© 2009 The McGraw-Hill Companies, Inc. All rights reserved. Slide 1 John W. Santrock Physical Development in Infancy 5

© 2009 The McGraw-Hill Companies, Inc. All rights reserved. Slide 2 Physical Development in Infancy How Do Infants Grow and Develop Physically? How Do Infants Develop Motor Skills? How Can Infants’ Sensory and Perceptual Development Be Characterized?

© 2009 The McGraw-Hill Companies, Inc. All rights reserved. Slide 3 Images of Children Bottle-feeding in developing countries –Unsterilized bottles, formula made with unclean water –Many children get common illnesses; may die Breastfeeding in developing countries –Breast milk has advantages; immunizes newborn Hospitals have vital role in educating mothers How Do Infants Grow and Develop Physically?

© 2009 The McGraw-Hill Companies, Inc. All rights reserved. Slide 4 Patterns of Growth 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?

© 2009 The McGraw-Hill Companies, Inc. All rights reserved. Slide 5 Fig. 5.1 Changes in Proportions of the Human Body During Growth

© 2009 The McGraw-Hill Companies, Inc. All rights reserved. Slide 6 Height and Weight Average North American newborn is 20 inches and 7½ pounds –Birth weight doubled by age 4 months; tripled at end of first year –First year growth averages 1 inch per month –1½ times birth length at end of 1st year How Do Infants Grow and Develop Physically?

© 2009 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?

© 2009 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 PET and MRI scans may harm infant EEG shows brain activity spurt from 1½ to 2 years of age How Do Infants Grow and Develop Physically?

© 2009 The McGraw-Hill Companies, Inc. All rights reserved. Slide 9 Brain Development Mapping the brain –Forebrain Cerebral cortex with 2 hemispheres 4 lobes in each hemisphere –Frontal, Occipital, Temporal, Parietal Each hemisphere has lateralization How Do Infants Grow and Develop Physically?

© 2009 The McGraw-Hill Companies, Inc. All rights reserved. Slide 10 The Human Brain’s Hemispheres Fig. 5.3

© 2009 The McGraw-Hill Companies, Inc. All rights reserved. Slide 11 The Brain’s Four Lobes Prefrontal cortex Fig. 5.4 (vision) (body sensations) (voluntary movement and thinking) (hearing)

© 2009 The McGraw-Hill Companies, Inc. All rights reserved. Slide 12 Brain Development Neuron: info processing nerve cell –Axons and dendrites Myelin sheath: layer of fat cells –Encases and insulates most axons –Myelination continues into adolescence Synapses: tiny gaps –Neurotransmitters How Do Infants Grow and Develop Physically?

© 2009 The McGraw-Hill Companies, Inc. All rights reserved. Slide 13 Fig. 5.5 The Neuron

© 2009 The McGraw-Hill Companies, Inc. All rights reserved. Slide 14 Fig. 5.6 The Development of Dendrite Spreading 24 months At birth1 month 3 months 15 months

© 2009 The McGraw-Hill Companies, Inc. All rights reserved. Slide 15 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?

© 2009 The McGraw-Hill Companies, Inc. All rights reserved. Slide Synaptic density 10, adult Age in days (from conception) AdolescenceNewborn Synaptic Density in Human Brain from Infancy to Adulthood Fig. 5.7

© 2009 The McGraw-Hill Companies, Inc. All rights reserved. Slide 17 Early Experience and the Brain Environmental experiences important in brain’s development Infant’s brain waiting for experiences to determine connections among neurons How Do Infants Grow and Develop Physically?

© 2009 The McGraw-Hill Companies, Inc. All rights reserved. Slide 18 Early Experience and the Brain Early experiences affect development –Enriched environment makes brain Heavier in weight with thicker layers Develop more neural connections Produces higher neurochemical activity –Impoverished environment Depression is common How Do Infants Grow and Develop Physically?

© 2009 The McGraw-Hill Companies, Inc. All rights reserved. Slide 19 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?

© 2009 The McGraw-Hill Companies, Inc. All rights reserved. Slide 20 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?

© 2009 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. 5.10

© 2009 The McGraw-Hill Companies, Inc. All rights reserved. Slide 22 Shared Sleeping 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?

© 2009 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 –Highest cause of infant death in U.S. –Highest risk is 4 to 6 weeks of age –Prone position increases risk How Do Infants Grow and Develop Physically?

© 2009 The McGraw-Hill Companies, Inc. All rights reserved. Slide 24 Sudden Infant Death Syndrome (SIDS) Increased risks if: –Lower birth weight –Siblings with SIDS –Sleep apnea –Lower SES groups –Exposure to cigarette smoke –Placement in soft bedding How Do Infants Grow and Develop Physically? –Highest risk in African American and Inuit infants

© 2009 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 –More fruits and vegetables, less junk food How Do Infants Grow and Develop Physically?

© 2009 The McGraw-Hill Companies, Inc. All rights reserved. Slide 26 Breast Versus Bottle Feeding Breastfeeding is better –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?

© 2009 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?

© 2009 The McGraw-Hill Companies, Inc. All rights reserved. Slide 28 Health Immunization begins in infancy Accident Prevention –Increased monitoring needed in infancy –Asphyxiation: leading cause of death under 1 –Chocking hazards: toys, chunky foods –Burn risks: sun, electrical, heaters, hot water –Other risks: car accidents, cuts, pet bites How Do Infants Grow and Develop Physically?

© 2009 The McGraw-Hill Companies, Inc. All rights reserved. Slide 29 Dynamic Systems Theory Gesell revealed motor skill development –Maturation: unfolding genetic plan Perceptions and motivation lead to new motor skills or fine tuning –Nervous system maturation –Repeated “cycles” of actions –Nature, nurture, and environment interact How Do Infants Develop Motor Skills?

© 2009 The McGraw-Hill Companies, Inc. All rights reserved. Slide 30 Built-in reactions to stimuli –Rooting: reaction to cheek/mouth touched –Sucking: automatic sucking object in mouth –Moro reflex: startle response causes back arching, rapid closing of arms and legs –Grasping: when something touches palm How Do Infants Develop Motor Skills? Reflexes

© 2009 The McGraw-Hill Companies, Inc. All rights reserved. Slide 31 Gross Motor Skills Milestones for large muscle activities –Development of posture –Learning to walk; locomotion, balance, and practice (crawling to walking) –Development in second year Skilled and mobile: pull toys, climb stairs Natural exercise: walk quickly, run stiffly How Do Infants Develop Motor Skills?

© 2009 The McGraw-Hill Companies, Inc. All rights reserved. Slide 32 Milestones in Gross Motor Development

© 2009 The McGraw-Hill Companies, Inc. All rights reserved. Slide 33 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?

© 2009 The McGraw-Hill Companies, Inc. All rights reserved. Slide 34 Fine Motor Skills Finely tuned (coordinated) movements –Perceptual-motor coupling necessary Finger dexterity (thumb and forefinger) Two types of grasps: Palmar and Pincer Wrists and hands turn and rotate more –Experience and exercise have impact How Do Infants Develop Motor Skills?

© 2009 The McGraw-Hill Companies, Inc. All rights reserved. Slide 35 What Are 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?

© 2009 The McGraw-Hill Companies, Inc. All rights reserved. Slide 36 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?

© 2009 The McGraw-Hill Companies, Inc. All rights reserved. Slide 37 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?

© 2009 The McGraw-Hill Companies, Inc. All rights reserved. Slide 38 Habituation and Dishabituation Habituation: decreased responsiveness to stimulus after repeated presentations Dishabituation: recovery of habituated response after change in stimulation Tracking: applied to vision and hearing –High-amplitude sucking, videos, computers How Can Infants’ Sensory and Perceptual Development Be Characterized?

© 2009 The McGraw-Hill Companies, Inc. All rights reserved. Slide 39 Visual Perception Visual acuity and color in newborn Perceiving patterns – patterns preferred Perceptual constancy – size, shape Depth perception –‘visual cliff’ study and visual expectations –Binocular cues and stereoacuity How Can Infants’ Sensory and Perceptual Development Be Characterized?

© 2009 The McGraw-Hill Companies, Inc. All rights reserved. Slide 40 –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

© 2009 The McGraw-Hill Companies, Inc. All rights reserved. Slide 41 Other Senses Hearing: begins in womb –Infancy changes: volume, pitch, localization Touch and Pain Smell: present shortly after birth Taste: may exist before birth How Can Infants’ Sensory and Perceptual Development Be Characterized?

© 2009 The McGraw-Hill Companies, Inc. All rights reserved. Slide 42 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?

© 2009 The McGraw-Hill Companies, Inc. All rights reserved. Slide 43 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?

© 2009 The McGraw-Hill Companies, Inc. All rights reserved. Slide 44 The End 5