Summary Psychological Science
Chapter 9: Human development
9.1 human development starts in the womb and extends into adulthood
The process begins at the moment of conception when a sperm unites with an egg to create
a zygote, the first cell of a new life. At about 2 weeks after conception, the zygote is firmly
implanted in the uterine wall, and the next stage of development begins embryo.
During this stage the organs and internal systems begin to form.
After 2 months the growing human is called a fetus, organs are formed, and the heart begins
beating. Most healthy full-term pregnancies end with the birth of the baby between 38 and
42 weeks.
Early brain growth has two important aspects:
- Specific areas within the brain mature and become functional
- Regions of the brain learn to communicate with one another through synaptic
connections
One important wat that brain circuits mature is through myelination.
Most neurons are already formed at birth, the brain’s physical development continues
through the growth of neurons and the new connections they make. Genetic instruction
leads the brain to grow, but the organ is also highly ‘plastic’. The brain organizes itself in
response to its environmental experiences, preserving connections it needs in order to
function in a given context and eliminating others. This process of synaptic pruning allows
every brain to adapt well to any environment.
When a child’s environment does not stimulate their brain, very few synaptic connections
will be made.
Teratogens are agents that harm the embryo or fetus. These agents can impair development
in the womb, sometimes with terrible consequences. Some children have birth defects and
other medical problems and experience slow growth. The most common teratogen is
alcohol. Drinking alcohol during pregnancy can led to fetal alcohol spectrum disorders.
Symptoms are low birth weights, face and head abnormalities, deficient brain growth, and
evidence of impairment such as behavioral or cognitive problems or low IQ.
9.2 biology and environment influence motor development
Newborn babies have various motor reflexes
that aid survival. Like the grasping reflex
when a baby held your finger (monkeys
holding on to their mother). Also appearing
at birth is the rooting reflex, the turning and
sucking that infants automatically engage in
when a nipple or similar object touches an
area near their mouth. If they find an object,
they will show the sucking reflex. These
reflexes help infants nurse.
,Does the timing of milestones (sitting up and walking) have more to do with nature or
nurture? Developmental psychologists now consider developmental milestones to be part of
a dynamic system. The dynamic systems theory views development as a self-organizing
process in which new forms of behavior emerge from the process of an organism repeatedly
engaging and interacting with its environment and cultural contexts.
9.3 infants are prepared to learn
Babies are born categorizing, and newborns already understand they are in the people
category, not the object category. The baby brain already has specific neural circuits for
identifying biological motion and inanimate object motion, along with specific circuits to
identify faces and facial movements.
Newborns normally come into the world with basic perceptual skills:
- Tasting: infants prefer sweet tastes to all other tastes
- Smelling: infants have a reasonably acute sense of smell, associated with feeding
- Hearing: infants’ sense of hearing is quite good; they are startled by loud sounds and
often will turn their bodies toward the source of the sounds
- Seeing: the sense of vision develops more slowly than hearing. Infants respond more
to objects with high-contrast patterns that to other stimuli
Infants are particularly attuned to human faces. They will look longer at familiar faces than
unfamiliar ones. One way how psychologists study the ability of infants to distinguish
between races is with the habituation technique (showing pictures of a certain race until the
baby becomes habituated).
The ability to retain explicit memories also develops
with age. Most adults remember few events that
occurred before they were 3 or 4 years old.
Sigmund Freud referred to this inability to
remember events from early childhood as infantile
amnesia. Some psychologists believe that children
begin to retain explicit memories acter developing
the ability to create autobiographical memory
based on personal experience.
9.5 infants develop attachments
An attachment is a strong, intimate, emotional
connection between people that persists over time
and across circumstances. Forming bonds with
others provides protection for individuals, increases
their chances of survival, and thus increases their
chances of passing along their genes to future
generations.
Caregivers shape much of an infant’s early
experience, from what the child eats to where the
child sleeps to what social connections the child
makes. The essence of attachment theory is that
these early interactions with people begin to shape
the developing human.
,9.6 Piaget emphasized stages of cognitive development
Jean Piaget viewed children as qualitatively different from adults, not simply as
inexperienced adults. He also viewed children as active learners: people trying to understand
the world around them by interacting with objects and by observing the consequences of
their actions.
From Piaget’s perspective, children think the way they do because their views of how the
world works are based on sets of assumptions that are different from those held by adults.
Piaget proposed that children form new schemes as they develop. Through assimilation, a
new experience is placed into an existing scheme. Through accommodation, a new scheme is
created or an existing one is dramatically altered to include new information that otherwise
would not fit into the scheme.
By systematically analyzing children’s thinking, Piaget developed the theory that children go
through four stages of development:
- Sensorimotor: from birth until age 2. The infants acquire information primarily
through their senses and motor exploration. One important cognitive concept that
develops in the sensorimotor stage is object permanence understanding that an
object continues to exist even when it is hidden from view
- Preoperational: from 2 to 7 years. Children can begin to think about objects not in
their immediate view. Having formed conceptual models of how the world works
children begin to think symbolically. Another cognitive limitation characteristic of the
preoperational period is egocentrism tendency for preoperational thinkers to view
the world through their own experiences
- Concrete operational: from 7 to 12 years. Piaget believed that humans do not
develop logic until they begin to perform mental operations on concrete objects in
the world. A concrete operational child is able to think logically about actual objects.
Although this development is the beginning of logical thinking, Piaget believed that
children at this stage reason only about concrete things
- Formal operational: from 12 years to adulthood. Piaget’s final stage of cognitive
development. This kind of thinking is characterized by the ability to form a hypothesis
about something and test the hypothesis through deductive logic
9.7 Piaget underestimated children’s cognitive abilities
Piaget’s framework leaves little room for differing cognitive strategies or skills among
individuals or among cultures. Work by Piaget’s contemporary Lev Vygotsky emphasized
social relations over objects in thinking about cognitive development. He argued that
humans are unique because they use symbols and psychological tools through which they
create culture. Culture dictates what people need to learn and the sorts of skills they need to
develop.
Central to Vygotsky’s theories is the idea
that social and cultural context
influences language development. In
turn, language development influences
cognitive development.
Another challenge to Piaget’s view is that
many children move back and forth
between stages if they are working on
tasks that require varying skill levels.
, 9.8 children learn from interacting with others
According to current thinking, infants’ early social interactions with caregivers are essential
for their ability to understand other people and communicate with them through language.
Children need to learn that social interaction is bidirectional, children’s action influence the
thoughts and feelings of others, and vice versa.
Humans have an innate ability to understand that others have minds and that those minds
have desires, intentions, beliefs, and mental states. David Premack and Guy Woodruff coined
the term theory of mind to describe this ability. Children’s development of theory of mind
appears to coincide with the maturation of the brain’s frontal lobes. In studies, prefrontal
brain regions become active when both children and adolescents are asked to think about
other people’s mental states.
Children as young as 4 years old can understand that someone experiencing pain might be in
distress and would benefit from a gift of hug. Seeking to comfort a person who is upset is an
example of prosocial behavior, which is any voluntary action performed with the specific
intent of benefitting another person.
9.9 moral development begins in childhood
Morality plays a central role in human life, influencing both trivial and consequential choices
and actions. Theorists divide morality into moral reasoning, which depends on cognitive
processes, and moral emotions, which are linked to societal things and avoid doing bad
things.
- At preconventional level: people classify answers in terms of self-interest or
pleasurable outcomes
- At the conventional level, people’s responses conform to rules of law and order or
focus on other’s disapproval
- At the postconventional level, the highest level of moral reasoning, people’s
responses center around complex reasoning about abstract principles and the value
of life
Psychologists call this dislike of unfairness inequity aversion. It begins possibly as young as 19
months of age and increases in strength throughout childhood.
9.11 puberty causes physical changes
Biologically, adolescence begins with puberty, the onset of sexual maturity and the ability to
reproduce. During puberty, hormone levels increase throughout the body. The increased
hormones stimulate physical changes:
- Adolescent growth spurt
- Primary sex characteristics: maturation of the male and female sex organs
- Secondary sex characteristics: pubic hair, body hair, muscle mass increases for boys
and fat deposits on the hips and breasts for girls
Puberty is affected by a complex and dynamic interaction between biological systems and
environmental experiences.
