Englisches Seminar der Universität zu Köln
Hauptseminar: First Language Acquisition
Semester: WS 06/07, 6. Semester

Language & Down’s Syndrome
An approach to the acquisition of grammar in the mentally retarded

by

Carsten Krumdiek

Content

I. Introduction 3

II. Down Syndrome – An overview 4

i. What is Trisomy 21? –A brief history 4
ii. Physical and cognitive consequences 5

III. Language of children with Down syndrome 6

i. General problems in speech 6
ii. Suggestions for Individual differences 8

IV. Morphosyntax in Individuals with Down Syndrome 9

i. General morphosyntactic problems 9
ii. The acquisition of grammatical morphemes 13

V. Conclusion 19

VI. Bibliography 20

I. Introduction

The acquisition of language has been a field of study rather new to research, emerging only in the middle of the last century. Among scholars it has been of great interest how people acquire their first language and there have been a great number of controversies what some of the suggested hypotheses are concerned. Another fairly interesting issue, as opposed to normal language acquisition, is the study of people who acquire language even though they are faced with quite particular learning conditions. These people, precisely those who suffer from mental retardation, usually do acquire language; however, this language seems to diverge from the one acquired by typically developing individuals. The present paper will discuss the linguistic problems of individuals with Down syndrome (DS), a genetic disorder, occurring in groups of any social or educational level. It is considered to be the “most common cause of moderate to severe learning disability in childhood”. (Buckley 2000: 10) Approximately one in 700-900 babies is born with Trisomy 21 by mothers of any age. (cf. Buckley 2000: 9-10)
The study of Down syndrome children in particular, offers several advantages. Due to their physiognomy, subjects with Down syndrome are fairly easy to identify. In addition, language impairment in DS individuals represents a very prominent feature of this group. In this paper, a brief overview on some of the keyfacts shall be given first of all in order to understand the general problems typical of this genetic disorder. Second, the difficulties in speech production will be discussed in relation to physiological and cognitive consequences. The last chapter will deal with the acquisition of morphosyntax in DS individuals as opposed to the grammar in typically developing subjects and will, additionally, consider one particular approach as an account for the apparent differences – the Critical Period Hypothesis.

II. Down Syndrome – An overview

i. What is Trisomy 21? –A brief history

In 1866, a London physician, called John Langdon Down, started to make first steps in investigating a phenomenon, well-known today, under the term Down’s syndrome. Down, being the pioneer in this field of study, introduced the term Mongolism due to the fact that individuals suffering from this disorder seemed to resemble people from a specific region in Asia. (cf. Warkany 1975: 9-10) His research led to the wrong conclusion that patients were dealing with a form of racial deviation. Down suggested the syndrome to be an indicator for a putative regression towards an evolutionarily earlier form – a somehow primitive racial type. (cf. Tamm 1994: 12) In this paper, the term Mongolism will not be used due to political correctness. Instead, Down syndrome and Trisomy 21 will be used interchangeably.
In the following 93 years, several other theories with regard to Down’s syndrome became object of research by a number of scholars. Among them were many misconceptions such as Alcoholism, Syphilis and Tuberculosis, to name only a few, which were regarded as the determinants for the condition. Even social differences came into consideration until it could be proven that cases of Down’s syndrome occurred in any social class regardless of nationality, ethnicity etc. However, scholars realized quite quickly, that older women were more likely to give birth to a child with Down’s syndrome, than it was the case with the younger ones. Nevertheless, many misconceptions were drawn such as maternal worries, exhaustion by many pregnancies etc. (cf. Warkany 1975: 10-11) Finally, in 1959, Lejeune and his co-workers made an amazing observation, when analysing the tissue cultures of nine Down’s syndrome patients. To be more precise, they discovered that all of the subjects showed 47 chromosomes in their cells instead of the usual 46. (cf. Warkany 1975: 13)

Usually the nuclei of human body cells contain 46 chromosomes. Two of them are crucial for the determination of sex (XX for women, XY for men). Normally, the other 44 chromosomes form pairs of two, one chromosome coming from the mother and the other from the father. Individuals suffering from Down’s syndrome show a deviation in this aspect with reference to the chromosome 21. The genetic information of this particular chromosome is not only present in a pair as it is usually the case, but it turned out to be tripled in most or all body cells. Hence, this led to the denomination Trisomy 21. (cf. Tann 1994: 14) Even though Trisomy 21 is known as the by far most frequent type of Down’s syndrome, there are other forms of this disorder such as the Translocation Down’s syndrome and the Mosaicism. (cf. Donnel et al. 1975: 20,25) Nevertheless, the impact on learning development does not vary very much among these different types. (cf. Buckley 2000: 9) For further depth consult Donnel et al. (1975). However, even though a lot of research has been done until today, the causes for the occurrence of Trisomy 21 have not been found. Maternal age turned out to be a major factor but recent research has shown that also paternal age seems to have an impact on the condition. (cf. Tann 1994: 15)
A diagnosis like Down syndrome brings along a number of physical and cognitive consequences for the individual. These will be dealt with in the following section, in order to understand possible problems which may interfere with the process of language acquisition in these subjects.

ii. Physical and cognitive consequences

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