© 2007 The McGraw-Hill Companies, Inc. All rights reserved. Slide 1 John W. Santrock Physical Development in Infancy 6

© 2007 The McGraw-Hill Companies, Inc. All rights reserved. Slide 2 Physical Development in Infancy How Do Infants Grow and Develop Physically?How Do Infants Grow and Develop Physically? How Do Infants Develop Motor Skills? How Can Infants’ Sensory and Perceptual Development Be Characterized?How Can Infants’ Sensory and Perceptual Development Be Characterized?

© 2007 The McGraw-Hill Companies, Inc. All rights reserved. Slide 3 Images of Children Bottle-feeding newborns in impoverished countries has become a trend –Formula mixed with unclean water –Bottles often unsterilized –Many children get common illnesses; may die –Breast milk would immunize newborn –Hospitals have vital role in educating mothers How Do Infants Grow and Develop Physically?

© 2007 The McGraw-Hill Companies, Inc. All rights reserved. Slide 4 Cephalocaudal and Proximodistal Patterns Cephalocaudal: size, weight, and feature differentiation gradually work from top to bottom Proximodistal: growth starts at center of body and moves toward extremities How Do Infants Grow and Develop Physically?

© 2007 The McGraw-Hill Companies, Inc. All rights reserved. Slide 5 Fig. 6.1 Changes in Proportions of the Human Body During Growth

© 2007 The McGraw-Hill Companies, Inc. All rights reserved. Slide 6 Height and Weight Average North American newborn is 20 inches and 7½ pounds –Birthweight doubled by age 4 months; tripled at end of first year –Growth during first year averages 1 inch per month –1½ times birth length at end of 1st year How Do Infants Grow and Develop Physically?

© 2007 The McGraw-Hill Companies, Inc. All rights reserved. Slide 7 Height and Weight Average 2-year-old –26 to 32 pounds and 32 to 35 inches tall (almost half of their adult height) –Growth rate considerably slower in second year How Do Infants Grow and Develop Physically?

© 2007 The McGraw-Hill Companies, Inc. All rights reserved. Slide 8 Brain Development Extensive growth in utero and infancy Shaken baby syndrome: brain swelling and hemorrhaging Neuron: nerve cell; all present at birth Dendrites How Do Infants Grow and Develop Physically?

© 2007 The McGraw-Hill Companies, Inc. All rights reserved. Slide 9 Brain Development Myelin sheath: layer of fat cells –Encases most axons –Insulates nerve cells Synapses: tiny gaps EEG activity spurts about 1½ to 2 years of age How Do Infants Grow and Develop Physically?

© 2007 The McGraw-Hill Companies, Inc. All rights reserved. Slide 10 Fig. 6.2 The Neuron

© 2007 The McGraw-Hill Companies, Inc. All rights reserved. Slide 11 Fig. 6.3 The Development of Dendrite Spreading 24 months At birth1 month 3 months 15 months

© 2007 The McGraw-Hill Companies, Inc. All rights reserved. Slide 12 Brain Development “Blooming” and “pruning” Synaptic overproduction peaks about 4 months after birth Prefrontal cortex overproduction peaks about 1 year of age –Adult density achieved in adolescence –Heredity and environment affect timing How Do Infants Grow and Develop Physically?

© 2007 The McGraw-Hill Companies, Inc. All rights reserved. Slide 13 Fig Synaptic density 10, adult Age in days (from conception) AdolescenceNewborn Synaptic Density in Human Brain from Infancy to Adulthood

© 2007 The McGraw-Hill Companies, Inc. All rights reserved. Slide 14 Brain’s Lobes and Hemispheres Four lobes and two hemispheres –Cerebral cortex Frontal lobe Occipital lobe Temporal lobe Parietal lobe –Lateralization of hemispheres How Do Infants Grow and Develop Physically?

© 2007 The McGraw-Hill Companies, Inc. All rights reserved. Slide 15 The Brain’s Four Lobes Prefrontal cortex Fig. 6.6 (vision) (body sensations) (voluntary movement and thinking) (hearing)

© 2007 The McGraw-Hill Companies, Inc. All rights reserved. Slide 16 The Human Brain’s Hemispheres Fig. 6.7

© 2007 The McGraw-Hill Companies, Inc. All rights reserved. Slide 17 Brain’s Lobes and Hemispheres Frontal lobe is immature in newborn –Ability to regulate physiological states and control reflexes in first year –Cognitive skills emerge later –More electrical activity in left hemisphere than right hemisphere when listening How Do Infants Grow and Develop Physically?

© 2007 The McGraw-Hill Companies, Inc. All rights reserved. Slide 18 Early Experience and the Brain Environmental experiences important in brain’s development; enriched environments enhance growth Infant’s brain waiting for experiences to determine connections among neurons How Do Infants Grow and Develop Physically?

© 2007 The McGraw-Hill Companies, Inc. All rights reserved. Slide 19 Sleep Regulation of wake-sleep cycle reflects neurological maturation; cycles vary REM (Rapid Eye Movement) sleep –Adults—fifth of sleep –Infants—half of sleep –May promote brain’s development in infancy How Do Infants Grow and Develop Physically?

© 2007 The McGraw-Hill Companies, Inc. All rights reserved. Slide 20 Sleep After about 4 months, infant has more adult-like sleep patterns Culture Affects Sleep Patterns –Length of sleep periods related to sleeping arrangements and parental activities How Do Infants Grow and Develop Physically?

© 2007 The McGraw-Hill Companies, Inc. All rights reserved. Slide 21 Sleep and Culture Culture and Sleeping Arrangements –Sharing bed common in many cultures –Crib/separate room common in U.S. –American Academy of Pediatrics discourages co-sleeping because of stress and SIDS risk How Do Infants Grow and Develop Physically?

© 2007 The McGraw-Hill Companies, Inc. All rights reserved. Slide Total daily sleep (hours) Older adultsNewbornInfantsChildrenAdolescentsAdults 1-15 days 90 yrs 6 mo 12 mo 18 mo 2 yrs 10 yrs 20 yrs 30 yrs 40 yrs 50 yrs 60 yrs 70 yrs 80 yrs Sleep Across the Human Life Span Fig. 6.7

© 2007 The McGraw-Hill Companies, Inc. All rights reserved. Slide 23 Sudden Infant Death Syndrome (SIDS) Infant stops breathing, usually during night, and dies without apparent cause –Also known as “crib death” –Prone sleeping reduces risk by 5 to 10 times How Do Infants Grow and Develop Physically?

© 2007 The McGraw-Hill Companies, Inc. All rights reserved. Slide 24 Sudden Infant Death Syndrome (SIDS) Increased risks if: –Lower birthweight –Siblings with SIDS –Sleep apnea –Lower SES groups –Exposure to cigarette smoke –Placement in soft bedding How Do Infants Grow and Develop Physically?

© 2007 The McGraw-Hill Companies, Inc. All rights reserved. Slide 25 Nutrition Healthy infants need –Loving, supportive feeding environment –50 calories per day per pound of weight –Fat; very important for growth –Breast milk (nature’s food) –Demand feeding becoming more popular How Do Infants Grow and Develop Physically?

© 2007 The McGraw-Hill Companies, Inc. All rights reserved. Slide 26 Breast-Feeding Versus Bottle-Feeding Breast-feeding recommended –Appropriate weight gain, lowers obesity risk –Prevents or reduces allergies and infections –Promotes neurological and cognitive growth –Lowers risk of SIDS and cancers –Better visual acuity and bone density –The only option in poor countries How Do Infants Grow and Develop Physically?

© 2007 The McGraw-Hill Companies, Inc. All rights reserved. Slide 27 Malnutrition in Infancy Infants can develop –Marasmus: wasting away of body tissues in infant’s first year, severe lack of protein –Kwashiorkor: deficiency in protein; child’s abdomen, feet become swollen with water – –If not fatal, effects are detrimental; lowest SES aided most by supplementary feeding How Do Infants Grow and Develop Physically?

© 2007 The McGraw-Hill Companies, Inc. All rights reserved. Slide 28 Toilet Training Ability to control affected by muscular maturity and motivation –Average child ready at age 2 –Controversy exists over “delaying” training Readiness approach recommended How Do Infants Grow and Develop Physically?

© 2007 The McGraw-Hill Companies, Inc. All rights reserved. Slide 29 Health Immunization begins in infancy Accident Prevention –Increased monitoring needed in infancy –Asphyxiation: leading cause of death under 1 –Chocking hazards: toys, food –Burn risks: sun, electrical, heaters, hot water –Other risks: car accidents, cuts, pet bites How Do Infants Grow and Develop Physically?

© 2007 The McGraw-Hill Companies, Inc. All rights reserved. Slide 30 Dynamic Systems Theory How infants acquire motor skills Perceptions and motivation leads to new motor skills or fine tuning –Nervous system maturation –Repeated “cycles” of actions –Nature, nurture, and environment create ever-changing system How Do Infants Develop Motor Skills?

© 2007 The McGraw-Hill Companies, Inc. All rights reserved. Slide 31 Reflexes How Do Infants Develop Motor Skills? Rooting: reaction when infant’s cheek is stroked or side of the mouth is touched Sucking: automatic sucking when something is placed in newborn’s mouth Moro reflex: startle response causes rapid closing of arms and legs Grasping: when something touches palm

© 2007 The McGraw-Hill Companies, Inc. All rights reserved. Slide 32 Gross Motor Skills Large muscle activities –Development of posture –Learning to walk; locomotion, balance, and practice –Development in second year Pull toys, climb stairs Walk quickly, run stiffly How Do Infants Develop Motor Skills?

© 2007 The McGraw-Hill Companies, Inc. All rights reserved. Slide 33 Milestones in Gross Motor Development Fig Age (months) Degree of motor development Prone, lift head Prone, chest up, arms for support Roll-over Sit without support Support some weight with legs Stand with support Pull self to stand Walk using furniture for support Walks alone easily Stands alone easily

© 2007 The McGraw-Hill Companies, Inc. All rights reserved. Slide 34 Cultural Variations in Guiding Infants’ Motor Development Infants reach motor milestones in different cultures based on activity opportunities –Variations not large –Milestones reached within normal age ranges How Do Infants Develop Motor Skills?

© 2007 The McGraw-Hill Companies, Inc. All rights reserved. Slide 35 Fine Motor Skills Reaching and grasping –Perceptual-motor coupling necessary –Initially move shoulders and elbows crudely; later move wrists and rotate hands –Coordinate thumb and forefinger –Experience affects reaching and grasping; becomes more refined during first 2 years How Do Infants Develop Motor Skills?

© 2007 The McGraw-Hill Companies, Inc. All rights reserved. Slide 36 Defining Sensation and Perception Sensation: occurs when information contacts sensory receptors—eyes, ears, tongue, nostrils, and skin Perception: interpretation of sensation How Can Infants’ Sensory and Perceptual Development Be Characterized?

© 2007 The McGraw-Hill Companies, Inc. All rights reserved. Slide 37 The Ecological View People directly perceive information in the world around them –Perception allows human-environmental interaction and adaptation –Affordances: opportunities for interaction offered by objects; enhanced by previous experiences How Can Infants’ Sensory and Perceptual Development Be Characterized?

© 2007 The McGraw-Hill Companies, Inc. All rights reserved. Slide 38 Studying Infant Perception Infant cannot talk –Head movement indicates some vision –Visual preference method: Fantz measured length of gaze and patterns of preference in “looking chamber” How Can Infants’ Sensory and Perceptual Development Be Characterized?

© 2007 The McGraw-Hill Companies, Inc. All rights reserved. Slide 39 Studying Infant Perception Habituation and Dishabituation –Habituation: decreased responsiveness to a stimulus after repeated presentations –Dishabituation: recovery of a habituated response after change in stimulation Tracking: applied to vision and hearing –Equipment: high-amplitude sucking How Can Infants’ Sensory and Perceptual Development Be Characterized?

© 2007 The McGraw-Hill Companies, Inc. All rights reserved. Slide 40 Visual Perception Visual acuity and color Perceiving patterns Perceptual constancy—size, shape Depth perception Visual expectations How Can Infants’ Sensory and Perceptual Development Be Characterized?

© 2007 The McGraw-Hill Companies, Inc. All rights reserved. Slide 41 –Shape constancy Recognition that object remains the same even though its orientation changes Perceptual Constancy How Can Infants’ Sensory and Perceptual Development Be Characterized? –Size constancy Recognition that object remains the same even though the retinal image changes

© 2007 The McGraw-Hill Companies, Inc. All rights reserved. Slide 42 Other Senses Hearing: begins in womb Touch and Pain Smell: present shortly after birth Taste: may exist before birth How Can Infants’ Sensory and Perceptual Development Be Characterized?

© 2007 The McGraw-Hill Companies, Inc. All rights reserved. Slide 43 Intermodal Perception Ability to relate and integrate information from two or more sensory modalities –Exist in world of objects and events –Crude exploratory forms of intermodal perception exist in newborns How Can Infants’ Sensory and Perceptual Development Be Characterized?

© 2007 The McGraw-Hill Companies, Inc. All rights reserved. Slide 44 Perceptual-Motor Coupling Perception and activity were traditionally considered separate. Dynamic systems approach and ecological approach both suggest they are linked. –Dynamic systems: infants assemble motor behavior for perceiving and acting –Ecological: action can guide perception and perception can guide action How Can Infants’ Sensory and Perceptual Development Be Characterized?

© 2007 The McGraw-Hill Companies, Inc. All rights reserved. Slide 45 The End 6