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Chapter 12

Chapter 12-lifespan development.docx

Course Code
Caroline Barakat

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Chapter 12: Lifespan Development
- Discussing the physical, intellectual and social changes that we go through as we age, and some
problems associated with abnormal development.
- Cross-sectional study: individuals of different ages are compared at the same time
- Longitudinal study: a study of development at which the same people are observed at different
times in their lives.
Conception through birth
Rapid physical development to nervous system and body
Birth -2
Motor development and attachment to primary
18 months- 12 years
Increasing ability to think logically and reason abstractly ;
refinement of motor skills, peer influences
13 -20
Thinking and reasoning becomes more adult like; identity
crisis; peer influences
Love , committed relationship; career; stability and then
decrease in physical abilities
Old age
65 -death
Reflection on life’s work and accomplishments , prepare
for death; death.
PRENATAL PERIOD- (nine months) between conception and birth, the period is separated ino three
developmental stages: zygotic, embryonic and the fetal phases.
- Genetic contribution of the egg and sperm that determines the genotype of the new individual
- Prenatal development is not a matter of cellular replication . All cells of an individual have the
same genetic content, they differ (blood cells vs. neurons and muscle cells) . 200 different types
of cell develop from the union of a sperm and zygote.
- X chromosome inactivation- important because it limits the total amount of proteins produced
by genes located on the X chromosome. Without this, the metabolism of a female would be
different from a male(only one X chromosome).
- X chromosome inactivation is a form of epigenetic modification, a modification of cell
inheritance that is not due to alterations of the DNA sequence.
- Epigenetic modifications produce a second factor of early development, and illustrate that the
cell’s chemical environment moderates the expression of its genetic code. Even though the
genetic information contained within a person is the same, the reproducing cells become
specialized as blood cells, neurons and muscle cells.
Prenatal Development
Zygote stage: (2 weeks) he first state of prenatal development, during which the zygote divides many
times and the internal organs begin to form.
- By the end of the first week the zygote consists of about a hundred cells, many of the cells ar
arranged into layers to accommodate for the skin, hair, nervous system, and sensory organs ,
etc. near the end of this stage, a third layer of cells that will eventually develop into muscles and
circulatory and excretory systems.
Embryonic Stage: (2-8 weeks) second stage of prenatal development beginning about two weeks and
ending about eight weeks after conception, during which the heart begins to beat the brain starts to
function , and most of the major body structures begin to form.
- Zygote turns into an embryo and development occurs at a rapid pace. Heart beats, brain and
spinal cord function, most of the major body structures begin to form.

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- Major body features are visible (arms, hands, fingers, legs, toes, shoulders, head and eyes)
- Embryo can react to stimulation
- Embryo is susceptible to external chemical influences, including alcohol , drugs, and other
toxins, known as teratogens.
- Teratogens are substances , agents and events that can cause birth defects.
- Beginning of sexual development occurs during the embryonic stage. Female contributes the x
chromosome and the male contributes the y. xx= female and xy=male .
- The embryo develops gonads that develop later into ovaries or testes. If a y chromosome is
present, the gene located on it causes a chemical signal that will produce testes , if not ovaries
will be produced from the gonads.
- Androgens: primary class of sex hormones in males. The most important androgen is
testosterone. Androgens bring about the development of male sex organs , penis and scrotum.
- Female sex organs develop naturally and DON’T NEED TO BE CREATED BY THE STIMULATION OF
Fetal stage: final period of prenatal development and lasts about seven months. It officially begins with
the appearance of bone cells and ends with birth.
- 2nd month: fetus is 4 cm in length and weights 30g.
- 3rd month: development of major organs is completed and the bones and muscles are beginning
to develop. 8 cm and 90g.
- 4th month: 15cm long weighs 170 g. it is now sleeping and waking regularly. Fetal movements
become strong enough to be felt by the mother , and the heartbeat is loud enough to be heard
by a stethoscope.
- 6th month: fetus grows to more than 30 cm long and weighs 700 g. the seventh month is critical
because if it is born prematurely it has a fair chance of surviving.
- During the last two months of prenatal development the fetus grows rapidly and gains nearly
250g per week. The fetus is about 50 cm long and weighs about 3.5 kg at the end of this period.
The fetus can be born at this point.
Threats to Normal Prenatal Development
- Mothers diet is an important factor- food she eats is the fetus’s source of nutrition. If she is
malnourished the fetus’s nervous system may develop abnormally, and intellectual deficits may
- Teratogens can cause birth defects. Use of cocaine can create premature birth, low birth weight,
and smaller than normal head circumference and can affect neural development as well.
- Smoking: carbon monoxide reduces the supply of oxygen to the fetus. Reduced oxygen levels
are harmful during the last two months of pregnancy when the fetus is developing quickly and
the demand for oxygen is high. (increases miscarriages, low birth weight, increased chance of
premature birth, caesarian section births)
- Chemical and biological toxins- agricultural pollution can lead to birth defects as well.
Physical and Perceptual Development in Infancy and Childhood.
Motor Development
- Normal motor development follows distinct patterns that seem to be dictated by the
MATURATION of the muscles and nervous systems.
- Maturation: is changes in thought, behaviour or physical growth that is due to the ageing
process and not to experience. Children tend to develop according to the same basic maturation

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- Infant’s important movements are reflexes- automatic movements in response to particular
stimuli. Reflexes include: rooting (moving head in direction of touch) sucking, and swallowing .
These reflexes are all important for a baby’s survival.
- Development of nervous system requires two ingredients: maturation of child’s nervous system
and practise. Development of nervous system is not complete at birth and continues within the
first several months, the amount of growth being associated with IQ in childhood later on.
- Certain movements are accompanied by certain neuromuscular systems. Physical development
of the nervous system depends on the ways in which the baby moves while interacting with the
environment. More complex movements depend on further development of the nervous
system, creating interplay between motor and neural development.
Perceptual Development
- Playing a recording of mothers voice increases the heart rate of the fetus, strangers voice did
- Newborns auditory system can detect sounds, (reacts to noises and squints at bright lights) ,
babies have a sense of balance, sense of taste, and a sense of detecting odours (can detect the
smell of mothers breast odour) .
- Preference occurs because of the fetus’s exposure to the mothers voice right after birth.
Form Perception
- Researchers study the visual perceptual abilities of infants by observing their eye movements
with an eye-tracking device while showing them visual stimuli.
- One month old baby does not look at the inside of a figure. The baby’s sight appears to be
trapped by the edges .
- Two months : baby is able to scan across the border to investigate the inside of a figure.
- 1-2 months , baby does not perceive complete shapes (scanning is limited to fixated points on
the object that they are looking at) .
- By three months old they can show clear signs of PATTERN RECOGNITION. (prefer to look at a
human face)
- Ability to perceive three dimensional objects comes at an early age. (placing 6 month old babies
on a visual cliff)
Critical and Sensitive Periods in Perceptual Development
- Psychologists use the term critical period to denote a specific time during which certain
experiences must occur if an individual is to develop normally.
- If infants are not exposed to a stimulating environment, and do not have the opportunity to
interact with caregivers during the first two years of their life, their cognitive development will
be impaired.
- Sensitive periods: occur when certain experiences have more of an effect on development than
if they occurred at another time.
- For example : a person can learn a second language throughout life, but s stated in chapter 10, a
second language is learned more easily in childhood. Critical and sensitive periods indicate that
human development is a continuous interaction between physical maturation and
environmental stimulation.
Cognitive Development in Infancy and Childhood
- As children grow their nervous systems mature and they undergo new experiences, and
perceptual and motor skills develop In complexity and competency.
Importance of a responsive environment
- Cognitive development- infants get to know more about the world around them and they learn
that events in the environment can be dependent on its own behaviour.
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