1. PHYSICAL DEVELOPMENT IN INFANCY
Chapter 5
PHYSICAL DEVELOPMENT IN INFANCY
© 2013 The McGraw-Hill Companies, Inc. All rights reserved.

2. Patterns of Growth
Cephalocaudal: The sequence in which the earliest growth always occurs at the top—the head—with physical growth and feature differentiation gradually working from top to bottom
Proximodistal: Growth starts at center of body and moves toward extremities 2

3. FIGURE 5.1 - CHANGES IN PROPORTIONS OF THE HUMAN BODY DURING GROWTH3

4. Height and Weight
Average North American newborn is 20 inches and 7½ pounds
Weight doubles at about 5 months; triples by first birthday
Height increase at least 50% in first year
Average 2-year-old
26 to 32 pounds and 32 to 35 inches tall
Growth rate considerably slower in second year
Growth appears continuous but actually occurs in spurts 4

5. Brain Development The brain is the command center of organism
Extensive growth in utero and infancy
Brain of neonate weighs less than one pound
By first birthday, the brain triples in weight, reaching nearly 70% of adult weight
EEG shows brain activity spurt from 1½ to 2 years of age 5

6. Mapping the Brain
Forebrain: The region of the brain that is farthest from the spinal cord and includes the cerebral cortex and several structures beneath it
Cerebral cortex: Tissue that covers the forebrain like a wrinkled cap and includes two halves, or hemispheres
Lateralization: Specialization of function in one hemisphere of the cerebral cortex or the other

7. FIGURE 5.3 - THE HUMAN BRAIN’S HEMISPHERES7

8. WHAT ARE NEURONS? Basic unit of nervous system
Receive and transmit messages
Neurons vary according to function and location, but all contain
Cell Body
Dendrites
Axon
Neurotransmitters

9. FIGURE THE NEURON 9

10. HOW DO NEURONS DEVELOP? As child matures Myelin
Axons grow in length
Dendrites and axon terminals proliferate
Connection networks become more complex
Myelin
Makes messages more efficient
Myelination occurs with maturation
Inhibition of myelination results in disease
Multiple sclerosis
Teaching Tip: Assign students to small groups and have them develop a nonlinguistic representation of the process of myelination. Present these in class and have students evaluate them in terms of clarity. Would someone who is not familiar with myelination understand how it function by viewing these representations?
Technology Tip: Have students find out more about current research on the causes and treatment of multiple sclerosis on the National Multiple Sclerosis Society website.
URL:

11. Brain Development Blooming and pruning
Synaptic overproduction peaks about 4 months after birth
Prefrontal cortex overproduction peaks about 3 year of age
Adult density achieved in adolescence
Heredity and environment affect timing 11

12. FIGURE 5.6 - THE DEVELOPMENT OF DENDRITIC SPREADING12

13. FIGURE 5.7 - SYNAPTIC DENSITY IN THE HUMAN BRAIN FROM INFANCY TO ADULTHOOD13

14. Early Experience and the Brain
The brain demonstrates both flexibility and resilience
Neuroscientists believe that what wires the brain is repeated experience
Neuroconstructivist view: Biological processes and environmental conditions influence the brain’s development
The brain has plasticity and is context dependent
Brain development is closely linked with cognitive development 14

15. Sleep Infants 0 to 2 years of age slept an average of 12.8 hours a day
With a range of 9.7 to 15.9 hours
The most common infant sleep-related problem reported by parents is nighttime waking
Infant nighttime waking problems have consistently been linked to excessive parental involvement in sleep-related interactions with their infant 15

16. REM (Rapid Eye Movement) sleep
The eyes flutter beneath closed lids
In non-REM sleep, this type of eye movement does not occur and sleep is quieter 16

17. FIGURE 5.10 - DEVELOPMENTAL CHANGES IN REM AND NON-REM SLEEP17

18. 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 18

19. 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 2 to 4 months of age
Prone position reduces risk
Less common in bedroom with fan and infant who sleeps with pacifier 19

20. Nutrition Healthy infants need Loving, supportive feeding environment
50 calories per day per pound of weight
Breast milk (nature’s food)
Gradual increase of chew-and-swallow
More fruits and vegetables, less junk food
Demand feeding becoming more popular
Poor dietary patterns can cause overweight 20

21. Breast Versus Bottle Feeding
Breast milk
Fewer gastrointestinal infections
Lower respiratory tract infections
Reduces effects of asthma in first 3 months
Reduce risk of skin inflammation
May lessen likelihood of obesity
Lowers risk of childhood and adult diabetes
Less risk of experiencing SIDS
Claims of no link to allergy prevention
Claims of no links to children’s cognitive development and cardiovascular system 21

22. EVALUATION OF BENEFITS FOR THE MOTHER
There is lower incidence of breast cancer in women who breast feed their infants
Reduction in ovarian cancer in women who breast feed their infants
Small reduction in type 2 diabetes in women who breast feed their infants

23. Malnutrition in Infancy
Early weaning can cause deficiencies
Infants can develop:
Marasmus: A wasting away of body tissues in the infant’s first year, caused by severe protein-calorie deficiency
Kwashiorkor: A condition caused by a severe deficiency in protein in which the child’s abdomen and feet become swollen with water
Usually appears between 1 to 3 years of age 23

24. Health Immunization begins in infancy Accident prevention
Increased monitoring needed in infancy
Most common accidents in infancy
Aspiration of foreign objects
Suffocation
Falls
Poisoning
Burns
Motor vehicle accidents 24

25. Dynamic Systems Theory
Dynamic systems theory: The perspective on motor development that seeks to explain how motor skills are assembled for perceiving and acting
When infants are motivated to do something, they might create a new motor behavior
Mastering a motor skill requires the infant’s active efforts to coordinate several components of the skill 25

26. Reflexes
Built-in reactions to stimuli that govern the newborn’s movements, which are automatic and beyond the newborn’s control
Rooting
Sucking
Moro
Babinski
Grasping 26

27. Gross Motor Skills Milestones for large muscle activities
Development of posture
Learning to walk
First year milestones - walks easily
Development in second year
Skilled and mobile: pull toys, climb stairs
Natural exercise: walk quickly, run stiffly 27

28. FIGURE 5.16 - MILESTONES IN GROSS MOTOR DEVELOPMENT28

29. Fine Motor Skills Motor skills that involve finely tuned movements
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 29

30. SENSATION AND PERCEPTION
Sensation: Stimulation of the sense organs.
Perception: Interpretation of that stimulation.
Process of integrating disjointed sensations into meaningful patterns through perception
Measuring Sensation/Perception
Habituation/Dishabituation
Head movement indicates some vision
Visual preference method: Measuring the length of time they attend to different stimuli
Tracking - Applied to vision and hearing
Technology

31. VISION Visual acuity at Birth Neonates have poor peripheral vision
Estimate of 20/600
Best see objects 7 to 9 inches from eyes
Greatest gains in visual acuity between birth and 6 months
By about 3 to 5 years of age, approximate adult levels
Neonates have poor peripheral vision
30 degree angle; By 7 weeks increases to 45 degrees; By 6 months of age, equal to adult (90 degrees)
Able to track movement within one day of birth
Preference for moving objects 31

32. VISION Visual accommodation Convergence Color perception
Self-adjustments made by eye lens to bring objects into focus
Neonates show little or no visual accommodation
Focus on objects 7 to 9 inches away
Convergence
Does not occur until 7 or 8 weeks
Color perception
At birth, cones are less well developed than rods
Fully mature around 3 months (Distinguish between blue/green)
By 4 months can distinguish between similar colors/hues
Teaching Tip: Education: Have students visit a toy store and locate toys specifically designed for infants. How do these toys encourage visual development? Students might also look online for infant toys. Discuss in class. 32

33. CONVERGENCE OF THE EYES
Figure 4.5 Convergence of the Eyes. Neonates do not have the muscular control to converge their eyes on an object that is close to them. However, they do show some convergence for objects at intermediate viewing distances.
Figure 4.5 33

34. THE LOOKING CHAMBER
Figure 4.4 The Looking Chamber. This chamber makes it easier for the researcher to observe the baby’s eye movements and to record how much time the baby spends looking at a visual stimulus. 34

35. VISUAL PREFERENCES Preferences Infants prefer faces Moderately complex
Movement
Contour
Infants prefer faces
Discriminate maternal and stranger faces
Prefer attractive faces
Pay most attention to edges
Teaching Tip: Parenting & Family Studies: Ask students to explore the variety of toys available for infants. Based on what is known about infant vision, what types of toys are best to encourage visual tracking, visual acuity, and visual interest? 35

36. Preferences for Visual Stimuli in 2-Month-Olds
Figure Preferences for Visual Stimuli in 2-Month-Olds. Infants appear to prefer complex to simple visual stimuli. By the time they are 2 months old, they also tend to show preference for the human face. Researchers continue to debate whether the face draws attention because of its content (i.e., being a face) or because of its stimulus characteristics (complexity, arrangement, etc.) 36

37. MOVEMENTS OF 1- AND 2-MONTH-OLDS
Figure Eye Movements of 1- and 2-Month-Olds. One-month-olds direct their attention to the edges of objects. Two-month-olds “move in from the edge.” When looking at a face, for example, they focus on the eyes and other inner features. Source: Salapatek (1975.) 37

38. DEPTH PERCEPTION Depth Perception Research using the Visual Cliff
Develops around 6 months (onset of crawling)
Research using the Visual Cliff
Gibson and Walk (1960)
Heart-rate response to determine fear
Relationship between crawling and fear of heights
Avoidance of the cliff and infants’ posture
Truth or Fiction
Infants need to have experience crawling before they develop fear of heights. (Mixed Evidence)
Teaching Tip: Ask students to explore the Internet for videos of the visual cliff experiment. Show the videos in class and discuss the implication of these studies on what is known about the development of depth perception in infancy. What implications might these studies have on what is known about the transmission of fear from parent to child? 38

40. HEARING Fetuses respond to sound Startled by loud noises
Can localize sound
Startled by loud noises
Neonates respond to amplitude and pitch
Show preference for mothers’ voices
Responsive to sounds and rhythms of speech
Capable of perceiving phonemes of other languages
Show no preference for specific languages
Teaching Tip: Ask students to bring in songs designed specifically for infants. If possible, have them bring songs from different countries. How are these songs similar and/or different? How do these songs demonstrate what we know about hearing in infants? 40

41. HEARING DeCasper & Spence (1986)
Newborns can remember and prefer a story read by mom during the last 6 weeks of pregnancy.
Exposed to 3 ½ hours of story.
Teaching Tip: Ask students to bring in songs designed specifically for infants. If possible, have them bring songs from different countries. How are these songs similar and/or different? How do these songs demonstrate what we know about hearing in infants? 41

42. Figure 4.7 A Neonate Sucking to Hear Her Mother’s Voice.42

43. DEVELOPMENT OF HEARING
By 1 month, infants perceive differences between similar speech sounds
By 3½ months discriminate caregivers’ voices
Infants perceive most speech sounds present in world languages
By 10 to 12 months, lose capacity to discriminate sounds not found in native language
By 6 months, they can detect high frequency sounds nearly as well as preschoolers.
By 6 months, they can appreciate distance.
Teaching Tip: Education: Ask students to interview a speech and language pathologist who works with young children. Discuss what, if anything, can be done to detect language delays in infancy.
Teaching Tip: Parenting & Family Studies: How might a family know that their child is experiencing hearing problems or language delays? What can be done to prevent and treat these delays? Have students discuss these issues in class. 43

44. SMELL AND TASTE Smell Taste Well-developed at birth
Demonstrate aversion for noxious and preference for pleasant odors
Vanilla and Strawberry
Recognize familiar odors
Recognize mom by 6 days
Taste
Sensitive to different tastes
Demonstrate facial expressions in response to tastes
Prefer sweet tastes
Teaching Tip: Have students discuss why infants may have inborn preferences for certain tastes? How might these inborn preferences shape their preferences for foods in later development? 44

45. Facial Expressions Elicited by Sweet, Sour, and Bitter Solutions
Figure 4.6 Facial Expressions Elicited by Sweet, Sour, and Bitter Solutions. Neonates are sensitive to different tastes, as shown by their facial expressions when tasting (a) sweet, (b) sour, and (c) bitter solutions. 45

46. TOUCH AND PAIN Touch Sensitive to touch
Touch elicits many reflex behaviors
Pain
Past belief that neonates are not sensitive to pain
Neonates not cognitively equipped to ruminate about pain
Conditionable – distress when confronted with situation that previously presented itself as painful
Teaching Tip: Discuss the pros and cons of circumcision during infancy. How does what is known about infants and pain shape decisions regarding early medical procedures? 46