CHAPTER 4: Physical Development in Infancy and Toddlerhood
Changes in the body size and muscle – fat makeup
End of the first year typical infants height is about 32 inches and 50 percent greater at birth.
2 years nearly 75 percent greater and 36 inches
Baby fat helps keep constant body temperature
Muscle tissue increases very slowly during infancy and will not reach a peak until adolescence.
Ethnic groups differ in body size. GROWTH NORMS: Height, weight averages for children age.
Children of the same age also differ in rate of physical growth, some progress more rapidly than others.
SKELETON AGE: A measure of bone development determined by X-raying the long bones of the body to see extent to which soft flexible cartilage has hardened into bone, a gradual process.
CHANGES IN BODY PROPORTIONS * As the child’s overall size increases, different parts of the body grow at different rates. * Two growth patterns describe these changes. * 1. CEPHALOCAUDAL TREND: During the prenatal period: the head develops more rapidly than the lower part of the body. At birth the head takes up ¼ of the body. * 2. PROXIMODISTRAL TREND: Growth start from the center of the body, outward (near to far)
PRENATAL PERIOD: The head, chest and trunk grow first then the arms and legs, finally the hands and feet.
INFANCY AND CHILDHOOD: The arms and legs continue to grow somewhat ahead of hands and feet.
BRAIN DEVELOPMENT: At birth, the brain is nearer to its adult size brain than other physical structure.
WE CAN BEST UNDERSTAND BRAIN GROWTH BY LOOKING AT IT FROM TWO POINTS OF VIEWS: 1. MICROSCOPIC level of individual brain cells. 2. Large level of the cerebral cortex, which is responsible for the highly developed intelligence of our species.
NEURONS: Store and transmit information
SYNAPSES: Tiny gaps where fibers from different neurons come close together but don’t touch.
NEUROTRANSMITTERS: Neurons send messages to one another by releasing chemicals, which cross synapses.
BRAIN GROWTH: How neurons develop and form this communication system.
EMBRYO’S PRIMITIVE NEURAL TUBE: Where the neurons are produced during pregnancy. * They migrate to form the major parts of the brain * Once the neurons are in place, they differentiate establishing their unique functions by extending their fibers to form synaptic connections with neighboring cells. * During the first two years, NEURAL FIBERS AND SYNAP CELLS increase at a fast pace because developing neurons require space for these connective structures and a surprising aspect of brain growth is that as synapses form, many surrounding neurons die 20-80 percent, depending on the brain region. * Fortunately, during prenatal period, the NEURAL TUBE produces more neurons that the brain NEEDS.
SYNAPTIC PRUNNING: Neurons that are rarely stimulated soon lose their synapse that returns neurons not needed at the moment to an uncommitted state so that they can support future development.
GLIAL CELLS: Responsible for MYLENATION, the coating of neural fibers with an insulating fatty sheath (myelin) which improves the efficiency of messenger transfer.
BRAIN DEVELOPMENT “Living structure” * After neurons and synapses are over produced, cell death and synaptic pruning sculpt away excess building material to form the mature brain: a process jointly influenced by a genetically programmed events and the child’s experiences.
METHODS FOR MEASURING BRAIN FUNCTIONING * EEG, ERP, FMRI, PET, NIROT
EEG AND ERP detect changes in electrical activity.
EEG examines brain wave patterns for stability
ERP detect general location of brain waves activity in the cerebral cortex. * (ERP) A method often used to study preverbal infant’s responsiveness to various stimuli and the impact of experience on specialization of cortical regions.
FMRI: Most promising method. * Doesn’t require X-ray * When an individual is exposed to a stimulus, FMRI detects changes in the body flow and oxygen metabolism, creating a colorful, moving picture of parts of the brain used to process information or perform an activity. * Requires you to lie down in a motionless environment; therefore, kids can’t do this.
NIROT
* Works well for children (fibers strapped to scalp)
Developmental of Cerebral cortex * Surrounds the rest of the brain * Shaped as a walnut * Largest, most complex * 85 % of the brain’s weight and containing neurons and synapses. * Receives information from the senses * Instructs the body to move and think
FRONTAL LUBES * Most extended period of development * Responsible for thought, consciousness, inhabitation of impulses, use of memory,
Reasoning and problem solving strategies * Age two: function properly and effectively. * Undergo rapid myelination and formation and pruning of synapses during the preschool and school years, followed by another period of accelerated growth in adolescence, when frontal lubes reach an adult level of synapses.
CEREBRAL CORTEX HAS 2 HEMISPHERES: LEFT AND RIGHT
LEFT: Verbal abilities (spoken and written languages) * Positive emotion (joy) * Newborns show more ERP brain activity and speech sounds. * Studies using FMRI reveal that the left hemisphere is better at processing information at sequential, communicative information; both verbal.
RIGHT: Spatial abilities (judging distances, reading maps, recognizing shapes.) * Negative emotion (distress) * Studies using fMRI reveal that humans cope more successfully with changing environmental demands.
BRAIN PLASTICITY: A highly plastic cerebral cortex, in which many areas aren’t committed to a specific function and have a high capacity for learning * If a part of the cortex is damaged, other parts can take over tasks it would have handled. * Once the hemisphere laterize, damage to a specific region means that the abilities it controls can’t be recovered as fully or as easily as earlier * Brain is more plastic at younger age
TWO TYPES OF BRAIN DEVELOPMENT 1. Experience-expectant brain growth: refers to the young brain’s rapidly developing organization, which depends on ordinary experiences – opportunities to see and touch objects to near language and other sounds and to move about and explore environment. 2. Experience- dependent brain growth: consists of additional growth and refinement of establishing brain structures as a result of specific learning experiences that occur throughout our lives; varying across individuals and cultures.
MELATONINE: A hormone within the brain that promotes drowsiness, much greater at night than during the day. Occurs during the middle of first year * At the end of the first year, the REM sleep declines and the baby sleep like a adult.
INFLUENCES ON EARLY PHYSICAL GROWTH 1. Heredity, 2. Nutrition, 3. Emotional well being
HEREDITY: When diet and health are adequate, height and rate of physical growth are largely determined by heredity.
CATCH UP GROWTH: A return to a genetically influenced growth path once conditions improve. The brain, heart and digestive system and many other internal organs may be permanently compromised prenatal nutrition for long term health.
Genetic make-up affects body weight.
BREAST FEEDING: best option!!! * Breast fed babies in poverty stricken regions are much less likely to be malnourished and 14-16 percent more likely to survive the first year. * Offers protection against respiratory and intestinal infections * Helps increase spacing between siblings
BOTTLE FEEDING: not good!!! * Poor sanitation = bad amount of deaths.
WAYS TO PRECENT OBESITY 1. Breast feeding for 6 months 2. Avoid foods with sugar, saturated fats and salts 3. Limit TV
MARASMUS: Waste condition of the body caused by a diet low in all essential nutrients. It usually appears in the first year of life when a baby’s mother is too malnourished to produce enough breast milk and bottle feeding is adequate. Painfully, thin and in danger of dying
KWASHIORKOR: Caused by an unbalanced diet, this is very low in protein. The disease usually strikes after weaning between 1-3 years of age. It is common in regions where children get enough calories from starchy foods but barely any protein.
NON ORGANIC FAILURE TO THRIVE: A growth disorder resulting from a lack of prenatal love is usually present by 18 months of age. Infants who have it show all the signs of MARASMUS. Their bodies look wasted and they are withdrawn and apathetic no organic cause for the baby’s failure to grow can be found.
HABITUATION: Refers to a gradual reduction in the strength of a response due to repetitive t
RECOVERY: A new stimulus change in the environment which causes responsiveness to return to a high level, an increase. * Habituation and recovery promote efficiency learning by focusing our attention on those aspects of the environment we know least about.
REMOTE MEMORY: Memory for the stimuli to which infants were exposed weeks/ months earlier.
IMITATION: Copying the behavior of another person. * Some researchers argue that certain newborns “imitative” responses are actually MOUTHING!!! – Common early exploratory response to interesting stimuli. * Harder to induce in 2-3 months old than just after birth * Therefore, skeptics believe that the newborn imitative response is little more than automatic response that declines with age, much like a reflex. * Others claim imitation doesn’t decline, but reflexes do. ANDREW MELTZOFF: Newborns imitate as much as older children and adults do by actively trying to match body movements they see with ones they feel themselves make. MIRROR NEURONS: Specialized cells in motor areas of the central cortex in primates. * Are identically when a primate hear or sees an action and when it carries out that action on its own * Believed to be the biological bases of a variety of interrelated, complex, social abilities; which includes imitation, empathic sharing of emotions and understanding of others intentions. * Early as in 6 months. ***IMITATION is the most powerful means of learning! MOTOR DEVELOPMENT: * Babies motor development achievements have a powerful effect on their social relationships. * Motor, social, cognitive, language competencies developed together and support. GROSS MOTOR DEVELOPMENT: Refers to control over actions that help infants get around the environment (crawling, waking, and standing) FINE MOTOR DEVELOPMENT: Smaller movements (reaching and grasping) CEPHALOCAUDAL TREND: Is evident, motor control of the head comes before the control of the arms and trunk. PROXIMODISTRAL TREND: Head, trunk and arm control precedes coordination of the hands and fingers. – Many influences (together to internal and external) to the child, join together to support the cast transportations in motor competencies of the first two years. DYNAMIC SYSTEMS THEORY OF MOTOR DEVELOPMENT: Mastery of motor skills involves acquiring increasingly complex systems of action. * When motor skills work as a system, separate abilities blend together, each cooperating with others to produce more effective ways of exploring and controlling environment. * Each new skill is joint together product of 4 factors: * 1. CNS development * 2.Bodys movement capacities * 3. The goals the child has in mind * 4. Environmental supports for the skill * Change in any element makes the system less stable and the child begins to explore and select new, more effective patterns. * Dynamic systems theory shows us why motor development can’t be genetically determined because it is motivated by exploration and the desire to master new tasks, heredity can map it out only at a general level. Rather than being hardwired into the NS, behaviors are softly assembled, allowing for different paths to the same motor skill. CULTURAL VARIATIONS IN MOTOR DEVELOPMENT: Wayne Dennis (1960) – Observed Iranian orphan infants who were deprived from tantalizing sounds. -Indians and Japanese discourage walking to prevent touching of stoves. FINE MOTOR DEVELOPMENT: Reaching and Grasping GREATEST MOTOR SKILL: Reaching! * Infant cognitive development * PRE-REACHING: Newborns make poorly coordinated swipes or wings towards an object in front of them, but because of poor arm and hand control, they rarely contact the object. * PASSIVE PROCESS: What they baby’s receptors detect when exposed to the stimulation. * Perception is active, when we perceive we organize and interpret what we see. HEARING: Babies organize sound into increasingly complex patterns. SPEECH PERCEPTION * ERP brain waves recordings reveal that around 5 months, babies become sensitive to syllable stress patterns in their own language. ANALYZING SPEECH STREAM * Research that shows that they have impressive statistical learning capacity- by analyzing the speech stream for patterns repeatedly occurring sequences of sounds that acquire a stock of speech structures for which they will later learn meaning, long before they state to talk around age 12 months. * VISION: Humans depend on vision more than any other source!!! * Vision activity: Improves steadily throughout the first year. * Vision cliff findings show that crawling and avoidance of drop offs are linked but now how they are related or when depth perception first appears. * FIRST DEPTH – MOTOR * Binocular depth cues arise because our 2 eyes have slightly different views on the visual field. PICTIONAL DEPTH DUE: The ones artists use to make a painting look 3 dimensional. * Examples are receding lines that create an illusion of perspective changes in texture, over lapping objects. Pattern Perception * Contrast sensitivity: Explains early pattern preferences. * Contrast refers to the difference in the amount of light between adjacent regions in a pattern. * If babies are sensitive to (can detect) the contrast in two or more patterns, they prefer the one with more contrast. * 4 months – can detect pattern Face perception * Other asserts that newborns prefer any stimulus in which the most significant elements are arranged horizontally in the upper part of the pattern like the eyes. INTERMODAL PERCEPTION * “We make sense of these running streams of light, sound, tackle, odor, and taste information by perceiving them as unified wholes. We know for example that an objects shape is the same whether we see it or touch it; that breaking a glass causes a sharp, crashing sound; that the pattern of footsteps signals the approach of a person. DIFFENTIATE THEORY * Infants actively search for invariant features of the environment – those remain stable in a constant changing perceptual world.