Week 4 Flashcards
Variability and IQ scores
More variability within groups than between groups
Influencing factors on ethnicity and IQ
economic differences
poverty
Nutrition
medical care
educational resources
Homes that are owned
Parent’s beliefs and attitudes about educationLow birth weight - lower IQ
Early exposure to lead and mercury
Access to intellectually stimulating material
Why IQ lower for some ethnicities?
IQ tests may have an inherent cultural bias to white children - test communication may be more familiar, general knowledge only might be general to the majority
Test relevant communication style - asking question when the examiner knows answer- confuses kids - ie. why are you asking
Particular to pedagogy in our culture
School Factors affecting IQ
How well funded the school is, resources, playground etc.
Lewis and Sparling- objectives -Carolina Abecedarian Project
Deliver educational resources to low ses groups of children - hope of raising IQ
Carefully measuring and comparing the results of different educational approaches to determine what kind of assistance was most effective - 6m-5yrs
EXP: intensive educational intervention tailored to their needs - specially designed day care, Games that the child played daily, focus on motor, social and cognitive for youngest, Older - language, math, science and music
CONTROL - nutritional and health but no educational
Follow up when children were 12, 15 and 21
21- measurable difference in IQ - academic achievement higher in young adulthood, more likely to attend college and stayed in school longer - measurably higher in intervention group - 5 points higher
SUCCESS DEPENDENT ON: starting early, delivering intensive intervention for a significant period of time
Heritability statistic must be calculated over …
large population with variance
Cannot measure all variance in genes or environment directly - can look at variance in population
Must be appreciable difference in the trait you are asking about - number of stomachs no
Only part of the stat that can be directly measured is the variance in the expressed trait - phenotype
family studies of intelligence
studies designed to estimate the heritability of a trait in which the concordance of a trait btw people is compared to their genetic relatedness -
genetic relatedness.
Genetic relatedness is the probability that a gene in one individual, selected at random, will be the same in another person by virtue of common descent.
adoption studies - controlled?
Do not have random assignment
parents are often matched to children, parents -
motivation and socio-economic status for adoption initially
Iqs of adopted are higher than average often
Twin studies
Concordance of a trait among monozygotic twins is compared to the concordance of the trait among dizygotic twins, allowing for the estimate of the association between genetic relatedness and the variance of the trait in the population
Strongest in terms of making heritability inferences
twin studies
Heritability varies… - how can we manipulate it?
Heritability stats are specific to the population for which they were calculated - heritability can change btw pops and change over time
group with less education, there is more variance in living circumstances and opportunities, and the association between environmental factors and IQ is greater
group with the highest level of education, environmental factors are relatively standard, and the association between variance in genes and variance in IQ is greatest
Heritability rates based on education and why
.26 - for people whose parents had a high-school education or less
.74 for those people whose parents had education beyond high school
Education beyond high school because there is less variance in the environment
More likely kids in higher ses go to school every day, eat breakfast each day
Constricted factors involved in environment and g*e
Heritability can change
Heritability within the experimental group increases
Heritability across the entire population decreases
educational environment became closer to standardized, the contribution of variance in the environment to variance in IQ - reduced, and more of the variance among people would be statistically associated with variance in genes - increased heritability of IQ
Heritability of IQ has changed over the last 2 centuries - why
Schooling and universal healthcare - standardizing
Variance in the environment is decreasing so heritability increases
Heritability of IQ increases with age
In late adolescence heritability of IQ is higher than infancy - IQ becomes more like biological parent and less like their adoptive parent
Heritability of trait depends on the pop being studied
as environments become more uniform, heritability rises
environments are not standardized across childhood, but public schooling, public libraries, standardized curricula, and other public programs and resources lead to somewhat less variance in the environment and thus a higher heritability of IQ.
IQ Tests impact on heritability - how can we change the test to get a different result?
Finally, we know that the more general the IQ test is, the more heritable IQ is.
Conversely, the more the tasks are restricted to a particular domain or cognitive skill set, the less heritable IQ is
What Heritability is NOT
Not the number that tells you how much of a trait comes from genes and how much from environment
—-heritability cannot be computed for an individual, and it tells us nothing about an individual
—heritability statistic is an index of the statistical relationship between differences in genes or differences in an environment to differences in a given trait between people
—-bucket analogy
Not an estimate of malleability
—-Phenylketonuria is a kind of intellectual disability that affects individuals who cannot process the amino acid phenylalanine. All you need to do is remove phenylalanine from the individual’s diet, and no intellectual disability will develop
—-Does this mean that height is not malleable? No. Add more water, food, and sun, and the plants will grow to be tall.
Does not tell us whether or not a trait or characteristic is inherited.
But a trait with a very low heritability may, nonetheless, be inherited. Adaptations that are universal are inherited, but not heritable.
—-Need variance
—-Adaptations have a very low heritability, approaching zero. Here is why: natural selection uses up variance
—-Selection pressure for white rabbits - not heritable by the end of the experiment
Adaptations are inherited but are not highly heritable
Final Lec Conclusions Heritatbility
Applies to a large population, never to an individual
Can differ markedly for groups of people who grow up in very different environments
Does not imply how much of a trait is attributable to genes
Does not indicate malleability
Does not tell you whether something is inherited
Norm of reaction -
The relationship between a specific environmental factor and a measurable phenotypic expression.
a plant of a given genotype might grow tall in lower altitudes but not in higher altitudes. Graphing height vs. altitude for this plant would illustrate its norm of reaction.
Measure IQ in a particular population and find it to be very heritable, does this mean that programs designed to promote intellectual development have no chance of success?
The high heritability of IQ says nothing about its malleability. Environmental influences could still have dramatic effects on IQ.
no one-to-one relationship between an environmental factor and its phenotypic effect: Different genomes respond differently across various levels of a given environmental factor (altitude, rainfall, nutrition, etc.).
many species, including humans, different environments lead to different but predictable phenotypic outcomes, and this happens by design. The developing organism is designed to develop a phenotype that is adapted to its environment. The EEA offered a range of normal developmental plans because a range of different environments were possible
Michael May - story and what can he not recognize?
1954 - typical child with typical visual system - 3.5yrs - blinded by chemical explosion
Speed record in downhill skiing by a totally blind person
But no longer is blind - new cornea and can now see
Cannot recognize sons or wife by looking at their faces
Cannot tell difference btw a man or a woman
Cant see objects as 3d unless theyre rotating
Visual development depends on a species-typical visual experience early in life
How does the brain construct our percepts?
seeing is a construction in your visual system
Optic nerve - point in the retina that is broken - interruption - where the optic nerve leaves the eye - brain is creating a plausible percept - dont see the hole
Motion in old fashioned movies - still image after still image - perceive motion - brain creates the perception of motion
The brain constructs percepts. Instinct blindness makes that process invisible to us.
What is NOT the function of perception
Not for our pleasure - avoid dangerous and poisonous hazards
Not to see the world as it really is
Not to see the world accurately
What is the function of perception?
Function is to allow us to behave sensibly in the world with respect to our survival and reproductive interests
Make behavioral decisions that increase survival and reproduction
Benefit from perceiving cues that inform decisions and behavior
EX. larger animals hear lower frequency sounds (thumping a mile away)
- smaller animals hear higher - likely to inform decisions about behaviors they engage in
Hearing things that allow them to make decisions to benefit their survival and reproduction
How is percpetion sensitive to cost and benefits?
Cost to build
Cost to operate and process the info
—-Benefit outweighs for it to be maintained by natural selection
Fish with no eyeballs - lives in complete darkness - no benefit to building a visual system
Evolution is sensitive to cost and benefits - no benefits after many generations
Gibson and the visual system
1 sensitive to wavelengths in only the range that the earths atmosphere lets through
2 That interacts via reflection and absorption with objects that are of interest to us- That reflects off of objects that are fitness relevant
It is not that light just happens to be visible to us.
Rather, we have named the part of the electromagnetic spectrum “light” that is visible to us, and it is visible
to us because the function of our visual system is to allow us to interact with the world.
Function of perception is an adaptive behavior examples
Disconnect between people’s ability to judge distance correctly when you ask them to report a distance and when you ask them to walk blindfolded - better when you walk than guess
Action relevant perception – People perceive the environment in terms of their own ability to act on it
—Softball players who hit better perceive the ball as larger - same with tennis and golf
—An object seems closer if one can reach it with a tool than if it is equally out of reach and no tool is available
—Judged a hill as steeper if they were tired - also if they were older or in poorer physical health
That which is interesting or beautiful is not determined by the world, but …
by our minds.
Things are beautiful because our perceptual systems are designed to perceive them as beautiful -attraction to them increases our reproductive success.
For example, flowers are beautiful to us, and flowers in a natural environment such as the EEAindicate the presence of a fertile, literally fruitful environment and portend the coming of a rich food source: fruit.
Ex. face more interesting because it conveys info that may be important to our social decisions
William james - blooming buzzing confusion
. Whether one considers visual stimuli, auditory stimuli, or tactile stimuli, for example, there is a constant torrent of information and sensations that each developing organism is exposed to
How is the developing infant to make sense of this overwhelming barrage of
stimuli?
infant needs to be able to orient to developmentally relevant (and not to superfluous) stimuli.
Orienting devices are necessary to allow perceptual systems to attend to, select, and use developmentally relevant information. We call those orienting devices interests.
Infants prefer to look at relevant stimuli, and social stimuli, such as faces are among the most important things they can look
