Part II: The Developing Person So Far: The First Two Years

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Over the first two years, body weight quadruples and brain weight triples. Connections between brain cells grow dense, with complex networks of dendrites and axons. Experiences that are universal (experience-expectant) and culture-bound (experience-dependent) aid brain growth, partly by pruning unused connections between neurons.

Brain maturation as well as culture underlies the development of all the senses. Seeing, hearing, and mobility progress from reflexes to coordinated voluntary actions, including focusing, grasping, and walking.

Infant health depends on immunization, parental practices (including “back to sleep”), and nutrition. Breast milk protects health. Survival rates are much higher today than even a few decades ago.

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As Piaget describes it, in the first two years, infants progress from knowing their world through immediate sensory experiences to “experimenting” on that world through actions and mental images.

Information-processing theory stresses the links between sensory experiences and perception. Infants develop their own ideas regarding the possibilities offered by the objects and events of the world.

Interaction with responsive adults exposes infants to the structures of communication and language. By age 1, infants usually speak a word or two; by age 2, language has exploded—toddlers talk in short sentences and add vocabulary each day.

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Babies soon progress to smiling and laughing at pleasurable objects and events, and experience anger, sadness, and fear. Toddlers develop self-awareness and social awareness, and experience new emotions: pride, shame, embarrassment, disgust, and guilt. All emotional reactions begin in the brain, but the links between expressed emotions and brain growth are complex.

Parents and infants respond to each other by synchronizing their behavior. Toward the end of the first year, secure attachment to the parent sets the stage for the child’s increasingly independent exploration of the world. Insecure attachment—avoidant, resistant, or disorganized—signifies a parent–child relationship that hinders learning. Infants’ self-awareness and independence are shaped by parents. Much of basic temperament is inborn and apparent throughout life. Sociocultural theory stresses cultural norms, evident in parents’ ethnotheories in raising their infants; some parents are more proximal (encouraging touch), others more distal (encouraging cognition). All provide allocare, essential for survival.