Development (Ch 10) Flashcards
The 3 questions human development aims to answer
- Does development unfold in distinct, discontinuous stages, or it is a gradual, continuous process?
- How do nature and nurture interact to make us who we are?
- To what extent do we stay the same over time versus change?
Interactionist approach
- interactionist believe that all three ideas are incorporated in human development:
- physical
- cognitive
- social-emotional
Cross-sectional design
- allows researchers to examine individuals of different ages at the same point in time
- allows researched to collect data quickly and inexpensively
- disadvantage is that participants grew up in different historical contexts, so researchers cannot be certain whether differences between groups are due to age or social and political conditions (Cohort effect)
Cohort Effect
-when it cannot be determined whether differences between experimental groups are due to age difference or growing up in different historical contexts (ie. different social and political conditions)
Longitudinal design
- avoids the cohort effect
- repeatedly test the same group of people over a number of years
- allows researchers to look at real age-related differences
- more sensitive to developmental influences
- more costly and time consuming
- participant drop-out (selective attrition) is a problem
- still cannot be sure whether changes in intellectual ability are due to aging or are unique to particular individual (history effect)
History effect
-unable to distinguish whether a change in intellectual ability is due to aging (and applicable to whole population) or whether is it unique to specific individual being researched
Longitudinal-sequential design
- addresses problem of cohort and history effects
- combination of cross-sectional and longitudinal designs
- researchers repeatedly test 2 or more age cohorts as they grow older
- can compare cohorts at same age to see if they exhibit the same behaviours
- can also determine whether cohorts follow a similar developmental pattern
- costly and time consuming
Germinal stage
- stage 1
- beings at conception
- lasts for two weeks
- at conception the fertilized egg is a single-celled zygote
- divides around 36 hours after conception
- by day 7, multi-celled organism (blastocyte) travels down Fallopian tubes to attach to uterine wall
- 30%-50% of blastocytes dont implant properly
Zygote
-single-called fertilized egg
Blastocyte
-multi-celled organism that develops around day 7
Embryonic stage
- occurs around 2 weeks if implantation is successful
- now called embryo
- stage is marked by formation of the major organs: NS, heart, eyes, ears, arms, legs, teeth, palate and external genitalia.
- continues until about 8 weeks
Duration of development of individual organs
- CNS: week 2-38
- Heart: 3-9
- Arms: 4-9
- Eyes: 4-38
- Legs: 4-9
- Teeth: 6-18
- Palate: 6-14
- External Genitalia: 7-38
- Ears: 4-18
Fetal Stage
- determined by formation of bone cells
- around 8 weeks
- between 8-12 weeks heart beat can form
- fetus rapidly increases in size
- neural growth can be approx. 3mil neurons per minute
- neurons begin neural migration
- soon after NS forms, embryo begins to move (4-6 months)
- begins to respond to sound around 26 weeks
- sounds that fetus is regularly exposed to changes their neural networks and are retained in memory for 4m after birth
- fetus sensitive to odour/taste in amniotic fluid
- at birth infants are near sighted until at least 6 months
Neural migration
- neurons move from one part of the brain to their more permanent home
- factors that interfere with neural migration (prenatal exposure to certain toxins or viruses) can increase risk of psychological disorders
Body and brain size at birth
- at birth the brain will only weigh about 25% as much as an adult brain
- by age 2 it will be about 75%
- by age 4 it will be about 90%
- at birth the body will weigh about 5% as much as an adult body
- by age 2 it will be about 20%
- by age 4 about 30%
Prenatal programming
- process by which events in the womb alter the development of physical and psychological health
- common factors are maternal nutrition, and teratogens (substances that can cause permanent damage)
Teratogens
- Substances that can cause permanent damage during prenatal stage
- known teratogens include viruses, alcohol, nicotine, prescriptions drugs, and radiation
- viruses may have a big impact early in pregnancy and little toward the end
- developing flu in the first 4-6 months increases risk of schizophrenia for child later in life
Maternal nutrition
-folic acid and vitamins used to reduce rates of abnormalities in the NS
-schizophrenia and antisocial personality disorder likely to occur if mother is malnourished
-iron deficiency can lead to infant anemia or low RBC count, which affects how well body functions and cognitive impairment, motor deficiencies and poor emotional functioning
-built in toxin detector… ie morning sickness
-most common with foods susceptible to moulds, and bitter substances (which can cause defects)
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Fetal alcohol spectrum disorder
- alcohol causes damage to central nervous system, low birth weight, physical abnormalities in the face, head, heart, and joints, intellectual disability, and behavioural problems
- in canada estimated that every 1 in 1000 children suffer from FASD
- can happen from having a single drink to excessively drinking
Nicotine effect on prenatal environment
- interferes with oxygen supply to the fetus
- can lead to premature and low-birth weight babies
- increased risk for stillbirth
- doubled risk of child developing bipolar disorder
Caffeine effect on prenatal environment
- studies yielded mixed results
- limited evidence that caffeine consumption leads to birth defects
- some studies suggest a link between heavy caffeine consumption and increased risk of miscarriage or low-weight baby
Prescription drugs on prenatal development
- antidepressants can cause respiratory problems, increased risk of premature birth, and short-lasting effects on motor development
- safest is to avoid prescription drugs prior to pregnancy
Early motor development
- children’s motor development follows a cepholocaudal trend (development processed from head downward)
- also follows a proximodistal patter (growth f=proceeds from centre of body outward)
Major motor development milestones in infancy
- by 2 months, babies lying on their stomach can life their head
- by 3 months babies can grab for objects
- by 4months they can hold objects
- 6 months can sit up
- 7 months pull themselves up and hold onto furniture
- 8-9 months walking by holding on
- many take first steps before age of 1
- by 17 months often can walk on their own
Grasping, sucking and rooting
- grasping: if you give a newborn a finger they will grasp it tightly
- rooting: open-mouth expecting to be breast fed
- sucking: when you place something in a babies mouth
- all involuntary responses to specific stimuli
Fine motor skill development
- involve coordination of the actions of many smaller muscles
- training in fine motor skills actually aids kindergarteners attention showing how joined cognition and action can be
Vision Development
-newborn vision is only about 20-600, meaning that infants can see an object that is 20feet away as I distinctly as an adult with normal vision would see an object 600feet away
-visual acuity improves during infancy, and by 6 months, vision is 20-100.
-by age 3 or 4 child’s vision is similar to adults
-newborns do not see colours very well and are best able to see black and white edges and patterns
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Habituation-dishabituations
- used to determine infant’s sensory abilities
- detects whether the infant notices the difference between a familiar and novel stimulus
- relies on fact that people prefer novelty and pay less attention (habituate) to a stimulus when it is repeatedly present
- babies dishabituation to new stimulus tells the researcher that the baby can discern the difference between 2 photos for example
Preferential looking
- another technique used to study infants’ preferences for certain visual stimuli
- infant shown 2 stimuli and the researcher measures how long the infant spends gazing at each to determine which one it finds more pleasurable/interesting
- babies prefer looking at complex objects rather than simple ones
Critical period
- a period in which individuals are biologically most receptive to a particular kind of input from the environment
- early months of childhood are critical period for vision
Visual cliff
- experiment to test depth perception in babies who have learned how to crawl
- create illusion of a cliff on the floor, and mothers try to encourage babies to crawl across it to see if they detect the “cliff” or not
- mothers were able to convince 6 months old to wiggle across, but 10 month olds stopped when reaching the cliff
- revealed that by the time they can crawl, babies can perceive depth
Synaptic pruning
- synaptic connections that do not receive stimulation from the environment die off
- natures way of making the brain more efficient
- problems with neural pruning are associated with neurological disorders such as schizophrenia and autism
Neural development
- at birth brain grows new neurons and we see a proliferation in the growth of new synapses over the first 2 years of life
- after age 2 some die off
- rate of change slows down considerably by age 6
- increases again in early adolescence, then settles after
- pruning has been seen in children pre-puberty
- number of neurons (grey matter) declines in adolescence but white matter (axons and connectivity) continues to grow into our 40s
Musical training and the brain
- shapes the structure of the brain
- more somatosensory cortex devoted to body parts involved in musical training (ie. fingers of guitar player)
- people who have had intensive training have thicker corpus callosum (greater communication between hemispheres)
- larger cerebellums
- musical training enhances neural activity in hippocampus which is associated with learning and memory
Brain plasticity in children
- children’s brains are more plastic and more sensitive to stimulation
- they have less myelin, which makes neural transmission more efficient but at a cost to neuroplasticity
- few neurons are myelinated at birth
- scientists have identified specific protein molecules within myelin that stop axons from sprouting and forming new connections
Piaget’s theory of cognitive development
- when children encounter a new situation or even, they form a schema (mental representation)
- schemas provide a framework for understanding our world - building blocks of cognitive development
- when children encounter something new they first try to assimilate that experience into an already existing schema
- accommodation occurs when a certain concept doesnt quite fit into an existing schemes and a new schema has to be formed to accommodate the new information
Sensorimotor stage (piaget’s theory)
- 0-2 years
- knowledge is though senses (tasting, seeing, smelling, touching, hearing)
- object permanence develops between 4-9 months
Preoperational stage (piaget’s theory)
- 2-5 years
- verbal and egocentric thinking develop
- can do mentally what once could only do physically
- conservation of shape, number, liquid not possible yet
- cognitive limitations include amniotic thinking, egocentrism and lack of conservation
Concrete operational (piaget’s theory)
- 6-11 years
- conservation of shape, number, liquid now possible
- logic and reasoning develop, but are limited to appearance and what is concretely observed
Formal operational (piaget’s theory)
- 12+
- absrtact reasoning - principles and ideals develop
- systematic problem solving is now possible (no longer just trial and error)
- ability to think about and reflect upon one’s thinking (metacognition)
- scientific reasonings
Object permanence
-ability to realize that objects still exist even when they are not being sensed
Animistic thinking
-idea that inanimate objects are alive