PSYA02- CHAPTER 11 DEVELOPMENT:
- rom birth to infancy, from childhood to adolescence, from young adulthood to old age, one of
the most obvious facts about human beings is that they change over time.
- Their development includes both dramatic transformations and striking consistencies in the way
they look, think, feel, and act.
- Developmental psychology is the study of continuity and change across the life span,
PRENATALITY: A WOMB WITH A VIEW:
- Zygote is a fertilized egg that contains chromosomes from both a sperm and an egg.
- If the egg is fertilized by a sperm that carries a Y chromosome, then the zygote is male; if the
egg is fertilized by a sperm that carries an X chromosome, the zygote is female.
- The 2-week period that begins at conception is known as the germinal stage, and it is during this
stage that the one-celled zygote begins to divide
- During the germinal stage, the zygote migrates back down the fallopian tube and implants itself
in the wall of the uteru
- The embryonic stage is a period that lasts from the second week until about the eighth week
(begins when zygote implants itself onto uterine wall)
- During this stage, the zygote continues to divide and its cells begin to differentiate
- The zygote at this stage is known as an embryo, and although it is just an inch long, it already has
a beating heart and other body parts, such as arms and legs.
- Embryos that have one X chromosome and one Y chromosome begin to produce a hormone
called testosterone, which masculinizes their reproductive organs, and embryos that have two X
chromosomes do not.
- Without testosterone, the embryo continues developing as a female.
- The fetal stage is a period that lasts from the ninth week until birth.
- The embryo at this stage is known as a fetus, and it has a skeleton and muscles that make it
capable of movement.
- During the last 3 months of the fetal stage, the size of the fetus increases rapidly. It develops a
layer of insulating fat beneath its skin, and its digestive and respiratory systems mature
- Why are human beings born with such underdeveloped brains when other primates are not?
- First, the human brain has nearly tripled in size in just 2 million years of evolution, and bigger
brains require bigger heads to house them.
- If a newborn’s head were closer to its adult size, the baby could not pass through its mother’s
- Second, one of our species’ greatest talents is its ability to adapt to a wide range of novel
environments that differ in terms of climate, social structure, and so on.
- Rather than arriving in the world with a fully developed brain that may or may not meet the
requirements of its environment, human beings arrive with brains that do much of their
developing within the very environments in which they will function.
- The womb is an environment that influences development in a multitude of ways
- he placenta is the organ that physically links the bloodstreams of the mother and the developing
embryo or fetus and permits the exchange of materials. - The foods a woman eats during pregnancy can also shape her child’s food preferences: Infants
tend to like the foods and spices that their mothers ate while they were in utero
- Almost anything a woman eats, drinks, inhales, injects, or otherwise comes into contact with can
pass through the placenta.
- Teratogens Agents that damage the process of development, which literally means “monster
- Teratogens include environmental poisons such as lead in the water, paint dust in the air, or
mercury in fish, but the most common teratogen is alcohol
- Fetal alcohol syndrome is a developmental disorder that stems from heavy alcohol use by the
mother during pregnancy
- The embryo is more vulnerable to teratogens than is the fetus, but structures such as the
central nervous system remain vulnerable throughout the entire prenatal period.
- Developmental psychology studies continuity and change across the life span.
- The prenatal stage of development begins when a sperm fertilizes an egg, producing a zygote.
The zygote, which contains chromosomes from both the egg and the sperm, develops into an
embryo at 2 weeks and then into a fetus at 8 weeks.
- The fetal environment has important physical and psychological influences on the fetus. In
addition to the food a pregnant woman eats, teratogens, or agents that impair fetal
development, can affect the fetus. Some of the most common teratogens are tobacco and
- Although the fetus cannot see much in the womb, it can hear sounds and become familiar with
those it hears often, such as its mother’s voice.
INFANCY AND CHILDHOOD: BECOMING A PERSON:
- Infancy is the stage of development that begins at birth and lasts between 18 and 24 months
PERCEPTUAL AND MOTOR DEVELOPMENT:
- Although infants can use their eyes right away, they must spend considerably more time
learning how to use most of their other parts
- Motor development is the emergence of the ability to execute physical actions such as
reaching, grasping, crawling, and walking
- Infants are born with a small set of reflexes which are specific patterns of motor response
that are triggered by specific patterns of sensory stimulation.
- For example, the rooting reflex is the tendency for infants to move their mouths toward any
object that touches their cheek, and the sucking reflex is the tendency to suck any object that
enters their mouths.
- cephalocaudal rule (or the “top-to-bottom” rule), which describes the tendency for motor
skills to emerge in sequence from the head to the feet.
- Infants tend to gain control over their heads first, their arms and trunks next, and their legs last
- proximodistal rule (or the “inside-to-outside” rule), which describes the tendency for motor
skills to emerge in sequence from the center to the periphery.
- Babies learn to control their trunks before their elbows and knees, and they learn to control
their elbows and knees before their hands and feet COGNITIVE DEVELOPMENT:
- Infants can see and move. But can they think? In the first half of the 20th century, a Swiss
biologist named Jean Piaget became interested in this question.
- He noticed that when confronted with difficult problems—Does the big glass have more liquid in
it than the small glass? Can Billy see what you see?—children of the same age made precisely
the same mistakes.
- And as they aged, they stopped making these mistakes at precisely the same time
- This led Piaget to suspect that children move through discrete stages of cognitive development
which is the emergence of the ability to think and understand.
- Between infancy and adulthood, children must come to understand (a) how the physical world
works, (b) how their minds represent it, and (c) how other minds represent it. These are the
three essential tasks of cognitive development
DISCOVERING THE WORLD:
- Piaget suggested that cognitive development occurs in four stages: the sensorimotor stage,
the preoperational stage, the concrete operational stage, and the formal operational stage
- The sensorimotor stage is a stage of development that begins at birth and lasts through
- infants at this stage use their ability to sense and their ability to move to acquire information
about the world in which they live.
- By actively exploring their environments with their eyes, mouths, and fingers, infants begin to
construct schemas which are theories about or models of the way the world works.
- If an infant learns that tugging at a stuffed animal causes the toy to come closer, then that
observation is incorporated into the infant’s theory about how physical objects behave, and the
infant can later use that theory when he or she wants a different object to come closer, such as
a rattle or a ball
- Piaget called this process assimilation which occurs when infants apply their schemas in
- if the infant tugs the tail of the family cat, the cat is likely to sprint in the opposite direction.
Infants’ theories about the world (“Things come closer if I pull them”) are occasionally
disconfirmed; thus infants must occasionally adjust their schemas in light of their new
experiences (“Aha! Inanimate things come closer when I pull them”).
- Piaget called this process accommodation which occurs when infants revise their schemas in
light of new information.
- infants do not have a theory of object permanence which is the idea that objects continue to
exist even when they are not visible
- infants act as though objects stop existing the moment they are out of sight.
- For instance, he observed that a 2-month-old infant will track a moving object with her eyes, but
once the object leaves her visual field, she will not search for it.
- Studies suggest that infants have some understanding of object permanence by the time they
are just 4 months old.
- Although infants seem to have a better understanding of the physical world than Piaget
suspected, it is still not clear just how much they know or how and when they come to know it.
DISCOVERING THE MIND: - The long period following infancy is called childhood which is the stage of development that
begins at about 18 to 24 months and lasts until adolescence which begins between 11 and 14
- According to Piaget, childhood consists of two stages. The first is a preoperational stage
which is the stage of development that begins at about 2 years and ends at about 6 years, during
which the child learns about physical or “concrete” objects.
- The second is the concrete operational stage which is the stage of development that begins
at about 6 years and ends at about 11 years, during which the child learns how various actions
or “operations” can affect or transform those objects.
- Conservation which is the notion that the quantitative properties of an object are invariant
despite changes in the object’s appearance.
- centration is the tendency to focus on just one property of an object to the exclusion of all
- the main reason why preoperational children do not fully grasp the notion of conservation is
that they do not fully grasp the fact that they have minds and that these minds contain mental
representations of the world.
- We realize that things aren’t always as they seem— that a wagon can be red but look gray at
dusk, a highway can be dry but look wet in the heat. We make a distinction between the way
things are and the way we see them. But preoperational children don’t make this distinction so
- When something looks gray or wet, they tend to assume it is gray or wet.
- As children develop into the concrete operational stage, they begin to realize that the way the
world appears is not necessarily the way the world really is.
- concrete operational children can understand that when water is poured from a short, wide
beaker into a tall, thin cylinder, it is still the same amount of water despite the fact that the
water level in the cylinder is higher.
- Once children can make a distinction between objects and their mental representation of
objects, between an object’s properties and an object’s appearance, they can begin to
understand that some operations change what an object looks like without changing what the
object is like
- it isn’t until they move on to the formal operational stage , which is the stage of development
that begins around the age of 11 and lasts through adulthood, that children can solve
nonphysical problems with similar ease
- Childhood ends when formal operations begin, and people who move on to this stage (and
Piaget believed that some people never did) are able to reason systematically about abstract
concepts such as liberty and love and about events that will happen, that might have happened,
and that never happened.
- The ability to generate, consider, reason about, or otherwise operate on abstract objects is the
hallmark of formal operations.
DISCOVERING OTHER MINDS:
- Egocentrism is the failure to understand that the world appears differently to different
PERCEPTIONS AND BELIEFS:
- Just as 3-year-old children have trouble understanding that others may not see what they see,
so, too, do they have trouble understanding that others may not know what they know. - Egocentrism colors children’s understandings of others, and it can also color their understanding
- In one study using the false belief test, children saw a puppet named Maxi deposit some
chocolate in a cupboard and then leave the room.
- A second puppet arrived a moment later, found the chocolate, and moved it to a different
- The children were then asked where Maxi would look for the chocolate when he returned—in
the first cupboard where he had initially put it or in the second cupboard where the children
knew it was currently.
- Most 5-year-olds realized that Maxi would search the first cupboard because, after all, Maxi had
not seen the chocolate being moved. But 3-year-olds typically claimed that Maxi would look in
the second cupboard because, after all, that’s where the children knew the chocolate really was
- Children all over the world begin to pass the false belief test somewhere between the ages of 4
DESIRES AND EMOTIONS:
- Surprisingly, even very young children (who cannot understand that others have different
perceptions or beliefs) seem to understand that other people have different desires.
- For example, a 2-year-old who likes dogs can understand that other children don’t and can
correctly predict that other children will avoid dogs that the child herself would approach.
- in contrast, children take quite a long time to understand that other people may have emotional
reactions unlike their own.
- When asked where Maxi will look for the chocolate that was moved while Maxi was out of the
room, they correctly say that he will look in the original location, but they incorrectly say that
Maxi feels sad.
- It is only at about 6 years of age that children come to understand that because they and others
have different knowledge, they and others may also experience different emotions in the same
THEORY OF MIND:
- theory of mind which is the idea that human behavior is guided by mental representations.
- autistic children fail to acquire a theory of mind. Although children with autism are typically
normal—and sometimes far better than normal—on most intellectual dimensions they have
difficulty understanding the inner life of other people.
- Specifically, they do not seem to understand that other people can have false beliefs, belief-
based emotions, or self-conscious emotions such as embarrassment and shame
- Research has shown that until children acquire a theory of mind, they are not generally
susceptible to the phenomenon of “contagious yawning”
- Just as learning a spoken language seems to help hearing children acquire a theory of mind, so
does learning a sign language help deaf children do the same
- it is clear that language—and especially language about thoughts and feelings—is an important
tool for helping children make sense of their own and others’ minds
DISCOVERING OUR CULTURES: - Vygotsky, unlike Piaget, he believed that cognitive development was largely the result of the
child’s interaction with members of his or her own culture rather than his or her interaction with
- Clearly, infants of all these species require something more from their caregivers than mere
sustenance. But what?
- Bowlby began by noting that from the moment they are born, goslings waddle after their
mothers and monkeys cling to their mothers’ furry chests because the newborns of both species
must stay close to their caregivers to survive
- Human babies, he suggested, have a similar need, but they are much less physically developed
than goslings or monkeys and hence cannot waddle or cling.
- Because they cannot stay close to their caregivers, human babies pursue a different strategy:
They do things that cause their caregivers to stay close to them. When a baby cries, gurgles,
coos, makes eye contact, or smiles, most adults reflexively move toward the baby, and Bowlby
claimed that this is why the baby emits these “come hither” signals.
- Bowlby claimed that babies begin their lives by sending these signals to anyone within range to
receive them, but during their first 6 months, they begin to keep a mental tally of who responds
most often and most promptly, and they soon begin to target their signals to the best responder
or primary caregiver.
- This person quickly becomes the emotional center of the infant’s universe. Infants feel secure in
the primary caregiver’s presence and will happily crawl around, exploring their environments
with their eyes, ears, fingers, and mouths. But if their primary caregiver gets too far away,
infants begin to feel insecure, and like the imprinted gosling, they take action to decrease the
distance between themselves and their primary caregiver, perhaps by crawling toward their
caregiver or by crying until their caregiver moves toward them.
- Human infants, Bowlby suggested, are predisposed to form an attachment—that is, an
emotional bond—with a primary caregiver.
- strange situation which is a behavioral test used to determine a child’s attachment style.
- The test involves bringing a child and his or her primary caregiver (usually the child’s mother) to
a laboratory room and then staging a series of episodes, including ones in which the primary
caregiver briefly leaves the room and then returns.
- Research shows that infants’ reactions tend to fit one of four attachment styles.
1) secure attachment style, meaning that, when the caregiver returns, infants who had been
distressed by the caregiver’s abse