Mental Development in the Infant

Because of the initial high placement of the larynx, the infant's initial sounds are often mewing and throaty. Between the ages of three and nine months, the k and g sounds are very common. This helps to explain why adults, in imitation, often say coo or goo to babies. Later in the first year of life, as babbling comes into play, the early g and k sounds are less prominent as the larynx drops and these sounds become less easy to produce. Once the larynx has moved down into the throat, the infant begins to babble. In the course of this babbling, the infant is likely to produce all of the phonemes—the basic sounds—of his language.

The importance of this early babbling for language acquisition has been demonstrated by recent studies of children who have had their vocal apparatus obstructed by the necessity of a breathing tube in their throats. Their inability to babble during the early months of life delayed not only their acquisition of correct articulation, but also their mastery of other expressive language skills. Because babbling is often a repetitive, rhythmic activity, it has been related to motor development. That is to say, some investigators have found that there is a correlation between motor development and linguistic development. The earlier a child walks, the earlier he is likely to talk. Other investigators, however, find that compensation, not correlation, is the rule. They report that children who walk early, talk late, and vice versa.

Current neurological research suggests that the relation between motor development and language development is more complex than the notion of either correlation or compensation suggests. Brain function is extraordinarily diversified and intricate. Many highly specialized functions combine to form more general functions in a number of different ways. Both language and motor development are linked to brain development, but the interconnections between these developments remain obscure. Put differently, there is no simple relation between motor development and language development, and all sorts of combinations can and do occur.

We can, however, describe the general course of language development. This development involves not only the growing ability to articulate sounds, but also the ability to express meaning and to comprehend the language of others. The babbling that infants engage in during the second half of the first year of life contributes to both of these achievements. First of all, infant babbling is a way of practicing and perfecting the production of speech sounds. Initially, the infant produces many more sounds than those of his native language. Gradually, through hearing adult speech and through being rewarded for making certain sounds that elate parents (like mama or dada), he begins to limit speech production to the sounds of his particular language environment.

Babbling, however, also serves a social function. Children differ in the extent to which they engage in babbling. Some infants babble to adults—any adults—whereas others are more circumspect. Likewise, some children stop babbling as soon as they start to speak, whereas others continue babbling long after they have a spoken vocabulary of several dozen words. Even before they have a spoken vocabulary, while they are still babbling, most infants already have a passive vocabulary of several dozen words. They demonstrate this passive vocabulary, for example, by pointing to a picture in a book when they hear the name of the depicted object.

By the end of the first year of life, most children begin speaking recognizable words. The process is different for different children. For some children the first words may simply be reproductions of words the child has heard over and over again. One child who loved the record Puff the Magic Dragon uttered Puff as his first word. Other children's first words may come from reinforcement by the parents. If a child says duh, an easy sound for the child, the parents may rejoice and say aloud, "He said 'Daddy.' Say 'Daddy' again for Daddy." Through this reinforcement and modeling, the child may acquire his first recognizable words.

For some children the understanding that words carry meaning, that they stand for something, comes as kind of a sudden "aha" experience. When this happens, the child's vocabulary explodes from dozens to hundreds of words. For other children, the understanding that words have meaning comes more gradually, an increasing awareness of the linkage between words and things. For these children, vocabulary growth is much more gradual than it is for those who gain sudden insight into the meaning of words.

Toward the second year, the child gives evidence of our truly unique human capacity: the ability to create words of our own. This capacity separates us from all other animals, including the higher apes. Although it has been possible to teach higher animals to use sign language and tokens and to respond to computer symbols, it remains doubtful that they can create new symbols on their own. Yet children do this with ease. When one of my sons was young he began talking about "stocks." I foresaw a glorious future for him on wall street and had his business school all picked. He soon indicated, however, that he was using stocks as a word for both his mother's stockings and his father's socks.

By the age of two, children show other evidence that their language is but one facet of a broader, symbolic capacity. For example, it is only after the age of two that children begin to report dreams and night terrors. These reports coincide with the appearance of REM brain wave patterns, which are usually associated with dreaming. After the age of two, children demonstrate their new symbolic abilities in other ways. They engage in dramatic play and dress up like Mommy or Daddy or teacher or firefighter. They also display deferred imitation, the ability to observe a behavior at one time and to imitate it at another. A child who visits the doctor, for example may return home and deploy a tongue depressor (given to him by the nurse) into the mouth of a younger sibling. In general, as children progressively represent their world internally (symbolize it), they can increasingly manipulate it internally.

In working with infants and young children it is important to enrich their language experience. While feeding or changing an infant, we can talk to him about everything and anything. Many infants will nod their heads as if totally absorbed in the discussion. Singing to infants and young children and reciting rhymes to them is also very beneficial to their language development. Infants and toddlers love the sounds and rhythms of songs and rhymes and are often soothed by them. By talking to infants and young children while we engage in routine activities and in play, we help them learn the all-important auditory discriminations they require to speak their language.