Early Physical and Motor Development PDF

CHAPTER 5: EARLY PHYSICAL AND MOTOR DEVELOPMENT untreated active tuberculosis, if she has been exposed to radiation, or if she is taking any drug that would not EARLY PHYSICAL DEVELOPMENT...

CHAPTER 5: EARLY PHYSICAL AND MOTOR DEVELOPMENT untreated active tuberculosis, if she has been exposed to radiation, or if she is taking any drug that would not EARLY PHYSICAL DEVELOPMENT be safe for the baby. PRINCIPLES OF DEVELOPMENT BREAST-FED BABIES… According to the cephalocaudal principle, growth Are less likely to contact infectious illnesses such as occurs from the top down. Because the brain grows diarrhea, respiratory infections, otitis media (infection rapidly before birth, a newborn baby’s head is of the middle ear), and staphylococcal, bacteria, and disproportionately large. urinary tract infections. According to proximodistal principle (inner to outer), Have a lower risk of SIDS and of post neonatal death. growth and motor development proceed from the Have less risk of inflammatory bowel disease. center of the body outward. Have better visual acuity, neurological development, and long-term cardiovascular health, GROWTH PATTERNS including cholesterol levels. Children grow faster during the first 3 years, especially Are less likely to develop obesity, asthma, eczema, during the first few months, than they ever will again. diabetes, lymphoma, childhood leukemia, and By 5 months, the average baby boy’s birth weight has Hodgkin’s disease. doubled to nearly 16 pounds, and, by 1 year, has more Are less likely to show language and motor delays. than tripled to exceed 25 pounds. Score higher on cognitive tests at school age and into As a baby grows into a toddler, body shape and young adulthood. proportions change too; a 3-year-old typically is slender compared with a chubby, potbellied 1-year-old. Have fewer cavities and are less likely to need braces. The genes an infant inherits have a strong influence on BREAST-FEEDING MOTHERS… whether the child will be tall or short, thin or stocky, or Enjoy quicker recovery from childbirth with less risk of somewhere in between. postpartum bleeding. Teething usually begins around 3 or 4 months, when Are more likely to return to their pre pregnancy weight infants begin grabbing almost everything in sight to put and less likely to develop long-term obesity. into their mouths. Have reduced risk of anemia and lowered risk of repeat By the 1st birthday, babies generally have 6 to 8 teeth; pregnancy while breast-feeding. by age 2 ½, they have a mouthful of 20. Report feeling more confident and less anxious. NUTRITION Are less likely to develop osteoporosis or ovarian and Proper nutrition is essential to healthy growth. Feeding premenopausal breast cancer. needs change rapidly during the first 3 years of life. THE BRAIN AND THE REFLEX BEHAVIOR Feeding a baby is an emotional as well as a physical act. Newborns’ response to a nipple and their sucking Such bonding can take place through either breast- movements that allow them to control their intake of feeding or bottle-feeding and through many other fluids are functions of the central nervous system---the caregiving activities, most of which can be performed brain and spinal cord (a bundle of nerves running by fathers as well as mothers. through the backbone) ---and of growing peripheral Nutritionally speaking, however, breast-feeding is network of nerved extending to every part of the body. almost always best for infants and mothers. Through this network, sensory messages travel to the Breast-feeding should begin immediately after birth brain, and motor commands travel back. and should continue for at least 1 year, longer if mother The brain at birth is only about one-fourth to one-third and baby wish. of its eventual adult volume. The only acceptable alternative to breast milk is an iron- By age 6, it is almost adult size, but specific parts of the fortified formula that is based on either cow’s milk or brain continue to grow and develop functionally into soy protein and contains supplemental vitamins and adulthood. minerals. Infants weaned during the 1st year should The brain’s growth occurs in fits and starts called brain receive iron-fortified formula. growth spurts. Different parts of the brain grow more Breastfeeding is inadvisable if a mother is infected with rapidly at different times. the AIDS virus or any other infectious illness, if she has  By birth, the growth spurt of the spinal cord and brain 2nd month of gestation: about 250,000 immature stem (the part of the brain responsible for such basic neurons are produced every minute through cell bodily functions as breathing, heart rate, body division (mitosis). temperature, and the sleep-wake cycle) has nearly run At birth: most of the more than 100 billion neurons in its course. a mature brain are already formed but are not yet fully The cerebellum (the part of the brain that maintains developed. balance and motor coordination) grows fastest during Between the 25th week of gestation and the first few the 1st year of life. months after birth: number of neurons increases most The cerebrum, the largest part of the brain, is divided rapidly. into right and left halves, or hemispheres, each with Originally the neurons are simply cell bodies with a specialized functions. This specialization of the nucleus, or center, composed of deoxyribonucleic acid hemispheres is called lateralization. (DNA), which contains the cell’s genetic programming. Left hemisphere: concerned with language and logical Most of the neurons in the cortex are in place by 20 thinking. weeks of gestation, and its structure becomes fairly Right hemisphere: concerned with visual and spatial well-defined during the next 12 weeks. functions such as map reading and drawing. Once in place, the neurons sprout axons (send signals Joining the two hemispheres is a tough band of tissue to other neurons) and dendrites (receive incoming called the corpus callosum, which allows them to share messages from them), through synapses, tiny gaps, information and coordinate commands. which are bridged with the help of chemical Four (4) lobes of cerebral hemisphere: messengers called neurotransmitters that are released 1. Occipital lobe – smallest of the four lobes and is by the neurons. primarily concerned with visual processing. Eventually, a particular neuron may have anywhere 2. Parietal lobe – involved with integrating sensory from 5,000 to 100,000 synaptic connections. information from the body. The multiplication of dendrites and synaptic 3. Temporal lobe – helps us interpret smells and connections, especially during the last 2½ months of sounds and is involved in memory. gestation and the first 6 months to 2 years of life, 4. Frontal lobes – the newest region of the brain, are accounts for much of the brain’s growth and permits involved with a variety of higher-order processes, the emergence of new perceptual, cognitive, and motor such as goal setting, inhibition, reasoning, abilities. planning, and problem solving. Integration – process by which neurons coordinate the The regions of the cerebral cortex (the outer surface of activities of muscle groups. the cerebrum) that govern vision, hearing, and other Differentiation – process by which cells acquire sensory information grow rapidly in the first few specialized structures and functions. months after birth and are mature by age 6 months, but At first the brain produces many more neurons and the areas of the frontal cortex responsible for abstract synapses than it needs. thought, mental associations, remembering, and As early experience shapes the brain, the paths are deliberate motor responses grow very little during this selected, and unused paths are pruned away. period and remain immature for several years. Cell death – in brain development, normal elimination Smiling, babbling, crawling, walking, and talking—all of excess brain cells to achieve more efficient the major sensory, motor, and cognitive milestones of functioning. infancy and toddlerhood—reflect the rapid This process begins during the prenatal period and development of the brain, particularly the cerebral continues after birth. cortex. Only about half the neurons originally produced survive Brain Cells and function in adulthood. The brain is composed of: Myelination 1. Neurons or nerve cells – send and receive Myelination – process of coating neural pathways with information. a fatty substance called myelin, which enables faster 2. Glia or glial cells – nourish and protect the communication. neurons.  Myelination begins about halfway through gestation, Rooting Baby’s Head turns, Birth 9 months peaks during the 1st year of life, continues into cheek or mouth lower lips opens, adolescence and persists through the third decade of is stroked sucking life. with movements In the fetus, myelin development progresses from the finger or begin nipple center out. Walking Baby is Makes 1 month 4 months Myelination continues to occur rapidly throughout held steplike infancy, accelerating at 12 to 16 months, and then under motions that slowing again from 2 to 5 years of age. arms, look like with bare well- At 5 years of age, the myelinated white matter volume feet coordinated in the brain is approximately 80 percent of that found touching walking in adults. flat surface EARLY HUMAN REFLEXES Swim- Baby is Makes well- 1 month 4 months REFLEX STIMULATI BABY’S TYPICAL TYPICAL ming put into coordinated ON BEHAVIOR AGE OF AGE OF water swimming APPERAN DISAPPE face movements CE ARANCE down Moro Baby is Extends legs, 7th month 3 months dropped or arms, and of Molding the Brain: The Role of Experience hears loud fingers, gestation noise arches, back, Although the brain’s early development is draws back genetically directed, it is continually modified by head environmental experience. Darwini Palm of Makes 7th month 4 months Our brains are not static; rather, they are living, an baby’s hand strong fist; of (graspin is can be raised gestation changeable organs that respond to environmental g) stroked. to standing influences. position if The technical term for this malleability of the brain both fists are is plasticity, which may be an evolutionary closed around a mechanism to enable adaptation to environmental stick change. Tonic Baby is laid Turns head 7th month 5 months neck down on to one side, of EARLY SENSORY CAPACITIES back assumes gestation Touch and Pain. fencer position, Touch is the first sense to develop, and for the first extends arm several months it is the most mature sensory and leg on system. preferred When a newborn’s cheek is stroked near the side, flexes opposite mouth, the baby responds by trying to find a limbs nipple, an evolved survival mechanism. Babkin Both of Mouth Birth 3 months Smell and Taste baby’s opens, eyes The senses of smell and taste also begin to develop palms close, neck are stroked flexes, head in the womb. at once tilts forward A preference for pleasant odors seems to be learned in utero and during the first few days after EARLY HUMAN REFLEXES birth, and the odors transmitted through the REFLEX STIMULA BABY’S TYPICAL TYPICAL mother’s breast milk may further contribute to this TION BEHAVIOR AGE OF AGE OF APPERAN DISAPPE learning. CE ARANCE This attraction to the fragrance of the mother’s Babinski Sole of Toes fan out; Birth 4 months milk may be another evolutionary survival baby’s foot twists in mechanism. foot is stroked  Hearing. Although boy babies tend to be a little bigger and more Hearing, too, is functional before birth; fetuses active than girl babies, there are no gender differences respond to sounds and seem to learn to recognize in infants’ motor development. them. Head control From an evolutionary perspective, early At birth, most infants, can turn their heads from recognition of voices and language heard in the side to side while lying on their backs. womb may lay the foundation for the relationship When lying chest down, many can lift their heads with the mother, which is critical to early survival. enough to turn them. Within the first 2 to 3 Sight months, they lift their heads higher and higher--- Vision is the least developed sense at birth, sometimes to the point where they lose their perhaps because there is so little to see in the balance and roll over on their backs. womb. By 4 months, almost all infants can keep their From an evolutionary developmental perspective, heads erect while being held or supported in a the other senses, as we have pointed out, are more sitting position. directly related to a newborn’s survival. Hand Control Visual perception and the ability to use visual Babies are born with a grasping reflex. If the palm information--- identifying caregivers, finding food, of an infant’s hand is stroked, the hand closes and avoiding dangers--- become more important as tightly. infants become more alert and active. At about 3 ½ months, most infants can grasp an object of moderate size, such as a rattle, but have MOTOR DEVELOPMENT trouble holding a small object. MILESTONES OF MOTOR DEVELOPMENT Next, they begin to grasp objects with one hand Babies first learn simple skills and then combine them and transfer them to the other, and then to hold into increasingly complex systems of action, which (but not pick up) small objects. permit a wider or more precise range of movement and Sometime between 7 and 11 months, their hands more effective control of the environment. become coordinated enough to pick up a tiny In developing the precision grip, for example, an infant object, such as a pea, using the pincer grasp. first tries to pick things up with the whole hand, fingers By 15 months, the average baby can build a tower closing against the palm. of two cubes. Later the baby masters the pincer grasp, in which A few months after the 3rd birthday, the average thumb and index finger meet at the tips to form a circle, toddler can copy a circle fairly well. making it possible to pick up tiny objects. Locomotion The Denver Developmental Screening Test is used to After 3 months, the average infant begins to roll chart progress between ages 1 month and 6 years and over deliberately (rather than accidentally, as to identify children who are not developing normally. before) --- first from front to back and then from back to front. The test measures gross motor skills (those using large The average baby can sit without help by about 8 ½ muscles), such as rolling over and catching a ball, and months. fine motor skills (using small muscles), such as grasping a rattle and copying a circle. Between 6 and 10 months, most babies begin to get around under their own power by means of It also assesses language development (for example, creeping or crawling. knowing the definition of words) and personality and Crawling infants become more sensitive to where social development. objects are, how big they are, whether they can be In learning to walk, an infant gains control of separate moved, and how they look. movements of the arms, legs, and feet before putting Crawling helps babies learn to judge distances and these movements together to take that momentous perceive depth. first step. They learn to look to caregivers for clues as to The developments follow the cephalocaudal (head to whether a situation is secure or frightening---a skill tail) and proximodistal (inner to outer) principles known as social referencing. outlined earlier.  By holding onto a helping hand or a piece of Eleanor and James Gibson’s Ecological Theory of furniture, the average baby can stand at a little past Perception age 7 months. Ecological Theory of Perception – theory developed by The average baby can let go and stand alone well Eleanor and James Gibson, which describes developing at about 11 ½ months. motor and perceptual abilities as interdependent parts During the 2nd year, children begin to climb stairs of a functional system that guides behavior in varying one at a time, putting one foot after another on the contexts. same step; later they will alternate feet. In a classic experiment by Richard Walk and Eleanor Also in their 2nd year, toddlers run and jump. Gibson (1961), 6-month-old babies were seated on top By age 3 ½, most children can balance briefly on of a plexiglass tabletop laid over two ledges. one foot and begin to hop. Between the ledges was an apparent drop. This illusory drop was made more prominent by using MOTOR DEVELOPMENT AND PERCEPTION both low lights to minimize any reflection from the Sensory and motor activity seem fairly well coordinated plexiglass and a bright checkerboard patterned cloth. from birth. From the far side of the table, the infants’ mothers then Infants begin reaching for and grasping objects at about beckoned their children. 4 to 5 months; by 5 ½ months they can adapt their To the babies, it appeared that their mothers were reach to moving or spinning objects. asking them to crawl over a visual cliff—a steep drop Piaget and other researchers long maintained that down to the floor. reaching depended on visual guidance: the use of the Walk and Gibson wanted to know if babies would eyes to guide the movement of the hands (or other willingly crawl over the deep end of the visual cliff when parts of the body). urged to do so by their mothers. Now, research has found that infants in that age group Locomotor development depends on infants’ can use other sensory cues to reach for an object. increasing sensitivity to the interaction between their They can locate an unseen rattle by its sound, and changing physical characteristics and new and varied they can reach for a glowing object in the dark, characteristics of their environment. even though they cannot see their hands. They can even reach for an object based only on Thelen’s Dynamic Systems Theory their memory of its location. Dynamic Systems Theory (DST) – theory which holds Slightly older infants, ages 5 to 7 ½ months, can grasp a that motor development is a dynamic process of active moving, fluorescent object in the dark---a feat that coordination of multiple systems within the infant in requires awareness, not only of how their own hands relation to the environment. move but also of the object’s path and speed, so as to Infant and environment form an interconnected, anticipate the likely point of contacts. dynamic system. More recently, researchers have realized that in Maturation alone cannot explain such an observation. younger infants, clumsy corrective movements are These same systems of dynamic influences affect all more likely to be illustrating immature cerebellar motor movements, from reaching for a rattle to sitting development. independently to learning to walk. Depth perception – ability to perceive objects and surfaces three-dimensionally. Kinetic cues are produced by movement of the object or the observer, or both. Haptic perception – ability to acquire information about properties of objects, such as size, weight, and texture, by handling them. Infants appear capable of using haptic information even prenatally.