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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.