Early childhood is a stage in human development. It generally includes toddlerhood and some time afterwards. Play age is an unspecific designation approximately within the scope of early childhood. Some age-related development periods and examples of defined intervals are: newborn (ages 0–5 weeks); infant (ages 5 weeks – 1 year); toddler (ages 1–3 years); preschooler (ages 3–5 years); school-aged child (ages 6–11); adolescent (ages 12–17).
In psychology the term early childhood is usually defined as the time period birth until the age of nine to twelve years, therefore covering infancy, kindergarten and the early school years up to grades 3,4,5 or 6. There are three simultaneous development stages:
Physical growth and development
In this phase there is significant synaptic growth and myelination of neural fibers in the brain, especially within the frontal lobes. For example, between the ages 2 and 6, the brain increases from 70% of its adult weight to 90%. The growth of the brain is followed by a surge in cognitive abilities. Around the age of five, children start speaking properly and master their hand to eye coordination.
It is optimal that an environment is provided that encourages physical development and allows the children to explore and try out new things. The physical development in children follows a pattern. The large muscles develop before the small muscles. The large muscles are used for walking, running and other physical activities. These are known as gross motor skills. Small muscles are used for fine motor skills such as picking up objects, writing, drawing, throwing and catching.
Cognitive growth and development
Called the preoperational stage by Jean Piaget, this is the stage during which the child repeatedly asks "Why?", and is used to build relationships with the child. The child can't yet perform the abstract thinking operations. The child has to be able to see what is being talked about, because they do not understand the concepts of logic, betrayal, contemplation, etc. This means that they think literally: if a child is told that they have to go to bed because "night is falling", they will ask how can the night (literally) fall from the sky. They also see the human characteristics in every object, e.g. the table "is bad" if they accidentally hit it with their foot and it hurts. They also exhibit egocentrism; not to be confused with egoism; that being said, they do not comprehend that the other person has beliefs and the children at this age think that what they think, everybody thinks. There is also a matter of perceptive centration, which causes the children to primarily see what is visually most prominent on someone/something, e.g. if a man has long hair, the child will think he's a woman.
Social-emotional growth and development
This includes children understanding a sense of 'self', relationships with others and sociability. The emotional development includes expressions, attachment and personality. Children manifest fear of dark and monsters and around the age of three notice whether they are a boy or a girl and start acting that way. Boys are usually more aggressive, whilst girls are more caring. However, aggression is manifested in two different ways: boys are more physically aggressive, while the girls are more socially aggressive (name-calling and ignoring). In this stage the individual differences become more prominent.