Physically, between birth and age three a child typically doubles in height and quadruples in weight. Bodily proportions also shift, so that the infant, whose head accounts for almost one-fourth of total body length, becomes a toddler with a more balanced, adult-like appearance. Despite these rapid physical changes, the typical three-year-old has mastered many skills, including sitting, walking, toilet training, using a spoon, scribbling, and sufficient hand-eye coordination to catch and throw a ball.Physical changes in early childhood are accompanied by rapid changes in the child's cognitive and language development. From the moment they are born, children use all their senses to attend to their environment, and they begin to develop a sense of cause and effect from their actions and the responses of caregivers.Over the first three years of life, children develop a spoken vocabulary of between 300 and 1,000 words, and they are able to use language to learn about and describe the world around them. A key moment in early childhood socioemotional development occurs around one year of age. This is the time when attachment formation becomes critical. Attachment theory suggests that individual differences in later life functioning and personality are shaped by a child's early experiences with their caregivers. The quality of emotional attachment, or lack of attachment, formed early in life may serve as a model for later relationships. We think about growth and development in five stages:
infancy from birth to one year
early years from one to three years
childhood from four to seven years
puberty from 8–12 years
adolescence from 13–16 years.
Birth to one year
New-born babies can:
see faces as fuzzy shapes
grasp an object that has touched the palm of their hand
turn their head to look for a nipple or teat if their cheek is touched suck...