12/3/20091Chapter 2: InfancyModule 2.1Physical Developmentin Infancy2/3/20092Looking Aheadz How do the human body and nervous system develop?z Does the environment affect the pattern of development?z What developmental tasks must infants accomplish in this period?z What is the role of nutrition in physical development?z What sensory capabilities do infants possess?22/3/20093GROWTH AND STABILITY2/3/20094Physical Growthz Rapid growth during first two years32/3/20095Head-to-body size ratio changes dramatically2/3/20096Nervous System and Brainz Nervous systemcomprises the brain and the nerves that extend throughout the bodyz Neurons are the basic cells of the nervous system42/3/200972/3/20098Cellular Basis of Brain Developmentz Migration of cellsz Formation and growth of axonsz Formation of dendritesz Formation of synaptic connectionsz Myelination52/3/20099How brains growz Birth: – 100-200 billion neurons– Relatively few neuron-to-neuron connectionsz During first two years:– Billions of new connections established and become more complex2/3/200910Use it or lose itSynaptic pruningz Unused neurons are eliminatedz Allows established neurons to build more elaborate communication networks with other neuronsz Development of nervous system proceeds most effectively through loss of cellsBut also note the importance of myelin62/3/200911Form and Function: Brain Growthz Neurons reposition themselves with growth, becoming arranged by function – Cerebral cortex– Subcortical levels2/3/200912Environmental Influences on Brain Developmentz Plasticityz Sensitive period72/3/200913Don’t shake the baby!z Shaken Baby Syndrome–Brain sensitive to injury–Shaking can lead to brain rotation within skullz Blood vessels tearÆsevere medical problems, long-term disabilities, and sometimes death2/3/200914MOTOR DEVELOPMENT82/3/200915Reflexes: Inborn Physical Skillsz Reflexes: learned, organized involuntary responses that occur automatically in presence of certain stimuli2/3/200916permanentSwallowingpermanentSuckingDisappears over first few weeks; replaced by voluntary head turningRootingpermanentPupillarypermanentEye-blinkpermanentBreathingMajor Reflexes in Full-Term Neonates: Survival92/3/2009172/3/200918First 8 weeksStepping4-6 monthsSwimmingArms and arching stop at 4-6 monthsMoro3-4 months; replaced by voluntary graspingPalmar grasping8 month-1 yearBibinski (plantar)Major Reflexes in Full-Term Neonates: Primitive102/3/2009192/3/200920112/3/2009212/3/200922Motor Development in InfancyMilestones of Normal Motor Development122/3/2009232/3/200924Motor Development in InfancyFine Motor Skills132/3/200925Developmental NormsComparing 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 cautionz Brazelton Neonatal Behavior Assessment Scale (NBAS)2/3/200926Nutrition in InfancyFueling Motor Developmentz Without proper nutrition, infants cannot reach physical potential and may suffer cognitive and social consequencesz Infants differ in growth rates, body composition, metabolism, and activity levels142/3/200927So what is a healthy caloric allotment for infants?z About 50 calories per day for each pound of weightz Most infants regulate their caloric intake quite effectively on their ownz If are allowed consume as much they seem to want, and not pressured to eatmore, they will be healthy2/3/200928Malnutritionz Children living in many developing countries z Slower growth rate z Chronically malnourished during infancy = later lower IQ score152/3/200929Learning about the Worldz Sensationz Perception2/3/200930Visual Perception: Seeing the Worldz Newborn’s distance vision ranges from 20/200 to 20/600 z By 6 months, average infant’s vision is already 20/20 z Other visual abilities grow rapidly– Binocular vision– Depth
View Full Document