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Growth and Stability Motor Development The Development of the Senses Growth and Stability Height and Weight Growth Although the greatest increase in height and weight occurs during the first year of life, children continue to grow throughout infancy and toddlerhood. Are there gender and ethnic differences in infant weight and length? Decreasing Proportions At birth, the head represents onequarter of the neonate’s body. By adulthood, the head is only one-eighth the size of the body. Why is the neonate’s head so large? Principles of Growth • • • • Cephalocaudal principle Proximodistal principle Principle of hierarchical integration Principle of independence of systems Can you give an example of each of these? Nervous System and Brain: Foundations of Development Nervous system comprises the brain and the nerves that extend throughout the body. Neurons are the basic cells of the nervous system. The Neuron Quick Check Neurons Dendrites Axons Neurotransmitters Synapses How great brains grow! Birth: – 100-200 billion neurons – Relatively few neuron-neuron connections During first two years: – Billions of new connections established and become more complex NEURON NETWORKS Over the first 2 years of life, networks of neurons become increasingly complex and interconnected. Why are these connections important? Source: From The Postnatal Development of the Human Cerebral Cortex, Vol I–VIII by Jesse LeRoy Conel, Camevebridge, Mass.: Harvard University Press, Copyright © 1939, 1975 by the President and Fellows of Harvard College. Use it or lose it! Synaptic pruning • Involves elimination of unused neurons Myelin • Includes fatty substance that provides protection and speeds transmission of nerve impulses • Allows established neurons to build more elaborate communication networks with other neurons • Development of nervous system proceeds most effectively through loss of cells • Is an outgrowth of a glial cel. Form and Function: Brain Growth Neurons reposition themselves with growth, becoming arranged by function – Cerebral cortex – Subcortical levels Shaken Baby This CAT scan shows severe brain injury in an infant suspected of being abused by caretaker shaking. Source: Malung, Bilo, Kuba & van Rijn, 2011. Environmental Influences on Brain Development Plasticity Sensitive period Do you know? What are some cultural or subcultural influences that might affect parents’ childrearing practices? What do babies do all day? Life Cycles of Infancy Wake Defecate Sleep Eat Rhythms and States Rhythms – Repetitive, cyclical patterns of behavior State – One of major body rhythms – Degree of awareness infant displays to both internal and external stimulation – Change in state alters amount of stimulation required to get infant’s attention Sleep: Perchance to Dream Sleep is major state – 16-17 hours daily (average); wide variations Different than adult sleep – 2 hour spurts; periods of wakefulness – Cyclic pattern – By 16 weeks sleep about 6 continuous hours; by 1 year sleep through night (See table 3-2) Infants sleep in spurts, often making them out of sync with the rest of the world. Primary Behavioral States Source: Adapted from Thoman & Whitney, 1990. Primary Behavioral States Source: Adapted from Thoman & Whitney, 1990. REM Sleep • Involves period of active sleep • Occurs when closed eyes begin to move in a back-and-forth pattern • Takes up around one-half of infant sleep As we age, the proportion of REM sleep increases as the proportion of non-REM sleep declines. In addition, the total amount of sleep falls as we get older. Source: Adapted from Roffwarg, Muzio, & Dement, 1966. • May provide means for brain to stimulate itself through autostimulation Do babies dream? Did you find examples in the text that suggest that cultural practices affect infants’ sleep patterns? SIDS Sudden infant death syndrome • Leading cause of death in children under 1 year of age • Back-to-sleep guidelines (AAP) Hypotheses about cause • Undiagnosed sleep disorders • Suffocation • Nutritional deficiencies • Problems with reflexes • Brainstem abnormalities • Undiagnosed illness Actual cause of SIDS remains elusive! Declining Rates of SIDS In the United States, SIDS rates have dropped dramatically as parents have become more informed and put babies to sleep on their backs instead of their stomachs. Source: American SIDS Institute, based on data from the Center for Disease Control and the National Center for Health Statistics, 2004. SIDS is found in children of every race and socioeconomic group and in children who have had no apparent health problems. Back-to-sleep is important! The major principles of growth are the cephalocaudal principle, the proximodistal principle, the principle of hierarchical integration, and the principle of the independence of systems. The development of the nervous system first entails the development of billions of neurons and interconnections among them. Later, the numbers of both neurons and connections decrease as a result of the infant’s experiences. Infants integrate their individual behaviors by developing rhythms—repetitive, cyclical patterns of behavior. The sleep of infants often comes in fits and starts initially coming in spurts of about two hours, followed by periods of wakefulness. Because of this, infants are “out of sync” with the rest of the world, for whom sleep comes at night and wakefulness during the day. The __________ principle states that growth begins with the head and proceeds down to the rest of the body; the __________ principle states that development proceeds from the center of the body outward. a. cephalocaudal; proximodistal b. proximodistal; cephalocaudal c. hierarchical integration; independence of systems d. independence of systems; hierarchical integration The process of synaptic pruning allows established neurons to build stronger networks and reduces unnecessary neurons during the first 2 years of life. • True • False Although brain development is largely genetically predetermined, it is also susceptible to environmental experiences; the ability of the brain to be modifiable by the environment is called (a) __________. a. plasticity b. synaptic pruning c. sensitive period d. critical period What evolutionary advantage could there be for infants to be born with more nerve cells than they actually need or use? How might our understanding of synaptic “pruning” affect the way we treat infants? Motor Development Reflexes: Inborn Physical Skills Reflexes: • learned, organized involuntary responses that occur automatically in presence of certain stimuli Why do reflexes come and go? Some Basic Reflexes in Infants Can you identify the approximate age of disappearance and describe each of these reflexes? • Rooting reflex • Stepping reflex • Swimming reflex • Moro reflex • Babinski reflex • Startle reflex • Eye-blink reflex • Sucking reflex HINT: Check Table 3-3! • Gag reflex Ethnic and Cultural Differences and Similarities in Reflexes Reflexes are: – Genetically determined – Universal Cultural variations in ways displayed – Example: Moro reflex Serve as: – Diagnostic tool – Social function – Survival function Moro reflex Rooting reflex Startle reflex INFANT REFLEXES Motor Development in Infancy Gross motor skills • Young infants accomplish some kinds of movements. Fine motor skills • As infants are perfecting their gross motor skills, such as sitting upright and walking, they are also making advances in their fine motor skills. Milestones of Motor Development Developmental Norms Group norms – Represent the average performance of a large sample of children of a given age. – Permit comparisons between a particular child’s performance on a particular behavior and the average performance of the children in the norm sample. – Must be interpreted with caution. Brazelton Neonatal Behavior Assessment Scale (NBAS) Cultural Influences • Norms are useful only to the extent that they are based on data from a large, heterogeneous, culturally diverse sample of children. Cultural influences affect the rate of the development of motor skills. • Many of the norms are based on groups of infants who are predominantly Caucasian and from the middle and upper socioeconomic strata Nutrition in Infancy Fueling Motor Development So what is a healthy caloric allotment for infants? • About 50 calories per day for each pound of weight • Most infants regulate caloric intake quite effectively on their own • If allowed consume as much they seem to want and not pressured to eat more, they will be healthy Malnutrition • More common in children living in many developing countries • Characterized by lower growth rate • Chronically malnourished during infancy = lower IQ score later What might be some of the reasons that malnourishment, which slows physical growth, harms IQ scores and school performance? How might malnourishment affect education in third-world countries? When Malnutrition Is Severe Marasmus Kwashiorkor Nonorganic Failure to Thrive Sufficient nutrition Symptoms Reversal “A fat baby is a healthy baby”? Is breast best? Introducing Solid Foods: When and What? Solids can be started at 6 months but are not needed until 9 to 12 months (AAFP) – Introduced gradually, one at a time – Cereal strained fruits • Among the Ache people of South America, infants spend nearly all their time in direct physical contact with mothers. • Study found that differences between cultures that restrict early motor movement and Western cultures fade by age six. • Cultural factors help determine the time at which specific motor skills appear. Reflexes are universal, genetically acquired physical behaviors. Among the major reflexes are the rooting reflex, the Moro reflex, and the startle reflex. During infancy children reach a series of milestones in their physical development on a fairly consistent schedule, with some individual and cultural variations. Goss motor skills include rolling over, sitting, and walking. Later, fine motor skills appear, such as grasping. Nutrition strongly affects physical development. Without proper nutrition infants cannot reach their physical potential, and may suffer cognitive and social consequences as well. The advantages of breast-feeding are numerous. Behavior becomes integrated through the development of ________, which are repetitive, cyclical patterns of behaviors. a. states b. rhythms c. REM sleep d. reflexes Which of the following is NOT one of the consequences of malnutrition during infancy? a. Malnourished children sleep, on average, 6 to 8 hours less than nonmalnourished children of the same age. b. Malnourished children show a slower growth rate by the age of 6 months. c. Malnourished children score lower on IQ tests later in life. d. Malnourished children have a lower height and weight by age 2 than nonmalnourished children. Breastfeeding has been associated with enhanced cognitive growth. • True • False What advice might you give a friend who is concerned that her infant is still not walking at 14 months, when every other baby she knows started walking by the first birthday? The Development of the Senses Learning the World Visual Perception: Seeing the World • Newborn’s distance vision ranges from 20/200 to 20/600 • By 6 months, average infant’s vision is already 20/20 • Other visual abilities grow rapidly – Binocular vision – Depth perception While an infant’s distant vision is 10 to 30 times poorer than the average adult’s, the vision of newborns provides the same degree of distance acuity as the uncorrected vision of many adults who wear eyeglasses or contact lenses. Visual Cliff • The “visual cliff” experiment examines the depth perception of infants. Depth perception is a particularly useful ability, helping babies acknowledge heights and avoid falls. • Most infants in the age range of 6 to 14 months cannot be coaxed to cross the cliff, apparently patterned area drops several feet. Infant Visual Preference Preferences that are present from birth – Genetically preprogrammed to prefer particular kinds of stimuli Fantz – 2- and 3-month-old infants preferred to look at more complex stimuli than simple ones. Auditory Perception: The World of Sound Infants – Hear before birth and have good auditory perception after they are born – Are more sensitive to certain frequencies – Reach adult accuracy in sound localization by age 1 – Can discriminate between groups of different sounds – React to changes in musical key and rhythm – Can recognize many language-related sounds Smell and Taste in a Small World Infants – Well developed at birth – Helps in recognition of mother early in life Infants – Have innate sweet tooth – Show facial disgust at bitter tastes – Develop preferences based on what mother ate during pregnancy Infants’ sense of smell is so well developed hey can distinguish their mothers on the basis of smell alone. Sensitivity to Pain and Touch Pain • Infants are born with the capacity to experience pain. Signs • Heartbeat increase, sweating, facial expressions of discomfort, and change the intensity and tone of crying when hurt • Developmental progression in reactions The Power of Touch Multimodal Perception: Combining Individual Sensory Inputs New area of study in infant research • Some researchers argue that sensations are initially integrated with one another in the infant. • Others maintain that the infant’s sensory systems are initially separate and that brain development leads to increasing integration. Which view is correct? What can professionals do? Persons who are born without the use of one sense often develop unusual abilities in one or more other senses. What can health care professionals do to help infants who are lacking in a particular sense? Exercising Your Infant’s Body and Senses • Attempts to accelerate physical and sensoryperceptual development yield little success (yet). • Infants need sufficient physical and sensory stimulation. Exercising Your Infant’s Body and Senses • Carry a baby in different positions. • Let infants explore their environment. • Engage in “roughand-tumble’ play. • Let infants touch their food. • Provide toys that stimulate the senses What are affordances? Perceptible affordances – Exist where information on actions that are afforded are perceptible – Are dependent on language, culture, context, and experience and vary for different individuals Infants’ sensory abilities are surprisingly well developed at or shortly after birth. Their perceptions help them explore and begin to make sense of the world. Very early, infants can see depth and motion, distinguish colors and patterns, localize and discriminate sounds, and recognize the sound and smell of their mothers. Infants are sensitive to pain and touch, and most medical authorities now subscribe to procedures, including anesthesia, that minimize infants’ pain. The multimodal approach to perception considers how information that is collected by individual sensory systems is integrated and coordinated. ______________ is the physical stimulation of the sense organs. a. Perception b. Crying c. Crawling d. Sensation We know that infants experience pain because their heartbeat increases, they sweat, they show discomfort, and their crying changes tone. • True • False The ______________ considers how information that is collected by various individual sensory systems is integrated and coordinated. a. multimodal approach to perception b. affordance theory c. multidisciplinary motor development cycle d. macrosystem If you were selecting a mobile as a gift for a young infant, what features would you look for to make the mobile as interesting as possible for the baby?