While body growth slows during early childhood, the brain continues to grow faster than other parts of the body. Lateralization increases, and language development is supported by the more rapid growth of the left hemisphere. Myelinization continues, and connections between parts of the brain increase, supporting improvements in physical and cognitive skills. Physical growth is affected by heredity through the regulation of hormone production, but as in earlier periods, environment contributes considerably. Emotional deprivation and malnutrition can interfere with physical development, and illness can interact with malnutrition to undermine children’s growth. However, the leading cause of childhood death is unintentional injury. Physical development during early childhood is exemplified by an explosion of gross and fine motor skills, influenced by a combination of hereditary and environmental factors.

Dramatic advances in mental representation occur during early childhood. Although Piaget’s preoperational stage emphasizes cognitive limitations, research on the young child’s theory of mind reveals that preschoolers use logical, reflective thought on familiar tasks. Still, Piaget’s theory has had a powerful influence on education, promoting child-oriented teaching approaches. Vygotsky regarded language as the foundation for all higher cognitive processes. As adults and skilled peers provide children with verbal guidance on challenging tasks, children incorporate these dialogues into their own self-directed speech. A Vygotskian approach emphasizes assisted discovery, including verbal support and peer collaboration. Some of Vygotsky’s ideas, like Piaget’s, have been challenged, especially regarding the role verbal communication plays in developing children’s thinking in different cultures.

A variety of information-processing skills improves during early childhood. Like adults, young children remember everyday events in a logical, well-organized fashion. Preschoolers develop a basic understanding of written symbols and arithmetic concepts through informal experiences. A stimulating environment, warm parenting, and reasonable demands for maturity predict mental development in early childhood. While at-risk children show long-term benefits from early intervention and high-quality child care, poor child care undermines the development of all children. Language development proceeds at a rapid pace in early childhood, supported by conversational give-and-take. By the end of the preschool years, children have an extensive vocabulary, use most grammatical constructions competently, and are effective conversationalists.