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  1. 1. Life-Span Development Twelfth Edition Chapter 4: Physical Development in Infancy 1
  2. 2.  Patterns of Growth:  $$ Cephalocaudal Pattern: sequence in which the earliest growth always occurs from the top downward ▪ Also applies to gains in motor development  Proximodistal Pattern: sequence in which growth starts in the center of the body and moves toward the extremities 2
  3. 3.  Height and Weight:  Average North American newborn is 20 inches long and 7 ½ pounds ▪ 95% of full-term newborns are 18-22 inches long and weigh between 5 ½ and 10 lbs. ▪ Newborns lose 5-7% of their body weight in the first few days of life ▪ They typically gain 5-6 ounces per week during the first month  Weight usually triples by their 1st birthday ▪ Newborns gain approximately 1 inch per month during the first year  Growth slows considerably during the 2nd year 3
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  5. 5.  The Brain:  Brain continues developing past infancy  Shaken Baby Syndrome: brain swelling and hemorrhaging from child abuse trauma  Brain imaging technologies cannot typically be used with babies ▪ EEGs show regular spurts in the brain’s electrical activity ▪ Spurts may coincide with important changes in cognitive development  At birth, the brain is 25% of its adult weight; at 2 years of age, it is 75% of its adult weight ▪ The brain does not mature uniformly 5
  6. 6.  Forebrain: portion of the brain farthest from the spinal cord; includes cerebral cortex Lateralization: specialization of function in one hemisphere of the cerebral cortex or the other  Some functions are lateralized, some are not ▪ Complex functions involve communication between both hemispheres $$ Electroencephalogram (EEG) is commonly used to study the brain in infancy. 6
  7. 7.  Neurons: brain nerve cells that communicate through electrical and chemical signals  Axons carry signals away from the cell body  Dendrites carry signals toward the cell body  Myelin sheath is a layer of fat cells that insulate axons ▪ Helps electrical signals travel faster  Terminal buttons release chemicals (neurotransmitters) into synapses ▪ Synapses: tiny gaps between neurons 7
  8. 8.  Depressed brain activity has been found in children who grow up in a deprived environment  Enriched environments promote faster brain development than deprived ones After birth: sights, sounds, smells, touches, language, and eye contact help shape the brain’s neural connections  Repeated experience wires (and rewires) the brain 8
  9. 9.  Typical newborns sleep 16-17 hours per day Infants vary in their preferred times for sleeping  Most have moved closer to adult-like sleep patterns by 4 months of age Factors involved in night waking:  Daytime crying and fussing  Distress when separated from mother  Breast feeding  Co-sleeping 9
  10. 10.  The practice of shared sleeping, in which a newborn shares a bed with mother, varies among cultures Potential benefits:  Promotes breast feeding and a quicker response to crying  Allows mother to detect potentially dangerous breathing pauses in baby American Academy of Pediatrics discourages shared sleeping  Increases risk of injury (rolling over baby) and SIDS $$ SIDS (Sudden Infant Death Syndrome): infants stop breathing and die without apparent cause  Highest cause of infant death in U.S. annually  Highest risk is 2-4 months of age  Risk decreases when infant sleeps on its back and when a pacifier is used 10
  11. 11.  Experts recommend that infants consume 50 calories per day for each pound they weigh U.S. parents typically do not feed infants enough fruits and vegetables  By 15 months, French fries are the most common vegetable eaten Increasing rates of overweight and obese infants  Other factors: ▪ Mother’s weight gain during pregnancy and pre-pregnancy weight ▪ Breast feeding vs. bottle feeding 11
  12. 12.  American Academy of Pediatrics strongly endorses breast feeding throughout the first year Benefits for baby can include:  Fewer gastrointestinal and lower respiratory tract infections  Potentially decreased risk of asthma  Less likely to become overweight or obese  Less incidence of diabetes  Less likely to experience SIDS Benefits for mother can include:  Lower incidence of breast and ovarian cancer  Lower incidence of Type 2 diabetes Breast feeding does not:  Help mother return to pre-pregnancy weight  Guard against osteoporosis  Decrease likelihood of experiencing post-partum depression 12
  13. 13.  Women less likely to breast feed:  Mothers who work full-time outside of the home  Mothers under age 25  Mothers without a high school education  African-American mothers  Mothers in low-income circumstances  Malnutrition in Infancy:  Early weaning and inadequate sources of nutrients can cause malnutrition  Marasmus: a severe protein-calorie deficiency ▪Results in a wasting away of body tissues  Kwashiorkor: a severe protein deficiency that causes the abdomen and feet to swell with water ▪Causes the vital organs to collect nutrients, depriving other parts of the body  Severe and lengthy malnutrition is detrimental to physical, cognitive, and social development 13
  14. 14.  Dynamic Systems View:  Infants assemble motor skills for perceiving and acting ▪ Motor skills represent solutions to goals ▪ $$ Arnold Gesell believed that motor skills come about through maturation  Development is an active process in which nature and nurture work together ▪ Development of nervous system ▪ Body’s physical properties and possibilities for movement ▪ Goal the child is motivated to reach ▪ Environmental support for the skill 14
  15. 15.  Reflexes: built-in reactions to stimuli; generally carry survival mechanisms  Rooting Reflex: when the infant’s cheek is stroked, the infant will turn its head to the side that was touched  Moro Reflex: automatic arching of back and wrapping of arms to center of body when startled  Grasping Reflex: infant’s hands close around anything that touches the palms Some reflexes continue throughout life; others disappear several months after birth Gross Motor Skills: skills that involve large-muscle activities  Walking, grabbing for objects 15
  16. 16.  Development in the 2nd Year:  Toddlers become more skilled and mobile  Motor activity is vital to the child’s development of competence and independence  By 18-24 months, toddlers can: ▪ Walk quickly or run stiffly ▪ Balance on their feet in a squat position ▪ Walk backward ▪ Stand and kick a ball without falling ▪ Jump in place 16
  17. 17.  Fine Motor Skills: involve finely tuned movements  Reaching and grasping is a significant milestone for infants  Palmer grasp: grasping with the whole hand  Pincer grip: grasping with the thumb and forefinger Perceptual-motor coupling is necessary for infants to coordinate grasping Experienced infants look at objects longer, reach for them more, and are more likely to mouth the objects Cultural Variations: mothers in developing countries tend to stimulate their infants’ motor skills more than mothers in more modern countries 17
  18. 18.  Sensation: occurs when information interacts with sensory receptors (eyes, ears, tongue, nostrils, and skin) Perception: the interpretation of what is sensed Ecological View: we directly perceive information that exists in the world around us  The perceptual system selects from the rich information provided by the environment  Perception enables interaction with, and adaptation to, one’s environment 18
  19. 19.  $$ Affordances: When we sense information from the environment, we are given the opportunity to interact with the environment  Eleanor and James Gibson  What affordances can infants or children detect and use? ▪ Children become more efficient at discovering and using affordances through perceptual development 19
  20. 20.  $$ Visual Preference Method: the studying of whether an infant can distinguish between two objects is done by measuring the length of time the infant looks at an object. Habituation: decreased responsiveness to a stimulus after repeated presentations Dishabituation: recovery of a habituated response after a change in stimulation 20
  21. 21.  Newborn’s vision is about 20/600 (an object 20 feet away appears as if it were 600 feet away) Bythe age of 6 months, vision is 20/100 or better  Vision approximates that of an adult by the infant’s first birthday Infants show an interest in human faces soon after birth  The way they gather information about the visual world changes rapidly with age 21
  22. 22.  Perceptual Constancy: sensory stimulation is changing but perception of the physical world remains constant 22
  23. 23.  $$ Two types of Perceptual Constancy Size Constancy: recognition that an object remains the same even though the retinal image of the object changes ▪ Babies as young as 3 months show size constancy ▪ Continues to develop until 10 or 11 years old Shape Constancy: recognition that an object remains the same shape even though its orientation to us changes ▪ 3-month-olds show shape constancy, but not for irregularly shaped objects 23
  24. 24.  Eleanor Gibson and Richard Walk studied development of depth perception using a “visual cliff”  Infants 6-12 months old can distinguish depth  Infants 2-4 months old show heart rate difference when placed on deep side of cliff  Infants develop binocular depth cues by about 3-4 months of age $$Stereoacuity: Fine-detail depth perception 24
  25. 25.  Fetuses can hear and learn sounds during the last two months of pregnancy and can recognize their mother’s voice at birth Newborns:  Cannot hear soft sounds as well as adults  Are less sensitive to pitch  Are fairly good at determining the location of a sound 25
  26. 26.  Touchand Pain: newborns respond to touch and can feel pain Smell: newborns can differentiate odors ▪ Preference for mother’s smell by 6 days Taste: sensitivity to taste may be present before birth 26