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2. Impairment 

The largest experiment in history

Where there are problems with respect to a child’s speech and language it makes sense to investigate this as just one of billions of cases over the entire course of modern human history of children learning to talk successfully and without help and how this extraordinary ability might have evolved. If this had been an experiment, the numbers would make this the largest experiment in the history of science. It should not be said that there is any shortage of data.

I am thus proposing that developmental issues with speeech and language should be viewed against the background of an evolution which may have lasted over a million or more years. The failures are either by non-activation or by activation at the wrong point or in the wrong way. They are mostly marginal. But some need specialised help to fix or address. The greatest developmental vulnerabilities are most likely to involve the most recently evolved characters, on which fixation is likely to be least robust.

This is not to suggest that such an evolutionary view will be useful or relevant in all cases. The human species specific faculty of speech and language is the most complex system in the whole of nature. Some children present with issues for which there is no plausible evolutionary account. But evolution suggests a useful for starting point for investigation.

If there was, as I contend here, an extended process by which the modern human faculty for speech and language evolved, it is not unreasonable to suppose that the emergence of this faculty in childhood is itself highly structured. This was the firm conclusion of Roger Brown (1973). That conclusion has not been significantly disputed. But while the entire modern apparatus is shared by the whole of the modern human population, it is still developmentally vulnerable.

This vulnerability is obviously quite different to the sort of damage which can orrur if a priviously healthy brain is deprived of oxygen or if the bain as a whole is affected by some violent trauma as in an accident.

Where there are problems with respect to a child’s speech and language it makes sense to investigate this as just one of billions of cases of children learning to talk successfully and without help and how this extraordinary ability evolved.

If this had been an experiment, the numbers would make this the largest experiment in the history of science. It should not be said that there is any shortage of data.

‘Processes’

Many incompetences involve incorrect adjustments of contrast within a structure, typically a word or phrase. ‘Assimilation’ reduces the contrast between two elements, as in “Good morning” in normally competent adult as GOOB MORNING. ‘Dissimilation’, much less common in competent speech. increases the contrast.

Many listings of supposed ‘processes’ in child speech do not mention dissimilation even though it is in fact quite common, represented here or there in the speech of most normally developing children between four and eight years old, as I showed in Nunes (2002)

By another process in the English of London and the Southeast of England, an R is inserted between the adjacent vowels in “osannah R in exccelsis Deo” and even between sentences in “I went skiing in Canada R and I broke my leg”. 

One of my problems with ‘process accounts’ of child speech and speech disorders is that they require two things to be happening simultaneously. learning one sort of process and unlearning another.

A leading idea

Impairment is obvious enough. But when it occurs with a child, will it last, or will it resolve? The leading idea here is that to understand the commonest pathologies, what are known as ‘Speech Sound Disorders’, Specific Language Impairment, stammering, Autistic Spectrum Disorder, and Central Auditory Processing Disorder, and their impacts on literacy, they should be viewed against the background of an evolution which may have lasted over two million or more years. The failures are either by non-activation or by activation at the wrong point or in the wrong way. They are mostly marginal. But some need specialised help to fix or address. The greatest developmental vulnerabilities are most likely to involve the most recently evolved characters, on which fixation is likely to be least robust.

If there was, as I contend here, an extended process by which the modern human faculty for speech and language evolved, it is not unreasonable to suppose that the emergence of this faculty in childhood is itself highly structured. This was the firm conclusion of Roger Brown (1973). That conclusion has not been significantly disputed. But while the entire modern apparatus is shared by the whole of the modern human population, it is still developmentally vulnerable.

The sense of ordered disorder

Many normally developing children of two three and four say little and middle as LIKU and MIGU and yellow as LELO, and at five, six and seven cardigan as KARDIDAN, hospital as HOSTIPU and spaghetti as BASKETI or PSKETI and magnet as MAGNIK. and at seven or eight, calculator as KALTALATOR, monopoly as MONOKOLI and hippopotamus as HITOPOTAMUS. Such characteristic incompetences, commonly described as the ‘processes‘ of child speech, can be analysed with respect to fractionally incorrect derivations, aspects of normal development where the child’s system is taken out of its comfort zone. But if such phenomena persist, this is likely to attract comment.

In magnet as MAGNIK, the back of the tongue articulation of the G is copied into the tongue tip T, without being lost at the point of origin. The segments contrast in their ‘voicing’, or the time relation between the release of the closure by the tongue. Most children, every child in my experience, preserve this contrast.

In spaghetti, the child’s system may reject the SP at the beginning of an unstressed syllable before the stressed syllable. So the S moves to the beginning of the stressed syllable, and the G become K‘ to match the samde property in its new neighbour. The structure is now more familiar except that the P has been left behind. It usually becomes a B. But in some children’s speech, as the S is moved, the initial unstressed vowel is left unrealised. And an initial cluster of PSK is formed in a pronunciation as PSKETI. Nobody would call this a natural way of making the word ‘easier to say’. But it has an easy derivation by one incorrect movement.

On an alternative ‘process account‘ BASKETI is commonly described in terms of ‘migration’. But this assumes a ‘process’ with only one common exemplar. It is more parsimonious to postulate a functionality which is justified independently in competent speech and language. On such reasoning, a process account is rejected here.

In hospital, competently pronounced, the tongue tip T at the beginning of the final syllable contrasts with whatever is left of the L sound. This often characterised as ‘syllabic’ because it works as a stand-alone syllable without an independent vowel. What is left consists mainly  in a lip rounding gesture similar to the vowel in pull, put or book, originating as a tongue tip L. In hospital as HOSTIPU, the T and P are reversed by what is known as ‘metathesis’. The tongue tip gesturing of the L is partially or completely lost in favour of a lip gesture, triggering a matching change at the beginning of the syllable. There are three steps here. First the lip-rounding of the final syllable is exaggerated. Second the lip action of the P is copied rightwards to the onset of the final syllable. Third, what is left behind at the start of the second syllable is a stop without a defined articulator. This is then said as a T.

By way of contrast, cardigan as KARDINTON is more suggestive of disorder possibly needing help. Here there is a sequence of steps, first changing the G to a D, then changing the D to a T, and then the N one syllable to the left. But these steps are likely to be taken at the very end of the derivation, inappropriate additions to it, all involving tongue tip articulations, after the stress has been assigned.

Even some apparently complex errors common in children’s speech can be reduced to the effect of minor misstatements of general, independently justified evolutionary principles. giving step by step increases in the possible complexity of syllables and forms of stress contour, both unusually complex in English. Failure is possible at any point along this pathway which gets increasingly intricate as it proceeds.