Lecture 5: Cognitive Ability Flashcards
Intelligence
capacity to acquire and apply knowledge and skills
-conceptual variable that doesn’t rlly exist
r of performance for an individual on different subjects and cognitive tests
r >0.3
- could be that the tests are all related in some way or that they all measure the same thing
General intelligence theory (g)
suggests that there is a common element that contributes to all cognitive abilities
- math ability, perceptual ability, spatial ability, language ability, verbal comp, recall speed
Are all cognitive abilities entirely driven by g?
No, g is not all that matters and correlation between any on cognitive ability is never perfect. A proportion of the variability in each ability must be explained by something else
what do g and s mean in general intelligence theory
g is the cognitive engine that is shared by all abilities
s is the specific factor that is unique to a specific ability
AKA general and specific forces
IQ test
most popular way to estimate g
- give individ many cognitive tasks (more than 10) and observe
WAIS tests
Weschler Adult Intelligence Scale
- best reliability and validity
- includes: verbal comp index, working memory index, perceptual organization index, processing speed index
Example of some cognitive tests
- picture completion
- block design
- raven’s progressive matrices
Correlates of IQ
- pos correlated with longevity and height/weight
- negatively correlated with criminal behav and divorce rate
- pos correlated with income but not a good predictor of wealth
Rmz and Rdz and h2 for IQ
MZ = 0.86 and DZ = 0.56 h2 = 0.4 - 0.8
Why does heritability of IQ increase with age?
- genes may affect our attraction to environments and our ability to benefit from them
- genes for IQ may take effect later on in life (innovation)
- and/or become increasingly important over time (amplification)
Contribution of genetics to g
Genetic drive for g accounts for 58% of the total genetic variance
- majority of genetic variance for a cognitive ability is related to g
Assortative mating
people mate in a way that is related to their phenotype
- positive AM: trait similarity between partners
- negative AM: trait differences (red hair)
Large GWAs for intelligence
269k individ of european ancestry
- 1016 genes and 205 genomic loci associated with intelligence
- vast majority of genes strongly expressed in brain being partic enriched in spiny neurons and hippocampal cells
- GWAS hits used to create a polygenic score that predicted only 4% of intelligence
Max amount of variability in intelligence that can be explained
4-10% using PS and GPS
What are genes for intelligence doing?
- brain volume, development, cortical thickness, myelination, surface area?
Cortical structure is highly correlated in
monozygotic twins partic in frontal lobe, sensorimotor strip and wernickes
Transgenic mice overexpressing NMDARs have
better spatial memory than controls
Issues with trying to find genes associated with intelligence
- need larger dataset
- many datasets dont use an intelligence test and if they do it isnt standardized
- educational attainment can be used as a proxy bc it is also heritable
polygenic scores for Educational attainment predict… better than they predict…
- intelligence
- EA
need intelligence for EA but dont always seek EA if you’re intelligent
Flynn effect
suggests environment matters for IQ
- overall increase in IQ throughout the 1950s on to 2000s even tho the genes arent changing duh
- improved food, improved IT acesss, familiarity with testing, changes in home envs
Genes and social economic status
positive correlation between SES and IQ, though direction is not obvious
- PS for educational attainment also predict social mobility
Scarcity mentality
decline in IQ when times are rough
- scarcity (lack of resources) and being worried about scarcity may impair cognition
- poor cognition can in turn lead to further financial difficulties and stress (positive feedback)
Genetic basis of cognitive disorders: PKU
No phenylalanine hydroxylase
- decreased NT levels (need dietary tyrosine)
Genetic basis of cognitive disorders: down’s syndrome
mild to moderate mental retardation
- NDJ
- risk increases with age of mother
Genetic basis of cognitive disorders: fragile X syndrome
second most prevalent cause of mental retardation
- problems with FMR1 gene in x chromosome
- gene encodes for fragile x mental retardation protein (FMRP) important for normal development
- triplet (CGC) repeat expansion in FMR1 gene (normal is 30 repeats and affected is 200 repeats)
- mutations can occur in unaffected individuals in their lifetime which could be passed onto next gen (would not cause in the given person themselves)
Is fragile x more common in males or females
hemizygous effect
- twice as common in males because of x inactivation in females, so only 50% of females carrying the affected gene have FXS
Genetic basis of cognitive disorders: Rett syndrome
Mutation in Xq28 on x chromosome
- codes for methyl CpG binding protein 2 which is a very very important regulatory protein for mature nerve cells
- part of silencing complex
- only seen in females, need at least one copy of this gene (lethal in males)
Genetic basis of cognitive disorders: AD
AD occurs in two forms:
- early familial onset (30-65, pretty rare)
- late onset AD (over 65)
genetics more important in early onset
- apolipoprotein E gene is only gene reliably associated with the disorder
- identified genetic factors only explain a small proportion of cases of the disease.
