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
Where do 1m and 2m olds look on the face? 6m?
1-month-old spent more time looking at the outline of the face while a 2-month-old looked more at the internal details of the face
At 6 months of age, infants begin to look in the direction of an adult’s eye gaze if they can see both the
adult’s eyes and head turning and if the object of interest is already within their visual field
Eye Tracking
Measure an observer’s direction of gaze - infer what in the visual scene that observer is looking at
Early attempts - research watching observer
Modern eye tracking - reflecting light off the cornea and recording the reflection of that light - infrared light doesn’t interfere because we cant see
Calibration - look at 3 known points - records the pattern of reflected infrared light while the observer looks at those known points
Adds temporal and spatial precision to the preferential looking paradigm, violation of expectation and habituation
Prenatal Perceptual Development
VISION
Altricial - Least developed at birth - not a lot of visual sensation in utero
Undefined lightness during day - complete darkness at night
Responds to sudden change in light by 28 W
No acuity or contrast
Prenatal Perceptual Development
HEARING
In order for prenatal hearing
1. Auditory system would have to be sufficiently developed
2. Have to be sounds that could travel through the mother’s tissues and arrive at the fetus’s auditory system
—–Sounds pass into utero clearly - microphone into uterus
Hear moms voice
Hear other peoples voices
Moms heartbeat and digestive system
DeCasper and Fifer - operant conditioning
1. Measure how long they pause between sucking - take baseline - train to increase or decrease pause by rewarding them with another womans voice
Heard and learned mothers voice before they were born
- Motivated to hear mothers voices more than the voice of an unknown woman - recognized voice
Later tested whether auditory experiences pre birth could affect preferences after birth
——7th month - Gave mothers who were seven months pregnant a story to read out loud twice per day until the baby was born
——Newborns preferred to hear the story that was read in utero - prefer familiar story even if read by stranger
Study underlies that there is always an environment - does not just start at birth
Mosquito Tones
Change in auditory perception with age
18 - gradually lose ability to hear highest pitches - decreases at a predictable rate - eventually making speech perception difficult
Changes in the cochlea - tiny hair cells - hair cells and nerve cells are lost - connections between hair and nerve cells are lost
prenatal - touch
Develops early - first responds to touch near lips at 8w gest and touch elsewhere except the back of head at 16w gest
Can touch things in utero and feel - grasp umbilical cord and suck thumb
TASTE - prenatal
Fetus has taste - swallow fluid that carries flavors and tastes recently eaten
Preference for garlic if mother ate it during pregnancy
Preference for sweetness - baby drinks more fluid - reduce amniotic fluid to reduce pressure in sac
Mothers drink carrot juice - preference for it in infancy - measured how much carrot juice
SMELL - prenatal
Amniotic fluid will smell like the foods that the mother has just eaten - comes into contact with odor receptors
Smell receptors are washed with amniotic fluid
Vision Post natal - why doesnt newborn have adult vision?
- Occipital cortex still developing after birth - muscles that allow lens to focus havent developed
- Fovea - not fully populated with photoreceptors
- Cells in visual cortex haven’t myelinated and have not specialized to the type of visual stimuli they will be most responsive to in adulthood
- Eye Movements are immature - slow and inaccurate
Postnatal acuity and teller acuity cards
orient to larger shapes over smaller shapes, because he can see them as distinct
Newborn has acuity of 20/600 - can see 20 ft what a normal adult can see at 600ft
Lens is inflexible - cant change focus - objects in focus are 20 cm from eye
experimenter stands behind a wall and watches the infant as the infant is presented with two side-by-side cards. One card shows black and white bars (either horizontal or vertical) and the other is solid grey
Preference for one of the cards?
When does vision reach adult levels
5yrs
When do contrast sensitivity and peripheral vision develop
8ys
Colour perception postnatal
Newborns can see black and white but colour is not well developed
Babies prefer to look at coloured objects - can only discriminate between green red white but not other colours
4m - mostly adult like
Color vision involves three different kinds of photoreceptors or cones that mature at different rates
4m prefers to look at saturated colours
Colour vision continues to develop into early childhood
Colours that humans see are those that would have benefited our ancestors most in their search for berries among green
Depth Perception
Visual cliff paradigm - large boxlike apparatus - top of the box was see through glass - red and white checker boards at different depths
—-6m-14m babies hesitated when they reached the dividing line - perceived the difference in depth
—-Hesitation associated with experience with self-propelled locomotion - walking or crawling - more likely to hesitate at the deep side and show evidence of depth perception
—-Heart rate increases on deep side
—-Visual exploration necessary for development of depth perception
MOTION PERCEPTION
Newborns can detect motion and track a moving object with their eyes
2-3m that an infant can smoothly move eyes in order to track a moving object
2-5 orient toward the moving object in an otherwise static visual field
3m - infant can use motion info to discriminate btw a display showing human shaped point light walker and group of lights
Can anticipate trajectory
Hearing- postnatal
Auditory system is fairly well developed from birth
Newborn can hear a variety of sounds and prefers to listen to human voices over pure tones
Not as sensitive as adults - not able to hear low
Can discriminate human speech
Touch -post natal
Most well-developed at birth - especially around mouth, palms of hands and soles of feet
—Early reflexes - responses to touch
Stroke cheek near mouth - turn towards
Finger - leads to sucking
Finger in hand - grasp
Babinski reflex - sole of foot - fan toes and twist foot
Respond to temperature and can feel pain
Taste post natal
Prefer sweet tasting liquid over water - relax facial muscles and show adult-like facial expression in response to sour and to bitter tastes
Neutral to salty - like by 4m
Ready to eat solids at 6m
Perceptual Dev Milestones - birth
Interested in faces over other images
Size constancy
Slow and inaccurate eye movements
Lightness perception well developed
Can discriminate red and green but not more subtle colors
Can detect motion
Startle response to unexpected noise
Prefers hearing mother’s voice over that of a stranger’s
Prefers hearing a story they heard before birth over a different story
Hears high-pitched sounds better than adults; low-pitched sounds worse than adults
Likes sweet tastes
Can discriminate smells; prefers human milk; likes the smell of bananas and chocolate
Sense of touch well developed, especially around mouth, palms of hands, and bottoms of feet
PDM - 1 Month
Looks mostly at the outline of faces
Early evidence of depth perception
PDM 2m
Ocular dominance columns have developed
Can see a variety of bright colors (blue, red, green, yellow)
Shape constancy
Looks mostly at the internal detail of faces
Brightness constancy (as long as the object is not too small)
PDM 3m
Can see biological motion in a point-light walker
Muscles needed to focus (by changing lens shape) are well developed
Can track a moving object smoothly and accurately
PDM 4m
Adult-like color vision
Can discriminate more or less between saturated and unsaturated colors
Color constancy
PDM 6m
Visual acuity of 20/40 (can see at 20 feet what a normal adult can see at 40 feet)
Consistently turns head toward direction of sound
Just as good at discriminating between two people’s faces and two monkey’s faces
PDM 9m
Now specialize in human faces, discriminating between people more easily than monkeys
PDM 5yrs
Adult-like acuity
Smell - postnatal
Functions from birth and can discriminate
Relax in response to banana or chocolate - frown to rotten eggs and turn head
Prefer smell of human milk over any other including amniotic
4days - prefer mothers milk over strangers, smell of a lactating woman over formula
Prefer mothers smell in general over other women
Intermodal Perception
The integration of percepts acquired via two or more modalities, or senses.
Babies turn head to sound because they expect to see object
Suck on pacifier - shown too - look longer at one they were sucking on - 1m and in new borns
Intermodal Perception - why was this problematic for piaget
PIAGET
Rejected this idea - thought info would be separate for first few months after birth
Difficult to explain from an associationist perspective -. Associationists would predict that once you have seen a pacifier you should be able to recognize it the next time you see it but not when you feel it.
Constancies
The perception of like objects as like (in terms of size, color, lightness, and brightness) despite radically different projections on the retina
Although constancies are functional, they are actually a failure of accurate perception - happens by design
Size Constancy
size constancy allows our visual system to see an object as the same size despite being viewed at radically different distances and thus casting wildly different proximal images on the retina
Slater - evidence for size constancy - habituation - two cubes - one double in size -
See only small at various distances
Test phase - two side by side - larger far away - look longer at new box despite the same size projection on the retina
Shape Constancy
looking at an ice cream cone straight on. Now imagine moving your head up (or the cone down) so that you see mostly a ball of ice cream with a little crescent of cone visible at the bottom. The image projected on the retina is radically different, but you have no problem still seeing the object as an ice cream cone and as the same shape.
Bower- 2m - conditioned to turn head to one stimulus that was presented repeatedly - new stimulus that may vary in orientation, distance, size or retinal size - turned their heads if same as original suggesting constancy
The phenomenon of constancies remind us that:
The visual system isn’t designed to see the world as it is
The visual system is designed to create representations that inform behavioral decisions
BRIGHTNESS constancy
Perceive object at same brightness across illuminations
Show at 7 weeks
Color Constancy
Colour is a perception
Colour is not determined by wavelength
Color constancy develops later than brightness constancy.
Fusiform face area
dedicated to face perception FFA
Specialized for face processing - sometimes be used for processing other objects - may be used sometimes for processing other objects that are special areas of expertise for certain individuals
Inversion Effect
the disruption in face processing that is observed when a face is viewed upside down
Which two pictures is identical to a third - if pictures inverted - slower to choose and less accurate
Cost of inversion is higher if the pictures are of faces - 10% less accurate with cars, houses, furniture but 25% less accurate if the pictures are of faces
evidence that faces are processed differently than other objects and that the perceptual mechanisms that process faces are so specialized that they do not work when face images are inverted.
Holistic Processing -
The integration of visual information from the whole of the perceived visual region of interest, usually the face region, in contrast to the perception and representation of component parts.
Composite face task
Composite face task
participants are asked to tell whether the upper half of a face is the same in two images that show the upper half of faces aligned with different bottom halves - brain is integrating top and bottom half
Can differentiate when misaligned
If the two top halves are identical, people find it very difficult to see that they are the same because they see each face as a whole, and the difference in bottom halves makes the two faces seem different
Holistic processing as early as 6yrs
Maurer and Barrera - 1981
2m (1981) prefer to look at faces - cartoon like faces scrambled
Measure how long looking at a face isolated
Goren, Sarty, and Wu newborn preference? (1975)
9min old infants - how far willing to turn their eyes and their heads farther to keep a schematic face in view than to see a scrambled or blank stimulus
People had believed that infants learned based on experience - conflicting evidence
Results were replicated 16 yrs later - infants show competence, lose it and show again - u shaped curve
Johnson and Morton - replication
What did they propose?
Replicated Goren, Sarty and Wu,
U shaped curve
Johnson and Morton proposed a two-process development plan wherein an early system orients the baby
to things in the environment that are likely to be faces, and the second process takes advantage of this visual
orientation to build its adult-like face template that will be used for face recognition throughout life.
Ocular Dominance Columns - Hubel and Wiesel
Single cell recordings - electrodes in a single cell - cat is looking at line at a particular slant
Cells respond to certain orientations
Ocular Dominance columns - column of neurons in the visual system that all respond to input from either the right or left eye
Within a particular column - one eye is dominant
Newborn cats do not have ocular dominance columns, evidence at 1m developed by 2m - Do not exist in newborns - cells respond to info in both eyes
Selective deprivation experiments in kittens
If the kitten was deprived of input from one eye, the entire visual system would become devoted to processing information from the other eye.
The columns that would otherwise have been devoted to, say, the left eye, would come to receive and process information from the right eye. And this switchover is irreversible.
If the developing kitten received no input from the left eye during the critical period, it would lose the ability to respond normally to input from that eye.
Experience expectant learning mechanism - ODC
developmental process that relies on experience by capitalizing on dependable environmental regularities
At birth sew one of the eyes shut - without experience in one eye - ocular dominance column would not develop
Open closed eye - no ocular dominance columns - critical period for development of the columns
No one realized that visual experience was necessary for the development of ocular dominance columns
What points did Hubel and Wiesel illustrate?
ONE Manipulating the environmental input by depriving visual input from one eye permanently changes the visual system
Nature and nurture question is wrong - working together want to know how the psychological process was designed to develop in the species- typical environment
TWO Critical periods - needed to be visual input into each eye at a critical time in development or the normal development of the visual system would never be possible - evo by ns selected for critical periods because they are an efficient method for building an adult organism
Perceptual Narrowing
A developmental process in which perceptual mechanisms become more specialized such that infants lose the ability to discriminate between categories that are irrelevant.
6m are better at 9m at discriminating between 2 monkey faces and human faces
9m - good at human faces but not monkey faces
Perceptual narrowing in face processing after only being exposed to a subset of faces - if only exposed to monkey faces could go the other way - japanese monkeys
The Case of Vision Restoration in Adulthood
Sidney Bradford -
Unable to see depth in 2d paintings - unable to solve necker cube
Could read from a clock
Report distance between objects in room
Unable to perceive faces
Was a skilled machinist but was unable to recognize tools he used before by sight
Natural experiment
A situation in which two or more groups exist through no action of the experimenter, allowing a comparison between these naturally occurring groups
Ex. cataracts
Maurer- Cataracts
Existence of cataracts in children - Maurer - young children who were born with bilateral cataracts that were so dense they completely blocked visual access in the center of the visual field
Early visual deprivation from cataracts had an effect on the development of face perception
Tested group who had been treated for congenital cataracts - complete early visual deprivation - compared to control - previsously deprived group were worse in facial recognition tasks
