Author: Stefan Fokuhi
Title: Child Development
Area: Social and Human Science
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School of Social and Human Science
Psychology is a large field that has
to be divided in divisions. One of
them is called Developmental
Psychology. This branch considers
all changes a human being experience
through the way of life. It
is not an own independent branch
that can be studied without
concerning the others. Because the
emphasis is on the changes not on
the subject, all other branches are
touched such as Cognitive
Psychology, Social Psychology and so
on. It is rather a branch that
accompany through the whole
life than a branch that covers a
certain topic independent of age. It
is rather longitudinal than
transverse regarding the lifespan,
and shows the experienced changes in
But Developmental Psychology is
still a too large area. The first
part of life has so much and
dramatic changes that it is
necessary to create an own part:
Child Development. Child Development
covers everything (psychological)
from conception to adolescence. In
other words the first two
Because the changes are so critical
and deciding what happens the rest
of the life, it is also an
extremely important and exciting
Everybody who works with children or
who has children or plan to have
children should be
interested in what child development
reveals about the process the kids
go through. They know
what's going on in a child, they can
compare with other age mates and, if
a deviation occurs they can
correct them. The education will be
more adequate, they don't over- or
under strain them.
It explains why and how a child
percept objects. Adult are able to
understand children's' abilities.
Then they are able to put themself
in the position of children.
It is important for schools and
institutes first to create tests and
then to find out how far developed a
child is and then to decide which
next step is the best toward the
future. Child development
provides possibilities to classify
and to predict.
In this sense Child Development is
even interdisciplinary. Because
Pediatricians must know the
bodily development it extends into
medicine. Child Development is
engaged in the Cognitive and
Intelligence Development, so it
touches the areas of pedagogy. And
finally social and moral
development is interesting for a
In this report some subbranches of
child development are covered.
The Prenatal Development and Birth
is sorted by event not by time,
whereas physical growth covers
all 20 years.
The next chapters are sensation and
perception, cognitive development,
memory- and intelligence
I don't mention at all other parts
such as language, social or moral
development due to the limits of
2 Prenatal Development
Before birth takes place the infant
grows first in the mothers womb.
This time starts with the
conception and lasts 38-40 weeks.
First of all, some definitions:
Gestation is the time from
conception to birth seen from the
Pregnancy is the same time
but from the mother's view.
Embryo is the new being from
conception to 8-12 weeks.
Later it is called fetus till
to the birth.
First it is shown how the body,
later how the brain develops. It is
discussed separately because it is
the most complex organ and the most
2.1 Body development
The womb is the safest place for a
new being to develop in. The
environment is warm, dark, silent
and protects from illness. It is
necessary because the body is
vulnerable and needs a calm place
time to grow up.
At conception that starts with one
cell, this cell divides uncountable
times. After few weeks the cells
start to specialize to different
organs. For example, the neural tube
is build after twenty-two and
twenty-eight days. Not much later
starts the construction of the
central nervous system. The heart
starts beating at the end of the
first month. At the same time
muscles, ribs and the digestive
begin to develop.
In the third month the organs,
muscles and nervous system start to
become organized and
After the period of 13 weeks all
organs are basically formed and just
need to enlarge. Eyes are
Lungs mature after 25 weeks and
after 23-37 weeks the senses
correspond with the brain.
After 26 weeks a baby is able to
survive outside the womb, but has
still trouble to breathe or to keep
the temperature constant, so help
from outside is necessary.
The development begins relatively
late. There are two main growth
spurts. The first starts during the
third month and lasts two month.
During this period the nerve cells
increase rapidly. It is also the
time where the brain is most
vulnerable. The second starts two
weeks before birth. In that time the
cells differ and the structure
between the cells develop. This
period lasts until three or four
The damages of the brain are so
dangerous because a small deviation
in an early period of time
grows up as well and causes later
There are some chemicals and other
influences that are able to destroy
the structure of the brain.
Everything that can damage the brain
is called a teratogen.
Alcohol causes face and head
defects, growth and mental
retardation, anomalies of the heart
other organs. Though the danger of
alcohol is well known among most
woman the prenatal
exposure is one of the leading
causes of mental retardation.
Alcohol is so dangerous because it
crosses the placenta easily. If a
mother is drunken, the baby is
drunken as well. The brain is the
vulnerable organ to alcohol. It
directly kills neurons and disrupts
the migration of neurons and glia.
These cells will not to rebuild they
are lost. The questions is how much
may a pregnant woman
consume. A threshold level where
alcohol starts to effect on the
fetus is still not known.
Cigarettes does not damage the brain
but the heart and lungs. In the
smoke there are several
teratogens such as nicotine and
carbon monoxide. They rushes into
the fetal circulation and disturb
the breathing dramatically. It
ranges then from apnea to rapid
breathing. It also increase the risk
sudden infant death syndrome after
The neural receptors are bind by
nicotine in a particular way. So the
normal development of
synaptic communication is blocked by
nicotine. That causes behavioral
A third dander caused by smoke is
the delay of growth. Babies
infiltrated by smoke have less
weight, they are weaker and more
vulnerable during birth than normal
The birth is the most drastic change
a child experiences even for the
whole life. No more else
changes the situation more than
here. The complete environment both
physiological and outside is
replaced at one sudden moment. The
baby is simply separated from the
mother. There are so much
modifications such as independent
breathing, regulate the
cardio-vascular system and blood
pressure, maintain the right
temperature. The nutrition begins,
followed by digestion. The motor
function alters because the child
experiences gravity in a different,
more complex way.
3.1 The process
The initiator of the entire complex
process is the fetus. There is a
chain of changes of the level of
some hormones that triggers several
hormonal changes in the placenta.
The fetal nervous system
only has all physiological
information to judge when the time
is ready to born. When all systems
mature enough to survive secure
outside then the fetus sends the
signal to get born.
The level was already higher since
some weeks before birth both to
prepare the fetal organs and to
strengthens the uterus's
contractions. They are not regular
and still weak.
The increase of the hormones inside
the placenta triggers the next step
within the hormonical chain.
As result the hormones that are
responsible for contractions are on
a higher level as well. These
increases convert the former
irregular coincidental contractions
to co operational strong
able to expel the fetus.
3.1.2 First Step
When it is time to birth first the
cervix opens due to strong, regular
and more and more frequent
contractions to a clear channel from
the uterus into the vagina called
birth canal. The opening lasts 6
to 14 hours depending on the amount
of former birth. During each
contraction the fetus presses with
the head against the still not
complete opened birth canal.
3.1.3 Second Step
Once the birth canal is fully open,
the second step begins. It lasts
only 20 to 50 minutes also
depending of the amount of former
birth. The contraction are very
strong now and the mother
presses with her whole power the
3.2 Physical traumas
During each contraction the head of
the fetus is pressed against the
birth canal. The umbilical cord
is squeezed repeatedly. This causes
a reduction of baby's supply of
If the birth canal is too narrow,
the head is molded. This may happen
because the skull bones are not
fused, they may slide together
without severely compressing the
fragile content inside.
Sometimes it is possible to see it
when the child is born. The head
seems to be malformed, but the
bones slide back to the normal
This facts sound dangerous to the
fetus, but the fetus is able to
compensate those stress factors.
are even beneficial for the babies.
Regarding the compressions the body
of the fetus surges the level of a
hormone catecholamine. The
hormone causes a decrease of the
heart rate and paralyzes the muscles
to conserve energy and
oxygen. The blood can be used just
for heart and brain now. More blood
is send to the brain to
supply the brain with sufficient
oxygen. The level of catecholamine
rise to twenty times level than
The rise of catecholamine causes
additional circumstances. When the
breathing is activated right
soon after birth the lungs are
prepared to absorb the remaining
fluid in the bronchial tubes. It
promotes the release of a surfactant
to exchange gas in the air cells.
Otherwise breathing wouldn't be
The metabolic rate is speeded up by
catecholamine. A risen rate helps to
regulate the body
temperature, builds larger reserves
of glucose and other energy sources.
Due to the contractions the fetus
has tight contact and touch to the
mother's body. This helps to
refine synaptic connections. In this
way frequently movements promotes
enough stimulation to
develop the last myelination before
The baby is alerted and fully awake
by the high level of stress hormones
and the rich stimulation
The narrow way through the birth
canal has another simple mechanical
benefit. During the passage
through the birth canal the liquid
in the lungs is squeezed
But there are still some dangers
that are too high to be compensated
by baby's hormone system.
3.2.1 Oxygen Deprivation
There is, of course, a threshold in
supporting the brain with oxygen
without supply from outside. If
the breathing doesn't start the baby
can survive up to 10 minutes without
damage. But if there is no
success to start breathing there
will be likely a brain damage
(Parer, 1998). This circumstance is
called Oxygen deprivation and is
always dangerous for babies life.
If the oxygen deprivation becomes
too severe the blood pressure might
become too high leading to a
tear of the capillaries, causing
bleeding. The bleeding can kill
brain cells, the consequences are
permanent mental or neurological
Retard breathing is not the only
cause for oxygen deprivation. The
umbilical cord can be squeezed
during a contraction especially when
the fetus is in the breech position.
Another cause is placenta abruptio
(premature separation of the
placenta). The fetus is no longer
supplied with oxygen and requires
immediately delivery (Ananth et al.,
3.2.2 Subdural hemorrhage
During the passage through the birth
canal sometimes occur injuries. Two
possible events are to be
distinguished. The first,
cephalohematoma, is a swelling on
the head. Fortunately it doesn't
the brain because the bleeding is
outside the protective membranes
that cover the brain, though it
looks frightened from outside. The
second, subdural hemorrhage, is
caused by a more severe
damage of the membranes. If the
membrane is teared the bleeding take
place inside the protection
and damages neurons. This bleeding
is lethal or leads to lasting
cerebral palsy or mental retardation
3.2.3 Cerebral palsy
A group of syndromes is covered by
this expression. They are all caused
during birth or early later.
The syndromes are disorders of
movement or posture. Cerebral palsy
(CP) is hard to detect before
toddler hood because the movements
of a new born are not organized.
Depending of the severity the
kids show paralysis or spasticity in
one or all four extremities. Mental
retardation also occur with a
half, a third have epilepsy.
3.3 Psychological traumata
The modifications mentioned above
may lead to a psychological trauma,
because nearly everything
changes. That must be a shock for
the baby to be pulled out of the
secure, known womb into a
bright, endless, cold and loud
environment. Rank (1924) and
Bernfeld (1925) assumed that this
experience caused all later fears.
But is this really true? Today's
opinion is that it is unlikely that
birth produces such bad traumata,
because nobody remembers the own
birth. It is more likely that a
child feels relieved after great
labor, stress and efforts. If Rank
and Bernfeld opinion were true,
everybody would start his life with
a trauma and bad experience. A bad
precondition to master daily
4 Physical Growth
From the first minute after birth
the fragile baby grows up, now
independent of mother's support. It
is a autonomous being. All
information to grow up lies in his
genetic code. Nobody else or nothing
else tells the kid how to get mature
concerning the physical development.
4.1 Body Size
From a newborn with a average size
of 50 cm to a adult with a size of
170 cm it takes a long time.
As adult the person is 3.4 times
bigger than a newborn. If we assume
a average life time of 75 years
and a time of growing of 16 years
then it takes about 20% of the life
to grow up. The most rapid
growth is during the first year.
When the child is on year old, the
size is 50 % bigger than as a
newborn, by 2 years it is 75 %
bigger. The weight is doubled after
5 month already. After one year
the growth slows down. From age 4 to
puberty it increase nearly linear.
The last spurt takes place
during puberty. The process of
growing is finished after puberty.
The following diagram shows it
Height and Weight Growth Process
The fetal skeleton is first soft and
elastic. Very soon (after six weeks)
bones start to harden. This
process lasts until adolescence
(Tanner, Healy & Cameron, 2001).
That's the reason why small kids
never or rarely brake bones.
Especially long bones have a special
way to grow. They don't grow
everywhere, they have certain
centers to grow. They are located at
the two end and called epiphyses.
They get thinner and finally
disappear. The size of the epiphyses
are a good measure to ascertain the
estimated final body size.
One exception is the skull. It grows
in the first two year very fast,
because the brain gets greater.
Additionally the skull has six gaps
called fontanels. These gaps make it
possible to overlap during
birth. The gaps are closed after two
years forming sutures. The sutures
disappear after puberty. Later
no growth is possible. The question
arise whether it wouldn't be
dangerous to have such big gaps on
the head where the fragile brain is
located. Obviously it is not a
problem, because there are no or
seldom accidents of toddlers at the
It is in particular interesting how
a toddler starts walking. The
ability of walking is such a complex
process, we learned it when we tried
to program roboters to walk. (Honda,
1991). Children are able
to do so after one and a half year.
That is an astonishing achievement.
The steps from birth to the
first steps are shown in the figure
"Steps to walking".
grasps moving objects
standing with holding
Steps to walking
4.4 Gross motor skills
The development of Gross motor skill
depends not only in the physical
growth namely the skeleton
and strength, but also on the
cognitive capabilities and the
perception. New ranges of
(by strength) offers more
possibilities to perceive and
discover something or someone new.
step these new experiences trigger
the brain to develop in the three
dimensional orientation. The
new neuronal capabilities can be
used again to get more mobile or to
learn new steps in movement
based on the old ones (Gibson,
1988). Here the circle is closed.
Now here is the emphasis on the
The step from birth to age 2 are
shown above. By age 2, the gaits
gets more smooth. The next step is
running and jumping on one spot. By
age 3 and 6 a child starts to jump
during running (Getchell &
Robertson, 1989). In the same age a
child is able to throw a object.
Later on all movements are improved
and refined. Now they are able to
play sport games that helps
a lot to improve the motor skills
and to get more strength in a
pleasant way. All these capabilities
are going to be improved until
There is a special time during the
way to adolescence called puberty.
Girls start earlier then boys.
They start puberty at an average of
11 and last 3 or 4 years (Tanner,
1990; Wheeler, 1991). Boys
start at an age of 12 and it lasts
also 3 to 4 years.
During puberty there are many bodily
changes for both girls and boys. The
maturing of the sexual
organs is accompanied by the rapid
growth of the body. There is the
last spurt before arriving
adolescence. The feminine
development of the sexual organs
don't start with the menarche, it is
embedded instead. The changes are
thoroughly. The masculine
development is additional
accompanied by the deepening of the
What influences the time of
First it is determined by heredity.
That is shown by identical twins who
begin with just one month
difference whereas fraternal twins
have a difference of up to 12 month
(Kaprio et al., 1995).
The second factor is nutrition. When
a girl eats fat food the puberty
starts earlier. The opposite, if
girls eats few or take sport
exercise the puberty starts later
Third, the health conditions also
contribute an early beginning. In
developed nations the menarche
starts at about the same time: all
countries have nearly the same
medical scheme and care. (Morabia
et al., 1998). In poor countries the
menarche starts later. But if there
is a rich family who can afford
higher medical care the girls start
Fourth, when children grow up safe
and protected menarche starts later.
In other words bad, deep
going experience and persistent
difficulties accelerate puberty.
Children from intact environments
begin later. (Ellis & Garber, 2000;
Moffitt et al., 1992).
When is the ideal time to begin
puberty. Early or late? It depends
on the gender and attitude of other
peers and adults. Early matured boys
are seen as self-confident, strong
and physically handsome.
Compared to age mates they are in
leader positions. Instead late
maturer are considered as fearful
(Brooks-Gunn, 1988; Clausen, 1975;
Jones, 1965). That's what the
environment expect but the
psychological stress is higher even
though they are admired(Ge, Conger &
Concerning girls it's just the
opposite: early mature girls are
considered as unself-confidence and
withdrawn and are seldom in leader
positions, they show more a negative
behavior and a worser
school achievement's, but late
starter are seen in the same way
like early boys: attractive and
Caspi et al., 1993; Dick et al.,
But what is the best timing for
them? Because of the pay a lot of
attention to the feedback from
others. The early boys and late
girls have an easier way through
puberty to adolescence. They did
not learn to handle difficulties and
their painful experiences. They are
later as adults inflexible and
discontent whereas the other group
is independent, flexible and
satisfied (Livson & Peshkin, 1980;
4.5.3 Psychological impacts
Because of the deep changes the
puberty influence not only the
bodily conditions. Normally a
person who experience the changes of
puberty is made insecure and reacts
with a mixture of
positive and negative feelings. A
way to prevent such deep changes is
to prepare and inform the kids
before the first changes start and
to accompany them during their
difficult time. An important role
plays the father of his daughter who
ideally is interested in her changes
and takes care of her
because of a deep relationship
established in earlier years.
Unfortunately many fathers fear a
relationship during puberty because
of their own insecurity how to
handle a maturing girl. They
don't support the daughter but drop
her. The result are more deeper and
worser emotions because of
their own insecurity and their
suddenly lost of support. They feel
unloved because of their changes
and try to go against it with even
worser results concerning the
Well prepared boys and girls do
better then surprised and
carelessed. The better, opener and
confident the relationship between
parents and their children before
puberty is, the better goes the
child though this time, because it
can trust in them and rely on their
5 Sensation and Perception
5.1 Perception during Infancy
Child's development has been studied
in about 90% in the age of infancy.
Scientists put so high
emphasis on this period for several
1. The perception is later more tied
with cognitive processes and
therefore more difficult to
distinguish or to analyze (Oerter et
2. The senses are well developed
after one year. There are no more
differences to adult. So there is
no need to perform further
investigations. The ability to
perceive will be improved during
growth, of course, but there are no
or only few changes concerning the
From the very beginning an infant is
able to smell. This sense might be
underestimated, but for a
newborn is to necessary to survival.
The reaction (positive and negative)
can be measured by
observing the facial expression and
the breathing rate. When a piece of
cotton wool is hold to the
nose the reaction is informative
enough to reveal the ability and
intensity how an infant smells.
The smell of banana-, strawberry- or
vanilla causes a positive reaction
and addle eggs and even fish
are not accepted by newborn (Rieser
et al., 1976; Steiner, 1979). After
five days the sensitivity will
be more different. After one week
the baby is able to differ the smell
of mother's breast from others
(MacFarlaine, 1975). So a child can
distinguish the mother from others
just by the sensitivity of
smell after one week.
If a newborn smells something
negative it is able to localize it
and to turn away to the other
directions (Reiser, Yonas, & Wikner,
Already two hours after birth the
baby tastes sweet, salty and bitter
liquids. The taste causes fast or
slow sucking depending on babies
preferences. The preferences change
fast because after four
month the salty taste seems to be
preferred. The preference is a bit
changeable and able to influence.
When a child alter likes salty food
it might have the origin in the
first months of live.
The sense of touch is may be the
most important sense of the lower
senses. It is important and
essential to construct and establish
emotional relationships between the
infant and the parents. The
touch also helps to stimulate
physical growth. No wonder that this
sense is the most well developed.
Especially the mouth, the palms and
the soles of the feet are sensitive
(Humphrey, 1978). When a
adult touch and caress a baby the
baby respond with smiling and pay
attention to that person (Stack
& Muir, 1992). It is good to observe
that babies "see" with the touch
sense. They put everything
new in the mouth and investigate it.
Babies are ables to distinguish
objects by touch (Streri, Lhote &
One property of sound is that it
penetrates the womb. The fetus is
already able to hear here what
were not possible for visibility.
Studies show that music played
during pregnancy is recognized after
birth. As the fetus grows it hears
continuously it's mother's voice.
That sound is already differed
from other voice after 4 days of
life (DeCasper & Fifer, 1980). This
is not valid for father's voice,
because his sound or voice was not
Babies seem to have a congenital
capability to distinguish acoustic
pattern that are similar to human
language. This is important for
development of the own language. The
baby likes obviously more
complex sounds than pure sounds
(e.g. A pure sinus tone). Already
after one month the child is able
to differ between all existent
language sounds of the world and
after six month the baby can differ
only those sounds that exist in the
own language. It get lost for the
rest of languages (Cooper &
Aslin, 1989). In that age of six
month the baby differs the sound
pattern as well as an adult (Olsho
al., 1987). It prefers the rhythm of
normal sentences more than sequences
with irregular breaks.
(Hirsh-Pasek et al., 1987).
Even a baby is able to ascertain
where a sound comes from. This is
possible because one ear is
farther than the other and the waves
arrive a bit later. As the child
grows the head and the offset
grows as well. The offset of the
waves increases and the brain has to
recalibrate it in order to get
again the right direction of the
sound. Because of these changes a
young child has problems to
locate the origin of a sound, but
the capabilities are still
Unlike the lower senses and the
hearing the vision sense isn't
developed well by birth. Several
functions are still under
1. The muscles of the lens that is
responsible for the sharpness are
still weak. So it isn't possible for
the newborn to see clear and
2. The retina contain lesser cells
than the retina of an adult. That
causes a lower density of the
3. The cells are still not mature.
The ability to see in colors doesn't
exist. In other words the baby
sees gray not colored.
4. The way to the brain that are the
optic nerve are underdeveloped as
well as the visual cortex.
Even if the eye could send exact
signals to the brain, they couldn't
processed adequate. (Banks &
5. The acuity is smaller than an
adult like. They see only objects
right in front of the eyes, though
they turns the eyes and head in the
Because of these fact a newborn sees
gray, unfocused and limited. It
changes rapidly after one to six
month. After three month the focus
is developed as well as adult like.
And already after two months
the color perception is so
discriminated that the eye can see
all spectrum colors.
At birth the best distance to see
most focused for a baby is 20-30cm.
It is the same distance from the
breast to mother's head. When the
child is being feeded it can see the
mother with the most
sharpness ever possible.
Depth perception of little children
was investigated by Eleanor Gibson
and Richard Walk 1960 the
first time. Because of the lack of
ability to see like an adult, it
seems to be that babies cannot
perceive depth. The question arise
when and how far is the development
A 3-4 months old baby can already
figure out the things are not flat.
How do they do it, when they
don't see focused? One hint is
called kinetic depth or cues. The
important information of depth is
gained by the motion if the child
and/or the surroundings move
(Arterberry, Craton & Yonas, 1993).
Test using looming shows that babies
at age 1 month already use kinetic
cues (Petterson et al.,
When the development processes the
infant is able to use binocular
depth cues assumed that the
development is far enough. Kinetic
cues provides a relative correlation
of two or more objects but
not a absolute measure. When a
babies uses binocular cues it can
distinguish absolute length and
distances. That's necessary to grasp
or reach near objects.
Coordination of Hand and Eye
As seen above binocular cues are
used to determine reachable length.
It has to be determined the
distance of the hand and the
distance of the object. A baby can
grasp systematic at age of 4 -5
month. But already at birth there
is a rudimentary link of eyes and
hands. That proofed von Hofsten
(1982) and was confirmed by Ennouri
& Bloch (1996). Trials of grasping
are not successful until
the third month. But they get better
When a baby is 4-5 month old, the
first step is that the baby observes
it's own hand and compares it
with the desired object until the
grasp is successful (Piaget,
The ability to grasp sure is
completed after 8 -9 month. They can
even grasp a object that changes
the direction of speed of movement.
Unexpected delays or deviations can
be compensated regularly
after 34-36 weeks (von Hofsten,
Crawling and depth perception
As the baby turns around and
discovers more and more of it's
environment the depth perception is
trained. There is a difference if
someone is driven or goes himself.
To be his own demands a higher
awareness of orientation and memory.
To find a way back it is necessary
to remind passed objects.
While moving the picture on the
retina changes depending on the own
movements. This experience
also strengthens the coordination of
the own movements and the depth
perception. It is also a
cognitive process. Experiments have
proofed the higher activity of the
brain while crawling (Bell &
Actually it is a circle: When the
body is strong enough to move first
trials of moving stimulate the
perception and brain processes,
these processes enlarge the
cognitive functions. As they are
developed enough the baby is able to
refine the own movements. The gross
and fine motoric skills
are improved and they get more
strength. So they are able to move
better and farther. Here is the
A pattern is recognizable by its
contrast. A contrast is a sharp
difference in the brightness of two
more adjacent borders. Even newborns
prefer to look at patterned rather
than plain objects. As they
get older, they prefer more complex
patterns (Brennan, Ames & Moore,
1966). The ability to detect
contrasts is precondition to
recognize pattern. This sensitivity
of detecting lesser contrasts
during infancy and childhood
(Gwiazda & Birch, 2001; Teller,
1997). A 1-month-old infant
discovers sharp contrasted pattern
whereas a 2 month infant explores
even internal features
(Bronson, 1991). When 4 month passed
since birth an infant detects an
organization and perceive
boundaries that in reality doesn't
exist. The perception is so
progressed that the imagination is
higher than the real sensation.
Because of the maturation of acuity,
sharpness and cells also the pattern
perception increases soon
and gets higher as the lifetime goes
One special pattern is the human
face. Newborns already show higher
interest in pattern that look
like a face. Faces that are upside
doen or unnaturally are not
preferred. Is seems that they have a
natural tendency to recognize faces.
They look even longer to faces that
are attractive to adults than
to ugly faces. It is believed that
this built-in ability the given to
select the own species from others.
(Johnson, 2001; Slater & Quinn,
2001). Another reason might be the
frequency of seeing a human
face from the very beginning of
6 Cognitive Development
Piaget (1896-1980) who was first a
zoologist became a cognitive
theorist. He researched the
cognitive development his entire
live and came up with uncountable
ideas to study observations
wrote a lot of papers. So, he is a
base person in cognitive psychology
and his works were a signal to
continue to study this branch of
His theory will be introduced now.
He has a flavor of biology. He
assumes that each individual gains
it's cognitive knowledge from the
own active learning. At the
beginning there is no knowledge. The
child gets everything later after
adding new and refining old
He has given some definitions that
are essential for his theory.
Adaptation is a process of creating
new psychological structures called
schemes. Whenever there
takes place a change in the
environment, the kid tries to adapt
it through direct interaction with
environment. There are two possible
ways that are complementary:
The own way to process changes in
the environment is to use own,
individual schemes and compare
and interpret the external world
until it fits. Sometimes the results
are really strange. This kind of
way works until there is nothing
that fits in the own schemes. Then
the second way is used.
If there is nothing fit able a new
structure is created or an old one
is adjusted. In this way the scheme
has to be revised and renewed. The
child learns completely new.
When over a certain period of time
someone more assimilate more than
accommodate this state is
called equilibrium or being in a
When new information is given that
doesn't match they accommodate more
than assimilate. This is
called Disequilibrium or cognitive
discomfort. After settling down the
new schemes the state
changes again to equilibrium.
The changes between equilibrium and
disequilibrium over time is called
According to Piaget every child goes
through four stages: sensorimotor,
operational and formal operational.
All four stages are introduced here
The first stage lasts from birth to
the second year of life. They know
so less about the world like a
blank sheet. That means that at the
very beginning they adapt the first
schemes only by
accommodation. But it starts by
baby's own activity. The child gets
the environment by chance and
refines it by trying again and
During the first two years there are
so many changes that it is necessary
to divide it into six
substages. These are:
This substage lasts from birth to
the first month. It consists of only
reflexes. The child can suck,
grasp and look.
Primary circular reactions
After around one month starts
substage 2 and lasts until the forth
month. As in substage one a baby
is just able to perform very basic
movements, but now they get more and
more controlled and
repeated. During this substages the
movements are still basic but are
done voluntary. Imitations
starts as well during this period,
but all movements are done toward
their own body.
Secondary circular reactions
After being able to sit up the
activity changes from the own body
to the environment. A child
reaches and hits or grasp object
near around. But it is still the
same sequence. It causes a change by
chance and repeats the movement
again and again. After a while it
refines the movements and use
the new experience to gain even more
complex movements. This time period
starts from the fourth
month and takes four month.
Coordination of secondary
From age 8 to 12 month babies act
now more intentional or directing to
a self given goal. The last
stage the activity was led by
random. Now a baby is even able to
solve simple problems. Piaget
found out that the babies already
gain to master object permanence
which means they remember an
object at the moment not visible as
before. But they still make the
A-not-B-mistake. They still
search for a hidden object at place
A even though seeing it be moved to
a second place B. That
shows a not complete object
Tertiary circular reaction
Toddlers do in this stages several
tries to solve a problem. This is an
evident that it is able to
perform more complex actions. The
kids also imitate others or actions
seen from others. The A-not-
B-mistake doesn't occur any more. To
sum up the action are more refined
and advanced now. This
substage emerges from 12 and lasts
again 6 months.
The main difference to the former
substage is that the children try to
solve the problem in their brain
first and then they perform the
action. In the former stage they
tried it by trail-and-error actions.
Now they use more the mental
capabilities. Two other evidences
are the deferred imitation
(imitating behavior of persons not
present), and performing imaginary
plays or games.
Many examples and studies made by
Piaget support this theory of
stages. They are completely
ommited due to the small range of
6.2.2 Preoperational Stage
The preoperational stage lasts from
2 to 7 years. The mental
representation increases during this
time obviously and steadily. Of
curse, it's still a process, which
means that the performance is
sometimes few perfectly.
Some signs are usable to proof how
far the mental representation is
developed. These are language
and thoughts, make-believe games and
Language and thoughts
Dealing with language provides a
more abstract thinking. Using a
language divides the situation
from thoughts. Thoughts can be
repeated without doing something
again and again. So, thoughts
can be repeated in different tenses
independent from the described
situation. This circumstance
helps to detach the daily life or
actions from creating some creative
ideas or plans.
Make-believe games show or proof the
capability of thinking without
seeing the same. Or is
provides an independent thinking of
Three views shows how a child grows
and masters a symbolic world:
The association is more and more
detached from the real world. A cup
is used as a cup first or a
simple car is played as a car first.
Children less 2 years don't use a
cup as a hat (Tomasello, Striano
& Rochat, 1999). Later they are able
to use everything as everything
(Corrigan, 1987; O'Reilly,
In early years the child itself
stand in the center of the play. The
direction is directed toward the
Later it changes toward other
objects. And more later there are
several objects that the child
pretends. The child learns that
pretending plays are not necessarily
depend on them self. (McCune,
The play gets more complex during
the growing. First only one action
or idea is pretended. Later
more action at the same time are
played.. They create also more roles
One advantage of playing
make-believe games is that they
contribute to the cognitive and even
social skills. The make-believe
games are played later in a group,
not only as stand-alone games. So,
kids who played a lot these games
are later able to be social
competent at school . It must not be
said that the other skills, such as
memory, logical thinking, language
and creativity also are
increased by playing those games.
(Bergen & Mauer, 2000; Dias &
Another markable sign is what
children draw on paper. Three steps
The very first drawings are made in
western countries at age 2. But the
drawings are unreadable.
After explanations from the drawer
the meaning can be guessed. (Winner,
Shapes and forms
Children learns that lines can be
used as boundaries of objects. The
discovering permits drawings of
shaped and intended drawings. At
first the drawings are still hard to
understand, also because of the
inability to draw straight. But
during the process the lines get
more accurate and the drawings get
more complex. A face doesn't consist
of only a circle but also eyes,
nose, mouth and hairs.
A drawing from a 6-years-old child
look already really realistic. Now
also other details are used.
Legs and arm have different length,
even depth cues. It shows that the
child starts to organize spatial
capabilities. As already said, the
progress is still not at the end and
the skills are still being
improved. (Case & Okamoto, 1996)
6.2.3 Concrete Operational Stage
At age 7 11 years there are a lot
of change concerning the cognitive
development. The thoughts
and cognitive ability resembles
more an adult than the thoughts of
younger children. The thoughts
are more logical, complex, organized
and flexible than at lesser age.
There are also some signs that
indicates a growth during that
period: conservation, hierarchical
thinking, seriation and spatial
capability. They will be introduced
shortly as well.
In this stage the kid is able to
perform conservation tasks. It is
possible now to conserve a certain
amount of changeable object such as
water or gas. When water is poured
into a taller glass the child
recognize the same amount of water.
When it is poured back the child
again recognized it right.
That's a sign is reversibility. The
child doesn't concentrate just to
one dimension but to more. That
proofs the capability of
decentration that is the same as
conservation. It doesn't concentrate
A given amount of different objects
can be classified by 7-10 old
children. They can categorize it in
several kinds. They can even
classify it hierarchical that means
not only in one level, but
in more tiers.
Imagine a child given some sticks
with different length each. A child
from age 6 or 7 is able to put
them in the right order. Older
children are able to do to even
mentally. This capability is called
transitive inference. The
performance is still improved until
age 8. (Andrews & Halford, 1998;
Markovitz et al, 1995). To order
something mentally some problems
arise. The child has to keep in
mind each length. Then it has to
compare them silently to each other.
The result, still mentally, must
lead them to put them in the right
order. The most work to processed in
School-ages kids get a more accurate
skill in 3D orientation. Three
different examples proof it:
A school-age child can easily grasp
the estimation of two or more
different far objects. When for
example there are two objects on a
table at different distances, a
preschool-age child is able to
distinguish the distance only if
there is a path marked between them,
but a school-age child can
distinguish the right distance
without help. 4-years-old can
estimate it only if the scene is
familiar because then they can fall
back on other (own) experience.
(Fabricius & Wellmann, 1993)
For this proof children can be
divided in three groups. The first,
age 5-6, are not able to put
in the position of a remote object.
If they had to go a path that turns
to the right they cannot
determine the new layout after
turning to the right. They will give
wrong information about the new
locations of other objects more far.
When a object is on the right ahd
side before turning, and on the
left hand side after turning to the
right, they are unable to choose the
right direction. A 7-8-aged
child starts to be able to imagine
it right because they imagine the
scene as if they walked the way
virtually. From age 8 children can
tell always and securely the right
directions but still walk the way
Sometimes children try to draw their
environment like a map on a paper.
It is characteristic for
preschoolers that they use
landmarks. Young school-age children
perform is better, but still have
problems with rotated maps (or
original). Then they are not perform
it accurately (Liben & Downs,
1993). The reverse direction
(finding objects guided by a map)
can be improved remarkable when
the landmarks on the map are
connected as a meaningful pattern.
Then they can use the analogy of
original and pattern when they go
through the original. (Uttal et al.,
6.2.4 Formal Operational Stage
The last stage according to Piaget
is called formal operational stage
and marks the beginning of
attract thinking. It starts around
age 11 and lasts until adolescence.
They don't need a concrete or
touchable object to imagine a
situation or problem. They use
general and abstract thought
independent of real objects or
The logical thinking is being
developed in that stage. A child in
the former stages needs to use real-
world objects to evaluate given
statements or propositions whereas
children belonging to this stage
don't need or need lesser real
objects to compare their own answer
to the given statement.
Logical thinking assumed two skills
to be developed. First the language
skill has to be so far
progressed that the child is able to
express complex correlations. The
second is the ability to solve
mathematical or logical problems.
6.3 Critism and Evaluation
Piaget made a lot of studies and
observations even with his own
children. Based on this he
developed his theory. But still he
assumed distinctive points of views
for he was a former zoologist.
Therefore some statements can be
queried, even because some other
studies emphasize an opposite
sight. Some of them are introduced
6.3.1 Sensorimotor Stage
According to Piaget's theory the
secondary circular reaction starts
at the fourth month. He says that
the child starts to explore the
environment. In fact, they do it
right after being born.
The discussion about object
permanence is controversial. Some
researchers had made studies that
proofs an earlier capability of
object permanence. Indeed other
researchers cannot confirm such
results and disagreed the former
Another case where Piaget's was
definitely wrong is mental
representation. He claims that
cannot mentally represent experience
prior to an age of 18 month. But
already 8-month old children
are able to do it. (McDonough,
1999). It is proofed by new studies
that younger infants are capable
to do it.
When Piaget studied deferred
Imitation he did it on his own
children. But he might have missed
many instances therefore he had been
led into a fallacy. Because newer
studies have shown that
deferred imitation occurs already at
the early age of six weeks.
(Meltzoff & Moore, 1994)
All these examples let suggest that
many tasks can be successfully done
earlier than Piaget stated.
But also the strict order of the
stages is not always valid. For
example, the deferred imitation
earlier than the object-hiding
solution, but Piaget stated that all
representational capacities begin at
the same time. Thus the clear given
order of stages is obviously
6.3.2 Preoperational Stage
Egocentricity leads the children in
that stage to look on their own and
even ignore others, believed
Piaget. But later studies have
proved that just the opposite
happens. Children at age 4 use a
language when speaking to
two-years-old than speaking to
adults. They use an appropriate
vocabulary and adapt to the
counterpart depending on their
capabilities far before entering in
Concerning the illogical thinking
that Piaget saw in the
preoperational stage, many newer
have contradict his statements. The
crux of the matter is that he used
too unfamiliar object.
Performing the same tests which
familiar object or situations
already 3-or-4 old children are able
give correct answers. (Rosen &
Rozin, 1993; Ruffman, 1999)
Piaget also stated that preschoolers
have difficulties with
classification. Even though already
month old infants use
classification. The categories are
not so fine organized like that from
children, yet they categories not
depending on their appearance.
2-5-year-olds can classify objects
despite they emerge in different
To sum up, children are basically
earlier able to think logically than
Piaget assumed, but they still
need to develop the skills over
6.3.3 Concrete Operational Stage
The entrance into this stage is far
more dependent on external
influences than assumed by Piaget.
Here is another example than the
stages cannot be ordered as neat as
in a laboratory. Some
influences that affect the ability
to apply mental skills are the
environment which the children live
in. Children who grow up in tribal
or village societies where the
children are not sent to a school
have a delay in conservation. They
enter not until age 11 (Fahrmeier,
Yet non-schooled children are
capable of mental problems when they
do similar tasks as demanded
in Piaget's studies. Then they are
used to do resembled tasks and
perform an even better result than
normal age mates (Ceci & Roazzi,
6.3.4 Formal Operational Stage
Here it is the same case like the
stage before. The reaching depends
on external influences and the
environment. The questions arises
whether even all adults reach this
Again, many tribal and village
societies never master formal
operational tasks (Cole, 1990).They
refuse to think in a formal or
We are normally only in that fields
able to think strong abstract enough
where we could gather rich
experience. Some of Piaget's tests
are so general and therefore
difficult even to well-educated
that likely 40-60 percent will fail
(Keating, 1979). Our skills are
mostly attached to our daily
experience our profession.
7 Memory Development
The memory is the crucial thing
without we are not able to survive.
If we remembered nothing, we
couldn't recognize nothing, not only
our familiar persons but also not
all things around us. We
couldn't know how to eat, how to
drink, how to walk and so on. So,
the memory is essential for our
daily life. Even the youngest child
is able and needs to be able to
The expressions used here have to be
defined or refined. Hence there are
some definitions given:
Recognition: Assumed that an
item is known then regognition means
the remembrance of that item
after a stimulation from outside.
Another person or object or
situation reminds someone and then
the remembrance is aware.
Recognition is used when someone
shows some items and we remember
the right one.
Recall: Assuming the same
knowledge someone remembers the item
oneself. The stimulation
comes not from outside, no example
is given to recognize.
Implicit memory: This memory
stores information at a unconscious
or unaware level. Here is all
our skills, habits and motions
stored. It takes a longer time until
a skill or movement like driving or
playing a music instrument is
memorized. But once stored, however,
it is unforgettable burned in.
Because of the longer period of
committing to memory, we are not
able to tell a exact date when we
Short term memory: Short time
memory is the first part of our
memory. It stores information for a
short time (about 45 sec) only. The
amount of the information is also
limited. It is used to process
sensory input, to store called
items from the long term memory or
the result of mental processes.
Long term memory: This part
of memory is unlimited concerning
time and storage. Information
passes short time memory to long
term memory not automatically. To
attain to the long term
memory either the information is
very impressive or repeated several
times. The latter process we
do while learning.
7.1 Memory development
Some parts of the memory or brain
complex system grows up earlier then
other parts. The basal
ganglia and cerebellum grow early
and fast during early infancy. Sub
cortical areas grow slower, but
the cerebral cortex takes a long
time to mature. The first mentioned
areas are the medium of the
implicit memory. But the cortex
contains all explicit information.
Because of the late maturation it
is clear that children starts late
and gradually emerge the control
over the explicit memory.
7.1.1 Fetal Memory
During pregnancy the brain develops
from the very beginning. But how can
the development of
memory be measured? It is even more
difficult to ascertain the progress
of a hidden and not
speaking object. Yet there are two
possibilities to find it out, this
is habituation and classical
Habituation starts as soon as the
baby begins to hear. While sending a
particular sound through the
abdomen a reaction of movements can
be observed by ultrasound. When the
stimulus is repeated
regularly, e.g. twenty seconds, the
reactions gets lesser and lesser as
if the stimulus belongs to the
natural environment. Finally it
ceases to react. Habituation takes
place. The first habituation was
observed in the 23rd week.
Reflecting the importance of
habituation it seems to be very
important. Imaging habituation
exist: Then each sound, each
movement causes a new exciting
reaction. The baby would newer find
rest. So, habituation is like a
filter to provide a restful time
despite sounds around.
But the base of habituation is
memory. The memory must work before
habituation takes place.
Otherwise the baby cannot recognize
already heard sounds and filter it.
Habituation is therefore also a good
indicator for diagnostic purposes.
If habituation still not occur
far later than normal, a damage of
the memory area or a delay of
maturation can be concluded.
The next process where memory is
used for it classical conditioning,
the learned association
between stimuli. Mothers are asked
to calm down whenever a certain
piece of music is played. Later
the fetus calm down just by hearing
the same piece of music. Even after
birth the baby becomes
calm whenever the music is played.
Obviously it remembers not only the
music, but also the
association between music and
calmness. (Berk, 2003)
7.1.2 The first six month
It is far more easier to study
newborns memory because the reaction
of them is visible and thus
more different. Newborn are able to
learn by operant conditioning. This
type of learning provides a
good method of probing how well and
how long the memory remains
numerousness studies it is proved
that 2-months-olds keep information
one or two days. Between
two and six month remember still
after one week and 6-month-olds can
remind information after
7.2 Capacity of memory
Till now the memory hasn't been
measured except time. That's too
inaccurate. Two suggestions
have been made to measure the brain
7.2.1 Memory span
The first kind of measure is called
memory span. A person is shown
several items in a certain order.
The task is to reproduce as much
items as possible in the right order
again. The amount of items that
can be reproduced right is the
measure of memory span. At age 6
children have the memory span of
4 and 12-years-old can remember 5
items. (Dempster, 1985)
7.2.2 Central memory unit
The idea of this measure is that the
memory has a given finite amount of
capacity. The model is like
the memory in a computer where the
capacity is limited by the inserted
chips. In this model the
capacity doesn't change at any age.
Two parts, operating space and
storage space, have to share the
capacity. The operating space is
that part of the memory where
cognitive processes take place,
whereas the storage space the short
term memory is. During getting older
just the allocation or
arrangement of these two parts
changes toward the storage space
because it is lesser and lesser
memory demanded to do the cognitive
processes. Therefore there is more
free space left for the
storage space. (Case, 1985)
7.3 Meta memory
Meta memory is simply the knowledge
about someone's own memory and the
processes in the
memory. The question here is: do
children have meta memory and if how
far it is used to improve
Studies have shown that already
young children know at least basic
facts about their own memory.
The more older the more specific is
the meta memory. It increases linear
during childhood and the
rising depends on how often and how
intensive strategies are used to
solve mental tasks (Joyner &
Kurtz-Costes, 1997; Schneider, 1999;
Schneider & Pressley, 1997).
This type of meta memory is called
declarative meta cognitive memory.
It is conscious, explicit and
valuable even by the own person.
The other part is procedural meta
cognitive knowledge which is
implicit, unconscious and not
influence able. It is used to
regulate or control the own
activities. This knowledge is not
measure. Surveys have been made to
find out how sensible children are
about their own memory
and cognitive skills. So, they know
whether a task is easy or takes a
lot of effort to solve it (Kreutzer
et al., 1975).
7.4 Infantile amnesia
In interesting thing concerning the
memory development is the fact that
nobody remember the first
years of the own life. Nobody
remembers events that happened
before the first three and a half
years. Except very very specific and
dramatic events after age 2 is
everything else lost. This
phenomenon is called infantile
The question is now why we cannot
remember these events. Is it a
problem of recalling or is it a
problem of maturation which means
the brain and memory wasn't able to
The first group of scientists who
agree to the former opinion think
that the information is stored, but
inaccessible. It just cannot be
recalled or be retrieved even by
The reason why it cannot be
retrieved is that the information is
stored in another way than language.
They guess that is it stored as
script. This script language is
later not known any more and hence
impossible to find. (Case 1985,
Leichtman und Ceci 1993). But the
language is learnt before 3 and a
half year. So, the earliest
remembrance must begin 3 and a half
Other scientists believe that
infantile amnesia is not a retrieval
problem but a problem of the
storage. The memory is still not as
mature as being able to store
information along time. All studies
involve the short term memory, but
never the long term memory. Because
of this reason they
believe that the long term memory
isn't matured yet before 3 and a
8 Intelligence Development
8.1 Bodily development
Our intelligence is performed in our
brain, no other organ. At time of
birth the brain weights 250g.
Already after one year the weight
increases to the triple, 750g. When
the child is five years old the
size is as big as an adult one,
1300g. But, of course, the volume it
weight of the brain doesn't make a
person intelligent. There are
studies about it that proof no
The speed of the mental process is
more deciding whether someone is
intelligent. According to
Elloit (1999) reacts brighter people
faster than others at simple tasks.
The correlation of reaction
with the IQ score is about 0.5. But
this is obviously, because a faster
comprehending brain can
either receive and process more
information in the same time or
takes shorter time for the same
information. If the amount of
information is equal there is
therefore more time left to do other
or to go already further. There are
less efforts to take.
How gains the speed in childhood?
When children are still young the
react very slow. But the older
they are the faster they perform
mental processes. The greatest gain
during childhood takes place
between age 5 and 11. When a child
is twelve years old it reacts still
as half as an adult. The greatest
gain speed at all is at age 15.
The speed of the mental performance
has also been measured by electrical
measurements. This tests
proves the processing speed in the
brain. A newborn brain processes or
the signal takes three times
slower or longer than an adult.
But not only speed is a considerable
measure, also the efficiency of the
process itself. This has
nothing to do with the speed as
shown above. The way how the
information goes through the brain
gets more and more efficient. It can
be said that the information finds
newer, shortener ways than
before. Studies have shown that the
involved areas in a 7-years-olds
brain are larger than in an
adult's brain to fulfill the same
task. It shows that the ways are
concentrated and therefore more
Case (1985) studied this phenomena
and found out that there are three
mechanisms to refine the
performance of the brain.
The first way to speed up is the
simply way of automation of always
repeated actions. First it takes a
long time and a lot of effort to do
something, but after automation a
task takes no longer effort and
goes faster and doesn't need as
large memory size as before. The new
gained space, time and effort
can be used for other tasks now.
The process of learning how to read
shows automation impressive. First
each letter is read hard, but
later even complete word are read
fluently. The saved time and effort
can be applied to understand
the word just read.
Each System in the brain grows up by
Myelinisation. While a child is
still little the Myelinisation is
not completed yet. It is obvious,
that systems still not completed
cannot work perfect. When this
process is completed each system is
ready to work at highest speed
Case & Griffin (1990) mentioned that
similar situations and structures
are generalized. The already
structured networks will be
reorganized and/or reconnected
according to the experience to more
general networks. They proofed by
many studies that generalization
improves the speed and
efficiency as well.
8.2.2 Development of strategies
Everybody of us uses strategies to
solve a problem. But first of all we
must define what a problem
Definition of problem and
A problem takes place when a person
wants to do something, but doesn't
know how to perform at
least one step or doesn't know in
which order the several steps have
to be done. (Newell & Simon,
The strategy is fully intended and
planned way to solve this problem
and to reach successful the
given final goal.
A strategy is, like the performance,
at the first time very exhausting
and takes a long time. The first
times the strategy is applied
conscious, but gets automated after
a while. Later the strategy is
unconscious, fast and without any
effort. (Bjorklund et al., 1990)
The improvement of the application
of a strategy happens by experience.
Often more than one
strategy is applied and the most
successfully is used then. So, the
child learns by comparing the
strategies and choose the best
strategy. It is easier if there are
a rich amount f possibilities or
available. The problem solver can
combine them in order to find out
the best strategy. 12-month-
olds are already able to chose the
best strategy despite the noticed
situation that might mislead to the
wrong way (Olson, 1966; Diamond,
Strategies at preschool age
As example for different ways to
solve the same task calculating is
taken. Children at preschool age
are already able to count or
calculate very simple numbers.
Siegler & Robinson (1982) studied
old children by asking them easy
adding problems. They observed four
Recall from memory
When a child the solution already
knows it recall it from memory. 64
percent of all tries were solved
by this way. The solution was found
after 4 seconds and 66 percent of
all solutions were right.
Presentation by using fingers
The fingers of the hand are used to
present the numbers, but they don't
count the fingers together.
Rather they attached both hands
together to show the result. 13
percent of all tries are performed
such a way. It took 6.6 seconds and
89 percent were solved right.
The children counted the numbers
silent or whispering without any
help (fingers). 8 percent of all
solutions are found by this method.
The time was 9 seconds and 54
percent of all answers were
The difference to b is that now the
fingers are counted together. It
takes the longest time (14 sec),
but was quite a sure strategy: 87
percent of all solutions were right.
It is interesting that the children
used all methods, not only one, even
at the same time. This shows
that the children are able to choose
between several strategies, but not
always decide which one is
Strategies at school age
During school age is is easy to
observe how the pupils learn to use
different ways to read a text. At
the very beginning the learn the
letters and very small words
containing these letters. At first
of elementary school they stay on a
point on the text 0.33 sec on the
average (fixation). An adult
fixates only 0.24 sec. The
difference is not much. But an adult
grasps more then double time words
per fixation, which means that an
adult gathers more information at
But 6-years-old have to correct very
often what they read. It is
observable how often they turns the
eyes back to an already read word.
This happens quite often, about the
half of all read words. This
amount diminishes very fast. An
adult seldom turns the eyes back to
read something again. I child
reads 80 words per minute and an
adult 280 words (Taylor et al.,
1960). There are some people who
read 800-900 words per minute.
This examples show not how a person
reads and which steps are necessary
to perform reading, but
shows how a human being improves
steadily the skill of reading.
8.3.1 Environment / Heredity
The discussion about
heredity/environment touches also
the influences of intelligence. How
affect the individual intelligence?
Bouchard & McGue (1981) and Scarr
correlations between several
different pair that can be compared
easily and significant.
Total number of pairs
Identical twins reared together
Identical twins reared apart
Fraternal Twins reared together
Fraternal Twins reared apart
Siblings reared together
Siblings reared apart
Parent-biological child living
Parent-biological child living apart
Parent adopted child
Correlations of several pairs.
The comparison between the same kind
of pair but different rearing
clearly shows an influence of
the environment because the
genetical background is the same.
But the greater the genetic
is, the more resembles their IQ
correlation. Another point is
important because those who reared
together had the same environment
and heredity. So, the two
parameters have to be added. This
table shows the it is not possible
to say or judge what and how much
really impact the IQ of a child.
8.3.2 Familiar environment
from the entire family
This kind of influence is called
shared environment influences
because they are "shared" or
experienced by all family members.
They affect all children in the same
way and intensity.
E.g. when parents takes care about
their children's development and
contribute and support them on
their way, it improves the
intelligence development enormously.
When parents talk often to their
young children the language
developments is demanded. That
triggers also other realms and
contributes to a higher achievement
in school (Hart & Risley, 1995).
Later, when kids are in school
age, the support of parents is very
important. The support not only
consists of helping at homework,
but also in motivating, choosing to
go the right next step and so on.
And parents who know how
important education is especially
contribute them. The result are
better achievements (Kao, 2000).
But as much as they try to treat
each child in the same manner, there
are still differences. The oldest
child is always treated different
than the youngest. So, the position
among siblings emerges
inevitable differences. The oldest
gets always the most attention (
just because the parents are
unexperienced and therefore more
fearful to make a mistake ). But
surprisingly these facts don't
impact the IQ (Rodgers, 2001).
8.4 Predicting IQ
Why it is important to know a
child's IQ score? Is it just for fun
or just to find out the actual
achievement potential? Is a IQ test
able to predict the ability in the
future? Many studies has been
performed to figure this out.
Parents wants to know how
intelligent is their child and the
IQ score is important to classify
8.4.1 Reliability of predictions
Tests can be performed already
between age 2-8 month. (Berk, 1999).
At that age only visual tests
possible. This test correlates by
factor 0.4 to IQ score at age eight.
Other tests at age one year, such
as memory recognition,
discrimination and object
permanence, show the direction, but
correlation is not very high. They
are still not egibile to support an
At age two or three the correlation
between a test score and later IQ
starts to be higher, but before
are five or six it is still too
One reason why such an early test is
unreliable is that they are based on
motor and perceptual skill
whereas later other skills are more
important. Verbal and spatial skill
are more used at school and
associated with intelligence. So,
tests are based on different not
As already seen it doesn't make
sense to test too early, otherwise
the correlation is too low. The best
age to start with predictable test
is at age 6. Or more general: the
older the child, the more reliable
predict the test is. (Hayslip, 1994;
When a testee is tested two times,
the time between those tests is also
remarkable. The closer the
time the more they correlate to each
other. Let's see the extreme
examples: if the time between the
two tests is two years (age 4 and
age 6) the correlation is .62 and if
the time difference is 14 years
(age 4 and age 18) the correlation
drops to .42 (Honzik, Macfarlane &
When a child is tested regularly
through childhood the IQ score often
changes to more or less than
10 to 20 points (McCall, 1993). The
reason why the scores are so
volatile is their environment.
Children who gain IQ score are more
independent. The parents paid more
attention to their
children's success and intervene
when necessary. Decliners have
either parents who didn't take care
of their children or the children
don't have enough discipline.
So, timetimes the deviations are not
a failure of the tests but a result
of the environment.
Of course, each chapter never covers
but only touched the wide and
interesting fields of child
development. Additionally, studies
are not mentioned. Each part is
based on numerous studies,
some confirm earlier studies, some
contradict. The followed discussions
with pros and cons cannot
be mentioned as well.
But it hopefully helps to understand
how child development wants to
examine and what all belongs
to it. I was really surprised that
there are so many parts and even
these parts are still huge fields to
Especially parents should be
interested in child development for
it provides all necessary
information worthful for education,
prevention and prediction. They are
able to compare each step
and might be happy when their
children reaches the next step. But
they can also be prepared well
when the offspring reaches a period
that is not easy to handle with. No
one will be a perfect parent,
but it provides helpful information
to educate better and more
But also others, such as teachers,
carer or attendants, find helpful
information about the world
children live in.
Therefore child development is an
important and interesting, because
applicable, parts in the science
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