Developmental Psychology

Infancy
As newborns, we were not empty-headed organisms. We had some basic reflexes, among them crying, kicking, and coughing. We slept a lot, and occasionally we smiled, although the meaning of our first smiles was not entirely clear. We ate and we grew. We crawled and then we walked, a journey of a thousand miles beginning with a single step. Sometimes we conformed; sometimes others conformed to us. Our development was a continuous creation of more complex forms. We needed the meeting eyes of love. We juggled the necessity of curbing our will with becoming what we could will freely. This section contains three chapters: “Physical Development in Infancy,” “Cognitive Development in Infancy,” and “Socioemotional Development in Infancy.”

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chapter 4
PHYSICAL DEVELOPMENT IN INFANCY
chapter outline
1 Physical Growth and Development in Infancy

Learning Goal 1 Discuss physical growth and development in infancy.

Patterns of Growth

Height and Weight

The Brain

Sleep

Nutrition

2 Motor Development

Learning Goal 2 Describe infants’ motor development.

The Dynamic Systems View

Reflexes

Gross Motor Skills

Fine Motor Skills

3 Sensory and Perceptual Development

Learning Goal 3 Summarize the course of sensory and perceptual development in infancy.

What Are Sensation and Perception?

The Ecological View

Visual Perception

Other Senses

Intermodal Perception

Nature, Nurture, and Perceptual Development

Perceptual-Motor Coupling

image1 ©Image Source/Getty Images

Latonya is a newborn baby inPage 105 Ghana. During her first days of life, she has been kept apart from her mother and bottle fed. Manufacturers of infant formula provide the hospital where she was born with free or subsidized milk powder. Her mother has been persuaded to bottle feed rather than breast feed her. When her mother bottle feeds Latonya, she overdilutes the milk formula with unclean water. Latonya’s feeding bottles have not been sterilized. Latonya becomes very sick. She dies before her first birthday.

Ramona was born in a Nigerian hospital with a “baby-friendly” program. In this program, babies are not separated from their mothers when they are born, and the mothers are encouraged to breast feed them. The mothers are told of the perils that bottle feeding can bring because of unsafe water and unsterilized bottles. They also are informed about the advantages of breast milk, which include its nutritious and hygienic qualities, its ability to immunize babies against common illnesses, and the role of breast feeding in reducing the mother’s risk of breast and ovarian cancer. Ramona’s mother is breast feeding her. At 1 year of age, Ramona is very healthy.

image2 (Top) An HIV-infected mother breast feeding her baby in Nairobi, Kenya. (Bottom) A Rwandan mother bottle feeding her baby. What are some concerns about breast versus bottle feeding in impoverished African countries?(Top) ©Wendy Stone/Corbis/Getty Images; (bottom) ©Dave Bartruff/Corbis/Getty Images

For many years, maternity units in hospitals favored bottle feeding and did not give mothers adequate information about the benefits of breast feeding. In recent years, the World Health Organization and UNICEF have tried to reverse the trend toward bottle feeding of infants in many impoverished countries. They instituted “baby-friendly” programs in many countries (Grant, 1993). They also persuaded the International Association of Infant Formula Manufacturers to stop marketing their baby formulas to hospitals in countries where the governments support the baby-friendly initiatives (Grant, 1993). For the hospitals themselves, costs actually were reduced as infant formula, feeding bottles, and separate nurseries became unnecessary. For example, baby-friendly Jose Fabella Memorial Hospital in the Philippines reported saving 8 percent of its annual budget. Still, there are many places in the world where the baby-friendly initiatives have not been implemented.

The advantages of breast feeding in impoverished countries are substantial (UNICEF, 2017). However, these advantages must be balanced against the risk of passing the human immunodeficiency virus (HIV) to babies through breast milk if the mothers have the virusPage 106 (Croffut & others, 2018; Mnyani & others, 2017; Wojcicki, 2017). In some areas of Africa, more than 30 percent of mothers have HIV, but the majority of these mothers don’t know that they are infected (Mepham, Bland, and Newell, 2011). Later in the chapter, in the section on nutrition, we will look more closely at recent research on breast feeding in the United States, outlining the benefits for infants and mothers and discussing several life-threatening diseases that infants can contract as a result of malnutrition.

topical connections looking back
Previously, we followed the physical development that takes place from fertilization through the germinal, embryonic, and fetal periods of prenatal development. We learned that by the time the fetus has reached full gestational age (approximately 40 weeks), it has grown from a fertilized egg, barely visible to the human eye, to a fully formed human weighing approximately 8 pounds and measuring 20 inches in length. Also remarkable is the fact that by the end of the prenatal period the brain has developed approximately 100 billion neurons.

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It is very important for infants to get a healthy start. When they do, their first two years of life are likely to be a time of amazing development. In this chapter, we focus on the biological domain and the infant’s physical development, exploring physical growth, motor development, and sensory and perceptual development.

1 Physical Growth and Development in Infancy
LG1 Discuss physical growth and development in infancy.

Patterns of Growth

Height and Weight

The Brain

Sleep

Nutrition

Infants’ physical development in the first two years of life is extensive. Newborns’ heads are quite large in comparison with the rest of their bodies. They have little strength in their necks and cannot hold their heads up, but they have some basic reflexes. In the span of 12 months, infants become capable of sitting anywhere, standing, stooping, climbing, and usually walking. During the second year, growth decelerates, but rapid increases in such activities as running and climbing take place. Let’s now examine in greater detail the sequence of physical development in infancy.