Why understand human development during infancy?

Welcome to the story of development from infancy through toddlerhood; from birth until about two years of age. Did you ever wonder how babies grow from tiny, helpless infants into well-developed and independent adults? It doesn’t happen overnight, but the process begins right from day one. Infancy is a time when tremendous growth, coordination, and mental development occur. Most infants learn to walk, manipulate objects, and can form basic words by the end of infancy. By 5 months a baby will have doubled its birth weight and tripled its birth weight by the first year. By the age of 2, a baby’s weight will have quadrupled!

Researchers have given this part of the life span more attention than any other period, perhaps because changes during this time are so dramatic and so noticeable. We know that much of what happens during these years provide a foundation for one’s life to come, however, it has been argued that the significance of development during these years has been overstated (Bruer, 1999). Nevertheless, this is a period of life that contemporary educators, healthcare providers, and parents have focused on quite heavily. It is also a time period that can be tricky to study—how do we learn about infant speech when they cannot articulate their thoughts or feelings? For example, through research we know that infants understand speech much earlier than their bodies have matured enough to physically perform it; thus it is evident that their speech patterns develop before the physical growth of their vocal cords is adequate to facilitate speech.

In this module, we will examine the rapid physical growth and development of infants, look at the influences on physical growth and cognitive development, then turn our attention toward emotional and social development in the early years of life. The early years are a time of rapid physical, cognitive, social, and emotional development, which have a direct effect on a baby’s overall development and the adult they will become.

What you’ll learn to do: describe physical growth and development in infants and toddlers

We’ll begin this section by reviewing the physical development that occurs during infancy, a period that starts at birth and continues until the second birthday. We’ll see how this time involves rapid growth, not only in observable changes like height and weight but also in brain development.

Next, we will explore reflexes. At birth, infants are equipped with a number of reflexes, which are involuntary movements in response to stimulation. We will explore these innate reflexes and then consider how these involuntary reflexes are eventually modified through experiences to become voluntary movements and the basis for motor development as skills emerge that allow an infant to grasp food, rollover, and take the first step.

Third, we will explore the baby’s senses. Every sense functions at birth—newborns use all of their senses to attend to everything and every person. We will explore how infants’ senses develop and how sensory systems like hearing and vision operate, and how infants take in information through their senses and transform it into meaningful information.

Finally, since growth during infancy is so rapid and the consequence of neglect can be severe, we will consider some of the influences on early physical growth, particularly the importance of nutrition.