Newborns reflexively yawn, grunt, burp, sigh, and produce an "undifferentiated" cry (Oller & Eiler, 1988). Over time. however, different needs are signaled by differentiated crying, different types of cries. This development suggests that the infant has learned that communicating in this way often lead to the fulfillment of certain needs such as resolving pain, hunger, and fatigue. As infants gradually establish control of breathing and coordination of muscles, they become capable of producing specific sounds.
As general cognitive abilities develop during the first year of life, language abilities also increase. Before speech acquisition, also called expressive language, children learn to understand speech, which is called receptive language (Wood, 1981). For example, at about six months, most children respond to their own names. They turn and look at a person who says their name. At about nine months, most children appropriately respond to words such as come and up.
As children begin to increase the number of their vocalizations, the role of adult modeling of language becomes increasingly important. Parents and other care providers model correct language, semantics (meaning of words), syntax (rules for sentence construction), and phonology (sounds) of language. They also provide models for the rules of conversational speech, called pragmatics, which include taking turns when speaking in a conversation. Adults provide reinforcement by responding to the child after the child vocalizes (Norman & McCormick. 1993).
Care providers and parents frequently use motherese. This style of speech uses a simpler, shorter, and more repetitious sentence structure. That is, adults reduce the complexity of their speech when talking to very young children. As a child matures and begins saying words, adults often expand on the child's vocalizations. For example, expansion is demonstrated when a child says, "Go car?" and the mother responds, "Yes, daddy went in the car." Motherese and expansion seem to enhance language development (Leonard, 1986).
Around three months, most babies begin cooing, which is comprised of soft melodic vowel sounds, including "ooh" and "ahh." Between six and fourteen months old, most babies begin to babble, which refers to repeating strings of vowels and consonants (e.g., babababa, mamama), When a child coos or babbles and an adult is present, the adult usually responds to the child in some way (Bloom, 1993), For example, after a child says, nananana, the adult may turn toward the child, imitate the child or respond in some other way. When adults respond to children in this manner, it often reinforces vocalizations. Children are more likely to coo or babble if an adult responds (Fey, 1986).
Children typically speak their first word at about twelve months. At this time, most children begin making their needs and desires known through words (Aitchison, 1996). These words are mental symbols that refer to objects, people, and events (Kuczak, 1986). The year-old child typically may say several words. These words are most often names of familiar people or objects such as mommy, daddy, and drink. These vocal symbols serve as a method for children to encode (store in memory) their experiences. They also provide methods for encoding information in long-term memory (Clark 1996). Children are likely either to overextend, applying a word broadly to a set of stimuli, such as using the word juice to refer to any drink, or underextend, restricting the use of a word to only one stimulus, such as using the word dog to mean only the child's toy dog (Carroll, 1986).
Children's use of art, symbols, and language to represent objects, people, and events is called symbolic thinking. The ability to think symbolically is directly related to language development (Gopnik & Meltzoff, 1986). Symbolic thought is evident in preschoolers' dreams, imagery, and play. This form of thought allows children to start fantasizing and creating novel images by manipulating symbols in complex and personal ways. Children's abilities to use symbolic thinking depends on prior development of cognitive abilities that allow them to think about, organize, and process information internally (Norman & McCormick, 1993),
Most toddlers (one to two years old) remember names of objects and pictures. They will imitate and use these names at a later time. They point to toys, pictures in a book, or parts of the body when named. They gradually begin to name objects themselves. In general, children comprehend more language than they can produce (Blank, Rose, & Berlin, 1978). For example, they may be able to respond appropriately to an adult saying, "Give me your shoes," yet be unable to produce the phrase, "Give me your shoes." During the first two years of development, most children without developmental disabilities use single words. Often these words represent a sentence. An example of a one-word sentence, called a holophrase, is when a child says, "juice!" The child is likely to be communicating, "I want a drink of juice!" (Yoder & Warren, 1993; Bloom & Lahey, 1978).
During the second year of life, short sentences begin to be a part of children's language. These sentences are typically composed of a verb and other words. Toddlers typically have acquired a vocabulary consisting of 25 to 300 words (Bloom, 1991), "Me do," "My ball," and "Mine!" are frequent words a two-year-old uses. These two-word utterances are likely to include telegraphic speech, which includes core words (key verbs and nouns) and omits less important words. For example, a toddler is likely to say, "more juice," rather than, "I want more juice." Large variations in toddlers' speech often occur. Although rare, some toddlers appear to be very reluctant to speak (selectively mute), but once they do, they typically display a rapid growth of vocabulary (Warren & Kaiser, 1988).
Wide variations in the number of words found in children's sentences are common even for children the same age. One method used by psycholinguists (psychologists who study language development) to measure children's language development is mean length of utterance (MLU). MLU increases gradually with age. The average sentence length for a child two years old is two words. Children typically use sentences about three to six words in length by three to four years of age (Hoffnung, 1989).
Children two to four years old develop language skills consisting of communicative and noncommunicative language. Communicative language involves children's ability to tell others what and how they themselves are thinking. Noncommunicative language consists of repetition, monologue, and collective monologue. Repetition is shown when children repeat what others say (Berko Gleason, 1989). This is frequently observed when children have older siblings or are in a preschool or daycare setting. Children often repeat someone else's statement, acting as if it is their own.
Children's language is referred to as a monologue when they talk out loud to themselves. Children often use this type of noncommunicative language during solitary play (while playing alone) (Berk, 1992). When many children sit together and talk, but not to each other, a collective monologue is being used. This type of language may help guide problem-solving. For example, a child may think aloud and say, "My tower is tall. I'd better be careful or it'll fall down." When preschoolers think aloud in monologues, they are often guiding their own thoughts and actions by communicating with themselves. For example, a four-year-old, while putting toys away might say, "This goes over here." A child who talks out loud also engages in positive self-talk such as, "I can do this." Children who use this type of self-talk are more likely to have a positive self-esteem than children who use negative self-talk such as, "I can't do this."
Children often control their impulses by inner speech, cautioning themselves as their parents would. This speech type may be seen when a child tries to stay out of the cookie jar by thinking or saying, "Wait until after dinner!" Inner speech helps direct children's thinking as they mature. During early childhood, inner speech begins as a whisper or mutter to oneself, and, as the child matures, self-talk (a form of inner speech) becomes silent talking, thinking inside the head (Greene, 1975). Inner speech, however, does not disappear altogether. Most people use it from time to time by saying things like, "I can't believe I did that," "I can't believe how that person is driving," or "I need to be more careful!"
By three or four years old, most children's vocabulary increases rapidly. At this time, children's language typically uses the basic rules of speech and grammar, the set of rules that govern how words are used, combined, and altered in a language (Bernstein & Teigerman, 1989). Children use simple sentences that follow a subject-verb-object word order. Children at three-and-a-half years have typically mastered the basic rules of grammar so well they frequently overapply the rules to words that are exceptions, called overregularization (Behren, 1988). For example, they may say, "The childs goed to the store." Although this sentence is not grammatically correct, it does indicate that the child understands that plurals are made by adding -s and the past tense is indicated by adding -ed.
Throughout the preschool years, children's communication skills continue to become more effective. They tell others what they want and may use language to manipulate how others perceive a situation. Preschoolers though, frequently cannot describe important features of objects. For example, a three-and-a-half-year-old tells an adult to take down a truck from the closet shelf. If the shelf has several trucks on it, the child may have difficulty clearly communicating the desired truck (Peccei,1994).