developmental science
an approach to studying the physical, cognitive, social and emotional changes that humans undergo from conception throughout life
major themes of development
1. nature vs. nurture
2. continuous or discontinuous
3. can the course of development be changed
4. one or many ways
nature vs. nurture
how do biology and experience interact to produce developmental outcomes?
are children active or passive in their own development?
continuity
is the process of development gradual and continuous or is it marked by abrupt, stage-like discontinuities?
plasticity
is development fixed or can it be influenced/changed?
if so- in what ways or how much can an individual or environmental impact outcomes?
individual differences
does everyone develop in the same way?
what accounts for differences between people?
theories
ideas/concepts of how something works
Piaget (1896-1980)
mainly interested in normal cognitive development (not individual differences)
believed children undergo qualitative stages as they go
assume children are active agents in their own learning
Piaget's 4 stages
1. sensorimotor (birth-2 y/o)
2. preoperational (2-7 y/o)
3. concrete operations (7- 11 y/o)
4. formal operational (11 + y/o)
information processing theory
seeks to understand thought processes by comparing them to computers
uses input, output, processing capacity and storage
quantitative changes in development --> continuity
Sociocultural Theory (Lev Vgotsky 1896-1934)
emphasizes social interaction and culture in cog development
children internalize directives from others
see development as involving quantitative and qualitative change
zone of proximal development
theory emphasizes instruction over discovery
current understanding
zone of proximal development
out of reach
psychodynamic theory (freud)
people are guided by innate drives
personality shaped by resolution of our drives (id, ego, superego)
psychosexual stages of development
emphasizes the importance of early experience and care giving environment
very early parent/child relationships are im
psychodynamic (erikson)
psychosocial stages associated with periods of development
psychosocial stages of development
trust vs mistrust (birth-1/yo) hope
autonomy vs shame&doubt (1-3 y/o) will
initiative vs guilt (3-6y/o) purpose
industry vs inferiority (6-11y/o) competence
identity vs role confusion (11-18 ish) fidelity
intimacy vs isolation (early adult) love
generativ
behaviorism/learning theory
nuture
positive reinforcement/punishment
all learning is a result of classical and operant conditioning
social learning theory (alfred bandura, 1925-)
learning and behavior can't be fully explained by operant and classical conditioning
learning occurs thru observation and imitation of others
emphasizes the expectation of reinforcement as a motivator
introducing importance of cognition to learning and be
longitudinal research methods
same subjects observed at different ages (many people)
less variability
development is complex
cross sectional research
subjects of different ages observed at a single point in time
less time
more people
same context
correlational methods
does not imply causation
2 variables
relationship that can exist
experimental methods
scientific hypothesis
control and experimental group
independent and dependent variables
random assignment is important
genotype vs phenotype
genetic makeup vs genetic appearance
differential gene expression
the dna of the nucleus of each cell is identical
as cells differentiate, only part of the dana is expressed
the RNA synthesized in each cell depends on the DNA expressed
heredibility and individual differences
individuals inherit different gene forms
allele
a specific form of gene that codes for a part trait
can be homozygous or heterozygous
pattern of heritability
1. dominant- recessive
2. incomplete dominance
3. x-linked
4. genomic imprinting
5. mutation
6. polygenic
dominant recessive
(autosomes)
dark vs. blonde hair
normal vision vs. nearsightedness
tay sachs, CF
incomplete dominance
(carrier express some characteristics)
carrier might express some characteristics
sickle cell
x-linked
(sex chromosomes)
alleles inherited via x chromosomes (mother)
muscular dystrophy, hemophilia
more common in males because they are XY rather than XX
genomic imprinting
if 1 of the allies will be expressed no matter what if inherited
fragile x syndrome, prader willi syndrome
mutation
denovo (new) change or error in transcription
cancer
chances inc. as we age
polygenic
due to many genes to influence traits
many attributes: skin color, heigh, personality, medical conditions
genetics and iq
genetic overlap frequently occurs
environment can also impact iq
-see additional graph on genetics, iq and poveerty
epigenetic framework
genetic and environmental influences are bidirectional and may change over time
gene-environment interaction
canalization
gene-environment correlation
environmental impacts on gene expression
preformation theory (17th century)
infants pass thru the womb full formed but still smaller
they grow until they are ready to be born
epigenesis
knowledge of cells
new structures and functions emerge during development and growth
a process affected by genetic and environmental factors and organism's developmental history
prenatal development periods
1. zygote (conception - 2 weeks) "germinal"
2. embryo (3rd-8th week)
3. fetus (9th week - birth) avg. 38 weeks
vs. trimesters divided into 3 months
cell processes
cell division
cell migration
cell differentiation
cell death (apoptosis)
zygote stage
weeks 0-2
from conception-uterine wall
rapid cell division
embryonic stage
weeks 3-8
from uterine wall attachment to formation of bone cells
achievements include formation of major organ systems
-cephalocauda (head to body)
-proximodistal (middle to outside)
general highest susceptibility to teratogens
formation of neural tube
c
brain development in embryonic stage
cell elaboration: axons and dendrites grow to connect to other cells
myelination begins
fetal suppport system
placenta: rich network of blood vessels that permits exchange between mother and child's bloodstreams and prevents some exchanges that would be harmful
umbilical cord: contains blood vessels connecting fetus --> mother
amniotic sac: membrane within which
sexual differentiation of fetus
no real sex differences until 7 weeks with exception of genetic endowment
in males : gonadal ridges form testes
-produce androgens (testosterone) "masculinize" organism
-suppress pituitary derived hormone characteristics of females
otherwise every fetus w
Fetal stage
week 9-wek 38 (birth)
viable at about 22-26 weeks
majors include: growth 3-->20 in
-movement felt by mother
-hearing at 5 months
-sensitive to light
Fetal Behavior
fetal breathing": expelling and inhaling small amounts of amniotic fluid
swallowing: helps ensure developing of palate and digestive tract
movements: yawn, suck thumb, grasp umbilical cord
develops behavior cycles: less active later on in pregnancy, slee
fetal learning
habituation and recovery patterns: observed with heart rate and movements
earliest demonstration: 32 weeks
ex. Cat in the Hat Study
-preference for mother's voice, familiar human flavors, familiar smells
teratogens
timing matters (most vulnerable in embryonic period)
effects on specific organism/system
individuals vary in susceptibility
greater concentrations --> grater risk
some with little impact on mother can have great impact on child
alcoholic teratogens
fetal alcohol syndrome (FAS), fetal alcohol effects (FAE)
-growth delays, facial features, learning differences, impairment in attention/memory, impulsive, hyperactive
-problems can be long lasting
types of teratogens
smoking--> LBW
cocaine--> LBW, impaired attention regulation
meds: thalidomine --> deformities of arms, legs, ears, genitals, organs
-accutane (1st tri)--> eyes, ears, skull, brain, heart, immune sys
maternal illness: rubella --> cataracts, deafness, hear
infancy development
-nervous system develops rapidly
-brain quadruples in weight from birth (most rapid growth is birth-5 y/o)
-cortex: 10 bill neurons
-max rate of about 250,000 neurons/min prenatally
-CNS and PNS develop
-cerebellum: controls movement and balance
-brain st
lobes of cerebral cortex
frontal: critical thinking and reasoning, managing memory, motor control
occipital lobe: vision
parietal lobe: sensation of touch, spacial abilities
temporal lobe: hearing and language, memory, emotion
basal ganglia
connection of nerve bundles important in modulating motor behavior
limbic system
collection of nucleus involved in emotion, memory and learning
ventricles
filled with fluid, protect brain, exchange nutrients between brain tissue & blood
brain development after birth
different areas mature at different rates
spinal cord& brain stem relatively mature at birth
areas for sensorimotor processing develop in infancy
primary motor cortex (frontal lobe)
primary sensory areas
cortical association areas continue to develop thru early adulthood
-pfc develops thru early 20s
neurons in infancy
pattern of inc. then dec. synaptic connections between neurons; connections refined thru life
experience expectant/dependent brain development
experience expectant: takes place in any "normal environment"
experience dependent: in response to individually specific experiences
neuronal development
neurogensis: neuron creation
cell migration
differentiation
synaptogenesis
neuronal cell death
synaptic rearrangement: connections are pruned & refined
myelination: neural axons insulated in fatty covering; speeds up condition; motor development
newbron reflexes (automatic)
grasping, suckling, stepping, swallowing, startle, crying
jimmy & johnny twin study
myrtle mcgraw study in 1935
study of exercise vs. restriction on the development of motor activities
up to 22 mo. johnny exercised daily in many activities
-jimmy remained in his crib during these times
infant preparedness
babies are ready to receive a full range of important environmental stimuli
they listen for it
-can distinguish full range of language sounds
-preference for human voices, native language
they look for it
-young infants scan dark rooms with eye movements
preparedness
neural mechanisms
-virtual explosion of new synaptic connections (synaptogenesis) thru about 10-12 months
-experience-expectant: stimuli usually universal
-corresponding abilities also universal
synaptic refinement occurs as unnedded connections are throw
piaget's sensorimotor period
infancy - 2/yo
qualitative changes (stage like)
children are "active little scientists:
infants understand the world thru sensory info and motor reflexes
assimilation and accommodation -->adaptation
infants use sense and motor abilities to understand begi
assimilation and accommodation
1. applying an existing capability w/o modification to a new situation
2. modifying an existing capability to meet a new demand of the environment
leads to adaptation: children change to function more effectively in their environment.
sensorimotor (6 substages)
birth- 1 mo: reflexes
1-4 mo: primary circulation reactions
4-8 mo: secondary circulation reactions
8-12 mo: coordination of schemes
12-18 mo: tertiary circulation reactions
18-24 months: beginning of represational thought (symbols)
-object permanence, ho
Challenges to piaget's theory
cog. skills may develop earlier than piaget thought
cognitive development may be more continuous and not stage like
some abilities might be innate
source of infants cognitive limitation ex. working memory, practice
object permanence : see alternative expe
information processing
1. sensory register
2. short term/ working memory
3. long-term memory
managed by the "central executive
mobile kicking task
tested memory
memory capacity rapidly increases during the 1st year
how long can infants remember the mobile trick? depends on age, time elapsed, cues/reminders
2 mo: next day
3 mo: 8 days
6 mo: 2 weeks
cued recall helps
memory development
shift around 6-9 months from implicit to explicit
ex. study of deferred imitation
do infants have emotions?
from birth: differential facial expressions identified from unbiased raters: disgust, distress, interest, content
expands within first year --> joy, anger sadness, fear and surprise
consistent across cultures
more recognizable with age
functional theory of emotion
emotions establish, maintain or change an individual's relationship with the social or physical environment in order to achieve a goal
positive and negative present at birth
more differentiate into childhood
early signs of emotion
have more to do w physiological state than social stimuli
contentment/smiling: full, focking, stroking, mothers
distress: hunger, pain
startle: loud noises, sudden movement
negative emotions: anger, sadness, fear
mad: pain, loss of control
still face paradigm
show reciprocity (begins at 4 months)
-babies want a social response from others
fear development
fear develops later (6-7 months of age, around crawling)
expressed in separation anxiety (6-8 months, peak at 14-18 months)
stranger anxiety (starts at 8 months, peaks at 9-10 months)
indvidual differences in attachment and temperament
emotions of others
infants respond to them appropriately
social referencing: looking to another person to asses how to respond to the situation
do infants understand the emotions of others?
self-conscious emotions
embarrassment, pride, shame, guilt and envy
appears 18-24 months and develops thru preschool years
requires understanding of self and of social rules/standards
1st displayed in front of adults
emotion regulation
ability to control arousal and expression
requires parental support (co-regulation)
12 months- infants will regulate emotions independently
6-12 mo: suck, avert gaze, move away
18-24 mo: talk to companions, distract self
infant temperament
early appearing, stable and consistent individual differences in reactivity and self-regulation
ex. Thomas and Chess study, 1977
-easy, difficult, slow to warm
new: 6 dimensions of infant temperament-
1. fearful distress
2. irritable distress
3. attention span and persistence
4. activity levels
5. positive effect
6. effortful control
behavioral inhibition
children high in fearful distress, difficulty with novel and stress situations
shyness vs sociability
individual differences in behavioral inhibitition appear early (as young as 3-4 mo)
risk factors: depression, anxiety, phobias, social withdraw
have higher heart rates, high conc. of cortisol
greater rise in bp, pupil dilation, body temp
caregivers can he
attachment relationships- john bowlby
why do infants form emotional attachments with caregivers?
-rely on rlns. to survive
-"biologically prepared"
-not guaranteed --? requires learning
attachment origins
freud's psychoanalytic theory
ethological studies (animals)
knorad lorenz: imprinting
harry harlowes: monkeys
bowlby's theory
relationship with caregiver begins with innate signals (crying, clinging, gazing) birth -6wks
infants respond different to caregivers than to strangers (6 wks -6/8 months)
separation anxiety begins (6/8 mo- 18/24 mo)
infant and caregiver form reciprocal r
mary ainsworth's strange situation
developed based on many observation hours
series of separations and reunions to characterize attachment relationships
consider: active play, exploration, greetings, distress vs. not distressed
types of attachment relationships
secure (60%): balance of attachment + exploration
insecure
-avoidant (15%) : minimizing attachment
-resistant (10%): maximizing attachment behavior
-disorganized (15%): source of comfort is also source of fear
what accounts for attachment differences
secure relationships: sensitive, responsive care-giving
insightful caregivers
goodness-of-fit
insecure attachment: why might an infant use a "strategy"?
disorganized attachment: context of neglect, extreme risk and or extreme parent psychopathy
outcomes of attachment
internal working models of relationships
secure attachment predicts positive adjustment
insecure attachment in infancy is a risk factor for a variety of neg outcomes
related to outcomes in adulthood
how to assess infant development
motor milestones
cognitive abilities
vocalizations
social interactions