week 4

Question 1

intelligence matters

Answer 1

one of the best predictors of important life outcomes such as education, occupation, mental and physical health and illness, and morality

Question 2

galton

Answer 2

First to distinguish between nature and nurture influences, he noted eminence running in families, leading to the conclusion that nature predominates over nurture.

Question 3

nature and eugenics

Answer 3

Eugenics is a flawed theory aiming to enhance humans through selective breeding. Its implementation has led to significant harm, particularly for marginalized populations.

Question 4

nature vs nurture debate

Answer 4

The influence of genes and the environment on intelligence and other traits is a complex interplay. Both factors contribute, and their relative importance can vary between traits and individuals.

Question 5

cognitive aging and intelligence

Answer 5

Steep increase in both fluid and crystalized intelligence in childhood
Clear distinction in what happens next:
- Crystalised abilties continue to rise for many years
From mid-twenties fluid intelligence declines

Question 6

stability of intelligence across the lifespan

Answer 6

Individual differences in intelligence display remarkable stability from childhood to old age. Research by Deary et al. in 2013 found a substantial correlation (r = 0.54) between IQ measured at age 11 and age 90, making it one of the most stable behavioral traits. Being smart in youth is a strong predictor of intelligence in old age, although the correlation is not perfect.

Question 7

heritability

Answer 7

Heritability estimates quantify how genetic differences contribute to trait variation in a population. For example, a heritability of 50% means genes explain half of the variance in intelligence within that population. It doesn’t specify the exact genetic influence on an individual but pertains to group-level differences.

Question 8

studying heritability

Answer 8

1) Family studies analyze family members’ resemblances based on their relatedness.
2)Twin studies compare behavior in monozygotic (MZ) and dizygotic (DZ) twins with varying genetic similarity.
3)Adoption studies involve comparisons between biological parents, adoptive parents, and adopted children.
Genetic similarity correlates with intelligence; as it decreases, so do IQ correlations. When twins or siblings are raised apart, their IQ similarity decreases due to environmental influences.

A comprehensive study by Plomin et al. in 2004 estimated intelligence heritability at approximately 50%. However, heritability estimates for intelligence vary widely in the literature, ranging from about 30% to as high as 80%.

Question 9

heritability of intelligence across the lifespan

haworth

Answer 9

Haworth et al. (2010) found that the heritability of intelligence varies with age, suggesting genetic-environment interactions. There’s a shift from more environmental influence in childhood to more genetic influence later on. Intelligence is one of the most heritable behavioral traits.

Issues with intelligence heritability research include the representativeness of adoption and twin studies, as they often involve high socioeconomic status families. The complexity of genetic influence is also a challenge, as we do not yet understand how genes contribute to intelligence, and no single gene predicts it.

Question 10

assortative mating

Answer 10

Couples tend to choose similar partners through assortative mating. Watson et al. (2004) found that newlywed couples’ IQs were correlated at around r = 0.40. This similarity results from mate selection (assortment), not convergence after living together. Assortative mating can inflate observed intelligence similarity in families and increase genetic variance.

Question 11

neurobiological perspective

Answer 11

Genes related to IQ can affect the brain, and intelligence is associated with both brain structure and function. However, having a bigger brain doesn’t necessarily mean someone is more intelligent. From an evolutionary perspective, brain size increased over time, potentially leading to better cognition.

Research by Mcdaniel (2005) involving 1,500 individuals found a positive correlation between brain volume and intelligence. Pietschnig et al. (2015) conducted a study with 8,000 individuals and reported a significant, albeit slightly smaller, correlation of 0.24.

Question 12

do intelligent people have a thicker cortex

Answer 12

Cortical thickness initially increases in childhood, followed by thinning during adolescence. High-IQ children show a prolonged thickening of the cortex, particularly in frontal areas, as observed by Shaw et al. (2006). Intelligence relates to the pattern of cortical growth rather than its thickness.

Question 13

do intelligent people have better neural highways?

Answer 13

Intelligence relies on a complex brain network, particularly the one connecting frontal and parietal lobes. White matter connectivity is linked to IQ, and age-related decline in white matter tracks is associated with cognitive decline in IQ. Higher IQ individuals tend to exhibit more efficient brain activity during tasks.

Question 14

environmental influences

Answer 14

Flynn observed that when people took both new and older IQ tests, they consistently scored higher on the older tests. This phenomenon is known as the Flynn Effect. Flynn’s interpretation suggested an ongoing “intelligence revolution.” One hypothesis for the Flynn Effect is the nutrition hypothesis, which attributes it to improved health and lifespan through nutrition.

Recent European studies suggest that the Flynn Effect may be plateauing or even reversing, indicating a potential change in intelligence trends.

Question 15

nutrition hypothesis

Answer 15

Increased intelligence is part of a nurturing environment that includes increased height and lifespan, improved health, decreased rate of infant disease, better vitamin and mineral nutrition

Question 16

cognitive stimulation hypothesis

Answer 16

Increased intelligence driven by, e.g. improved visual analysis skills, improved schooling, changes in parental rearing styles, better-educated parents, smaller families, greater availability of educational toys

Question 17

environmental influences on intelligence

Answer 17

Neisser et al (1996) identified 4 main areas
1. Biological environment (e.g. prenatal environment, nutrition)
2. Family environment
3. School and education
4. Culture

Question 18

pre natal environment

Answer 18

Substance abuse
mortensen et al (2005): smoking
- Mothers who smoked 20+ cigarettes daily late in pregnancy were likely to have children who performed less well on iq tests age 18/19

Mattson and riley (1998): alcohol
- Children prenatally exposed to alcohol exibit problems with memory and attention
Fetal alcohol syndrome: deficits in abstract thinking, planning and organizing info

Question 19

breastfeeding

Answer 19

Oddy et al. (2003), children breastfed for more than 6 months scored 3-6 more IQ points on a vocabulary IQ test. However, it’s essential to consider that maternal intelligence is positively correlated with the likelihood of breastfeeding, as shown by Der et al. When controlling for parental IQ or genetics, the breastfeeding effect appears to be much smaller, if present at all, as demonstrated by Walfisch et al. in 2013.

Question 20

family size and birth order

Answer 20

• Children from larger families had a lower iq (controlled for social class)
• first born child always had a better iq: declining scores with rising birth order
  Debate around whether effects of family size and birth order are confounded

Question 21

group socialization

Answer 21

Judith Harris (1995) suggested that non-shared factors outside the family may have a more significant impact on a person’s intelligence as they grow older. Children tend to become more influenced by factors beyond their family as they age. This includes identifying with various social groups based on factors like age, gender, ethnicity, abilities, interests, and personality. These group norms can influence their behaviors, personality, and intelligence.

Socio-economic status (SES) of the family, which encompasses income, parental education, occupation, and community status, is significantly correlated with intelligence (with an r-value of 0.3-0.4). Improving SES can also lead to improved intelligence.

Question 22

education

Answer 22

Sending children to school is a highly effective strategy to raise IQ. Ceci’s meta-analysis in 1991 found that regular school attendance is associated with higher IQ scores. Each year of schooling adds about 2.7 IQ points. However, it’s essential to acknowledge that there’s a bidirectional relationship between intelligence and factors like school attendance and quality, as highlighted by Neisser et al. in 1996.

Question 23

culture and intelligence

Answer 23

consists of shared beliefs, attitudes, traditions, and behaviors that influence how a group perceives and responds to the world. For example, Western and Asian cultures value academic abilities, while rural African cultures prioritize practical skills. Cultural differences can lead to unfamiliarity with certain concepts, like the importance of task speed in some Western cultures.

Question 24

cocodia

Answer 24

• compared cultural perceptions of intelligence in Asia, Africa, and Western cultures
• For instance, in Luo of East Africa people’s notions of intelligence consists of 4 main concepts:
  – Rieko: similar to the Western idea of academic intelligence
  – Paro: practical thinking
  – Luoro: social attributes (respect, responsibility, consideration) – Winjo: comprehending instructions

Question 25

is iq culturally biased?

Answer 25

• Ravens progressive matrices are often described as a culture fair or reduced test as it consists of non verbal items thereby reducing language loading of the test
  However, language loading is not the same as culture loading