児童心理学
Child development involves the biological, psychological and emotional changes that occur in human beings between birth and the conclusion of adolescence. Childhood is divided into 3 stages of life which include early childhood, middle childhood, and adolescence. Early childhood typically ranges from infancy to the age of 6 years old. During this period, development is significant, as many of life's milestones happen during this time period such as first words, learning to crawl, and learning to walk. There is speculation that middle childhood or ages 6–13 are the most crucial years of a child's life, ranging from the starts of some sorts of formal schooling to the beginning of puberty, and this is also the period where many children start to gain a more sense of self. Adolescence, is the stage of life that typically starts around the time puberty hits, all the way up until legal adulthood. In the course of development, the individual human progresses from dependency to increasing autonomy. It is a continuous process with a predictable sequence, yet has a unique course for every child. It does not progress at the same rate and each stage is affected by the preceding developmental experiences. Because genetic factors and events during prenatal life may strongly influence developmental changes, genetics and prenatal development usually form a part of the study of child development. Related terms include developmental psychology, referring to development throughout the lifespan, and pediatrics, the branch of medicine relating to the care of children.