Williams Syndrome and the language Instinct

Williams Syndrome is a rare developmental disorder that affects 1 in 20,000 people. Its genetic origin has been discovered it emerges as a result of a deletion of some 17 contiguous genes on chromosome 7q 11.23 (Gerrans: 2003). Despite working with people with intellectual disabilities of various different kinds I have only ever worked with one child with Williams Syndrome. It is not the place here to discuss the child. I will merely note that the child was friendly, fun and did indeed seem from an intuitive perspective to have a verbal IQ which far outstripped his general IQ. However, as we all know a person’s subjective impressions are not a sound basis for a scientific analysis. I merely mention my subjective impressions to indicate that I can see why Nativists were led to arguing that syntax was spared in people with Williams Syndrome. This is the subjective impression that people with Williams Syndrome give, and a lot of early tests indicated that language, in particular syntax was indeed spared in people with Williams Syndrome.

In his excellent 1994 book ‘The Language Instinct’, Steven Pinker mounted a series of arguments for his theory that people have an innate domain specific language faculty. He gave evidence from a variety of different quarters, poverty of stimulus arguments, the speed a child and apparent effortlessness that children learn their first language, the fact that children can allegedly learn language without any correction for ungrammatical mistakes etc. I have gone through all of his arguments in other blogs and have been very critical of them. I will not repeat the material here. In this paper I just want to discuss his claim that an apparent double dissociation occurs with Specific Language Impairment (SLI) and Williams Syndrome and that this is evidence for an innate domain specific language faculty.

In a nut shell Pinker (1994) argued that in SLI people have unimpaired general IQ but they constantly make specific grammatical mistakes. While in people with Williams Syndrome he argued the opposite appears to be the case. With Williams Syndrome people have a low general IQ (between 50 and 70) but have unimpaired syntax. Pinker used these two disorders as evidence that language and general intelligence were separate faculties; and in particular that there was indeed an innate domain specific language faculty.

The evidence for SLI has become increasingly under pressure in the 20 years since Pinker wrote ‘The Language Instinct’. People with SLI typically have damage to the FOXP2 gene, this fact lead people like Pinker to argue that FOXP2 was actually a gene for language.  It turns out that the FOXP2 gene which the press dubbed the language gene is shared by a number of other animals, so it isn’t specific to just humans and hence isn’t solely responsible for creating a language faculty. Experimental research into FOXP2 in other animals reveals that the gene plays a big role in motor control. It also turns out that a lot of the supposedly syntactic deficits in people with SLI are actually deficits in speech based on poor motor control. Furthermore despite Pinker’s assertions; people with SLI do not typically have a normal IQ, in fact they show a lot of non-linguistic cognitive problems, and have a general IQ of between 75 and 91 (See Plomin and Kovas ‘Generalist Genes and Learning Disabilities’ 2005). Overall despite the initial hype there is little reason to think that SLI offers any convincing evidence for a disassociation between language and general intelligence.

Pinker didn’t just speak of dissociation between language and intelligence; he spoke of a double dissociation. The case of SLI doesn’t stand up to critical scrutiny, however Williams Syndrome fares a bit better. The relatively spared syntactic abilities of people with Williams Syndrome, is good evidence for the existence of a language faculty, however, the data on the disorder is not as straight forward as it may seem.

Nativists typically argue that in Williams Syndrome, language (in particular syntax) is spared despite the fact that general intelligence is badly affected. However, in Grant et al 2000 ‘A study of Relative Clauses in Williams Syndrome’ they found that in a simple elicited imitation task examining the syntax of relative clauses; older children and adults with WS only reach the level of a typical five year old. This is an important result and is badly at odds with claims that syntax is spared in people with WS. They note that despite claims to the contrary the non-verbal skills of WS children who do well on language tests are not so low as to suggest idiot savants either.  Furthermore they argue that each time an empirical study is done on people with who are clinically and genetically diagnosed the language turns out to be delayed or deviant (Grant et.al. p404) They conclude that syntactic structure poses some difficulty for people with WS. People with WS are seriously delayed in syntactic development, even into adulthood. Older children and Adults with WS are significantly impaired in their ability to correctly repeat relative clause sentences. The data suggests that WS people are dependent on overt markers in order to process multi-clause sentences.

Now Grant et al is an interesting paper which clearly shows that claiming that language and syntax are spared in people with WS while general IQ is extremely low is a bit of an exaggeration. Syntax is not entirely spared as can be seen with the difficulties children with WS have with imitating various kinds of relative clauses. While as children with WS that are more proficient with language typically have a higher IQ than less verbal WS suffers. Nonetheless, Grant et al. still indicates that syntax, while not entirely spared, is surprisingly good given the typical general intelligence of WS suffers. So the research could at a stretch be used to support a Nativist position, though this would not be a straight forward matter and a lot more work would need to be done.

The fact that syntax is not entirely spared in people with WS adds shows that the data is more complex than some Nativists assume. Another complexity about WS is that children with it actually acquire language in a different way than normally developing children.  Laing et al. (2002) ‘Atypical development of language and social communication in toddlers with Williams Syndrome’ showed that people with WS are impaired in the triadic interaction that is necessary for the referential uses of language. Their study further showed that WS children don’t show the typical correlations between socio-interactive markers and language seen in typical controls.  In WS toddlers speech preceded pointing where as it followed pointing in the typically developing and DS toddlers. This fact suggests that despite acquiring a big vocabulary people with WS acquire language in a different way than typically developing people.  In previous studies Mervis et al (1999) showed that in a free play situation, toddlers with WS did not spontaneously use the pointing gesture. Other studies indicated that children with WS did not engage in co-ordinated joint attention until well after the vocabulary spurt. Laing et al wanted to further test these claims and to test whether problems with motor control was behind the fact that children with WS typically didn’t engage in pointing. They discovered that the WS group produced much less pointing behaviour than the control group… and the data shows the WS group are less interested in objects as the control group. It was noteworthy that the WS group were more social than the control group but the control group produced more triadic eye contact (Laing et al p. 237). WS people are deficient in production and comprehension of pointing. Their motor tests showed that the lack of pointing could not be attributed to poor motor control. Despite the lack of triadic eye contact, and pointing do children with WS do use words referentially.  Over all they take their studies to show that WS language acquisition follows a different developmental trajectory than normal language acquisition.

The fact that children with Williams Syndrome seem to acquire language in a different way than typically developing children is important, but not necessarily inconsistent with the Nativism hypothesis. Nativists[1] typically argue (wrongly as we have seen) that syntax is spared for people with WS. The fact that children with WS have difficulty both producing and interpreting pointing is not necessarily relevant to the issue of an innate domain specific language faculty. Chomsky, for example, restricts the ‘faculty of language narrow’ (FLN) to pure syntax (the operation of merge), and he would argue that pointing and learning the meaning of words are operations of the sensory motor system and the conceptual intentional system so have little to do with the faculty of language narrow which what is spared with WS. Theorists like Pinker who don’t divide up “Language Faculty” in Chomsky’s way, can still argue that it is syntax that Nativists argue is spared so the fact that children develop the ability to use language pragmatically differently is not that relevant.

However I think a closer look at the developmental phases children go through when acquiring language is vital. We know that their syntax is different, their semantics is different, and they acquire their language differently than typically developing subjects. It seems obvious to me that before we start talking about spared language abilities in WS subjects we need to do a lot more research. A lot of research has focused on experiments done on about 10 subjects on average. I think that more corpus analysis of the actual speech patterns of people with WS is needed and more longitudinal studies are necessary as well. We have more and more sophisticated recording data available than ever before. Using this data (assuming permission from parents of subjects and subjects themselves), we can record and analyse it; this is surely vital, and will vastly increase our knowledge. Another vital area that needs to be researched is the effects of various forms of therapy on people with WS (ABA, Speech and Language Therapy etc) in improving their linguistic skills and their general reasoning abilities. Until more research of this kind is done I think claims of spared language abilities in people with WS is irresponsible.

Martens et al (2008) ‘Research Review: Williams syndrome: a critical review of the cognitive, behavioural, and neuroanatomical phenotype’ analysed the recent studies into WS. In this meta-analysis they note that while it was originally believed that language (in particular syntax) was relatively spared in people with WS more recent studies have called this belief into question. People with Williams Syndrome use fewer gesturing skills than typically developing people. They have a vocabulary size well below the average for their age. They display atypicalities in their substitution of articles and prepositions. They also show evidence of typical but delayed, as well as atypical syntax, morphology and vocabulary (Martens et al p. 581) some recent research has revealed atypical performance in grammatical comprehension, gender agreement, morphosyntax, pragmatics, oral fluency, and semantic fluency.  They make the following important point:

“Variable findings across grammatical studies most likely reflect methodological issues such as differing sample sizes and the use of various language tests and comparison groups, as well as inconsistencies in language skills between and within WS individuals.  (Stojanovik et al. 2001 p. 37) stated that ‘any attempt to generalize from group studies should be approached with extreme caution.’ Despite this, generalisations frequently occur in secondary sources (Grant et al 2002) and findings of RELATIVE strengths evolve into claims of SPARED language skills in WS. (See Pinker, 1994 1999)”

Martens et al. (2008) ‘Research Review: Williams Syndrome: A critical review of the cognitive, behavioural, and neuroanatomical phenotype’.

I agree entirely with the above point; it is not that Nativists have been conclusively refuted on the WS issue; rather it is that the data indicates that we simply don’t know enough to decide either way on the issue. As the old cliché goes; more research is needed, as well as less extravagant claims by popular writers like Pinker. There is indeed good evidence that syntax is surprisingly good in WS subjects but there is also growing evidence that it is not entirely spared. In her ‘What’s Within’ Fiona Cowie notes that Rubba (1991) found that 19 percent of WS subject’s uses of prepositions was deviant. Clark and Lappin (2011) quote Brock (who did very large a survey of recent studies into the language of people with WS) Brock concluded “There is currently little evidence for selective preservation of linguistic skills in Williams Syndrome”. Furthermore people with WS typically have the same mental age as 5 year old children and 5 year old children have relatively fluent linguistic abilities.

I think the facts show that Nativists have not yet made their case. Nonetheless given how little we know at this stage more research is what is needed not dogmatic claims which stretch beyond the known evidence.

In this blog because of time constraints I have not described and analysed the experimental techniques used in the papers I mentioned. Furthermore I have not used enough data from meta-analysis to indicate why I think that future research needs to take the road I advocate. In my next blog on Williams Syndrome I will deal with these topics.

[1] I am being a bit vague in my use of Nativist. Obviously there are many different Nativist theories in the Generative Grammar literature. In the space limitations imposed by a blog I cannot go into the all of the different Nativist theories. I may in the future examine which different theories of Nativism are more consistent with the WS data.

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s