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Chapter 4

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  1. Chapter 4 Physical Development in Infancy

  2. The Newborn Baby • What is the neonatal period? • Newborn—neonate—about 20 inches long, 71/2 lbs. • Are boys or girls bigger? • Are first borns or later borns bigger? • Some features: • Large head (1/4 the body length) • Receding chin—why? • Head may be misshapen—why? • Why do babies have “soft spots” on their heads? What are they called? • Pinkish cast—thin skin covering capillaries where blood flows • What is the fuzzy prenatal hair that newborns have on their bodies called? • What is the oily protection that babies are covered with when they are born? What purpose does it serve?

  3. Body Systems continued • First few days secrete meconium—what is that? • When bowels and bladder are full, sphincter muscles open automatically—no control yet • Why do some babies have yellowish cast to skin 3-4 days after birth? If left untreated what can happen? • Layers of fat that develop at end of fetal development help babies keep body temperature, as does increasing activity when air temp drops

  4. Physical Growth • General principles ◦Directionality ◦Cephalocaudal ◦Proximodistal • Norms and Individual Differences ◦Represent average outcomes ◦Wide variation in individual differences occur within normal range ◦Growth affected by larger genetic and cultural factors

  5. Figure 4.2: Changes in Body Proportions from Prenatal Development Through Adulthood

  6. Growth Chart

  7. Figure 4.3: Differential Growth Rates in the Human Body

  8. Development of the CNS • Division of the nervous system that consists of brain and spinal cord • Processes information and directs behavior • Develops at many levels at the same time • Reciprocal interplay between biology and context affects brain development • Brain and nervous system develop rapidly during the first 2 years

  9. The Brain • Brain development ◦Subcortical(below the cortex) structures—develop first—control states of arousal (asleep, awake, drowsy, etc.) ◦Limbic system—next, manages emotions ◦Cortex and association areas—last—involved with awareness, attention, memory, integration of information

  10. The Brain continued • 2 halves—hemispheres, connected by corpus callosum—responsible for transferring information between hemispheres • Visual cortex—regulates sight (occipital lobe) • Auditory cortex—sound (temporal lobe) • Sensorimotor cortex—processes touch • Motor cortex—voluntary movement (rear portion of the frontal lobe) • Frontal cortex—thinking, planning, initiative, impulse control, creativity • In the left cortex—Wernicke’s area—language comprehension; Broca’s area—language production, speech

  11. Figure 4.4—Areas of the Brain

  12. 3-D Brain •

  13. Brain Cells • Neurons ◦Cell body ◦Dendrites ◦Axon •

  14. Figure 4.5: The Neuron and Synapse

  15. Synaptic Development • Synaptogenesis ◦The creation of synapses—connections between neurons ◦ Occurs rapidly during first years after birth ◦ Happens in spurts ◦ Brain weight quadruples by age 4 • Pruning ◦ Eliminating unused neural pathways and connections • Prenatal brain development - YouTube

  16. Synaptic Development • Plasticity ◦ The brain’s ability to change in response to experience • Use it or Lose it ◦ Intellectually challenging environment creates a more complex network of synapses. ◦ So stimulate your baby!!! • Researchers Still Learning from Romania's Orphans : NPR

  17. Brain Plasticity • Experience-expectant processes ◦Prewired processes in the brain • Experience-dependent processes ◦Involve the active formation of new synaptic connections in response to experience • Types of plasticity ◦Modifiability: Development that asserts that, although cells are predestined for specific functions, their function can be changed • Compensation: Cells substitute for others, permitting recovery of function after loss or damage

  18. The Autonomic Nervous System • Regulates many body activities without voluntary control ◦Many systems cycle in identifiable and predictable rhythms. ◦States of arousal ◦Regulation of sleep-wake cycle

  19. Reflexes and Development • Reflexes are simple, involuntary responses to certain stimuli ◦Approach reflexes ◦Avoidance reflexes ◦Other reflexes • Most develop before birth and are normally present for four to eight months after birth

  20. Reflexes and Behavioral States Adaptive reflexes • Help survival ◦ Sucking ◦ Withdrawal from pain ◦ Opening and closing of pupil • Weak or absent reflexes warn of possible neuronal development problems •

  21. Reflexes and Behavioral States Primitive Reflexes • Controlled by less sophisticated parts of the brain—examples: ◦ Moro (or ―startle) Reflex, Babinski, Plantar, etc. • • These primitive reflexes should disappear by eight months • • Persistence (just as in absence) may indicate neurological problems

  22. Reflexes and Behavioral States States of Consciousness • Patterns of sleep and wakefulness stabilize with age • Neonates sleep 80% of the time • By 8 weeks, babies begin to sleep through the night • By 6 months, babies average 14 hours sleep per day • Clear nighttime patterns and daytime naps are established

  23. Reflexes and Behavioral States • Cries ◦ Basic cry signals hunger – rhythmic pattern click ◦ Anger cry – louder and more intense ◦ Pain cry – very abrupt onset • Cross-cultural studies suggest crying increases until 6 weeks then tapers off • Can you spoil a baby?

  24. Sensing and Perceiving • Five senses ◦Seeing • Pattern, shape, and form • Depth • Movement • Color ◦Hearing ◦Touching ◦Tasting ◦Smelling

  25. Vision • Rapid development of visual acuity—adult-like by about 6 months (20-20) • Color Vision • Red, green and blue present by 1 month • Infant’s ability to sense color almost identical to an adult’s by 4 months • Tracking • The process of following a moving object • Initially inefficient but improves rapidly

  26. What Babies Look At • Babies initially scan for light/dark contrast. • At 2 months, babies scan entire objects and scan for patterns • Caron and Caron (1981) suggest that by 3 – 4 months babies can find and pay attention to patterns

  27. What Babies Look At—Faces • Prefer mother’s face from the earliest hours of life • Focus on internal features of the face at about age 2-3 months

  28. Depth Perception • Visual Cliff – Gibson and Walk (1960)-- ◦ Initially showed that 6 - month old babies would not cross the visual cliff ◦ Recent Research • Babies use kinetic information as early as 3 months • Binocular cues are used at 4 months • Linear perspective cues are used last, at 5 – 7 months ◦ 3 month olds have some depth perception •

  29. Infant Perception of Motion and Object Continuity

  30. Hearing, Smelling and Tasting, Touch and Motion • Hearing • Fetuses respond to sounds beginning at 3 months of gestation • By 4 months will reach in the direction of sound • Infants prefer infant-directed speech (motherese) • Smelling and Tasting • Newborns react differently to each basic taste as early as birth • Prefer some tastes to others—sweet, sour, bitter substances produce facial expressions • Touch and Motion • Best developed of all senses • Babies use touch to explore the world—central to Piaget’s theory about the sensorimotor stage • Harlow demonstrated the importance of touch to development •

  31. Multimodal and Cross-Modal Perception • Our senses interact with another and fuse perceptions into wholes. • Information obtain by sight, sound, and touch are coordinated very early in life. • Self-knowledge might be based on the coordination of information.

  32. Sudden Infant Death Syndrome—SIDS • Leading cause of death in U.S. infants 1- 12 months • More common in babies with apnea (brief cessations in breathing) • More frequent in babies who sleep on their stomachs • Higher risk if mother smokes during pregnancy or smoking in the home after birth