CHILD DEVELOPMENT

the growth of perceptual, emotional, intellectual, and behavioral capabilities and functioning during childhood. The term childhood denotes that period in the human lifespan from the acquisition of language at one or two years to the onset of adolescence at 12 or 13 years. The end of infancy and the onset of childhood are marked by the emergence of speech at one to two years of age. Children make enormous progress in language acquisition in their second year and demonstrate a continually growing vocabulary, an increasing use of words in combinations, and a dawning understanding of the rules of grammar and syntax. By their third year children tend to use sentences containing five or even six words, and by the fourth year they can converse in adultlike sentences. Five- and six-year-olds demonstrate a mastery of complex rules of grammar and meaning. Early childhood (two to seven years) is also the time in which children learn to use symbolic thought and language to manipulate their environment. They learn to perform various mental operations using symbols, concepts, and ideas to transform information they gather about the world around them. The beginnings of logic, involving the classification of ideas and an understanding of time and number, emerge in later childhood (7 to 12 years). Children's memory capacity also advances continually during childhood and underpins many other cognitive advances they make at that time. As both short-term and long-term memory improve, children demonstrate an increasing speed of recall and can search their memory for information more quickly and efficiently. Young children's growing awareness of their own emotional states, characteristics, and abilities leads to empathy-i.e., the ability to appreciate the feelings and perspectives of others. Empathy and other forms of social awareness are in turn important in the development of a moral sense. The basis of morality in children may be said to progress from a simple fear of punishment and pain to a concern for maintaining the approval of one's parents. Another important aspect of children's emotional development is the formation of their self-concept, or identity-i.e., their sense of who they are and what their relation to other people is. Sex-role identity, based on gender, is probably the most important category of self-awareness and usually appears by the age of three. The onset of the physical and emotional changes of puberty and the acquisition of the logical processes of adults mark the end of childhood and the start of adolescence.