Abstract:
The literature on mental retardation, Down's Syndrome, language acquisition and language programmes for the mentally retarded, was briefly reviewed, and the possibility of using sign language for communication with the retarded raised. The investigation examined the possibility of using a 'phonetic sign language', devised by the investigator, in which each phoneme of the English language was paired with a specific manual sign, in order to facilitate expressive speech and reduce a typical behaviour in a group of subjects with Down's syndrome. Ten subjects aged between 8 1/2 and 17 years (IQs 20-40) were assigned to two groups; five in the 'experimental' group and five in the 'control’ group, so as to match the two groups as closely as possible.
Both groups were taught in periods of 20 minutes duration on four days of the week for a total of 12 weeks. The experimental group was taught the 'simultaneous' language in which the phonemes were presented verbally and with the corresponding manual signs. The control group was taught the phonemes verbally only. An experimental vocabulary was generated by imposing a limit of a maximum of three phonemes per word using the 15 vowels and 10 consonants most frequently used in the English language.
Before and after the investigation, the subjects were tested on the Illinois Test of Psycholinguistic Abilities (ITPA), and the Reynell Developmental Language Scales (RDLS). Measures of each subject's attempts at verbal communication (AVC), attempts at non-verbal positive interaction (NVI), and an a typical behavioural rating (ABR) were recorded during a randomly chosen 20 minute observational period each week, in the subject's training area placement.
Only on the ITPA Psycholinguistic Age (PLA) scores did the experimental group perform statistically better than the control group. The results of measurements on the other variables examined were inconclusive, and several possible reasons, such as experimenter bias, the measuring instruments not being sensitive enough, and insufficient training, were suggested.
