used for selection, diagnosis, and evaluation in schools, job performance, lifespan and death predictability

5. Link to mental health

   • Savage (2015) IQ is protective of ADHD and alzheimers, and small increased risk of SCZ
   • Genotype Biomarker > Outcome
   • Mendelian randomisation = assign subjects to groups, based on genetics
   • Hill et al (2018)
     • IQ 1 SD below the mean, 60% greater chance of SCZ, 50% mood disorders, and 75% aclohcol
     • High IQ = anorexia and ASD
     • Low IQ = MDD, ASD, ADHD and BD
     • Education = strong, negative correltion with IQ

6. Predicting

   • Can screen for genetic mutations, high IQ and identify babies needing social support in the future
   • Plomin & Von-Stumm (2018) suggested Polygenic screening is a poor predicotr of intelligence. The variability of scores due to genetics is less than 10%
   • Polygenic score (PS) identify SNP, take DNA and genotype sites, each site calculate high IQ sites, multiple number of allex by ratio to get risk score, add all for overall PS score
   • Deary (2013) = consequences of IQ are = staying in school longer, more professional jobs, better workplace, better scoial status and better health

7. Link to brain

   • Wilderman et al (1991) reported a correlation of 0.35 between IQ and brain size
   • McDaniel (2005) reported 0.33 correlation between brain size and IQ
   • ANdreason et al (1993) suggested IQ is linked to temporal, intracranial and cerrebuallr regions in the brain
   • Savage et al (2018) identified 206 genomic loci and implicated 1041 genes with IQ
   • Harier et al (2005) suggested IQ is linked to parietal-frontal regions in males and frontal lobe in females
   • Jung & Harier (2007) suggested broadman and pareital areas linked to IQ, fronto-parietal theory
   • Goriovnova et al (2018) = action potentials in pyramidial neurons, high IQ individuals have fast AP and larger neurons = more efficient

8. Genes

   • study of genes and IQ is relatively new
   • Neurogenetic = 22q11.2, angelmans syndrome, down syndrome and prader-wlli syndrome linked to low IQ
   • GenexEnvironment interaction
   • Bouchard & McGUe (1991) suggested correlation of 0.86 heritbaility in MZ twins
   • Coleman et al (2019) suggested CA1 and GABA role
   • Wilson (1975) developed the wilson effect = heritability increases with age, as MZ twins become more alike and DZ twins become less like.
   • Plomin et al (1997) suggested adopted children resemble their adoptive parent early in life, but there biological parents later
   • Flynn Effect = IQ scores been getting better through the years
   • Zabenah et al (2015) suggested 3 variants of ADAM12 = plexin related to high IQ
   • Hillet et al (2019) suggested 538 genes
   • Theory of X-linakge (Lehrke, 1972) many genetic mutations are x-linked affecting IQ, 11% implciated