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Infancy_ Physical Development Truth or Fiction_

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					Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus
                                                                            Chapter 5




                 Chapter 5
       Infancy: Physical Development
Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus
                                                                            Chapter 5

     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 body’s central axis toward periphery
  • Differentiation
       – Tendency of behavior to become more specific and distinct
Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus
                                                                            Chapter 5

           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
Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus
                                                                            Chapter 5




    Figure 5.2 Changes in the Proportions of the Body
Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus
                                                                            Chapter 5

                       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
Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus
                                                                            Chapter 5

           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 cow’s milk delayed until 9 to 12 months
       – Teething biscuits in later part of first year
Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus
                                                                              Chapter 5

                    Guidelines for Infant Nutrition


  • Build up variety of foods
  • Avoid overfeeding or underfeeding
  • Don’t restrict fat and cholesterol
  • Don’t overdo high-fiber foods
  • Avoid items with added sugar and salt
  • Encourage high-iron foods




                                             U.S. Dept of Agriculture, 2000
Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus
                                                                            Chapter 5

 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
Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus
                                                                            Chapter 5

          What are the Advantages and Disadvantages
                        of Breast Milk?
  • Advantages of breast milk
       – Conforms to digestion process
       – Possesses needed nutrients
       – Contains mother’s 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
Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus
                                                                            Chapter 5




     Development of the Brain and
           Nervous System
Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus
                                                                            Chapter 5

                           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
Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus
                                                                            Chapter 5




    Figure 5.3 Anatomy of a Neuron
Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus
                                                                            Chapter 5

                      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
Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus
                                                                             Chapter 5

                            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
Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus
                                                                            Chapter 5

                         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
Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus
                                                                            Chapter 5




    Figure 5.5 Structures of the Brain
Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus
                                                                            Chapter 5

                    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
Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus
                                                                            Chapter 5




    Figure 5.6 Increase in Neural Connections in the Brain
Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus
                                                                            Chapter 5

     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
Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus
                                                                            Chapter 5




                 Motor Development
Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus
                                                                                   Chapter 5

                     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
Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus
                                                                            Chapter 5

            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
Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus
                                                                            Chapter 5




            Sensory and Perceptual
                Development
Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus
                                                                            Chapter 5

     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
Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus
                                                                            Chapter 5

             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
Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus
                                                                            Chapter 5




    Figure 5.11 Preferences in Visual Stimuli in 2-Month-Olds
Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus
                                                                            Chapter 5




    Figure 5.12 Eye Movements of 1- and 2-Month Olds
Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus
                                                                            Chapter 5

     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
Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus
                                                                            Chapter 5




    Figure 5.13 The Visual Cliff
Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus
                                                                            Chapter 5




                        A Closer Look

              Strategies for Studying the
           Development of Shape Constancy
Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus
                                                                            Chapter 5

                 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 object’s size remains stable
     although retinal size may differ
       – Appears by 2 1/2 to 3 months
   • Shape constancy – perception of object‘s shape remains stable
     although shape on retina may change
       – Appears by 4 to 5 months
Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus
                                                                            Chapter 5

     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
Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus
                                                                                    Chapter 5




    Figure 5.14 Declining Ability to Discriminate the Sounds of Foreign Languages
Childhood and Adolescence: Voyages in Development, Second Edition, Spencer A. Rathus
                                                                            Chapter 5

 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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