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Physical Development in Infancy Chapter 4 Robert S. Feldman Copyright © 2011 Pearson Education, Inc. All rights reserved. Looking Ahead How do the human body and nervous system develop? Does the environment affect the pattern of development? What developmental tasks must infants accomplish in this period? What is the role of nutrition in physical development? What sensory capabilities do infants possess? GROWTH AND STABILITY Physical Growth Table 4-1. The Major Principles Governing Growth Can you give an example of each principle? An Interesting Head Count Figure 4-2. Decreasing Proportions Are there gender and ethnic differences in infant weight and length? See how they grow… Nervous System and Brain Nervous system comprises the brain and the nerves that extend throughout the body Neurons are the basic cells of the nervous system Coming to terms with your brain… Neurons Dendrites Axons Neurotransmitters Synapses And a few more! Brain stem Limbic system Cerebral cortex How great brains grow! Birth: 100-200 billion neurons Relatively few neuronsneuron connections During first two years: Billions of new connections established and become more complex Use it or lose it! Synaptic pruning Unused neurons are eliminated Allows established neurons to build more elaborate communication networks with other neurons Development of nervous system proceeds most effectively through loss of cells Myelin Form and Function: Brain Growth Neurons reposition themselves with growth, becoming arranged by function Cerebral cortex Subcortical levels Don’t shake the baby! Shaken Baby Syndrome Brain sensitive to form forms of injury Shaking can lead to brain rotation within skull Blood vessels tear severe medical problems, long-term disabilities, and sometimes death Brain Development: Influences and Definitions • Environmental Influences • Sensitive Period • Plasticity Do Baby Einstein programs really work? What do babies do all day? Life Cycles of Infancy Wake Sleep Eat Eliminate Rhythms and States 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 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 4-2) Table 4-2 REM Sleep Period of active sleep Closed eyes begin to move in a back-and-forth pattern Takes up around one-half of infant sleep 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 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! SIDS Sudden Infant Death Syndrome Leading cause of death in children under 1 year of age Back-to-sleep guidelines (AAP) Differential risk Boys African American infants Low birthweight Low APGAR scores Mother’s smoking Some brain defects Child abuse Declining Rates of SIDS Review and Apply REVIEW The major principles of growth are the ____ principle, the ____ principle, the principle of ____ ____, and the principle of the ____ of systems. The development of the ____ system first entails the development of billions of neurons and interconnections among them. Later, the numbers of both ____ and ____ decrease as a result of the infant’s experiences. Review and Apply REVIEW ____ ____, the susceptibility of a developing organism to environmental influences, is relatively high. Researchers have identified ____ periods during the development of body systems and behaviors— limited periods when the organism is particularly ____ to environmental influences. Babies integrate their individual behaviors by developing ____—repetitive, cyclical patterns of behavior. A major rhythm relates to the infant’s state—the awareness it displays to ____ and ____ stimulation. Review and Apply APPLY 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? What are some cultural or sub-cultural influences that might affect parents’ child-rearing practices? MOTOR DEVELOPMENT Reflexes: Inborn Physical Skills Reflexes: learned, organized involuntary responses that occur automatically in presence of certain stimuli What did you see? Take two minutes to list the reflexes you saw in the clip. Why do reflexes come and go? Ethnic and Cultural Differences and Similarities in Reflexes Reflexes Genetically determined Universal Cultural variations in ways displayed Moro reflex Serves Diagnostic tool Social function Survival function Motor Development in Infancy Milestones of Normal Motor Development Dynamic Systems Dynamic systems theory describes how motor behaviors are assembled Motor skills do not develop in vacuum Each skill advances in context of other motor abilities As motor skills develop, so do non-motoric skills Theory places emphasis on child’s own motivation (a cognitive state) in advancing important aspects of motor development Developmental Norms Comparing Individual to 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) Developmental Diversity Cultural Dimensions of Motor Development Using information from your text, answer the following: Does earlier emergence of a basic motor behavior in a given culture has lasting consequences for specific motor skills and for achievements in other domains? Nutrition in Infancy Fueling Motor Development Without proper nutrition, infants cannot reach physical potential and may suffer cognitive and social consequences Infants differ in growth rates, body composition, metabolism, and activity levels So what is a healthy caloric allotment for infants? About 50 calories per day for each pound of weight Most infants regulate their caloric intake quite effectively on their own If are allowed consume as much they seem to want, and not pressured to eat more, they will be healthy Malnutrition Children living in many developing countries Slower growth rate Chronically malnourished during infancy = later lower IQ score Are problems of malnourishment restricted to developing countries? Undernutrition: Dietary Deficiencies Undernutrition also has long-term costs, including mild to moderate cognitive delays Up to 25% of 1- to 5-year-old US children have diets that fall below minimum caloric intake recommended by nutritional experts When Malnutrition Is Severe Maramus Kwashiorkor Nonorganic Failure to Thrive Sufficient nutrition Symptoms Reversal “A fat baby is a healthy baby”? From Research to Practice Fast-Food Babies Develop taste for certain foods at an early age and then tend to stick with those foods as they get older Like food mother likes Often consume convenience foods that are high in sugar and fat and low in nutrients Why does it matter? Question: What was US toddlers’ reported favorite vegetable in a recent study? Answer: So… If you were to advise new parents on the right and wrong foods to offer their newborn child, what would you tell them? Is Breast Best? Social Patterns in Breast-Feeding 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 Cerealstrained fruits Review and Apply REVIEW Reflexes are ____, ____ acquired physical behaviors. During infancy children reach a series of milestones in their ____ development on a fairly ____ schedule, with some individual and ____ variations. Training and cultural expectations affect the ____ of the development of ____ skills. Review and Apply REVIEW Nutrition strongly affects ____ development. ____ can slow ____, affect ____ performance, and cause diseases such as marasmus and kwashiorkor. The victims of undernutrition also suffer negative effects. The advantages of breast-feeding are numerous, including ____, ____, ____, and ____ benefits for the infant, and physical and emotional benefits for the ____ as well. Review and Apply APPLY 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? Review and Apply APPLY What might be some of the reasons that malnourishment, which slows physical growth, also harm IQ scores and school performance? How might malnourishment affect education in third world countries? Learning the World Sensation Perception If all the lights in this room went out RIGHT NOW, what would your senses tell you (sensation)? What you think about being in the dark with your class (perception) or about an instructor who was crazy enough to go to blackout to teach a concept (fill in this part yourself)? 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 Infant Visual Preference Preferences that are present from birth Genetically preprogrammed to prefer particular kinds of stimuli Prefer to look at patterned over simpler stimuli 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 groups of different sounds React to changes in musical key and rhythm Can discriminate many language related sounds Smell and Taste in a Small World Smell Well developed at birth Helps in recognition of mother early in life Taste Have innate sweet tooth Show facial disgust at bitter taste Develop preferences based on what mother ate during pregnancy Ouch! Contemporary Views on Infant Pain Developmental progression in reaction to pain Infants born with capacity to experience pain; produces distress Exposure to pain in infancy may lead to permanent rewiring of nervous system resulting in greater sensitivity to pain during adulthood The Power of Touch • Touch is one of most highly developed sensory systems in a newborn • Even youngest infants respond to gentle touches • Several of the basic reflexes present at birth require touch sensitivity to operate Does massage work? 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 infant’s sensory systems are initially separate and that brain development leads to increasing integration What are affordances? Perceptible affordances Exist where information on actions that are afforded are perceptible These are dependent on language, culture, context, and experience and vary for different individuals Becoming an Informed Consumer of Development Exercising Your Infant’s Body and Senses Attempts to accelerate physical and sensoryperceptual development yield little success but infants need sufficient physical and sensory stimulation. How can this be accomplished? Carry a baby in different ways Let infants explore their environment Engage in “rough-and-tumble” play Let babies touch their food and even play with it • Provide toys that stimulate the senses, particularly toys that can stimulate more than one sense at a time • • • • Review and Apply REVIEW Infants are sensitive to ____ and ____, and most medical authorities now subscribe to procedures, including anesthesia, that ____ infants’ pain. Infants also have a keen ability to ____ information from more than one ____. ____ refers to the activation of the sense organs by ____ stimuli. ____ is the analysis, interpretation, and integration of sensations. Review and Apply REVIEW Infants’ sensory abilities are surprisingly ____ ____ at or shortly after birth. Their ____ help them explore and begin to make sense of the world. Very early, infants can see ____ and ____, distinguish ____ and patterns, localize and discriminate sounds, and recognize the ____ and ____ of their mothers. Review and Apply APPLY What might be the advantages and disadvantages of swaddling, a practice in which a baby is snuggly wrapped in a blanket and which usually calms an infant? Persons who are born without the use of one sense often develop unusual abilities in one or more other senses. What can healthcare professionals do to help infants who are lacking in a particular sense? EPILOGUE Turn back for a moment to the prologue of this chapter, about a baby’s first steps, and answer these questions: Which principles of growth (i.e., cephalocaudal, proximodistal, heirarchical integration, independence of systems) account(s) for the progression of physical activities that precedes Allan’s first steps? Were Allan’s parents right to worry when Allan was “behind schedule” with his first steps? What would you say to them, or to other parents in similar circumstances? EPILOGUE In walking at 10 months of age, Todd outpaced his little brother Allan by three months. Does this fact have any implications for the comparative physical or cognitive abilities of the two brothers? Why? Do you think anything changed in the environment between the time Todd and Allan were born that might account for their different “first step” schedules? If you were researching this question, what environmental factors would you look for?