Vocabulary development

In order to build their vocabularies, infants must learn about the meanings that words carry. The mapping problem asks how infants correctly learn to attach words to referents. Constraints theories, domain-general views, social-pragmatic accounts, and an emergentist coalition model have been proposed to account for the mapping problem. From an early age, infants use language to communicate. Caregivers and other family members use language to teach children how to act in society. In their interactions with peers, children have the opportunity to learn about unique conversational roles. Through pragmatic directions, adults often offer children cues for understanding the meaning of words. Throughout their school years, children continue to build their vocabulary. In particular, children begin to learn abstract words. Beginning around age 3–5, word learning takes place both in conversation and through reading. Word learning often involves physical context, builds on prior knowledge, takes place in social context, and includes semantic support. The phonological loop and serial order short-term memory may both play an important role in vocabulary development. Infants begin to understand words such as 'Mommy', 'Daddy', 'hands' and 'feet' when they are approximately 6 months old. Initially, these words refer to their own mother or father or hands or feet. Infants begin to produce their first words when they are approximately one year old. Infants' first words are normally used in reference to things that are of importance to them, such as objects, body parts, people, and relevant actions. Also, the first words that infants produce are mostly single-syllabic or repeated single syllables, such as 'no' and 'dada'. By 12 to 18 months of age, children's vocabularies often contain words such as 'kitty', 'bottle', 'doll', 'car' and 'eye'. Children's understanding of names for objects and people usually precedes their understanding of words that describe actions and relationships. 'One' and 'two' are the first number words that children learn between the ages of one and two. Infants must be able to hear and play with sounds in their environment, and to break up various phonetic units to discover words and their related meanings. Studies related to vocabulary development show that children's language competence depends upon their ability to hear sounds during infancy. Infants' perception of speech is distinct. Between six and ten months of age, infants can discriminate sounds used in the languages of the world. By 10 to 12 months, infants can no longer discriminate between speech sounds that are not used in the language(s) to which they are exposed. Among six-month-old infants, seen articulations (i.e. the mouth movements they observe others make while talking) actually enhance their ability to discriminate sounds, and may also contribute to infants' ability to learn phonemic boundaries. Infants' phonological register is completed between the ages of 18 months and 7 years. Children's phonological development normally proceeds as follows: 6–8 weeks: Cooing appears 16 weeks: Laughter and vocal play appear