Biological and Behaviourist Perspectives on Intelligence Flashcards
What does Intelligence help us to do?
plan
- reason
- solve problems
- quickly learn
- think on our feet
- survive
How to measure intelligence?
Intelligence Quotient (IQ) strongly correlates with life outcome
What are the advantages of higher intelligence?
socioeconomic status
- education
- social mobility
- job performance
- lifestyle choices and longevity
intelligence as a stable trait in an individual from young to old
betweeen ages of 11 and 16 correlation of 0.81 on tests of educational achievement (Deary et al., 2007)
-test taken at 11 still highly correlates when taken again at 90 (Deary et al., 2013
intelligence has a strong … component?
genetic
heritability of intelligence?
studies demonstrate heritability to be large: 50%-80% (Posthuma et al., 2001)
-one of the most heritable behaviour traits (Plomin & Deary, 2015
intelligence can…
can be measured by cognitive tests
- is stable over time
- has high heritability
- predicts major life outcome
brain size and intellgence - what did many old studies fail to do?
old studies (19th century onwards) failed to observe differences in size when dissecting brains of deceased scientists and artists-trying to see what made people have exceptional ability or talents
what assumptions were made about smarter people’s brains?
stats/studies?
that they tend to have bigger brains. - when considering multiple studies this does seem correct
advances in neuroimaging have allowed for in vivo studies-meta-analysis of 37 studies with 1500 participants found moderate positive correlation of 0.33 between brain volume and intelligence (McDaniel, 2005)
-subsequent meta-study of 88 studies with over 8000 individuals also found significant small positive correlation of 0.24 (Pietsching et at., 2015)
brain areas of intelligence - Andreasen et al 1993
Early imaging studies tried to locate area of general intelligence within the brain-also tried to link specific types of cognition to specific brain areas-
Andreasen et al. (1993) found that IQ associated with intracranial, cerebral, temporal lobe, hippocampal, and cerebellar volumes: almost all brain areas
whats Voxel-based morphemetry (VBM)
a neuroimaging analysis technique that makes it possible to test whether areas of intelligence are clustered or distributed throughout the brain
-multiple areas correlated with cortical thickness and IQ
throughout development brain structure changes throughout childhood and also in adulthood; influenced by what 4 factors?
- learning
- hormonal differences
- experience
- age
what do changes in the grey matter may involve
rearrangements of dendrites and synapses between neurons-acquisition of new skills associated with changes in the related brain regions
what else influences brain structure?
sex and age differences influence brain structure and areas associated with intelligence
-many contradictory findings in terms of associations of brain areas associated with intelligence between men and women, but the overall relationship between brain tissue volume and IQ not different
brain structure changes during normal development
gray matter increases during early ages
-thought to be result of overproduction of synapses-
strongest correlations between gray matter volume and intelligence around 10 years of age
brain structure changes during puberty
thinning occurs through adolescence and young adulthood
- synaptic pruning
- at around age 12 negative correlation between gray matter volume and intelligence emerges
differences in brains with more intelligent/higher IQ kids
pattern of cortical maturation unfolds differently in more intelligent children
-children with higher IQ seem to have a particularly plastic cortex: higher phase of cortical increase followed by higher phase of cortical thinning
2 types of intelligence?
crystallized – based on prior knowledge and experience
-fluid – adaptive reasoning in novel situation
what does fluid intelligence rely on?
on the more efficient function of distributed cortical areas
- the lateral frontal cortex is strongly associated, but also the parietal lobe and posterior cortex
- negatively correlated with the cortical metabolic rate (more efficient neural circuits)
- also associated with the structure and function of the frontal lobe region
what does crystallized intelligence rely on?
- on the cortical structure and thickness in lateral areas of temporal lobes and temporal pole
- largely relies on verbal ability, associated with areas responsible for integrating diverse semantic information
intelligence - genes
how can genetic diffs relating to intelligence between people be explored?
using Genome-wide association studies (GWAS)-used for investigating underlying variation in many traits and diseases
GWas test for associations between phenotypes and genetic variants
single-nucleotide polymorphisms (SNPs)
-usually in large groups of unrelated participants
•Most SNPs are apparently irrelevant or have very little impact on biological pathways
-some SNPs, however, have functional consequences that allow us to identify genetic underpinnings
GWAs studies/stats
GWAS studies have, over the last decade, become a useful tool for trying to identify genes relating to intelligence
•Initial studies, using smaller studies, did not provide clear results
-A meta-analysis of 31 cohorts (53,949 people) could only find about 1.2% variance in general cognitive function (Davies et al., 2015)
•More recent studies use much larger sample sizes to try to identify contributing genes
-Looking at educational attainment as proxy for intelligence increased sample size to 400,000
•Intelligence is a highly polygenic trait – many genes are involved
Intelligence as a polygenic trait
A large 2018 study has identified 206 genomic loci and implicated 1041 genes as being important for intelligence (Savage et al., 2018)
-this is 191 more genomic loci and 963 more genes than before•
Many different genes involved in intelligence
- each gene generally makes a very small difference overall
- most probably have different influences at different stages of development
•Small genetic effects at critical stages of development might have large consequences on brain development and function
-useful not only to know which genes are involved, but also when and where they are expressed within the tissues of the brain