1. Chapter 5: Physical Development in Infancy
McGraw-Hill
© 2006 by The McGraw-Hill Companies, Inc. All rights reserved.

2. Physical Growth
and Development
in Infancy

3. Infant physical development is extensive in first 2 years of life
Within 1st year
Child grows out of having a gigantic head disproportionate to the body
From some basic reflexes, to capacity to sit, stand, climb, and walk almost anywhere
During 2nd year: rapid growth sequence

4. Cephalocaudal pattern of development
Sequence of growth occurs from top (head) to bottom (feet) – size, weight, and sensory and motor development
Proximodistal pattern of development
Growth sequence begins at center of body and moves toward extremities
Average length and average weight of North American newborns are 20 inches and 7.5 pounds, respectively
95% of newborns are full-term

5. Brain continues developing past infancy
Shaken baby syndrome: brain swelling and hemorrhaging from child abuse trauma
At birth, brain is 25% of adult weight; at 2 years of age, it is 75%
Brain’s primary motor areas develop earlier than other areas

6. The Neuron
Figure 5.2

7. Myelination for vision usually completed in 6 months after birth and for hearing at 4 or 5 years of age
Some myelination continues into adolescence
Most dramatic changes in brain occur in first 2 years of life (see Fig. 5.3)
Synapses are tiny gaps between neurons; chemical interactions occur here between axons and dendrites
“Pruning” of connections: overproduction of synapses leads to gradual retraction

8. Development of Dendritic Spreading
At birth
3 months
1 month
15 months
24 months
Figure 5.3

9. EEG measures brain’s electrical activity
PET: Positron-emission tomography
MRI: Magnetic resonance imaging
Cerebral cortex divided into 2 hemispheres
Lateralization: hemispheric specialization
Each hemisphere is divided into 4 main areas:
Frontal lobe: voluntary thinking and movement
Occipital lobe: vision functions
Temporal lobe: hearing functions
Parietal lobe: processing body sensations

10. Language comprehension
The Brain’s Hemispheres and Emotions
Front
Concentrating, planning, problem solving
Motor cortex
Language structure
Sensory cortex
Approach behaviors
Withdrawal behaviors
Left
Right
Distress, misery, agony, disgust, contempt, resentment, fear, horror, anxiety
Joy, bliss, pride, anger, hostility, jealousy, interest, concern, responsibility
Interpreting experiences
Primary hearing
Primary visual
Language comprehension
Based on Figure 5.6

11. 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
Cultural variations influence infant sleep patterns; newborns sleep an average of 16–17 hours per day
The practice of shared sleeping, in which a newborn shares a bed with mother, varies among cultures

12. SIDS: sudden infant death syndrome – infants stop breathing and die without apparent cause
Highest risk is in first 4–6 weeks of life
Highest cause of infant death in U.S. annually
Risk decreases when infant sleeps on its back
Higher risk factors associated with SIDS:
Infants with siblings who died from SIDS
Infants with sleep apnea or low birthweight
Infant passively exposed to cigarette smoke
Being from lower SES or being African American or Eskimo

13. Nutrition is important as infant nearly triples weight in 1st year
Low-fat, low-calorie foods and skim milk can retard baby’s development in first 2 years of life
Benefits for infant from breast milk can include
Denser bones in childhood/adulthood
Reduced childhood cancers and breast cancer as female adult
Improved neurological and cognitive development
Improved visual acuity

14. Mother should not breast-feed if she has AIDS or other infectious diseases or active tuberculosis or is taking drugs that can be transmitted through breast milk
Prolonged and severe malnutrition can be detrimental to child’s cognitive, physical, and social development
Toilet training should be a positive experience starting at around 2 years of age or older

15. Motor Development

16. Dynamic systems view:
Motor development is not a result of nature alone but an active process in which nature and nurture work together
Infants assemble motor skills for perceiving and acting, as solutions to goals
Environment motivates infants to act
Perceptions help infants fine-tune movements
Three factors enable new behaviors to emerge

17. Converging factors enabling new behaviors to emerge:
Development of nervous system and body’s physical capabilities
The goal that the child is motivated to reach
The environmental support for the necessary skills used to reach a goal

18. Baby masters balance and grasping things
Baby begins to crawl and grasp things
Child is encouraged by grandmother
Child is nurtured by mother
Perceptions, nurturing, and practice allow baby to fine-tune grasping

19. Motor development begins with reflexes
Sucking and rooting reflexes disappear about 3–4 months after birth
Moro reflex (automatic arching of back and wrapping of arms to center of body when startled) disappears about 3–4 months after birth
Grasping reflex (infant’s hands close around anything that touches the palms) disappears as voluntary grasp develops
Gross motor skills enable large-muscle activities

20. Support some weight with legs
Milestones in Gross Motor Development
Stand with support
Sit without support
Walk alone easily
Support some weight with legs
Degree of motor development
Stand alone easily
Roll over
Walk using furniture for support
Prone, chest up, arms for support
Pull self to stand
Prone, lift head 1 2 3 4 5 6 7 8 9 10 11 12 13 14
Age in months
Figure 5.13

21. Cultural variations: mothers in developing countries treat infants differently from mothers in developed cultures
Jamaican mothers
Regularly massage infants and stretch their arms and legs
On average, their babies sit and walk alone 2–3 months earlier than English babies
Algonquin infants in Quebec, Canada
Strapped to cradleboard for 1st year
Sit, crawl, and walk about same time as those in cultures raised without cradleboard

22. Fine motor skills for finely tuned activities
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
Four-month-olds often rely on touch while eight-month-olds rely on vision to determine how they will grip an object

23. Perceptual Development
Sensory and
Perceptual
Development

24. Information is transmitted through smell, touch, hearing, taste, and vision to sensory receptors
Perception is an interpretation of what is sensed
Ecological view sees environment as rich with information and sees perceptual system as selecting from it
Perception enables interaction with, and adaptation to, one’s environment

25. Infants gain adult-like color vision by 2 months
Two-month-olds scan wide areas of faces and show preferences for target and stripped patterns
Perceptual constancy in seeing sizes and shapes starts to develop between 3 and 5 months of age
Depth perception as tested by “visual cliff” is evident in 2- to 4-month-old infants
Infants develop expectations about future events at about 3 months of age (on average)

26. Infants aged 6–8 months can perceive gravity and understand that objects can fall or roll
Fetuses can hear sounds during the last 2 months of pregnancy and recognize the mother’s voice at birth
Newborns
Show a preference for human speech
Are born deaf in about 1 in 1,000 cases
Can feel pain at birth
Are sensitive to taste before birth
Sensory input detection is affected by experience

27. The End