Infancy: Physical Development Truth or Fiction

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Chapter 5Infancy Physical Development
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Infancy Physical Development Truth or Fiction?

• The head of the newborn child doubles in length
  by adulthood, but the legs increase in length
  about five times.
• Infants triple their birth weight within a year.

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Infancy Physical Development Truth or Fiction?

• Breastfeeding helps prevent obesity later in
  life.
• A childs brain reaches half of its adult weight
  by the age of 1 year.

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Infancy Physical Development Truth or Fiction?

• The cerebral cortex the outer layer of the
  brain that is vital to human thought and reason
  is only one-eighth of an inch thick.
• Native American Hopi infants spend the first year
  of life strapped to a board, yet they begin to
  walk at about the same time as children who are
  reared in other cultures.

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Infancy Physical Development Truth or Fiction?

• Infants need to have experience crawling before
  they develop fear of heights.

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Infancy Physical Development

• Physical Growth and Development

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What are the Sequences of Physical Development?

• Cephalocaudal Development
• Upper part of the head to the lower parts of the
  body
• Proximodistal Development
• Trunk outward from bodys central axis toward
  periphery
• Differentiation
• Tendency of behavior to become more specific and
  distinct

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What Patterns of Growth Occur in Infancy?

• Weight doubles at about 5 months triples by
  first birthday
• Height increase by 50 in first year
• Infants grow 4 to 6 inches in second year and
  gain 4 to 7 pounds
• Growth appears continuous but actually occurs in
  spurts

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Figure 5.1 Growth Curves for Weight and Height
(Length) From Birth to Age 2 Years
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Figure 5.2 Changes in the Proportions of the Body
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What is Failure to Thrive?

• Growth impairment during infancy and early
  childhood
• Causes may be organic or non-organic
• Biologically based or non-biologically based
• Links to physical, cognitive, behavioral and
  emotional problems
• Deficiencies in caregiver-child interaction may
  play a role
• Canalization catch up growth once FTT is
  resolved

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What are the Nutritional Needs of Children?

• Infants require breast milk or iron fortified
  formula
• Solid foods may be introduced about 4 to 6 months
• Iron-enriched cereal, strained fruits, vegetables
  and meats
• Whole cows milk delayed until 9 to 12 months
• Teething biscuits in later part of first year

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Guidelines for Infant Nutrition

• Build up variety of foods
• Avoid overfeeding or underfeeding
• Dont restrict fat and cholesterol
• Dont overdo high-fiber foods
• Avoid items with added sugar and salt
• Encourage high-iron foods

U.S. Dept of Agriculture, 2000
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Developing in a World of Diversity

• Alleviating Protein-Energy Malnutrition (PEM)

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Why do Women Bottle-feed or Breastfeed their
Children?

• Choice to breastfeed is influenced by
• Attitudes regarding benefits for bonding and
  infant health
• Fear of pain, unease with breastfeeding and
  public breastfeeding
• Domestic and occupational arrangements
• Community and familial support
• Level of education

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What are the Advantages and Disadvantages of
Breast Milk?

• Advantages of breast milk
• Conforms to digestion process
• Possesses needed nutrients
• Contains mothers antibodies
• Helps protect against infant diarrhea
• Is less likely, than formula, to cause allergies
• Disadvantages of breast milk
• HIV, alcohol, drugs and environmental hazards may
  be transmitted through breast milk
• Physical demands on mother

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Development of the Brain and Nervous System
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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

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Figure 5.3 Anatomy of a Neuron
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How do Neurons Develop?

• As child matures
• Axons grow in length
• Dendrites and axon terminals proliferate
• Connection networks become more complex
• Myelin Sheaths
• Makes messages more efficient
• Myelination occurs with maturation
• Inhibition of myelination results in disease

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What is the Brain?

• Command center of organism
• Brain of neonate weighs less than one pound
• By first birthday, the brain triples in weight,
  reaching nearly 70 of adult weight

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Figure 5.4 Growth of Body Systems as a Percentage
of Total Postnatal Growth
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Structures of the Brain

• Medulla
• Controls basic body functions - heartbeat,
  respiration
• Cerebellum
• Maintains balance, control motor behavior,
  coordinate eye movements with body sensations
• Cerebrum
• Allows human learning, thought, memory and
  language

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Figure 5.5 Structures of the Brain
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How Does the Brain Develop?

• Growth Spurts in Brain Development
• Prenatal fourth and fifth months
• Proliferation of neurons
• Prenatal 25th week through 2 years old
• Proliferation of dendrites and axon terminals

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Figure 5.6 Increase in Neural Connections in the
Brain
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Brain Development in Infancy

• Myelination
• At birth brain areas well myelinated include
• Heartbeat and respiration
• Sleeping and arousal
• Reflex activity
• Myelination of sensory areas
• Hearing begins about 6th month of pregnancy
  and continues to age 4
• Vision begins shortly before full term but
  develop rapidly

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How do Nature and Nurture Affect the Development
of the Brain?

• Brain development is affected by maturation
  (nature) and sensory stimulation and motor
  activity (nurture)
• Rats in enriched environment
• More dendrites and axon terminals
• Human infants have more neural connections than
  adults
• If activated by experience, connection survives
• If not activated, connection does not survive

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Motor Development
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What is Motor Development?

• Developments in the activity of muscles, and is
  connected with changes in posture, movement, and
  coordination
• Follows cephalocaudal and proximodistal patterns
• Lifting and holding head before torso
• Voluntary reaching
• Locomotion
• Sequence rolling over, sitting up, crawling,
  creeping, walking, running

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What are the Roles of Nature and Nurture in
Motor Development?

• Maturation (nature)
• Myelination and differentiation is needed for
  certain voluntary motor activities
• Experience (nurture)
• Experimentation to achieve milestones
• Slight effect in training to accelerate motor
  skills

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Sensory and Perceptual Development
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How do Sensation and Perception Develop in the
Infant?

• Process of integrating disjointed sensations into
  meaningful patterns through perception
• Focus on vision and hearing
• Most research is one these areas

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Development of Visual Acuity and Peripheral Vision

• Neonates are nearsighted
• 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
• Perceive stimuli within 30 degree angle
• By 7 weeks increases to 45 degrees
• By 6 months of age, equal to adult

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What Captures the Attention of Infants? How do
Visual Preferences Develop?

• Neonates attend longer to stripes than blobs
• By 8 to 12 weeks, prefer curved lines over
  straight
• Infants prefer faces
• Discriminate maternal and stranger faces
• Prefer attractive faces
• Pay most attention to edges

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Figure 5.11 Preferences in Visual Stimuli in
2-Month-Olds
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Figure 5.12 Eye Movements of 1- and 2-Month Olds
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How do Researchers Determine Whether Infants will
Go Off the Deep End?

• Depth Perception
• Develops around 6 months (onset of crawling)
• Research using the Visual Cliff
• Gibson and Walk (1960)
• Relationship between crawling and fear of heights

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Figure 5.13 The Visual Cliff
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What are Perceptual Constancies? How do they
Develop?

• Perceptual constancy perception of object
  remains stable although sensations may differ
  under various conditions
• Size constancy perception of objects size
  remains stable although retinal size may differ
• Appears by 2 1/2 to 3 months
• Shape constancy perception of objects shape
  remains stable although shape on retina may
  change
• Appears by 4 to 5 months

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A Closer Look

• Strategies for Studying the Development of Shape
  Constancy

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What are Perceptual Constancies? How do they
Develop?

• Perceptual constancy perception of object
  remains stable although sensations may differ
  under various conditions
• Size constancy perception of objects size
  remains stable although retinal size may differ
• Appears by 2 1/2 to 3 months
• Shape constancy perception of objects shape
  remains stable although shape on retina may
  change
• Appears by 4 to 5 months

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How Does the Sense of Hearing Develop in Infancy?

• Neonates can orient toward direction of a sound
• 18 months locate sounds as well as adults
• By 3 1/2 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

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Figure 5.14 Declining Ability to Discriminate the
Sounds of Foreign Languages
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A Closer Look

• Effects of Early Exposure to Garlic, Alcohol, and
  Gulp - Veggies

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Do Children Play an Active or Passive Role in
Perceptual Development?

• Neonates perception is largely passive
• Later, intentional action replaces capture
• Systematic search replaces unsystematic
• Attention becomes selective
• Irrelevant information gets ignored

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What is the Evidence for the Roles of Nature and
Nurture in Perceptual Development?

• Sensory changes are linked to maturation of
  nervous system (Nature)
• Experience also plays a role (Nurture)
• Critical periods
• Newborn kittens with patched eye become blind
  in that eye
• Nature and nurture interact to shape perceptual
  development.

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Lessons in Observation Sensation and Perception
in Infancy

• What does research tell us about the sensory
  capacities of newborns, such as Carter and
  Aiden?Cite evidence from the video that supports
  this research in regard to vision and hearing.

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Lessons in Observation Sensation and Perception
in Infancy

• Discuss how the newborns capacities for vision
  and hearing are adaptive in the context of
  Carters initial interaction with mom.
• Infants have clear visual preferences. Discuss
  the visual preferences of infants in the context
  of the response of 2-month-old Giuseppina to the
  stimuli presented by Dr. Basow.What method is
  Dr. Basow using as a test of Giuseppinas visual
  preferences?What other methods are commonly used
  to study infant sensory and perceptual
  capacities?

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Lessons in Observation Sensation and Perception
in Infancy

• Does the newborns preference for looking at
  faces more than at other objects indicate that
  form perception is innate? Why or why not?