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Toddling into Language

Precocious Language Development
in Children with Spinal Muscular Atrophy

By Jechil S. Sieratzki and Bencie Woll

Clinical Communications Studies - City University London
Defying their physical impairment, children with SMA are great communicators, and often appear particularly gifted for language. According to Prof.Victor Dubowitz, they "often speak at an early age and may be able to make long sentences by the age of 2 years, well in advance of the norm". However, two previous studies of SMA-patients aged 6-16 years have shown just average verbal and non-verbal abilities. No reports are available for younger children with SMA.

With the assistance of the Jennifer Trust for Spinal Muscular Atrophy we have collected data on ten children with SMA-II (intermediate type) aged 18-35 months. All 10 children were able to sit without support and, except for the youngest, feed themselves, build small tower blocks, and hold a pen. None of the children had difficulties with speaking or swallowing. Several were able to stand with leg braces, but not before age 24 months.

The language test used was the British version of the MacArthur Communicative Development Inventory, a parental checklist of a child's language development. The results reveal a particular pattern of language learning in children with SMA:

Vocabulary production:
Under the age of 2 years, when an able bodied child learns many words through direct physical interaction with objects in its environment, the number of words produced by SMA-children is slightly below average. In particular, words relating to mobility ("action words", "outside things", "places to go") may be missing. However, vocabulary expands rapidly after the 2nd birthday, as children with SMA begin to use language confidently for social interaction and as a tool to reach towards objects of their curiosity. Scores are now moderately above average.
Sentence length:
We did not record any exceptionally long sentences in children under the age of 2 years. Similar to vocabulary, the number of words per sentence is at first slightly below average. In children aged 29-35 months, the longest sentences were 10-15 words, above average but not exceptional.
Sentence complexity:
The sentences produced by children with SMA tend to be moderately more advanced and correct than those of an average child of the same age. For instances they may say "I can't do it" when many children still say "I no do it".
Irregular nowns and verbs:
Knowlege of words with unusual plurals ("foot-feet") or past tenses ("break-broke") is overall moderately above the scores for vocabulary.
Over-regularisations:
We found exceptionally high scores on over-regularisations, with 8 out of 10 SMA-children being far above average, in some cases up to 10 times higher than the norm for their age. Over-regularisations are errors which all young children make with irregular words. They represent important milestones in language learning, for the following reasons.

Young children may say words such as "foots" or "feets" (for "feet"), and "ated" or "eated" (for "ate") even though they have previously learned the same words in their correct form. Children appear to note that most words follow a regular pattern for plurals ("house-houses") or past tenses ("walk-walked"), and to apply this experience as a general rule even to irregular words. For some time they use both correct and incorrect form of the same word side by side. Over-regularisations gradually disappear as the child's language develops further.

Previous studies of normal children have suggested a strong connection between a "critical mass" of vocabulary, i.e. a threshold-number of words used by a child, and the beginning of the appearance of over-regularisations when their vocabulary is still relatively limited. This is of great theoretical importance for language scientists, as it demonstrates that the brain learns language rules separately from vocabulary.

Why does this particular advance occur in children with SMA? It cannot be explained by the fact that parents may spend more time with or pay more attention to a child with SMA. Adult language does not contain over-regularisations; these grammatical errors are not picked up from the language environment but produced by the child itself. Also, if children with SMA were overall advantaged for language, this should be seen in all areas of language including vocabulary, and not only in over-regularisations. Paradoxically, early vocabulary learning is slightly delayed in children with SMA, whereas development of grammar, which over-regularisations represent, is accelerated.

Our explanation is that children with SMA explore language in place of a world which they cannot reach, manipulating words and trying out different word-forms where typical toddler activities and interactions with the physical environment are not possible. This specific early linguistic advantage is no longer seen in older children with SMA, since normal children soon catch up. Children affected by SMA maintain and refine, however, their exquisite communication skills and ability to manipulate their social environment.

We would like to thank all the parents and children who participated in this first study; a more detailed study is being planned for the future.

For further information you can write to

Prof. Bencie Woll, Clinical Communications Studies, City University, London EC1V 0HB.
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Author : Jechil S. Sieratzki and Bencie Woll, Clinical Communications Studies - City University London.

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First published by The Jennifer Trust for Spinal Muscular Atrophy : 2nd June 1998

Latest update : 2nd June 1998