The Phonological Development of Child Language and Aphasia as a Linguistic Problem
Types of Linguistic Activity
"The child provides the only opportunity that we have to observe language in its nascent state", as Karl Bühler has recently written, and one could continue accordingly: Pathological speech disturbances of a central nature provide the only opportunity that we have to observe language in dissolution.
5. Principle of Least Effort and Cessation of Babbling Sounds
The fact that a fixed order must be inherent in language acquisition, and in phonological acquisition in particular, has repeatedly been noticed by observers and has often been explained by appealing to the principle of least effort. First mentioned in Buffon, this principle is nonetheless generally cited as Schultze's law of the succession of phonological development, since it was Fritz Schultze who, fifty years ago, energetically sought to prove that those speech sounds which require the least physiological effort for their production are learned first by children. This questionable hypothesis was indeed often opposed, particularly because of the quite arbitrary nature of the criteria for determining the degree of effort required for the sounds in question. Nevertheless, a remnant of such a conception is still continually found even in the newer works on child language, e.g., in the famous handbook by Stern. But this hypothesis is completely refuted by an essential fact of the child's linguistic development.
The actual beginning stages of language, as is known, are preceded by the so-called babbling period, which brings to light in many children an astonishing quantity and diversity of sound productions. A child, during his babbling period, can accumulate articulations which are never found within a single language or even a group of languages -- consonants of any place of articulation, palatalized and round consonants, sibilants, affricates, clicks, complex vowels, diphthongs, etc. According to the findings of phonetically trained observers and to the summarizing statement of Grégoire, the child at the height of his babbling period "is capable of producing all conceivable sounds".
As all observers acknowledge with great surprise, the child then loses nearly all of his ability to produce sounds in passing over from the pre-language stage to the first acquisition of words, i.e., to the first genuine stage of language. It is easy to understand that those articulations which are lacking in the language of the child's environment easily disappear from his inventory. But it is striking that, in addition, many other sounds which are common both to the child's babbling and to the adult language of his environment are in the same way disposed of, in spite of this environmental model that he depends on. Indeed, the child is generally successful in recovering these sounds only after long effort, sometimes only after several years. This is the case, e.g., with palatal consonants, sibilants and liquids. Inasmuch as the child continually repeats these sounds during the babbling period, their motor image is necessarily imprinted on him, and the acoustic image must also exist. The observation of deaf and dumb children shows clearly that for normal development the acoustic impression of one's own sound productions is all-important, and that the child reacts to just this perceptual impression when he attempts to imitate his own sound productions in the process known as autoecholalia.