chapter 3: the nature-nurture debate Flashcards
what is natural selection
some individuals are better adapted to their environment, and offspring inherit these adapted features
features of natural selection
variation, struggle, heritability, adaptions
beaks of Darwin’s finches
Finches can have bigger or smaller beaks depending on what food is available
When nuts with thicker shells start to be available more often – more finches have bigger beaks because they are better adapted
Kettlewell’s moths
When put on light trees – the rate of survival is higher for light moths than for dark moths – the number of dark moths drastically falls within a couple of generations
A factory opened near – ash on the nature surrounding it – dark moths have an advantage – within a few generations, the number of light moths drastically falls
two types of animals based not heir degree of maturity when born
precocial (the young are physically mobile and able from the moment of birth or hatching - hens, ducks, geese, swans, sheep, horses, goats - imprinting) and altricial (the young are incapable of moving on their own and are dependent on parent for safety and food - rodents, cats, dogs, humans, many birds, marsupials)
what is a superprecocial species
Maleo bird - no parental support, no need for environmental input
sexual selection
some features are selected because they’re attractive to sexual partners (can be detrimental for survival)
nativism
the view that many skills or abilities are native or hard wired into the brain at birth, the result of genetic inheritence
empiricism
the view that humans aren’t born with built-in core knowledge or mental content and that all knowledge results from learning and experience
who devised the first intelligence test, when and why
Alfred Binet, 1905, to select children unlikely to benefit from regular school systems
mental age
an individual’s level of mental ability relative to others
chronological age
a person’s actual age, as opposed to their mental age
intelligence quotient
a measure of person’s level of intelligence compared to a population of individuals of approximately the same age, a score around 100 indicates average intelligence
what’s the formula for IQ
IQ = MA/CA x 100
four important things about IQ tests and scores
- The simple formula is no longer used, but the purpose of IQ tests is to compare people’s scores with those from people of the same population and age
o The average IQ at a given time is always 100 – tests are standardised (a test of psychological characteristic that has been standardised on a representative sample of the population)
o Children’s and adults’ raw scores tend to increase from one generation to the next
o The items on IQ tests invariable proceed from simple to complex, an individual’s raw score is derived from the number of items passed before they make a mistake
most well known IQ tests
Stanford-Binet (ages 2 to adulthood), the Wechsler scales (the Wechsler Preschool and Primary Scale of Intelligence – WPPSI, the Wechsler Intelligence Scale for Children – WISC, the Wechsler Adult Intelligence Scale – WAIS), the Differential Ability Scales (DAS-II from infancy to adolescence)
what is G
the term used to denote general intelligence
how is occupation related to IQ
o Teachers, doctors, accountants, pharmacists, lawyers and those in similar occupations – mean IQ over 100
o People in semi- or low-skilled occupations (barber, farmhand, labourer) have a mean IQ below 100
o Many non-cognitive factors influence test performance and job performance (reduced motivation, increased anxiety and stress, levels of self-confidence, self-esteem and self-efficacy beliefs)
abilities of intelligence
o Verbal subscales
- Similarities – in what way things might be similar
- Comprehension – child’s common sense and understanding
- Recall of digits – correlates well with verbal rather than performance subscales
o Performance subscales
- Block design – the child is given a set of blocks with coloured patterns on them and asked to use them to make patterns that the tester shows
- Copying – the child is shown a drawing and asked to copy it on a sheet of paper (get progressively more complex)
heritability
a statistical measure that describes how much of the variation of a trait in a population is due to genetic differences (rather than environmental differences) in that population
types of alleles
dominant or recessive
o Homozygotes: AA and aa
o Heterozygotes: Aa and aA
what does heritability mean
o Heritability of 0.5 means that on average, about 50% of the individual differences that we observe may be attributable to genetic differences between the individuals in that population
Doesn’t mean that 50% of any person’s intelligence is due to their genes and the other 50% is due to their environment
If the environment is fairly uniform, heritability may be high, if environmental differences are large, the heritability may be low
genetic determinism
the hypothesis that people become who they are as a consequence of their genetic inheritance
environmentalism
the hypothesis that people become who they are as a consequence of the learning and experiences they have had throughout life
familiar resemblance
the resemblance between relatives whose genetic relationship to each other is known
types of twins
o Monozygotic (MZ, identical) – share 100% of their genes, developed from one ovum and one sperm which divides into two shortly after conception
o Dizygotic (DZ, fraternal) – share 50% of their genes just like other siblings, conceived at the same time but result from two eggs being fertilised by different sperm
problem with studies with identical twins raised apart
Even when their environment is different, it is likely that the adoption agencies will ensure that the adoptive environments are very similar
how’s heritability of IQ at a very young age
23% when children are 2-4 and 62% when they’re 7-10
McCartney explanation of heritability
Influence of genes is: passive (environment is not actively created by a child), evocative (evokes reactions from your environment), active – niche picking (as a child gets older, it can pick their own environment that suits their genes)
jensen’s argument
African Americans have a 15 points lower IQ and because of high heritability he concluded that this is innate
problems with Jensen’s argument
heritability is a measure of variance, not a biological mechanism (the high heritability of IQ doesn’t tell us something about the innateness of the trait + the heritability of IQ might be high in white middle-class environment just because of good schooling (little environmental variance) while the schooling of African Americans is probably much more variable
what’s the missing heritability
the failure to find any of the genes associated with cognitive abilities
probably all genes with expression in the brain somehow relate to intelligence
genotype
an individual’s inherited genetic makeup
phenotype
the interaction of genetic and environmental influences to create an individual’s physical appearance and behaviour: genotype and environment interactions
examples of phenotype things
PKU, COPD, breastfeeding, MAOA
differential susceptibility
o Some individuals remain stable under whatever circumstances – dandelions
o Other individuals are vulnerable under negative conditions, but can excel under positive conditions – orchids
Skeel’s study
orphanages - much higher IQ and better profession if left when younger than 6 months
romanian adoption study
psychological and cognitive problems directly proportional to the amount of time spent in the orphanages
group of children assessed at 4,6, 11 and 15 years – spent their first few months or years in the Romanian orphanages before being adopted by good families in the UK
o Children who came to the UK before turning 6 months were able to completely catch up in terms of cognitive ability
o However those who were older than 6 months showed signs of developmental catch-up, but had cognitive levels that were well below those in the comparison group (IQ 15 points lower than the under 6-month-old group)
environmental drift
changes in developmental functions that result from, and are in the direction of changing environments
deprivation specific patterns in Romanian study
o Quasi-autistic symptoms – intense circumscribed interests and abnormal preoccupations – deficits in the theory of mind
o Disinhibited social engagement – disregard for social boundaries + undue familiarity with strangers and a willingness to walk off with strangers and to ask inappropriate questions
o Inattention/overactivity – shares many features with ADHD
o Cognitive impairment – reduced IQ
SES adoption
65 adopted children who, prior to adoption, had been neglected or abused and had been removed from their biological families by court order
o In the year before adoption all of their IQs were below 86, average of 77
o IQs after adoption: low SES family: 85, middle SES: 92, high SES: 98
Flynn effect
an increase in the average intelligence quotient test scores over generations - average IQ risen by 20 points since 1950
raven’s progressive matrices
a culture-free non-verbal intelligence test with items arranged in order of difficulty
explanations for the Flynn effect
a reduction in family size (children get more parental input), improvements in education, improvements in diet, and the increasing complexities of modern societies which include complex technological inventions such as computers, cell phones, video games, social media
does Flynn effect still exist
Flynn effect is reducing in US and UK, rises in China and India
malnutrition
a serious condition that occurs when a person’s diet doesn’t contain the right amount of nutrients
poverty
the minimum level of income deemed adequate in a particular country
o Absolute poverty – limited access to food and clean water
o Relative poverty (developed countries) – households that earn 60% or less than the median income
how many children live below the poverty line
In the UK and Us somewhere between 1/3 and ¼ of children live below this relative poverty line
children from families with limited financial resources - brain differences
frontal lobe, temporal lobe and the hippocampus
head start - USA, 1965
Aim: help break cycle of poverty of low-income children from birth to age 5 (prior to formal schooling) – provide children with comprehensive programme to support cognitive, social, nutritional and emotional needs
increase of about 10 IQ points, but disappeared after stopping - parents essential
o Positive benefits: reduced numbers of US children to repeat a grade, fewer children were placed in special education classes, teachers rated the children more positively on attitudes to teaching, the children had higher self esteem and self efficacy, in later life they were less likely to get in trouble with the police
sure start, UK, 1998
o Aim: giving children the best possible start in life by providing play sessions, family support and advice, guidance on health, speech and language therapy, access to specialist support services
o Parents thought to: increase positive child behaviour through praise, improve parent-child interactions, set clear expectations, apply gentle consequences for problem behaviour
epigenetics
changes in gene expression that are relatively stable during cell division, sometimes even over generations, but are independent of the genetic code itself
