Chapter 5 Infancy: Physical Development

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.

Infancy: Physical Development: Truth or Fiction? Breastfeeding helps prevent obesity later in life. A child’s brain reaches half of its adult weight by the age of 1 year.

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.

Infancy: Physical Development: Truth or Fiction? Infants need to have experience crawling before they develop fear of heights.

Infancy: Physical Development Physical Growth and Development

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

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

Figure 5.1 Growth Curves for Weight and Height (Length) from Birth to Age 3 Years. The curves indicate the percentiles for weight and length at different ages. Lines labeled 97th show the height and weight of children who are taller and heavier than 97% of children of a particular age. Lines marked 50th indicate the height and weight of the average child of a given age. (Source: Figures 1-4, Kuczmarski, R.J., et.al. [2000, December 4]. CDC Growth charts: United States. Advance data from vital and health statistics, no. 314. Hyattsville, MD: National Center for Health Statistics.) Figure 5.1 Growth Curves for Weight and Height (Length) From Birth to Age 2 Years

Figure 5.2 Changes in the Proportions of the Body Figure 5.2 Changes in the Proportions of the Body. Development proceeds in a cephalocaudal direction. The head is proportionately larger among younger children. Figure 5.2 Changes in the Proportions of the Body

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

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

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

Developing in a World of Diversity Alleviating Protein-Energy Malnutrition (PEM)

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

What are the Advantages and Disadvantages 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

Development of the Brain and Nervous System

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

Figure 5.3 Anatomy of a Neuron Figure 5.3 The Anatomy of a Neuron. “Messages” enter neurons though dendrites, are transmitted along the axon, and then are sent through axon terminals to muscles, glands, and other neurons. Neurons develop via proliferation of dendrites and axon terminals and myelination. Figure 5.3 Anatomy of a Neuron

How do Neurons Develop? As child matures Myelin Sheaths 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

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

Figure 5.4 The Growth of Body Systems as a Percentage of Total Postnatal Growth. The brain of the neonate weighs about one-fourth its adult weight. In keeping with the principle of cephalocaudal growth, it will triple in weight by the first birthday, reaching nearly 70% of its adult weight. Figure 5.4 Growth of Body Systems as a Percentage of Total Postnatal Growth

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

Figure 5.5 Structures of the Brain Figure 5.5 Structures of the Brain. The convolutions of the cortex increase its surface area, and apparently, its intellectual capacity. (In this case, wrinkles are good). The medulla is involved in vital functions such as respiration and heartbeat; the cerebellum is involved in balance and coordinator. Figure 5.5 Structures of the Brain

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

Figure 5.6 Increase in Neural Connections in the Brain Figure 5.6 Increases in Neural Connections in the Brain. A major growth spurt in the brain occurs between the 25th week of the prenatal development and the end of the second year after birth. This growth spurt is due primarily to the proliferation of dendrite and axon terminals. Figure 5.6 Increase in Neural Connections in the Brain

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

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

Motor Development

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

What is Motor Development?

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

Sensory and Perceptual Development

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

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

What Captures the Attention of Infants 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

Figure 5.11 Preferences in Visual Stimuli in 2-Month-Olds Figure 5.11 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 (that is, being a face) or because of its stimulus characteristics (complexity, arrangement, etc.) Figure 5.11 Preferences in Visual Stimuli in 2-Month-Olds

Figure 5.12 Eye Movements of 1- and 2-Month Olds Figure 5.12 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.) How do researchers explain this change? Figure 5.12 Eye Movements of 1- and 2-Month Olds

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

Figure 5.13 The Visual Cliff Figure 5.13 The Visual Cliff. This young explorer has the good sense not to crawl out onto an apparently unsupported surface, even when mother beckons from the other side. Do infants have to experience some of life’s “bumps” before they avoid going off the deep end?” Figure 5.13 The Visual Cliff

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

Strategies for Studying the Development of Shape Constancy A Closer Look Strategies for Studying the Development of Shape Constancy

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

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

Figure 5.14 Declining Ability to Discriminate the Sounds of Foreign Languages. Infants show a decline in the ability to discriminate sounds not found in their native language. Before 6 months of age, infants from English-speaking families could discriminate sounds found in Hindi (red bars) and Salish, a Native American language (green bars). By 10 to 12 months of age, they could no longer do so. (Source: Werker, 1989) Figure 5.14 Declining Ability to Discriminate the Sounds of Foreign Languages

Effects of Early Exposure to Garlic, Alcohol, and – Gulp - Veggies A Closer Look Effects of Early Exposure to Garlic, Alcohol, and – Gulp - Veggies

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

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.

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. Slide 05:48 (Chapter 5, Slide 48) Slide was omitted in original chapter presentation

Lessons in Observation Sensation and Perception in Infancy Slide 05:48 (Chapter 5, Slide 48) Slide was omitted in original chapter presentation

Lessons in Observation Sensation and Perception in Infancy Discuss how the newborn’s capacities for vision and hearing are adaptive in the context of Carter’s 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 Giuseppina’s visual preferences? What other methods are commonly used to study infant sensory and perceptual capacities?

Lessons in Observation Sensation and Perception in Infancy Does the newborn’s preference for looking at faces more than at other objects indicate that form perception is innate? Why or why not?