Lec 11: Human Development Flashcards
What two factors shape human development
genes (nature) and the environment (nurture)
genome
master blueprint for making an organism
genotype
an organism’s genetic makeup; never changes
phenotype
an organism’s observable physical characteristics; always changing
what factors influence phenotype
genetics and environment
twin studies
used by behavioral geneticists to assess the degree to which behavioral traits are inherited (phenotypes)
compare similarities between monozygotic (identical) and dizygotic (fraternal) twins to determine the genetic basis of specific traits
greater similarity of monozygotic twins (raised together or apart) due to genetic influence
monozygotic
identical twin siblings that result from one zygote splitting in two and therefore share the same genes
DNA isn’t as similar as originally thought, due to subtle differences in how the mother’s and father’s genes are combined
dizygotic twins
fraternal twin siblings that result from two separately fertilized eggs and therefore are no more similar genetically than non-twin siblings
adoption studies
behavioral geneticists use this method to assess the degree to which behavioral traits are inherited
compare biological relatives and adoptive relatives
Caspi experiment
Caspi and his colleagues followed more than 1,000 New Zealanders from birth until adulthood
every few years, info was collected about the participants and when the participants were 26 years old, they investigated which factors predicted who had become a violent criminal
results of caspi experiment
not all mistreated children became violent
hypothesized that the enzyme monoamine oxidase (MAO) is important in determining how susceptible one is to mistreatment
low levels of MAO have been implicated in aggressive behaviors
in the experiment, mistreatment at home + low MAO gene accounted for nearly 50% of criminality
prenatal factor: hormones
hormones that circulate in the womb influence the developing fetus
ex: if the mother’s thyroid does not produce sufficient amounts of hormones, the fetus is at risk for lower IQ and diminished intellectual development
prenatal factor: emotional state
mother’s emotional state can affect the developing fetus
ex: high levels of stress hormones (cortisol) may interfere with normal development, producing low birth weight and negative cognitive outcomes that can persist throughout life
teratogens
environmental agents that damage the embryo or fetus such as drugs, alc, bacteria, viruses, and chemicals
extent to which a teratogen causes damage depends on when the fetus is exposed to it, the length and amount of exposure, and genetic susceptibilitiy
fetal alcohol spectrum disorders
drinking alc during pregnancy can lead to multiple defects aka FASD
most severe is FAS
alc interferes with normal brain development and can cause permanent brain damage
can negatively affect learning, attention, the inhibition and regulation of behavior, memory, causal reasoning, and motor performance
how does the mind develop
adaptively
new skills appear at appropriate times, often in the absence of specific training
ex: raise head to 45˚ at 2 months; sit without support at 5.5 months
grasping reflex
basic reflex for newborn that aid survival
newborn grasps your finger
some scholars believe this reflex is a survival mechanism that has come from our primate ancestors (monkeys)
rooting reflex
basic reflex for newborn that aid survival
turning and sucking action that infants automatically do when a nipple or similar object touches an area near their mouths
at birth the brain
is sufficiently developed to support basic reflexes, but further brain development appears necessary for cognitive development to occur
synaptic pruning
when the synaptic connections in the brain that are used are preserved, and those that aren’t are lost
brain organizes itself in response to its environmental experiences, preserving connections it needs in order to function in a given context
ex: two children play the piano, one reasonable well, one becomes virtuoso. virtuoso will have more dense synaptic connections than the child who can play reasonable well
myelination
brain’s way of insulating its “wires”, which helps to speed signal transmission
allows every brain to adapt well to any environment in which it may find itself
occurs in different brain regions at different stages of development
first 2 years involve incredible increases in myelination
what affects aspects of brain development and myelination?
environmental stimulation, interaction, and nutrition
sensitive (critical) periods
periods when specific skills develop most easily; more neuroplasticity
ex: language is one skill that’s easier to learn during early sensitive periods when the brain is more plastic (5-10 yrs)
ex: emergence of close emotional attachments with caregivers
attachment
a strong emotional bond that persists over time and across circumstances
bonding
an adaptive trait
forming bonds with others provides protection for individuals, increases their chances of survival, and increases their chances of passing along their genes to future generations
one of the fundamental needs infants have is to bond emotionally with those who care for them
babies attend to
high pitched voices
in basically every culture, men women and children raise the pitch of their voices when talking to babies and babies respond by maintaining eye contact
imprinting
a sensitive period during which young animals become strongly attached to a nearby adult
contact comfort (physical touch and reassurance) is crucial in building this attachment and aids in social development
Harlow’s monkeys
scientist harlow placed infant monkeys in a cage with two different mothers
one was made of bare wire and could give milk through an attached bottle; the other was made of soft terrycloth and couldn’t give milk
monkeys clung to the cloth mother way more in times of comfort and threat and only approached the wire mother when they were hungry
established the importance of contact comfort
results of harlow experiment
infants could survive without a real mother and as long as food was available, the monkeys underwent normal physical growth and development
however, lacked basic social skills, regardless of which mother was present
when they had their own young, they lacked mothering skills and even abused their young, showed no affection
did not get along with other monkeys
experiment showed that certain behaviors are not genetically programmed and are actually learned
lack of nurturing skills have long term neg. conseq
separation anxiety
when the infants cannot see or are separated from their attachment figures or are left with babysitters and may become distressed
strange-situation test
ainsworth developed it
in a small playroom, a child, their caregiver and a friendly but unfamiliar adult engage in a series of 8 semi-structured episodes
over the course of the episodes, the child experiences increasing distress and a greater need for caregiver proximity
extent to which the child copes with distress and the strategies he or she uses to do so indicate the quality of the child’s attachment to the caregiver
using this test, ainsworth identified infant/caregiver pairs that appeared secure as well as those that appeared insecure or anxious
secure attachment
attachment style for a majority of infants.
the infant is confident enough to play in an unfamiliar environment as long as the caregiver is present and is readily comforted by the caregiver during times of distress
research shows that secure attachments are related to better socioemotional functioning in childhood, peer relations, and successful adjustment at school
insecure (anxious) attachment
the attachment style for a minority of infants
infant may exhibit insecure attachment through various behaviors, like avoiding contact with the caregiver or by alternating btw approach and avoidance behaviors
oxytocin
Hormone related to ‘intimacy’. Plays a role in
maternal tendencies, feelings of social acceptance
and bonding, and sexual gratification
Infant sucking during nursing triggers the release of
oxytocin in the mother and stimulates the
biological process that moves milk into the milk
ducts so the infant can nurse
preferential-looking technique
Researchers show an infant two things.
If the infant looks at one
of the two things longer, the researchers concludes the infant
can distinguish between the two and finds one more interesting
habituation
researchers can create a response preference in an infant for one stimulus over another
Researchers might show the infant a picture or an object until the infant is familiar
enough with it that the infant adapts to the stimulus.
At that point, the
researchers can measure whether the infant reacts to a change in the stimulus.
visual perception
The ability to visually distinguish differences among shapes, patterns, and colors
develops early in infancy
infant vision
Infants’ visual acuity is poor when
they are first born;
it increases
rapidly over the first six months and
reaches adult levels at around a year
after birth
due to motor coordination problems; two eyes are often not working together perfectly, so visual input is misaligned=poorer vision in first 5 months
mobile experiment
to test infant memory researchers put babies in a crib with a mobile hanging over them that was attached to their ankle
infant learned that he could move the mobile by kicking
the rate at which the infant kicked when the mobile was not attached served as the baseline
when the infant was tested later, the ribbon was attached to the ankle but not to the mobile, so the kicks could no longer move the mobile
if the infant recognized the mobile, it would kick faster than the baseline rate to try to make the mobile move
results of crib experiment
older infants remembered better the association between mobile and kicking
infantile amnesia
the inability to remember events from early childhood
various explanations
1) Perhaps children only begin to retain memories after developing the brain
structure and ability to create autobiographical memory
2)Perhaps childhood memory develops with language acquisition
because the ability to use words and concepts aids in memory retention
3)Perhaps children younger than 3 or 4 do not process and understand
contexts well enough to store memories accurately
Piaget’s stages of cognitive development
Piaget developed the theory that children go through 4 stages of development:
sensorimotor, preoperational, concrete operational, and formal operational
believed that each stage builds on the previous one through two learning processes, in which schemas evolve
assimilation
The process by which we place new information into an existing ‘schema’
accommodation
The process by which we create a new schema or alter an existing schema to
include new information that otherwise would not fit into the schema
from piaget’s perspective
children’s views of how the world works are based
on different sets of assumptions than those held by adults
example of assimilation and accommodation
banging is a favorite scheme used by babies to explore their world
(bang a rattle)
assimilation occurs when they incorporate new objects into the scheme
(bang a block)
accommodation occurs when the new object doesn’t fit the existing scheme
(bang an egg and it cracks)
sensorimotor stage
birth-2 years
first stage
infants acquire info about the world through their senses and motor skills
one important concept that initially doesn’t exist, but develops during this stage is object permanence
object permanence
the understanding that an object continues to exist even when it can’t be seen
ex: hiding a toy behind a paper; toy is still there
preoperational stage
2-7 years
second stage
children think symbolically about objects, but they reason based on intuition and superficial appearance rather than logic
ex: pretend a stick is a sword or a wand
have no understanding of the law of conversation of quantity
ex: a 6 year old understands that 2 identical short glasses of water contain the same amount of water
she then pours from one of the short glasses into a tall glass
when asked which glass has more water she points to the taller glass even tho, the water amount is same
law of conservation quantity
even if a substance’s appearance changes, its quantity may remain unchanged
key cognitive limitations of pre-operational stage
centration and egocentrism
centration
occurs when a child cannot think about more than one detail of a problem-solving task at a time
egocentrism
the tendency for pre-operational thinkers to view the world solely through their own experiences
ex: a 3 yr old may play hide and seek by standing next to a large tree and facing it with their eyes closed; child believes that if he or she cannot see other people, other people cannot see them
concrete operational stage
7-11 years
3rd stage
children begin to think about and understand logical operations and are no longer fooled by appearance
ability to understand than an action is reversible enables children to begin to understand concepts such as conservation of quantity
children at this stage reason only about concrete things and don’t have the ability to reason abstractly or hypothetically about what might be possible
Formal operational
12-adult
final stage
people can think abstractly and they can formulate and test hypotheses through deductive logic
can think about many viewpoints at once
challenges to piaget
his framework leaves little room for differing cognitive strategies or skills among individuals or cultures
many adults continue to reason in concrete operational ways, instead of employing critical and analytical thinking skills
piaget also underestimated the age at which certain skills develop
ex: object permanence develops in the first few months of life, instead of 8 or 9 months old
rod-block experiment
a 4 month old is shown a rod that moves back and forth behind a block and the infant becomes habituated to this stimulus
infant is then shown one event, in which the block is removed to reveal a solid rod moving back and forth behind the block
then the infant is shown a second event: the block is removed to reveal two separate rods moving back and forth behind the block
infant spends more time looking at the two rods, indicating that they expected the rod moving behind the block to be one continuous object rather than two small ones
object quantity
piaget concluded that children don’t understand quantity in terms of number but in length (marble experiment)
others found that 3-year olds chose the correct quantity as long as it was something motivating like candy (m&ms)
theory of mind
describes the ability to explain and predict another
person’s behavior as a result of recognizing her or his mental state
Even though preschool-age children tend
to view the world through their own
perspectives, evidence suggests that they
understand others’ perspectives
Children’s development of theory of mind
appears to coincide with the maturation
of the brain’s frontal lobes
