Lecture 4 - Intelligence

Question 1

Define intelligence

Answer 1

• Most people have a ‘folk’ concept of intelligence
• Sternberg and Detterman (1986) show psychological definitions commonly include:
  o Higher level abilities (e.g. abstract reasoning)
  o Valued by culture
  o Executive processes (regulating flow of information toward goal achievement, e.g. attentional control, working memory)
• Intelligence comprises the “mental abilities necessary for adaptation to, as well as shaping and selection, of any environmental context” (Sternberg, 1997) i.e. making decisions to make environments suit our needs

Question 2

What is measured by an intelligence (IQ) test?

Answer 2

o Usually assess IQ which is standardised to a mean score of 100 and standard deviation (SD) of 15
o Norming involves administering IQ test to a representative sample of a population to obtain norms or referential scores for different subgroups (e.g. age groups)

Question 3

What is the IQ distribution?

Answer 3

Normal distribution - geniuses at one end, intellectual disorders at the other end

Question 4

What are some key concepts and theories in intelligence?

Answer 4

• IQ has dominated the intelligence research agenda
  o General intelligence (g)
  o Crystal vs fluid intelligence
  o Relationship between personality and IQ
  o Gardner’s theory of multiple intelligences

Question 5

What are the different branches of IQ (cognitive abilities) research?

Answer 5

• Real life impact = studies interested in how differences in cognitive abilities influence health outcomes, education achievement, employment success etc.
• Psychometric studies = more interested in measurement (structure of intelligence)
• Cognitive = try and look at cognitive manifestations e.g. reaction time, inspection time etc.
• Biological = look at neural structures e.g. brain event related potentials, nerve conduction velocity, brain size, functional brain scanning

Question 6

What is the structure of intelligence (psychometric IQ)?

Answer 6

• G (general intelligence) factor introduced by Spearman
• Performance on cognitive tasks seem to be correlated, reflecting general intelligence
• Cattell divided G factor into fluid intelligence (biological potential e.g. reading speed, abstract reasoning, logic) and crystalised intelligence (knowledge accumulation i.e. culturally specific)
• IQ test captures 7-17% fluid intelligence and 83-93% crystalised intelligence

Question 7

What is fluid intelligence (Gf)?

Answer 7

• “A capacity to perceive relationships independently of previous specific practice or instruction related to those relationships” – Horn and Cattel (1966)
• Focuses on process independent of content or knowledge domain
• Seen to include executive control and working memory tasks (may also be referred to as fluid cognition)
• Seen as biologically instantiated in the pre-frontal cortex
• Declines in later life (Bugg et al., 2006)

Question 8

What is crystal intelligence (Gc)?

Answer 8

• Gc test = vocabulary etc. represent acquired knowledge
• Gc is a product of Gf
  o Investment theory (Cattell) – investment of fluid intelligence in a specific body of knowledge
• Knowledge (acquired) increases over lifetime

Question 9

How do Gc and Gf change over the lifetime?

Answer 9

• Conventional wisdom is that fluid intelligence peaks relatively early in life and then declines
• Crystal intelligence increases over lifetime
• This is challenged by more current research suggesting heterogeneous effects on different cognition domains (e.g. Hartshone & Germine, 2015)

Question 10

What have behavioural genetics shown about the heritability of IQ?

Answer 10

• Heritability estimates for IQ range from .42 to .62 (up to .80)
• This means between 48% and potentially up to 80% of the variability in IQ scores in the population is attributed to genetic variation?
• Heritability is not equivalent to genetic determinism
• Mind the heritability gap! (Plomin & Deary, 2015)
  o Heritability gap = the variance in heritability of intelligence that is not explained by specific genes
• Chabris et al. = most reported genetic associations with general intelligence are probably false positives (polygenes and not enough data)

Question 11

How has heritability of g and Spearman’s hypothesis created group differences controversies?

Answer 11

• Behavioural genetics assume independence of genes and environment
• Also tends to assume that fluid intelligence is fixed and crystallised intelligence less so
• Spearman’s hypothesis:
  o People’s performance on a cognitive test was correlated with their performance on other comparable cognitive tests. Hence, Spearman proposed a common latent factor g that broadly represents cognitive capability.
  o Noticed that the more strongly a test correlated with IQ, the wider the difference in Black and White Americans’ performance on the test
  o Hypothesized that Black-White differences on tests of cognitive ability correlate positively with a test’s g-loading
  o Extended by other authors (e.g., Arthur Jensen, Charles Murray, J. P. Rushton, Hans Eysenck) to suggest that racial IQ differences are genetic in origin
• Racial group differences in intelligence

Question 12

What does contemporary evidence tell us about racial group differences in IQ?

Answer 12

• Fagan and Holland (2002, 2007) = no performance differences between Black and White Americans given equal prior exposure to test-relevant information. Group differences reflect unequal opportunity to acquire information, not differences in cognitive processing capacity
• Nisbett et al. (2012) = a review by 16 leading intelligence researchers concluded that evidence for a genetic basis for group differences is weak, and that environmental factors (SES, schooling quality, stereotype threat, health disparities) are sufficient to account for observed gaps
• Genome-wide evidence (Bird, 2021) = large-scale polygenic analyses find no evidence that intelligence was under divergent selection across ancestral populations, suggesting genetic differences between racial groups are not a meaningful driver of IQ gaps

Question 13

What is a key principle of heritability within groups?

Answer 13

• Heritability within groups tells us nothing about the causes of differences between groups
• E.g. need information about environmental conditions

Question 14

How does the Flynn Effect demonstrate that genetic determinism cannot be the whole story?

Answer 14

• Generation rise in IQ by average of 10 percentage points (range 5-20 points)
• This is seen across at least 14 countries
• It is more substantial for Gf than Gc
• Stronger among adults than children
• Highest in the Netherlands, below average in the UK, ceased in Sweden and reversed in Norway
• What is the cause of this?

Question 15

What is the heritability paradox?

Answer 15

• If heritability is so strong and environmental effects so little, how can environmental changes produce large changes in IQ?
• Social multipliers
• Averaging
• Gene-environment matching

Question 16

What are social multipliers?

Answer 16

• Environmental factors potentially contributing to an increase in IQ:
  o Internet and access to information
  o TV?
  o Gaming (reaction times and speed)?
  o Education (spending longer in education than previous generations)
  o Group learning and studying
  o Rising standards of living
  o Better nutrition

Question 17

What is averaging?

Answer 17

• As individuals’ ability rises, this will also influence those around them
• Small effects over time will influence the population more widely
• The population average will increase

Question 18

What is matching?

Answer 18

• Gene-environment correlation – people seek out environments that match their phenotype
• The process by which the ability and the environment are matched produces increases in that initial ability
• Thus, environment increases genetic/biological ability

Question 19

How do environmental toxins influence IQ?

Answer 19

• US Americans born in the 60s lost up to six IQ points on average due to lead exposure (McFarland et al., 2022)
• Removal of lead from petrol was followed by measurable population-level IQ increases across multiple countries (Reyes, 2007)

Question 20

What did Turkheimer et al. (2003) show about gene-environment interaction in heritability of IQ?

Answer 20

• Socio-Economic Status
• Heritability high for high SES - h2 = 72%
• Heritability virtually zero for low SES - h2 = 10% and environment = 60% (environment plays a much bigger role)
• In disadvantaged environments, environmental differences explained much more of the IQ variation than genetic differences
• Why?
• Genetic primacy is a phenomenon of relative privilege. Genes can only express potential once basis environmental conditions are met. Effect of genes on IQ depends on environment
• Environment can act as a regulator – inhibit or amplify genes

Question 21

What is ‘The Wilson Effect’?

Answer 21

Gene-environment correlation (Bouchard Jr., 2013)
- Heritability increases with age
- 40% in childhood, 60% in adulthood and 80% in old age
- Why?
- Genes need the appropriate environment to express
- High IQ people will seek out high IQ contexts and as they get older their intelligence will show (less control/choice of environments as a child)

Question 22

What did Sauce and Matzel (2017) show about heritability and malleability of intelligence?

Answer 22

• Heritability is not the same as genetic influence
• Some traits are genetically-determined with low heritability
  o Heritability of number of human fingers is next to zero. Main predictors of variance are environmental (e.g. traumatic amputations, birth defects)
• Some traits are highly heritable but are not genetically determined
  o In the US, heritability of voting is 53% and heritability of voting for specific parties is 46%
• Due to gene-environment interplay, IQ is more malleable than previously assumed
• The most heritable subsets are also the most culturally loaded i.e. the g factor itself partly reflects cultural experience and education, not just biological potential (Kan et al., 2013)

Question 23

What does current research say about the heritability of g?

Answer 23

• Hereditarian views on race and intelligence were highly controversial
• Current research has confirmed that IQ is heritable
• There is no evidence of significant genetic determination of racial differences in IQ
• Group differences in IQ may be entirely explained by environmental factors

Question 24

How did Ackerman (2018) show that intelligence is process, personality, interests and knowledge?

Answer 24

• How intelligence is an individual difference and contributes to personality to shape achievements etc.
• Four factors constantly interacting where personality acts as a mediator determining the intensity you invest intelligence into different interests
• Interaction of four factors leads to knowledge you acquire – process (Gf), Gc (knowledge), interests, knowledge
• Knowledge influences interests and this is mediated by personality

Question 25

How did Chamorro-Premuzic and Furnham (2008) show that personality adds to IQ?

Answer 25

- Examined FFM traits and IQ to predict performance in university exams a year later - Gf = -6% - Conscientiousness = +27% - Openness = +4% - Conscientiousness explains an extra 27% of performance on university exams once IQ (Gf) is controlled for, and openness an extra 4%. Thus, being hardworking, methodical and organized add significantly to exam performance above IQ - Personality enables you to take advantage of intelligence to improve exam performance

Question 26

How do the Big 5 personality traits influence IQ?

Answer 26

- Openness to experience (r ≈ .20–.30 with g): strongest Big Five correlate of IQ. Consistent with investment theory: curious individuals invest more cognitive effort and build greater Gc over time - Intelligence compensation hypothesis (Moutafi et al., 2006): observed small negative correlation between conscientiousness and Gf suggests lower-ability individuals may develop greater diligence as an adaptive strategy. **debunked** - Neuroticism (r ≈ -.09 to -.18 with g) = small negative association with Gc and Gf; predicts steeper age-related cognitive decline (Gow et al., 2005) - Extraversion and agreeableness = near-zero correlations with overall g (Anglim et al., 2022) - Practical implication = IQ predicts learning speed; Conscientiousness and Emotional Stability predict occupational functioning; Openness predicts creative achievement. A full picture of human potential requires both cognitive and personality assessment

Question 27

What is Gardner's theory of multiple intelligences?

Answer 27

- Howard Gardner was concerned by the tendency to focus only on linguistic and logical-mathematical symbolism in educational settings - Argued that g (general intelligence) is most closely aligned with linguistic and logical mathematical intelligences (2 our of 8 forms of intelligence he proposed) - His definition of intelligence recognises biological and cultural influences (what is valued by a culture)

Question 28

What are Gardner's 8 dimensions?

Answer 28

- Logical-mathematical = logic smart (e.g. scientist, mathematician) -> sensitivity to, and capacity to discern logical or numerical patterns and handle long chains of reasoning - Linguistic = word smart (e.g. poet, journalist) -> sensitivity to the sounds, rhythms and meanings of words and sensitivity to the different functions of language - Musical = music smart (e.g. composer, violinist) -> abilities to produce and appreciate rhythm and pitch and timbre, and appreciate the forms of musical expressiveness - Spatial = picture smart (e.g. navigator, sculptor) -> capacities to perceive the visual-spatial world accurately, and to perform transformations on one's initial perceptions - Bodily-kinaesthetic = body smart (e.g. dancer, athlete) -> abilities to control one's body movements and to handle objects skilfully - Interpersonal = people smart (e.g. therapist, salesman) -> capacities to discern and respond appropriately to the moods, temperaments, motivations and desires of other people - Intrapersonal = self smart (e.g. person with detailed, accurate self-knowledge) -> access to own feelings and ability to discriminate among them and draw upon them to guide behaviour, knowledge of one's own strengths, weaknesses, desires and intelligence - An eight dimension – ‘naturalistic intelligence’ was added later. This refers to human perceptiveness of and sensitivity to the natural world

Question 29

What are some applications of multiple intelligences theory?

Answer 29

- Project Zero (Gardner, Harvard) = the Spectrum Project assessed children across MI domains through naturalistic observation and performance tasks rather than standardised tests - Differentiated instruction (Kornhaber, 2001) = teachers applying MI principles diversify pedagogy through project-based learning, cooperative tasks, multimodal presentations - Clinical and counselling applications = therapists integrating MI report enhanced therapeutic alliance and more flexible intervention strategies, particularly for clients whose strengths lie outside verbal-linguistic domains (Pearson et al., 2015)

Question 30

What are some empirical challenges to Gardner's theory of multiple intelligences?

Answer 30

- The eight intelligences intercorrelate positively (consistent with a general factor) - Many studies of MI effects in teaching did not follow standard scientific practices or explore alternative explanations - Some studies show support for distinct neural bases of multiple intelligences (e.g., Shearer & Karanian, 2017) - Neuroscience research overwhelmingly refutes Gardner’s suggestion that the brain is organised in modules dedicated to specific forms of cognition (Waterhouse, 2023)

Question 31

Summary

Answer 31

- Intelligence is a multidimensional construct o g captures meaningful variance, but Gc and Gf have distinct developmental trajectories that are shaped by biology and experience - Heritability of IQ is substantial, but heritability statistics cannot tell us why groups differ - The Flynn effect shows that IQ is environmentally malleable at the population level - Personality and intelligence are distinct but interacting systems (e.g. openness amplifies intellectual development through investment in knowledge acquisition) - Gardner’s MI challenges the cultural narrowness of g-centric approaches to intelligence, though its psychometric foundations remain contested