Lecture 7 - Intelligence Flashcards by Fran Hodgkins

What are the five factors that make up g?

Reasoning
Spatial ability
Memory
Processing speed
Vocabulary

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What statistical method was used to identify what contributes to g?

Factor analysis

Isolate a single factor that can predict performance on a range of cognitive tests
Used factor analysis to measure which things are consistent with intelligence - can identify what causes variability in intelligence

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What is fluid intelligence? (Cattell)

Primary reasoning ability
e.g. inductive reasoning in abstract sequences
Abstract
Not cultural

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What is crystallised intelligence? (Cattell)

Acquired knowledge/skills
e.g. vocabulary, social rules

Related to cultural/historical background of individuals

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What is fluid intelligence tested with?

Raven’s progressive matrices

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What is crystallised intelligence tested with?

Weschler scales

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When do fluid and crystallised intelligence peak?

Fluid - peaks in young adulthood then declines
Crystallised continues to increase throughout lifespan, maybe tailing off towards the end

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What ability is fluid intelligence strongly associated with?

Working memory

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What does the Weschler test target?

Cultural knowledge
e.g. requires you recognising certain objects and knowing what they are used for
e.g. general knowledge questions
e.g. dealing with abstract social conventions, rules and expressions (no correct answer, just justification)

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What is Raven’s progressive matrices base on?

Rules and logic
Questions get harder and harder

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What kind of intelligence measure is IQ useful for and what is it good for predicting?

Used for relative ranking within a population
Good for predicting educational achievement etc

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Does IQ measure fluid or crystallised intelligence?

Both

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What are three criticisms of IQ as a measure of intelligence?

Scope
- Emphasis on analytic and verbal components
- Less so on creativity, problem solving etc

Biases
- Less developed tests for e.g. visually impaired
- Does not dissociate gf from gc

Flynn effect
- Gradual rise in IQ over last century

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What is the concordance rate for IQ when one person takes the same test twice? What about MZ twins reared together?
(Matt Ridley)

87% - same test twice
86% - MZ reared together

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What is the concordance rate for IQ for identical twins reared apart and biological siblings reared together?

76% - MZ twins reared apart
47% - Bio siblings reared together

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What did Ridley’s work on concordance rates of intelligence rely heavily on?

Lots of findings came from Bouchard’s Minnesota Study of Twins reared apart.

Bouchard and McGue (1981) did a meta analysis of 111 studies
Ridley’s work relies heavily on Bouchard and McGue (1981)

Loehlin also found similar concordance rates

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What is the classic heritability formula?

2 (Y Concordance in MZ Twins MINUS Y Concordance in DZ twins)

e.g. 2 (Concordance of IQ in MZ Twins reared together MINUS Concordance of IQ in DZ twins reared together)

Lower values indicate more effect of environment than genetics

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What kind of data is missing from heritability concordance rates?

Data about both MZ and DZ twins reared apart

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What factors can affect the validity of MZ twins reared apart being perfect measures of the effect of genetics?

1) Shared prenatal environment is increasingly recognised to be important.

MZ twins typically share ONE placenta, DZ twins have one placenta each, (i.e. there are two placentas altogether).
This aspect of the environment is ‘biological’ but not genetically-controlled.

2) Some level of gene-environment interaction is required just to make those twins grow up well, with sufficient stimulation:
at least a permissive level of nutrition and good parenting.

Adopted twins usually go to good homes with similarly high levels of SES

Does heritability contribute to a trait or ability in a fixed manner?

Probably not

Is genetic influence fixed over a lifetime?

No - heritability is not constant - genetic influence on some traits varies over lifetime

Is the environment more important for intelligence for someone growing up impoverished? Why?

Yes
For someone who is more affluent - genes are better determinants of intelligence

Your brain can be stunted if it does not have sufficient ‘nutrients’.
When environmental resources are scarce, the margins between ‘sufficient stimulation’ and a sort of ‘neglect’ make all the difference.

When you have all you need in your environment (attention, money, books, stimulation), the main thing that determines your brain growth, relative to others also in rich circumstances, are genes controlling brain growth.

Is heritability higher in families of low economic status?

No - higher in families with high economic status

Is socio-economic status a purely environmental variable?

No
Genes have likely contributed somewhat towards the affluent-to-impoverished SES variance.

Gray et al. (2003) tested whether fluid intelligence (gF) is mediated by brain regions that support attentional executive control (an aspect of working memory). What did he use to measure working memory and gF? How did he measure brain activity?

‘n back task’, - test of working memory - a challenging ‘3-back task’ - purposely varied interference using lures - lures impaired accuracy gF measured by Raven’s Advanced Progressive Matrices fMRI scanning: during working memory task performance

In Gray et al. (2003), how did the n-back task work?

Breaks between tasks - allow brain activity to go back to baseline - helps temporal Participants viewed stimuli one after other, appearing every 2.4 seconds Instructed to respond quickly and accurately whether each stimulus matches or does not match the stimulus seen 3 items ago, using 2 response buttons. There were LURE trials, designed to probe performance under higher interference e.g. repeating an item that appeared 4 items ago not 3 to catch people out

What did Gray et al. (2003) find out about fluid intelligence and working memory?

There was a POSITIVE correlation (r = + 0.36) between: Accuracy on LURE trials (working memory) AND scores on Raven’s APMs (fluid intelligence) i.e. working memory predicted fluid intelligence scores

Gray et al. (2003) - what is activity in the left lateral PFC associated with?

fMRI activation in LEFT LATERAL PFC in CORRECT LURE trials (Y axis) correlates with Fluid Intelligence scores on Raven’s matrices (X Axis). In other words: Left lateral PFC activity in high-interference working memory trials predicts a classic measure of fluid intelligence quite well. Left lateral PFC = Brodmann areas 46/45 More LPC activity = higher score on lure trials

What network connectivity did Finn et al (2015) say predicted fluid intelligence?

Fronto-parietal network connectivity

What is functional connectivity?

Functional connectivity indexes the degree to which activity in region X predicts activity in region Y. (informally: ‘How strongly do regions X & Y talk to each other?’) NOT volume NOT absolute activity

Finn et al (2015) measured fluid intelligence using Raven’s Progressive Matrices, and measured between-node connectivity across selected brain networks during tasks and rest. What did they find?

Patterns of Frontoparietal network connectivity best: a) identified different individuals from one another b) Predicted scores on fluid intelligence Summary: How Frontal regions including prefrontal cortices are functionally connected with each other and with parietal regions (involved in numeracy) predicts fluid intelligence scores. Parietal regions support spatial cognition and mathematical ability. Some of what IQ tests test is spatial & mathematical.

How can functional connectivity predict someone's IQ?

Train a network to learn which connectivity patterns correlate with intelligence from 99 subjects including Susan but excluding Jane. Given that correlation template, predict Jane’s IQ score. Compare it to Jane’s observed IQ score. Now leave out Susan, include Jane, and similarly predict Susan’s IQ. Do this 100 times, leaving out each participant once.

Thompson et al (2001) assessed correlations between volume of different brain regions and IQ (and heritability), how did he do this?

10 MZ pairs, 10 DZ pairs, DNA tested for zygosity and MZ and DZ pairs matched for age IQ score taken from Vocabulary, Similarities, Block design, and Digit symbol subtests of the Wechsler Adult Intelligence scale-Revised.

Thompson et al (2001) - what was the correlation between frontal gray matter volume and Weschler IQ measure?

Around +0.4

Broadly, what is inherited when someone inherits intelligence?

Good working memory A large brain, and in particular A large, well-functioning lateral prefrontal cortex

Blokland et al. (2008) looked at twin performance on the n-back working memory task, while recording task-related brain activity. What were the heritability percentages for: 2-back performance accuracy IQ Grey matter volume Left lateral PFC activity during WM task

2-back performance accuracy = 73% IQ = 74% Grey matter volume = 69% Left lateral Prefrontal Ctx activity in WM task = 36%.

Did Blokland et al (2008) find that working memory was highly heritable?

Yes - so WM plausibly contributes to the heritability of intelligence

Bartley et al (1997) looked at overall brain volume in MZ and DZ twins. What was the heritability for overall brain volume?

94%

Sullivan et al (2001) looked at brain volume in elderly twins. What heritability rates did he find for: Hippocampal volume Temporal lobe volume Corpus callosum volume Intracranial volume

Heritability of hippocampal volume = 0.4 Heritability of temporal lobe volume = 0.6 Heritability of corpus callosum volume = 0.8 Heritability of intracranial volume = 0.8

Why is hippocampal volume heritability low?

Region high in plasticity. Factors controlling neurogenesis and stress damage in adulthood.

In Baare et al (2001), estimated genetic factors almost entirely accounted for individual differences in whole brain volume, gray matter volume and white matter volume. What were the heritability rates?

Whole brain volume (90%) – ie all brain tissue Gray matter volume (82%) – ie all brain tissue minus white matter White matter volume (88%) – ie all (myelinated) fibre tracts

The dorsolateral PFC is involved in intelligence. Does it mature early or late? Is grey matter volume in it heritable?

Late. The last cortical area to myelinate. Yes, it is heritable

Is the lateral PFC likely evolutionarily new?

Yes i.e. well-developed in humans but not in other species

What political orientation is predicted by childhood intelligence? Is this mediated by any factors? (Deary et al)

g at age 10 predicts liberal attitudes at age 30 Not mediated by education and class

In America, what was found to predict subsequent political orientation?

Adolescent intelligence predicts subsequent political orientation