A baby's brain grows and develops rapidly during the first year of life. His mental, emotional and physical development processes are interconnected. For example, cognitive, or mental growth, leads to the refinement of motor skills. Babies mature at different rates, but there are general timelines for development milestones. A pediatrician can assess whether a child's developmental rate is normal.
Brain Development
The most important aspect of infant brain development is the creation of synapses, neural connections that control mental function. Brain development begins in utero, but environmental factors play a major role in the types of connections the brain builds after birth. The brain creates far more synaptic connections than the baby will ever use, so a pruning process begins at around age two and continues until adolescence. During this process, the brain essentially "weeds out" unused connections.
Another important process of brain development beginning in infancy is called myelination. Myelin is a brain substance that enhances transmission. Myelination begins in the sensory and motor cortex, which is why these skills develop earlier than higher thinking skills do. Myelination continues into early adulthood.
Cognitive Development
Biologist Jean Piaget developed a list of steps in intellectual development known as Piaget's Stages of Cognitive Development. The first two years of life are called the sensory motor period. These cognitive stages are directly connected to physical development because a baby must first learn how to interact with his environment. A baby's earliest movements are survival reflexes, including grasping, rooting and sucking for nourishment. At around two months, a baby begins repetitive actions, called circular reactions, such as opening and closing the fingers. These circular reactions mature over the next ten to twelve months, leading to increasingly complex processes. By around two years of age, most babies display problem-solving behaviors and have discovered new ways to obtain results.
Physical Development
By about three months, most babies can hold up their heads and grasp at their own hands. By six months, infants have developed core strength that allows them to roll over. They also grasp at objects and put things in their mouths as a means of exploration. Most babies begin to crawl and to pull objects toward themselves by about nine months. By about one year, babies can usually sit upright, stand on their own and throw things. Most babies can also take a few guided steps at this age. By two years old, babies can walk unaided, and their fine motor skills have improved, allowing them to scribble and complete tasks such as putting rings on a peg.
Psychological and Emotional Development
Psychoanalyst Erik Erikson theorized that a baby's physical and emotional needs must be fulfilled in order for the child to complete various psychological stages of development. The primary stage of psychological development in infancy is known as trust versus mistrust. For example, if a baby learns that crying results in his needs being met in a caring manner, he will learn to trust his environment. A baby whose cries are ignored or met with negativity will become uncertain, leading to mistrust.
