Williams syndrome is a metabolic disorder, characterized mainly by abnormalities in both calcium and calcitonin metabolism, a failure to thrive in the first year of life, a mental age consistently lower than the actual age and an ‘elfin-like’ facial appearance. This syndrome interests us mainly because it sheds light on the relationship between linguistic and cognitive functions, since it is one of the rare cases in which language outstrips other cognitive abilities.
According to a model of language acquisition, language reflects cognitive growth. Nevertheless, two experiments -conducted by U. Bellugi, S. Marks, A. Bihrle and H. Sabo- show that Williams syndrome children, despite of their linguistic abilities, were unable to deal with two specific cognitive abilities -seriation and conservation- considered by various authors (e.g. Shaffer & Ehri 1980) to be connected to linguistic functioning. Interestingly though, despite of topographic disorientation, spatial memory deficits and visuoconstructive impairments, Williams syndrome people, when tested, have shown an unexpected capacity to recognize and discriminate unfamiliar faces in different orientations.
People affected by Williams syndrome show remarkable linguistic abilities, despite of their cognitive deficits. In addition to their bubbly characters- they are very loquacious, social and interactive- their distinctive characteristic is the use of unusual vocabulary such as ‘surrender, sauté, nontoxic, commentator, and brochure’ involving awareness demonstrated by their ability to define words used spontaneously, for example ‘It’s non toxic. That means it is not dangerous’. Moreover, a formal language test in which the subject is required to give oral definitions for 20 common English words shows an unusual vocabulary which scores higher than would be expected from children of equivalent mental ages.
The children’s expressive language is complex and generally correct. A measure of language complexity is the mean length of utterance (MLU) in morphemes. For example the MLU in morphemes of 100 consecutive utterances during a storytelling task for three Williams syndrome adolescents is approximately 10.00 in average, which is much higher than the one for Down’s syndrome.
The Williams syndrome children’s expressive language is also complex in terms of morphological and syntactic structures. For example Ben said ‘ After it stopped hurting, I was told I could go to school again and do whatever I feel like doing’. The children demonstrated proper use of grammatical inflections, tense and aspect markers, passives, conditionals and all the complex structures of English. Moreover, the Test for Reception of Grammar (TROG) shows that their ability is not only related to production but also to comprehension of specific grammatical structures that have been linked to particular cognitive skills that these children have not mastered- for example the ability to seriate-.
Last but not least, Williams syndrome children studied so far have shown some ability to handle metalinguistic tasks such as grammaticality judgements and relevant corrections, which involve awareness and manipulation of grammar.
In conclusion, this syndrome gives evidence for the modular view, according to which linguistic abilities are independent of the other cognitive abilities.