cog lifespan 4 physical (1)
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Physical development (ii)
At birth, the brain is near adult size
- Growth in individual brain cells- Growth in cerebral cortex
At birth the brain weighs 30% of the adult weight. By age 2yrs, it reaches 70%
4 months: The infant's brain responds to every sound produced in all the languages of the world.
8 to 9 months: Babies can form specific memories from their experiences, such as how to push a ball to make it roll.
10 months: Babies can now distinguish and even produce the sounds of their own language (such as "da-da") and no longer pay attention to the sounds of language that are foreign.
12 months: Babies whose parents say, for example, "Lookeee at the doggiee," will go to the appropriate picture of a dog in a picture book more often than those babies who are talked to in normal, flatter voices.
12 to 18 months: Babies can keep in memory something that has been hidden and find it again, even if it has been completely covered up. They can also hold memory sequences of simple activities, such as winding up a Jack-in-the-box until the figure pops up.
24 months: Preschool children now have clear pictures in mind of people who are dear to them, and they get upset when separated from these people (even their peers).
30 months: Preschool children can hold in mind a whole sequence of spatial maps and know where things are in their environment.
36 months: A preschool child can now hold two different emotions in his mind at the same time, such as being sad that he spilled ice cream on his clothes but glad that he's at a birthday party.
As neurons form connections, they need stimulation to survive. Lack of stimulation could lead to synaptic pruning
Approximately 40% of synapses will be pruned during childhood and adolescence through lack of stimulation
Grows most quickly in comparison to othersIncrease from 70% to 90% of adult weight
between age of 2 to 5 yearsCerebral cortex thickens as mylination
occurs – rapid growth in frontal lobe/cortex
Improvement in physical coordination, perception, attention, memory, language, thinking and imagination linked to mylination
The two areas with marked growth
Neural Development and Plasticity The human brain and nervous system consists of
many highly specialized cells that work together to transmit electrical and chemical signals across synapses
All the neurons a person will ever have – some 100 to 200 billion of them – have already formed by the end of the second trimester, before the brain growth spurt has even begun
The major contributor of the brain growth spurt is the development of a second type of nerve cell, called gliaIt nourishes the neurons and eventually encases them in
insulting sheaths of a waxy substance called myelin The brain shows plasticity up until puberty
Cell Differentiation and Synaptogenesis Neurons assume specialized functions. Influenced
by the sites to which they migrate Cells of the visual and auditory areas
The process of synaptogenesis proceeds rapidly during the brain growth spurt
The average infant has far more neurons and neural connections than adults doNeurons that successfully interconnect with other
neurons crowd out those that don’t, so that half the neurons produced early in life also die early in life
The fact that its cells are highly responsive to the effects of experience
Brain Differentiation and Growth Myelinisation is the process by
which neurons are enclosed in waxy myelin sheaths that facilitate the transmission of neural impulses
The myelin sheath acts like an insulator to speed the transmission of neural impulses, thus allowing the brain to communicate more efficiently with different parts of the body
Myelinisation of the higher brain centers may increase adolescent attention span and explain why they process information faster than elementary school children
Cerebral Lateralisation It is the specialization of brain functions in the left
and the right cerebral hemispheres The highest brain centre, the cerebrum, consists
of two halves connected by a band of fibres called the corpus callosum.Each of the hemispheres is covered by a cerebral
cortexLeft cerebral hemisphere controls the right side of the
body, it contains centres for speech, hearing, verbal memory, decision making, language processing, and expression of positive emotions
Right cerebral hemisphere controls the left side of the body and contains centres for processing visual-spatial information, tactile sensations, expressing negative emotions and non-linguistic sounds such as music
- Reflection of greater capacity of one cerebral hemisphere over the other
- No genetic link to handedness- Language centres may be
opposite- Can be trained – in fact, practice
helps
At 6 months, majority of infants show clear hand preference
90% of 5 year olds have dominant hand
Dominant cerebral hemisphere is the hemisphere responsible for skilled motor action.
Left hemisphere is dominant in right-handed individuals.
In left-handed individuals, motor and language skills are often shared between the hemispheres.
The brains of left-handers tend to be less strongly lateralized than those of right-handers. Many left-handers are ambidextrous.
The two hemispheres of the cortex develop at different rates.
The left hemisphere shows dramatic activity between 3 and 6 years and then levels off.
Activity in the right hemisphere increases slowly throughout early and middle childhood, showing a slight spurt between ages 8 and 10.
There is typically no new growth after adolescence
From the age of 20, brain cells will not reproduce
Gross motor development: big actions that are associated with moving around the environment
Fine motor development: smaller more intentional movements such as grasping and reaching for items within the environment
Basic Trends in Locomotor Development
Motor development proceeds in a cephalocaudal direction
Activities involving the head, neck, and upper extremities precede those involving the legs and lower extremities
The Motor Skills as Dynamic, Goal-Directed Systems views motor skills as active reorganizations of previously mastered capabilities that are undertaken to find more effective ways of exploring the environment or satisfying other objectives
Mastery of motor skills involves integration and blending of various smaller skills
Central Nervous System developmentBody movement capacityGoalEnvironmental support
Acquisition, practice, refinementMotor development is NOT genetically
determined
The Maturation viewpoint describes motor development as the unfolding of a genetically programmed sequence of events which the nerves and muscles mature in a downward and outward direction
The Experiential Hypothesis believe that opportunities to practice motor skills are also very important
Investigators who have charted motor development over the first 2 years of life find that motor skills evolve in a definite sequence
Infants who are quick to proceed through this motor sequence are not necessarily any brighter or otherwise advantaged, compared with those whose rates of motor development are average of slightly below average Therefore, a child’s rate of motor development
tells us very little about future developmental outcomes
These are rough ages
Children who are not given the stimulation or opportunity develop slower
Advise: let the child nap on the floor, do not carry child all the time, avoid using the popular yaoyao sarong
Motor skill Mean age achieved 90% infant attain
Holds head upright, steady 6 weeks 3wks – 4mths
Lift self by arms when prone 2 months 3wks – 4mths
Rolls from side to back 2 months 3wks – 5mths
Grasps cube 3mths 3 weeks 2-7 months
Rolls from back to side 4 ½ months 2-7 months
Sits alone 7 months 5-9 months
Crawls 7 months 5-11 months
Pulls to stand 8 months 5-12 months
Plays pat-a-cake 9mths 3 weeks 7-15 months
Stands alone 11 months 9-16 months
Walks alone 11mths 3 weeks 9-17 months
Builds tower out of 2 cubes 11mths 3 weeks 10-19 months
Scribbles vigorously 14 months 10-21 months
Walks up stairs with help 16 months 12-13 months
Jumps in place 23mths 2 weeks 17-30 months
Walks on tiptoe 25 months 16-30 months
Fine Motor Development Development of Voluntary Reaching
An infant’s ability to reach out and manipulate objects changes dramatically over the first year. Newborns are equipped with a grasping reflex
By 2 months of age, infants’ reaching and grasping skills may seem to deteriorate Reflexive palmer grasp disappears and pre-reaching occurs
much less often
These apparent regressions set the stage for the appearance of voluntary reaching
Achieving motor skills at different stages can help foster perceptual development and self-esteem.
Fine Motor Development Development of Manipulatory Skills
At 4 to 6 months of age the palmnar grasp emerges, which is when an infant grasps objects by pressing the fingers against the palm
The next major step in the growth and hand skills occurs near the end of the first year as infants use their thumbs and forefingers to lift and explore objects The pincer grasp transforms the child into a
skillful manipulator who may soon begin to capture crawling bugs and to turn knobs, dials, etc.
Largely dependent on environmental stimulation and opportunities available
Orphanage children (Iran) – delayed skillsJapanese, rural Indian – discourage early
development because of the dangers involved
Kenya, Jamaica – encourage early sitting, standing
Starts as gross skills that are tuned to fine skills
Development of control – Proximodistal trend i.e. palmer grasp before pincer hold
Depends on visual acuity
Beyond Infancy: Motor Development in Childhood and Adolescence Boys and girls are nearly equal in physical
abilities until pubertyBoys continue to make gains on tests of large-
muscles activities, whereas girls level off or decline
Biological development does not account for all the differences in large muscle performance between boys and girls Nor does it explain the declining performance of
many girls, who continue to grow taller and heavier between ages 12 and 17
Gross motor developmentBodies are more streamlined thus CG shifts
downwards allowing greater balance and more use of the larger muscles
By age 2, gait becomes smooth and rhythmic, leading to running, jumping, hopping, galloping, and skipping.
Individual differences more impressive than gender differences
Lag behind gross motor skills (proximodistal)
Become self-sufficient at dressing and feeding.Great satisfaction from managing their own
bodies.Shoe tying
Mastered around age 6 Requires a longer attention span Memory for an intricate series of hand
movements Dexterity
Scribble – 2nd yearRelated to both cognitive and fine
motor developmentAdvances in perception contribute to
the ability to form letters and words
Except for throwing, no evidence that motor development can be taught.
Preschools, child care centers, and playgrounds need to accommodate a wide range of physical abilities
Criticism of a child’s motor performance, pushing specific motor skills, and promoting a competitive attitude may undermine young children’s motor progress.
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