patterns of syntactic development in children with williams syndrome and down's syndrome:...

Patterns of syntactic development in children withWilliams syndrome and Down’s syndrome: Evidence frompassives and wh-questions

VICTORIA JOFFE1, & SPYRIDOULA VARLOKOSTA2

1City University, London, UK, and 2University of the Aegean, Rhodes, Greece

(Received 23 February 2007; accepted 16 May 2007)

AbstractThis study investigates the syntactic abilities of ten individuals with Williams syndrome (WS) (meanchronological age: 8;9 years; mean mental age: 4;8 years) and Down’s syndrome (DS) (meanchronological age: 8;7 years; mean mental age: 4;6 years), matched individually on chronological age,mental age and performance IQ. The syntactic components investigated include the comprehensionof passives and the production, comprehension and repetition of wh-questions. Performance iscompared to ten younger typically developing (TD) controls matched individually to bothexperimental groups on mental age (mean chronological age: 4;4 years; mean mental age: 5;0 years).Participants were given a standardized measure of grammatical ability and non-standardized tasksexploring the comprehension of active and passive sentences, and the production, comprehension andrepetition of a range of wh-question types: wh-subject, wh-object, which NP-subject and which NP-object. Participants with WS and DS performed similarly on the standardized measure of grammaticalability, as well as on the experimental tasks that tapped comprehension of passives, and productionand comprehension of wh-questions. Participants with DS performed significantly more poorly thanboth the WS cohort and TD controls on the repetition of wh-questions. Both the WS and DS cohortsperformed significantly more poorly on most of the syntactic tasks compared to the younger TDcontrols. Individuals with WS and DS experienced significant difficulties in tasks measuring aspectsof syntactic ability and performed more poorly than mental age-matched TD controls. Implications ofthese findings, with regards to the debates around language ‘‘intactness’’ in WS, as well as thesimilarities and differences in language abilities in WS and DS, dependent on age and developmentalstages studied, are explored.

Keywords: Syntactic development, passives, wh-questions, Williams syndrome, Down’s syndrome

Introduction

Knowledge of language involves the internalization of a system of implicit grammatical

rules that ‘‘determine how sentences are formed, understood and used’’ (Chomsky, 1965:

25). This linguistic knowledge is usually evident relatively early in the child’s development

and allows young children between the ages of one and five years to typically master the

richness and complexities of language with apparent ease and rapidity (Chomsky 1965;

Correspondence: Victoria Joffe, Department of Language and Communication Science, City University, Northampton Square,

London EC1V 0HB, UK. Tel: +44 (0)20 7040 4629. Fax: +44 (0)20 7040 8577. E-mail: [email protected]

Clinical Linguistics & Phonetics, September 2007; 21(9): 705–727

ISSN 0269-9206 print/ISSN 1464-5076 online # 2007 Informa UK Ltd

DOI: 10.1080/02699200701541375

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Crain, 1991; Slobin 1974). Typical acquisition and development of language usually

progresses hand in hand with other areas of cognitive development (Piaget & Inhelder,

1969; Vygotsky, 1962). There are, however, a small minority of children who fail to master

the rules of language and present with delayed or disordered language. These language

impairments are typically associated with similar levels of cognitive impairments and in

many congenital neurological syndromes, language and cognitive abilities correlate highly

(Levy & Kave, 1999).

However, some developmental disorders have been cited as examples of differential

progression in language and cognitive development (Pinker, 1991; 1994; 1999). These

disorders have been used as evidence for Fodor’s (1983) Modularity Hypothesis which

maintains that certain cognitive processes are undertaken by specialized brain systems,

termed modules. A module, according to Fodor, is a domain specific brain system

responsible for handling a specific and circumscribed mental representation. Evidence for

this view comes from studies of adults with acquired brain damage who show what is

termed a double dissociation (Shallice, 1988; Fromkin, 1997): one group of patients shows

impairment in function X but not function Y, whilst a second group shows the opposite,

impairment in function Y but not function X (Shallice, 1988; Mayeux & Kandel, 1991).

Double dissociations show that function X and Y are independent of one another. Pinker

(1999) in fact argues for the existence of such a ‘‘genetic double dissociation’’ when

discussing two developmental disorders, Specific Language Impairment and Williams

syndrome: the former reportedly characterized by impaired grammar and spared

intelligence, and the latter, impaired intelligence and the sparing of grammar (p. 262).

This perspective argues for the independence of language from other cognitive functions

and allows for disorders to manifest with uneven levels of language and cognitive abilities.

An extension of the Modularity Hypothesis is that the language faculty is itself divided into

separate and independent subcomponents which function independently, i.e. the

independence of the lexicon, semantics, phonology and syntax (see Chomsky, 1981,

1995; Jackendoff, 1992, 1997, for different views on intralinguistic modularity). Evidence

to support intralinguistic modularity would come from differences in performance across

linguistic subcomponents, and such differences have been shown to exist in studies looking

at participants with Autism, Specific Language Impairment, Fragile X Syndrome, Williams

syndrome and Downs’s syndrome (Bellugi, Bihrle, Jernigan, Trauner, & Doherty, 1990;

Bellugi, Wang, & Jernigan, 1994; Fowler, 1998; Tager-Flusberg & Sullivan, 1998; van der

Lely, 1997, 1998, 2005).

Researchers have focused most attention on three developmental disorders in order to

explore possible differential patterns of cognitive and linguistic processing: Specific

Language Impairment (SLI), Down’s syndrome (DS) and Williams syndrome (WS).

These disorders all present with significant language impairment, but their reported uneven

linguistic and cognitive profiles have been used as evidence for the independence of

language from cognition, as well as the interdependence of the subcomponents of language

(Bellugi, Marks, Bihrle, & Sabo, 1988; Bellugi et al., 1990; Bellugi, Linchtenberger, Jones,

Lai, & St.George, 2000; Clashen & Almazan, 1998, 2001; Fowler, 1995, 1998; Laws &

Bishop, 2003; Perovic, 2001, 2002; Rondal, 1995; Tager-Flusberg & Sullivan, 1998; van

der Lely, 1996a; van der Lely, 1997, 1998, 1999, 2005).

Children with SLI experience difficulties in learning language in the absence of any other

primary co-existing physical, emotional, neurological or intellectual impairment (Leonard,

1998). The prevalence of SLI is reported to be around 7% (Leonard, 1998). The uneven

linguistic and cognitive profile of SLI and the reported greater difficulties experienced with

706 V. Joffe & S. Varlokosta

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grammar and syntax have been used to further the Modularity debates (Laws & Bishop,

2003; Pinker, 1994; 1999; van der Lely, 1997, 1998; van der Lely, Rosen, & Adlard, 2004;

van der Lely, 2005). Participants with SLI have been found to have significant difficulties

with the rule governed aspects of language (for example, passives, regular past tense and

plurals, binding) and perform better with tasks targeting lexical processing (for example,

receptive vocabulary, irregular past tense and plurals) (Laws & Bishop, 2003; van der Lely,

1996a; van der Lely & Stollwerck, 1997; van der Lely, 1999; van der Lely & Ullman, 2001;

van der Lely, 2005). The specificity of the language impairment in SLI has more recently,

however, been contested with findings of associated cognitive and/or sensory impairments

with this disorder (Johnston, 1999; Norbury, Bishop, & Briscoe, 2002; Botting, 2005;

Hick, Botting, & Conti-Ramsden, 2005).

Down’s syndrome (DS) and Williams syndrome (WS) are two genetic conditions which

have been used to further explore the modularity debates. Down’s syndrome is a congenital

disorder, caused in 95% of cases by non-disjunction of chromosome 21 and the presence of

an extra 21st chromosome, and in the remainder of cases, involving translocation (4%) or

mosaic (1%) patterns of chromosomal arrangement (Mutton, Alberman, & Hook, 1996). It

has an incidence of approximately 1 in 650–1000 live births and is the most common

genetic cause of severe learning difficulties (Lejeune, Turpin, & Gautier, 1959; Hook,

1981). It is characterized by severe language impairment in conjunction with moderate to

severe levels of cognitive impairment. Language in DS is reported not to be a simple

function of cognitive ability as more profound language impairments than predicted from

level of cognitive functioning have been reported (Fowler, Gelman, & Gleitman, 1994;

Perovic, 2001, 2002; Vicari, Caselli, & Tonucci, 2000), as well as several cases of

exceptional language ability in the context of poor cognition (Rondal, 1995). Furthermore,

differences within the language module have been observed with better performance in

receptive vocabulary and pragmatics (more commensurate with cognitive ability) than in

grammatical morphology and syntax (Chapman, 1995; Chapman, Seung, Schwartz, &

Kay-Raining Bird, 1998; Fowler, 1990; Laws & Bishop, 2003; Vicari et al., 2000) as well as

a specific syntactic deficit also reported (Perovic, 2001, 2002; Ring & Clashen, 2005).

Laws and Bishop (2003) found many similarities in the language profile of participants with

SLI and DS, with verbal skills lagging significantly behind non-verbal abilities and better

performance in vocabulary compared with syntactic abilities.

Williams syndrome identified by Williams, Barrett-Boyes and Lowe (1961) is a rare

neurodevelopmental disorder usually caused by the spontaneous deletion of a short

sequence of contiguous genes on chromosome 7 at 7q11.23 (Ewart et al., 1993). The

incidence of the condition has long been quoted as 1 in 25,000 live births although a more a

recent estimate given is 1 in 7500 (Greenberg, 1990; Stromme, Bjornstad, & Ramstad,

2002). Individuals with WS present with a range of physical and cognitive difficulties, and

typically have mild to moderate learning difficulties as well as renal and cardiovascular

problems (Korenberg et al., 2000). A fluorescent in situ hybridization (FISH) test is

routinely used to confirm the clinical diagnosis (see Donnai & Karmiloff-Smith (2000) for

description of condition). Great attention has been given to this syndrome since it was

described by Bellugi and colleagues in pioneering work as having a profile of intact

language in conjunction with severe cognitive impairments, particularly in visuo-spatial

abilities (Bellugi et al., 1988; Bellugi, Bihrle, Neville, & Doherty, 1992; Bellugi et al.,

1994). A number of more recent reports have reinforced this view of relatively intact areas

of language processing, and furthermore, have provided evidence of differential

performance within the language module itself, i.e. enhanced grammatical ability compared

Syntactic development in children with WS and DS 707

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with lexical ability and better performance in grammar over lexical semantics (Bellugi et al.,

1988, 1990, 1994, 2000; Clahsen & Almazan, 1998, 2001; Clashen & Temple, 2003; Ring

& Clahsen, 2005). Claims have also been made about differences in performance within the

grammatical subcomponent itself with good performance on tasks tapping the computa-

tional system for grammar (concerned with rule governed operations) and poor

performance on tasks which rely solely on accessing information from the lexicon

(Clahsen & Almazan, 1998, 2001; Clashen & Temple, 2003; Ring & Clahsen, 2005).

Clahsen and colleagues argue for a clear distinction between grammatical and lexical

aspects of language with their WS participants performing well on rule-governed operations

(for example, passives, binding, formation of regular past tense and plurals) compared with

a marked poorer performance on tasks involving lexical processes (for example, irregular

past tense and irregular plurals) (Clahsen & Almazan, 1998, 2001; Clahsen & Temple,

2003; Clashen, Ring, & Temple, 2004; Ring & Clahsen, 2005). Clahsen and Almazan

(1998, 2001) conclude that WS subjects are impaired in accessing particular kinds of

information from the lexicon leading to problems with irregular forms. In contrast, they

have an intact grammatical system which allows them to learn and generalize rules. Studies

that have included comparisons in language performance in WS and DS populations have

reported better performance across language measures in WS compared to DS (Bellugi et

al., 1990, 2000; Schaner-Wolles, 2004; Volterra, Capirci, Caselli, & Vicari, 2004; Ring &

Clahsen, 2005).

The reported sparing of language ability as well as strengths in morphosyntax in WS has

not, however, gone unchallenged. There is a large body of research questioning this view

and providing evidence for impaired linguistic processing in this population as well as poor

morphosyntax (Joffe & Varlokosta, 2007; Karmiloff-Smith et al., 1998; Karmiloff-Smith,

Brown, Grice, & Peterson, 2003; Mervis & Klein-Tasman, 2000; Thomas et al., 2001;

Stojanovik, Perkins and Howard, 2001, 2004; Volterra, Caselli, Capirci, Tonucci, & Vicari,

2003). Stojanovick et al. (2004) compared the performance of five participants with WS

(mean age: 9;2 years) and five with SLI (mean age: 10;0 years) on a range of receptive and

expressive verbal measures including measures of morphosyntax, and found similar

performance across the two groups on the verbal tests. Hence, there was no indication of

spared language abilities (see Bellugi et al., 1988, 1990, 2000) and both groups presented

with significant language impairment. Similarly other research has shown that older

individuals with WS (adolescents and adults) scored significantly below their vocabulary

age and chronological age on a standardized test of grammar (Karmiloff-Smith et al.,

1997); and only performed at the level of 5-year-old controls in a task requiring the

imitation of sentences with relative clauses (Grant, Valian, & Karmiloff-Smith, 2002).

A recent study by Joffe and Varlokosta (2007), comparing linguistic performance in ten

8-year-old participants with WS and DS, supports this finding of impaired linguistic

processing, with the WS group presenting with significant difficulties on a range of

measures of receptive and expressive semantics and grammar. Participants with WS and

DS, matched individually on chronological and mental age and performance IQ showed

similar patterns of performance. These results support the more recent research challenging

the idea of a relatively intact language system in WS (Brock, 2007; Karmiloff-Smith,

Ansari, Campbell, Scerif, & Thomas, 2006; Mervis, 2006; Mervis, Robinson, Rowe,

Becerra, & Klein-Tasman, 2004; Stojanovik et al., 2001, 2004; Volterra, Capirci, Pezzini,

Sabbadini, & Vicari, 1996; Volterra et al., 2004).

Thus even though WS, SLI and DS have been used as examples of non-linear

relationships between cognitive development and linguistic competence, as well as evidence


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for differential patterns of performance within the language module itself, the picture is far

from clear and the debates about the exact and specific nature of language impairment in all

three disorders is still somewhat contentious. This paper compares the language abilities of

participants with WS and DS, with a focus on two core syntactic phenomena, both of which

have been shown to be vulnerable to language impairment: passives and wh-questions.

Both passives and wh-questions require knowledge of syntactic movement, a core feature of

the computational system of language. Passives require movement of the direct object

Noun Phrase to the subject position of the clause, where it can be assigned nominative case

(Chomsky, 1981, 1995). The formation of wh-questions involves movement of the wh-

phrase from its base position to the beginning of the clause as well as subject-auxiliary

inversion in non-subject questions (Chomsky, 1981, 1995). Both of these syntactic

constructions have been shown to be impaired in children with SLI (van der Lely, 1996a,

1997, 1998; van der Lely & Battell, 2003) and in adults with aphasia (Edwards & Salis,

2005; Grodzinsky, 2000; Hickok & Avrutin, 1995; Tait, Thompson, & Ballard, 1995).

Mixed results have been reported on the syntactic abilities in both people with DS and

WS. Following the proposal of an intact computational system in WS put forward by

Clahsen and colleagues, it would be expected that individuals with WS would do well on

tasks exploring passives and wh-questions since they require rule-governed computational

analysis. Bellugi and colleagues (Bellugi et al., 1990, 1994) reported that their cohort of

adolescents with WS performed much better than DS controls and nearly at ceiling on

comprehension of passive sentences. The WS cohort obtained a mean of above 90% on a

passive task using semantically-reversible sentences. Their adolescents with WS were also

shown to use in their spontaneous expressive language a range of well-formed

grammatically correct sentences with complex syntactic structures including passive

sentences and relative clauses (Bellugi et al., 1994). They concluded from this that the WS

group showed good syntactic comprehension and processing. Support for this comes from

Clashen and Almazan (1998) who report data on the understanding of passives from four

participants with WS with a chronological age of 13;1 years and performance IQ of 52. The

WS group obtained maximum scores in the understanding of passives and the researchers

concluded from this that the interpretation of passives is intact in the WS group. The WS

performance on passives was better when compared with the SLI cohort on the same task

reported by van der Lely (1996a). Ring and Clashen (2005) explored the understanding of

passives in eight adolescents with DS and ten with WS with similar full IQ scores and

derived mental ages of approximately 6;5 and 5;9 years respectively. Whilst their DS cohort

experienced significant difficulties with the passive task, the participants with WS obtained

higher scores and showed a similar performance to typical mental age-matched controls.

Further cross linguistic studies exploring the understanding of passives in WS in Greek

and German largely support this view of good syntactic comprehension. Schaner-Wolles

(2004) reported on a single case study of a 12-year-old girl (mental age: 5;8 years) who

scored 100% in the comprehension of reversible passives. Interestingly, Bartke (2004)

reported on differential performance in the comprehension of passives in her 10 German-

speaking WS participants depending on mental age. Participants with a mental age at or

below 4-years performed more poorly than controls whilst those with a mental age of

greater than 5-years obtained scores equivalent (near ceiling) to that of the mental age-

matched control group. This good performance on passives is replicated by Stravrakaki

(2003) cited in Ring and Clashen (2005) with five Greek WS participants who obtained

better scores than mental age and language matched controls, although accuracy scores

were not at ceiling (60–70%).


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Other research studies have reported more difficulties in the understanding of passives in

WS. Karmiloff-Smith et al. (1998) tested eight individuals with WS with mental ages

ranging from 14;9 to 34;8 years and 18 normal adults ranging in age from 19–29 years.

Whilst the control group obtained almost 100% success rates, the WS group did much

more poorly with scores ranging from 14–37% (and a mean success rate of only 24%).

Stojanovik et al.’s (2004) WS cohort with a mean age of 9;2 years performed poorly on

reversible passives from the Test for the Reception of Grammar (TROG) (Bishop, 1982)

and even obtained slightly lower scores than their SLI cohort. They concluded that the

computational system is not intact in WS and that their linguistic performance is

comparable to that of participants with SLI. Their conclusions, however, regarding

performance on passives is based on only four items from the TROG.

There has been far less exploration of the comprehension and production of wh-

questions in WS. Zukowski (2001) reported results from a wh-question production task of

12 WS participants (mean chronological age: 12 years) and 12 younger TD controls (mean

age: 5;7 years). She explored the production of a variety of questions: yes/no questions (Do

you like hamburgers?); wh-object affirmative questions (what kind of pets do you have?), wh-

object negative questions (what flavour don’t you like?), wh-adjunct affirmative questions

(where does your tarantula sleep?) and wh-adjunct negative question (where don’t you want to

live?). The WS cohort performed as well as the younger mental age-matched controls with

the best performance across both groups for positive yes/no and affirmative wh-questions

(success rates of 86% and above) and much lower scores for negative wh-questions (around

46%). It is important to keep in mind that the WS performance is similar to a group of

children more than 6 years younger than they are. Stravrakaki (2004) reported on the

performance of three Greek-speaking WS individuals (14;10, 10;5 and 9;2 years). The two

older children were at ceiling on the production of wh-questions, with the youngest child

obtaining an accuracy level of around 60%, with poorest performance (25%) on ‘‘which

NP-object’’ type sentences. In contrast to the good performance of the WS cohort, was the

poorer performance of the younger SLI cohort (mean chronological age: 8;1 years) on the

same task.

It appears from these results, that syntactic performance in WS and DS varies depending

on the developmental stage and ages studied (for example, differences in results depending

on chronological age of the cohort) as well as possibly the type of sentence structure

investigated (for example, differences in performance on the various types of wh-

questions). Most of the studies investigating syntactic ability in WS have included

adolescents or adults with WS. It has been acknowledged that this focus on the older

participants with WS has not been replicated with younger individuals (Karmiloff-Smith et

al., 2006). This research addresses this gap by including a younger cohort of participants. It

explores the comprehension of passives and the comprehension, repetition and production

of wh-questions in a younger cohort of chronological age and mental age-matched

individuals with WS and DS, and compares their performance to a mental age-matched

group of TD controls.

Method

Participants

There were three matched triplet groups of participants:1 ten individuals with Williams

syndrome (WS), ten individuals with Down’s syndrome (DS) and ten typically developing


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(TD) children. The WS and DS groups were matched individually for performance IQ

(PIQ) (within 5 points), chronological age (CA) (within 14 months) and mental age (MA)2

(within 12 months). There were no significant differences between the two groups on CA

(F (1, 19)5.029, p5.866), PIQ (F (1, 19)5.149, p5.704) or MA (F (1, 19)5.208,

p5.654). The WS and TD groups were matched within 6 months on MA with no

significant differences in MA across the three matched groups (F (2, 29)5.313, p5.734).

All participants were native-speaking English children and were recruited from special

schools or mainstream provision.

The 10 participants with WS (positive fluorescent in situ hybridization—FISH-test) had a

mean CA of 8;9 years (range: 6;9–13;10), PIQ of 52.0 (range: 46–69) and MA of 4;8 years

(range: 3;7–6;3). Participants were recruited from the Williams Syndrome Foundation in the

UK and came from a wide geographical area across the UK. Eight of the participants with

WS were recruited from special schools with the remaining two coming from mainstream

educational provision. The WS group consisted of six males and four females.

Ten participants with DS (six females; four males) acted as cognitive and chronological age-

matched controls. They had a mean CA of 8;7 years (range: 5;11–14;0), PIQ of 50.7 (range:

46–71) and MA of 4;6 years (range: 3;2–6;5). The DS cohort was recruited from mainstream

and special schools in the South East of England. As many of the DS participants as possible

were recruited from the same schools as the WS individuals. Three of the participants with DS

came from special schools and the remainder came from mainstream provision.

The TD group (four females; six males) was a younger cohort of typically developing

children matched individually to each participant with WS and DS on MA. They had a

mean CA of 4;4 years (range: 3;3–6;5), PIQ of 104.0 (range: 85–121) and MA of 5; 0

(range: 3; 8 – 6; 8). The children were recruited from mainstream schools in the South East

of England. This group was younger than the participants with WS and DS and acted as an

exemplar for the typical developmental progression. Teachers were asked to refer children

with no history of speech, language or communication impairments, or other develop-

mental disorders. Table I lists the participants’ details.

Materials

Non-verbal ability. Non-verbal ability was measured by the performance subtests of the

Wechsler Intelligence Scale for Children-III edition (WISC III) (Wechsler, 1992) or the

Wechsler Preschool and Primary Scales of Intelligence-Revised (WPSSI-R) (Wechsler, 1990).

Grammatical ability. The Test for Reception of Grammar-2 (TROG2) (Bishop, 2003) was

administered as a measure of overall grammatical understanding. This is a picture selection

Table I. Chronological age (CA) (years, months), performance IQ (PIQ) and derived mental age (MA) (years,

months) of matched groups: Williams syndrome (WS), Down’s syndrome (DS), and typically developing (TD)

groups.

WS GROUP DS GROUP TD GROUP

CA (SD) 8;9 (2.5) 8;7 (2.9) 4;4 (.96)

Range 6;9–13;10 5;11–14;0 3;3–6;5

PIQ (SD) 52.0 (7.4) 50.7 (7.6) 104.0 (11.2)

Range 46–69 46–71 85–121

Derived MA (SD) 4;8 (1.0) 4;6 (1.2) 5;0 (1.0)

Range 3;7–6;3 3;2–6;5 3;8–6;8


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task where children are required to identify the correct picture, which matches a target

word or sentence provided, from a choice of four. A range of grammatical structures are

assessed including passives, negation, subordination, comparatives and tense. The child is

required to pass all four items within a block of four questions focusing on a specific

grammatical structure. Testing is discontinued when the child fails five consecutive blocks.

The test was administered and scored as per test manual instructions.

The following measures were also given to explore the participants’ syntactic abilities:

comprehension of active and passive sentences, and production, comprehension and

repetition of wh-questions.

Comprehension of active and passive sentences. The Test of Active and Passive Sentences

(TAPS) was used to assess the understanding of transitive active and passive sentences (van

der Lely, 1996b). This is a picture selection task exploring the understanding of

semantically reversible sentences with a choice of four pictures representing four possible

responses: transitive (actional) (man eating fish), semantic distracter (remains of a man),

adjectival (stative) (an eaten fish on a plate) and reversal (fish eating man). There were a

total of 48 items with four sentence types (12 sentences per each condition):

simple active sentences (e.g. the man eats the fish), full passive sentences (e.g. the fish is

eaten by the man), short progressive passive sentences (e.g. the fish is being eaten) and

short ambiguous passive sentences (e.g. the fish is eaten). Half of the sentences contained

regular actional verbs (e.g. the doll was mended by the girl) and half irregular

actional verbs (e.g. the fish was eaten by the man). The correct response for the

active, full passive and short progressive passive sentences was the transitive (actional)

response, whereas short ambiguous passive sentences were ambiguous between a transitive

(actional) and an adjectival (stative) interpretation. Participants were told that there

may be more than one correct picture but were encouraged to point to the picture that

best matched the sentence given. Administration and scoring followed test manual

instructions.

Production, comprehension and repetition of wh-questions. (a) A wh-question elicitation task

based on Thornton’s (1990) elicitation technique and on Varlokosta (2004) assessed

knowledge of wh-movement. The experimenter acted out a story with toys in front of the

participants and told them to ask a puppet a question about the story acted out. An

example protocol for eliciting a subject wh-question is the following:

Here we have a horse, a cat and a lion. In this story, the lion hugged the horse [the action is acted

out]. Ask the puppet who? [Target utterance: Who hugged the horse?]

There were a total of 16 items: four ‘‘who’’ subject; four ‘‘what’’ object, four ‘‘which-NP’’

subject and four ‘‘which-NP’’ object questions.

(b) A wh-question comprehension task based on Varlokosta (2004) assessed under-

standing of wh-questions. The experimenter acted out a story with toys in front of the

participants and asked them a question about the story. For example:

Here is a horse, a cat and a lion. In this story, the horse punched the lion and the lion punched the cat

[the action is acted out]. Who punched the lion?

Children were required to point to the correct toy/object which was displayed on the table

with the other toys/objects used to act out that specific story. The comprehension task was


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administered after the elicitation task to ensure that priming of the target sentences did not

occur.

(c) A wh-question repetition task. The participants were required to repeat the same 16

wh-questions that were used in the elicitation and comprehension tasks. This task assessed

recall and reproduction of wh-questions to explore whether participants were able to

imitate syntactically complex sentences. A relationship has been reported between the

ability to repeat syntactic structures and overall syntactic ability, both in typical

development (Brown, 1973) and in children with language impairments (Conti-

Ramsden, Botting, & Faragher, 2001). Sentence imitation tasks have been used previously

with individuals with WS as they are reported to have less task demands than

comprehension and elicitation tasks, and therefore may be a more direct assessment of

syntactic competence (Grant et al., 2002). The children were asked to repeat to the

experimenter the target utterance that had been given to them by a puppet (for example,

‘‘Which horse hit the giraffe?’’). The repetition task was always administered after the

elicitation and comprehension tasks.

Procedure

All participants were seen by researchers trained by a speech and language therapist at their

respective schools or at home. These tests were given as part of a larger battery of language

tests. The tests reported on in this paper were administered over approximately three

sessions of around 40 minutes in length usually within a 4-week period.

Data analysis

Standard scores were used for data analysis for the TROG2 and raw scores and percentages

for the non-standardized language tasks. A series of one and two-factor mixed between and

within subjects ANOVAs were used to measure differences in performance across the

groups exploring between subject main effects for group (WS, DS and TD), within subject

main effects for types of task (elicitation, comprehension and repetition), sentence types

(actives, full passives, short passives, ambiguous passives), response categories (reversals,

adjectival, semantic distracter), question type (wh-subject, wh-object, which NP-subject,

which NP-object) and interaction effects. Tukey post-hoc tests were performed to explore

any significant differences across the three groups. Correlations across tasks and CA and

PIQ were performed using two-tailed Pearson correlations.

Results

Overall grammatical understanding: Performance on TROG2

Table II gives means and SDs of age equivalent scores, standard scores (SS) and total

number of blocks passed on the TROG2. The WS and DS cohorts obtained similar

standard scores on the TROG2 (WS556; DS557), performing more than 2 SDs below the

mean (mean5100, SD515) with the TD group scoring age appropriately (SS596). The

TROG2 age equivalent scores for the WS and DS groups were approximately 5;4 years and

4;9 years behind their chronological ages, and 9 and 4 months behind their mental ages

respectively. A one way ANOVA revealed a main effect for group with significant

differences in performance in both standard score (F (2; 29)535.993; p5.000) and total


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blocks passed (F (2; 29)53.574; p5.042). Post-hoc tests showed the differences in

performance between participants with WS and DS not to be significant. However, both

the WS and DS groups scored significantly below their mental age-matched peers on

standard score (p5.000 for both groups). The DS group obtained significantly less blocks

correct than the TD group (p5.045), with the difference between the WS (3) and TD (6)

cohorts failing to reach significance (p5.126).

Performance on the comprehension of active and passive sentences (TAPS)

Table III presents the scores for the TAPS. There were significant differences in

performance across the groups for overall understanding of the three passive sentence

types in the TAPS (F (2; 29)55.297; p5.011). Post-hoc tests revealed that participants

with WS and DS performed similarly across all conditions of the TAPS. Both the WS and

DS cohorts understood significantly less passives than the TD controls (p5.013; p5.050

respectively). A two-factor mixed ANOVA with group (WS, DS, TD) as the between factor

and type of task (actives, full passives, short passives, ambiguous passives) as the within

factor revealed a significant main effect of task (F (3, 25)512.929, p5.000). As a group,

subjects scored significantly better with active versus passive sentences (full passives and

Table II. Performance on TROG2 [mean (standard deviation)] for WS, DS and TD groups.

TROG2

WS GROUP (MEAN CA:

114.2) (DERIVED MA: 58.3)

DS GROUP (MEAN CA:

111.0) (DERIVED MA: 55.5)

TD GROUP (MEAN CA:

58.3) (DERIVED MA: 60.6)

AE 49.5 (3.0) 51.4 (8.5) 64.7 (29.7)

SS 56.7 (3.9) 57.1 (4.7) 96.5 (19.9)

Number of blocks

passed rs/20

3.2 (1.9) 2.4 (2.2) 6.4 (5.3)

Passives:

Number of

items passed

rs/4

n54* n52* n56*

1.0 (.81) 1.5 (.70) 3.5 (.54)

Key: CA: Chronological Age in months. MA: Mental Age in months. TROG2: Test for the Reception of

Grammar, version 2. AE: Age Equivalent in months. SS: Standard Score. rs: raw score. n5number of participants

for each group was 10, except where specified. *5reduced n due to discontinue rule of test.

Table III. Performance (% correct) on the Test of Active and Passive Sentences for WS, DS and TD groups

[means (standard deviation) and range].


Overall score across all sentence types (%) 43.3 (18.4) 45.4 (15.7) 62.2 (15.4)

range: 72 range: 52 range: 45

Overall score for passive sentences (%)

(excluding actives)

36.1 (18.6) 40.5 (14.4) 58.3 (14.1)


Active sentences (%) 64.1 (28.8) 55.5 (27.4) 74.1 (23.0)


Full passive sentences (%) 42.5 (22.0) 44.1 (14.1) 63.3 (20.4)

range: 75 range: 50 range: 58.3

Short progressive passive sentences (%) 35.0 (22.1) 39.1 (16.2) 68.4 (22.4)


Ambiguous sentences (%) 31.6 (18.7) 38.3 (21.5) 44.1 (19.2)



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short passives) and obtained significantly higher transitive (actional) responses with full and

short passives than ambiguous passives. Thus, a similar pattern of performance was evident

in the TAPS across the three groups with best performance with active sentences and

lowest transitive (actional) responses for ambiguous passives. There was also a main effect

for group (F (2; 27)53.923, p5.032). Pairwise comparisons revealed no significant

differences across all conditions between the WS and DS cohorts. The TD group

performed significantly better with short passives than the WS (p5.004) and DS (p5.013)

cohorts. Their better performance with full passives fell just short of significance for both

WS (p5.056) and DS (p5.084) groups. There were no significant differences across the

three groups with active or ambiguous passive sentences. When comparing performance on

sentences with regular versus irregular verbs, all three cohorts performed better with regular

(WS: 12.4; DS: 11.5; TD: 15.20) versus irregular (WS: 10.7; DS: 10.3; TD: 14.7) verbs

but a main regularity effect fell just short of significance (F (1; 27)53.179; p5.086). There

was a significant main effect for group (F (1; 27)54.142; p5.027) with pairwise

comparisons revealing no differences in performance across groups on sentences with

regular verbs, whilst differences on sentences with irregular verbs were significant (F (2;

29)54.340; p5.023). The WS and DS cohorts performed similarly on sentences with

irregular verbs but obtained poorer scores compared with their mental-aged matched TD

controls (p5.057 and p5.033 respectively).

An error analysis was undertaken to explore the different types of responses across the

three groups (see Table IV). A two-factor mixed ANOVA with group (WS, DS, TD) as the

between factor and response category (reversals, adjectival, semantic distracter) as the

within factor revealed a significant main effect for response category (F (2, 26)5199.359,

p5.000) and group (F (2, 27)54.080, p5.028). Pairwise comparisons showed that the

group as a whole made significantly more reversal than adjectival (p5.014) and semantic

distracter (p5.000) responses, and more adjectival than semantic distracter responses

(p5.000). Significant differences across the WS, DS and TD groups in number of reversal

(11.2; 18.5; 7.9) and adjectival (11.8; 4.7; 8.4) responses were evident with the DS cohort

making more reversal responses than both the WS (p5.014) and TD (p5.000) groups.

Participants with WS gave more adjectival responses (11.8) than both the DS (4.7) and TD

(8.4) groups, although this was only significant in comparison to the DS group (p5.006).

Semantic distracter responses were very low across all three groups.

As a group (n530), there was a significant positive correlation between PIQ and

performance on the three passive sentence types of the TAPS (r5.592; p5.001) and a

significant negative correlation between CA and passive performance (r52.448; p5.013).

This negative correlation disappeared when PIQ was entered as a control. However, the

significant correlation between PIQ and passives remained even after CA was controlled for

(r5.433; p5.019). There were no significant correlations between passives and PIQ or CA

in either the WS or DS cohorts. In the TD group, the only significant correlation was

between passives and PIQ (r5.738; p5.015).

Table IV. Response categories on the Test of Active and Passive Sentences for WS, DS and TD groups [mean raw

score out of 48 (standard deviation)].


Reversal response 11.2 (5.2) 18.6 (4.7) 7.9 (6.9)

Adjectival response 11.8 (6.4) 4.7 (3.8) 8.4 (3.2)

Semantic distracter response 1.7 (1.7) 2.8 (3.3) 1.8 (1.8)


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It was also possible to explore the participants’ understanding of passives by looking at

the TROG2 which has a block of four passive items. The total number of participants was

reduced (see Table II), as some participants did not reach this level owing to the

discontinue rule of the test. However, it is interesting to note that results from the TROG2

are consistent with the TAPS with significant differences in performance evident across the

three groups (F (2; 11)518.750; p5.001). Post-hoc tests showed that while participants

with WS and DS scored similarly, they performed significantly more poorly than the TD

group (p5.001 and p5.013 respectively). A significant correlation was evident for the

whole group on performance on TROG2 passives and the three passive sentence types of

the TAPS (r5.741; p5.006).

Performance on the wh-question tasks: elicitation, comprehension, repetition

Table V reveals that all three groups performed better on comprehension (WS: 57%; DS:

43%; TD: 83%) than elicitation (WS: 20%; DS: 6%; TD: 50%). The best performance for

the WS and TD groups was for repetition (63% and 91% respectively), although this was

not the case for the DS group who scored more poorly on repetition (18%) than

comprehension (43%), and only slightly better on repetition than elicitation (6%). Whilst

Table V. Means, standard deviations, ranges of scores (% correct) on wh-question tasks for WS, DS and TD

groups.

TASKS WS GROUP DS GROUP TD GROUP

Wh-question elicitation (total %) 20.6 (28.7) 6.2 (13.1) 50.6 (36.9)


Wh-question elicitation (wh-subject) (%) 35 (39.4) 12.5 (27.0) 70.0 (48.3)


Wh-question elicitation (wh-object)(%) 22.5 (38.0) 5.0 (15.8) 60 (37.6)


Wh-question elicitation (which NP-subject) (%) 15.0 (31.6) 5.0 (15.8) 42.5 (42.5)


Wh-question elicitation (which NP-object) (%) 12.5 (31.7) 2.5 (7.9) 30 (40.4)


Wh-question comprehension (total %) 57.5 (18.1) 43.1 (19.1) 83.1 (19.7)


Wh-question comprehension (wh-subject) (%) 50.0 (28.8) 37.5 (27.0) 87.5 (24.2)


Wh-question comprehension (wh-object) (%) 60.0 (21.0) 50.0 (28.8) 87.5 (21.2)


Wh-question comprehension (which NP-subject) (%) 67.5 (28.9) 42.5 (31.2) 80 (25.8)


Wh-question comprehension (which NP-object) (%) 52.5 (27.5) 42.5 (31.2) 77.5 (32.1)


Wh-question repetition (total %) 63.7 (26.8) 18.75 (30.4) 91.2 (1.1)


Wh-question repetition (wh-subject) (%) 87.5 (17.6) 37.5 (41.2) 97.5 (7.9)


Wh-question repetition (wh-object) (%) 67.5 (39.1) 15.0 (31.6) 97.5 (7.9)


Wh-question repetition (which NP-subject) (%) 52.5 (29.3) 12.5 (31.7) 95.0 (10.5)


Wh-question repetition (which NP-object) (%) 47.5 (43.2) 10.0 (31.6) 75 (28.8)



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ceiling scores were obtained for the TD group on the repetition task (91%), this was not the

case for either the WS (63%) or DS (18%) cohorts.

A two-factor mixed ANOVA with group (WS, DS, TD) as the between factor and type of

task (elicitation, comprehension, repetition) as the within factor revealed a significant main

effect of task (F (2, 26)528.970, p5.000). As a group, subjects scored significantly better

on comprehension than on elicitation of wh-questions, and also significantly better on

repetition than elicitation.

There was also a main effect for group (F (2; 27)522.256, p5.000). Pairwise

comparisons revealed no significant differences in performance on the elicitation and

comprehension tasks in the WS and DS cohorts. The participants with WS performed

significantly better than DS participants on repetition (p5.001). Participants with WS and

DS performed significantly more poorly than their mental age-matched younger peers on

comprehension (p5.015 and p5.000 respectively) and repetition (p5.045 and p5.000).

The TD controls also obtained significantly better scores on elicitation than the DS group

(p5.004) with their superior performance compared to the WS cohort falling just short of

significance (p5.061).

A similar pattern of performance was evident across question types with all three groups.

The order of difficulty for elicitation and repetition was identical for the three groups (from

easy to most difficult): wh-subject, wh-object, which NP-subject, which NP-object. A two-

factor mixed ANOVA with group (WS, DS, TD) as the between factor and type of question

(wh-subject, wh-object, which NP-subject, which NP-object) as the within factor revealed

a significant main effect for question type for both elicitation (F (3, 25)54.394, p5.013)

and repetition (F (3, 25)56.932, p5.001). The group as a whole performed significantly

better in both elicitation and repetition on wh-subject questions than on which NP-subject

and which NP-object questions, and significantly better on wh-object questions than which

NP-object questions; and on which NP-subject questions compared with which NP-object

questions. There was no similar consistent pattern across the three groups in the

comprehension task with no main effect for question type.

A correlational matrix for the group as a whole (n530), revealed significant correlations

between questions and CA and PIQ, although correlations were in the opposite direction.

A significant positive correlation was evident between PIQ and the elicitation (r5.557;

p5.001), comprehension (r5.703; p5.000) and repetition (r5.605; p5.000) of wh-

questions, whilst a significant (but weaker) negative correlation was obtained between CA

and wh-question elicitation (r52.364; p5.048), comprehension (r52.456; p5.011) and

repetition (r52.361; p5.050). Similar to the correlations for passives, once PIQ was

entered as a control, the negative correlation between CA and all wh-questions tasks

disappeared, while the positive correlations between wh-questions and PIQ remained even

after CA was accounted for. When looking at the groups individually, similar correlational

patterns were noted. In the WS cohort, significant correlations were only observed between

PIQ and CA and comprehension of wh-questions, with a positive correlation for PIQ

(r5.714; p5.020) and negative correlation for CA (r52.688; p5.028). In contrast, the

only significant correlation in the DS cohort was between PIQ and wh-question repetition

(r5.881; p5.001). There were no significant correlations in the TD cohort.

Discussion

The pattern of results across all tasks assessing syntactic ability was consistent: the

individuals with WS, with a mean CA of 8;9 years, and mean MA of 4;8 years performed


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similarly to individuals with DS, matched individually on CA, MA and PIQ, on a

standardized measure of grammatical ability (TROG2) and on the comprehension of

passives and the comprehension and production of wh-questions. Furthermore, both the

WS and DS cohorts obtained significantly lower scores on most of the syntactic tasks

compared to the younger mental age-matched TD cohort. These results support the more

recent evidence for significant language impairment, and more specifically, impaired

syntactic processing, in individuals with WS (Brock, 2007; Grant et al., 2002; Joffe &

Varlokosta, 2007; Karmiloff-Smith et al., 1997; Karmiloff-Smith et al., 1998; Mervis et al.,

2004; Mervis, 2006; Thomas et al., 2001; Stojanovik et al., 2001, 2004). They are not

consistent with the claims of intact language or more specifically, a strength in

morphosyntax (Bellugi et al., 1988, 1990, 2000; Clashen & Almazan, 1998; Ring &

Clashen, 2005). Furthermore, at this younger age group, their performance also calls into

question the idea of even a relative sparing of language abilities compared with mental age

(as discussed by Mervis, 2006), as they performed significantly worse than a much younger

mental age-matched control, and similarly to another developmentally delayed group (DS).

The poor performance of the DS cohort on the syntactic measures is, however, consistent

with previous reports on language functioning in individuals with DS (Bellugi et al., 1990;

Perovic, 2001, 2002; Ring & Clashen, 2005; Vicari et al., 2000; Volterra et al., 2004).

Both the WS and DS cohorts were just within the third standard deviation below the

mean for the TROG2, signifying a very significant grammatical impairment. It is fair to say,

however, that the TROG2 measures both lexical and grammatical components and is,

therefore, not a pure measure of syntactic ability. However, the poor performance on the

TROG2 is consistent with their poor performance across all the other syntactic measures

given to the participants. It is interesting to note their poor performance on syntactic

measures, despite their better performance on receptive and expressive semantics

compared with grammar reported elsewhere for the same group of participants (Joffe &

Varlokosta, 2007). Their performance on the syntactic tasks in this study is consistent with

the difficulties they experienced with the comprehension and production of past tense as

well as the linguistic impairment with which they presented and is reported in Joffe and

Varlokosta (2007).

On the TAPS task, both the WS and DS cohorts performed worse than the TD controls,

with the difference between the DS and TD cohorts significant. The comprehension of

reversible full passives in typical development is usually achieved around the age of 4;6 to

5;0 years for actional verbs (de Villiers & de Villiers, 1973; Maratsos, 1974; Borer &

Wexler, 1987), with errors still occurring up until around 6 years for non-actional verbs

(van der Lely, 1996a).3 Moreover, short passives have been argued to be acquired earlier

than full passives (Horgan, 1978) and adjectival passives earlier than verbal passives at least

in some languages (Guasti, 2002). It was, therefore, expected that errors in performance

would occur, but a similar performance would nevertheless be found across the groups

matched on mental age. This was, however, not the case. Despite the close matching

procedures, individuals with WS and DS did not perform as well as their younger TD

controls in the understanding of passives. There were predictably no differences in the

understanding of active sentences, which are syntactically less complex than that of passive

sentences, across the three groups. There was also no difference in the understanding of

ambiguous sentences, again a predictable finding in light of the ambiguity inherent in the

sentence stimulus. Van der Lely (1996b) reports scores for the transitive (actional)

response of between 6 to 12 out of a total of 12 for typically developing children and adults

with the ambiguous sentences. This is almost reached by the TD cohort (rs55.3/12) but


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not by the WS (3.8/12) or DS (4.6/12) cohorts. This may indicate that unlike the TD

group, the WS and DS cohort were not that sensitive to the ambiguity of these sentences,

showing a preference for the adjectival reading. This preference for the transitive (actional)

reading has been also observed in SLI children (van der Lely, 1996a). The WS and DS

cohorts performed more poorly on both full and short passives compared with the TD

controls. Thus, the pattern of behaviour for both the WS and DS cohort with respect to full

and short passives is different than that of typically developing children and interestingly,

did worse than TD controls on sentences with irregular verbs than those with regular verbs.

All three groups did in fact do slightly better with regulars than irregulars. The poor

performance on the TAPS was reinforced by the low scores the WS and DS cohorts

obtained on the passive items of the TROG2 (1/4 and 1.5/4 respectively) compared with

the TD controls (3.5/4). The score of 1.0 obtained by the WS cohort in this study was

poorer than that of 2.4 obtained by the similarly aged WS group studied by Stojanovik et al.

(2004).

The findings do not replicate those of Clashen and Almazan (1998) who report 100%

performance on all passives on the TAPS for their WS cohort with a mean CA of 13;1

years, or with the findings from Ring and Clashsen (2005) whose WS cohort, with a mean

CA of approximately 12;7 years, scored much higher than the WS cohort in this study (78–

88%), and performed similarly to TD controls and much better than a DS group matched

on overall IQ. Scores for the DS group were reported to be much poorer than both the WS

and TD controls, ranging from 48% to 58%. Thus younger school-aged children with DS

and WS show similar difficulties in the interpretation of passives, and did not reveal a

robust understanding of passives reported elsewhere with older adolescents and adults

(Bartke, 2004; Bellugi et al., 2000; Clashen & Almazan, 1998; Schaner-Wolles, 2004; Ring

& Clashen, 2005). Our WS cohort experienced difficulties with passive interpretation as

did the WS participants with a mean CA of 9;2 years reported by Stojanovik et al. (2004),

and the younger children with WS with mean mental ages of below 5 years discussed by

Bartke (2004). The overall accuracy score of 36% for our WS group is, however, similar to

the mean accuracy score of 24% reported by Karmiloff-Smith et al. (1998) with their older

WS cohort (mental age range: 14;9 to 34;8 years) on a sentence picture matching task.

The error analysis revealed similar findings to those reported by Ring and Clashen

(2005) with low semantic distracter responses across the three groups and the DS cohort

making significantly more reversal responses, taking the first NP as the agent argument,

than either of the other two experimental groups. An increased number of reversal

responses for passives were also noted by van der Lely (1996a) in her adolescent SLI

cohort. The WS cohort does give more adjectival responses than the other two groups, with

the DS group giving the least number of adjectival responses. The WS group seemed less

sensitive to the acceptability of the verbal/transitive (actional) responses for these sentences.

The pattern of results for the comprehension and production of wh-questions was similar

to those obtained for the passives. Previous research based on spontaneous data has shown

that typically developing children tend to acquire simple wh-questions by the age of 3;0

years, with object questions preceding subject questions (Stromswold, 1995). A number of

experimental studies on the production of simple wh-questions have shown that children

aged 3;4 to 3;6 do poorly on both subject and object questions, while older children

between 4;1 to 4;7 perform better on subject compared to object questions (Wilhelm &

Hanna, 1992). The better performance on subject compared to object questions is also

evident in a number of comprehension studies (Tyack & Ingram, 1977).4 Better

performance on which-NP subject compared to which-NP object questions has been


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reported by Avrutin (2000). In light of this developmental data, and the good syntactic

skills reported elsewhere for WS, it was predicted that poor performance for wh-question

tasks would be observed in the DS cohort, with better performance in the WS and TD

groups. This pattern was not seen. The group as a whole performed better on the

comprehension compared with the elicitation of wh-questions, a finding that is consistent

with the typical developmental sequence of reception before expression (Brown, 1973).

The WS and DS groups performed similarly in both the comprehension and production of

wh-questions, with very low scores obtained for production (20.6% and 6.2 % respectively)

and more poorly than the younger controls (50%).5 Whilst their scores on comprehension of

wh-questions were better, and above chance level of 33% (57% and 43%), they were still

significantly poorer than their mental age-matched controls (83%). A different pattern of

results was obtained for the repetition of wh-questions, with the DS cohort obtaining

significantly poorer scores on repetition than both the WS and TD groups. This difficulty

with repetition was also found in the same cohort with the repetition of past tense and plural

items (Joffe & Varlokosta, 2007) and reflects the reported difficulties experienced in

individuals with DS in articulation (Dodd, 1976) and possibly may also be due to the high

incidence of fluctuating hearing loss in this population (Downs, 1980).

The TD controls also did much better on repetition (91%) than the WS group (63%)

illustrating that even with direct imitation, and despite their reportedly good phonological

short term memory (Jarrold, Baddeley, & Hewes, 1999; Wang & Bellugi, 1994) and their

normal phonological development (Mervis, Morris, Bertrand, & Robinson, 1999), the WS

group experienced difficulties repeating syntactically complex sentences. This finding is in

line with results reported by Grant et al. (2002), where their WS cohort experienced

problems on a simple imitation task exploring the syntax of relative clauses. The difficulties

experienced by both the WS and DS cohorts on the repetition of wh-questions, in

comparison with the younger TD controls, may very well reflect a difficulty with this type of

syntactic construction. Previous research has shown a close association between the

imitation of syntactically complex sentences and overall syntactic abilities (Brown, 1973;

Conti-Ramsden et al., 2001).

The difficulties in wh-question interpretation and production conflicts with the better

performances reported elsewhere. Zukowski (2001) reported that her WS cohort (mean

CA512 years) performed at a similar level to a mental age matched TD control group

(mean CA: 5;7 years) on the elicitation of wh-questions. She reported much higher

percentage scores for her WS group on the elicitation of all her question types: positive yes/

no (95%), positive wh-questions (86%) and negative wh-questions (45%). Our WS cohort

also did much worse than all three participants with WS (CA: 14;10, 10;5 and 9;2)

reported by Stavrakaki (2004). The two older participants with WS in Stavrakaki (2004)

obtained 100% success rates (as did the TD controls) on all questions types. Even the

younger individual with WS (CA of 9;2 years) obtained higher scores than the WS

participants in this group (62.5% and above for subject who-questions, object who-

questions and subject which-NP questions and 25% for object which-NP questions)

compared with scores ranging from 12.5% to 35% for the four questions types for the WS

cohort reported in this study.

The pattern of results across sentence types for both elicitation and repetition was

identical across the three groups with wh-subject questions the easiest across all

participants and which NP-object the most difficult. Wh-question types were easier than

which-NP questions for all participants, a pattern replicated in Stavrakaki’s (2004)

youngest participant with WS.


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The participants with WS in this study show clear difficulties in morphosyntax as

evidenced on the TROG2 and with certain syntactic phenomena including the

interpretation of passives and the understanding and production of wh-questions. Their

performance is comparable to participants with DS and poorer than mental age-matched

controls. Whilst this pattern of performance is consistent with some reports (Grant et al.,

2002; Karmiloff-Smith et al., 1997, 1998; Stojanovik et al., 2004), it does not support

other findings which show much better syntactic abilities in individuals with WS (Bartke,

2004; Clashen & Almazan, 1998; Ring & Clashen, 2005; Schaner-Wolles, 2004). It is

important to explore why these differences may exist, and the differences in ages of the

participants with WS across all these studies must be acknowledged. The studies which

report better (and often adult-like) performance on syntactic tasks include adolescent and/

or adult participants with WS, with higher chronological and mental ages than the younger

cohort of participants with WS reported on in this study. Furthermore, Bartke (2004)

reports different levels of performance in the understanding of passives in her younger

versus older WS groups. The age differences may therefore account for the differences in

results reported. Support for this comes from a hypothesis put forward by Jarrold,

Baddeley, and Hewes (1998) about the developmental trajectories of verbal and non-verbal

abilities found in WS. They hypothesize different developmental trajectories of verbal and

non-verbal abilities, with certain verbal abilities developing at a faster rate than non-verbal

abilities, particularly later on in development. Hence, the discrepancy between verbal and

non-verbal performance will be more marked in older participants with WS. Therefore,

according to this hypothesis, verbal abilities will only be observed to be superior compared

to non-verbal performance ‘‘…in individuals who have developed to such an extent that a

developmental difference between these domains has emerged’’ (p. 519). Support for this

view comes from Rossen, Bihrle, Klima, Bellugi, and Jones (1996) who report a group

difference in receptive vocabulary between a DS and WS group in adolescents but not in

younger participants. Consistent with this are the reports of extreme delay in language in

WS at the earliest stages of language development, with the discrepancy between verbal and

non-verbal abilities only becoming evident at a later stage in development (Bellugi et al.,

1990; Mervis, Robinson, Rowe, Becerra, & Klein-Tasman, 2003; Mervis, 2006). Thus it

may be the case that the WS participants in this study are too young to show the verbal-

performance discrepancy and any differences in favour of the WS group compared with the

DS group. Only by following up this cohort of children would we be able to ascertain

whether with time they will develop a better syntactic understanding, which would not only

result in them possibly scoring better than participants with DS, but looking more similar to

the older participants with WS reported on in other research (Bartke, 2004; Clashen &

Almazan, 1998; Ring & Clashen, 2005; Schaner-Wolles, 2004). The importance of

longitudinal studies in exploring language abilities in WS (of which there are very few) must

be emphasized (Karmiloff-Smith, 1998), as well as including a wide range of age levels in

cross sectional studies to ensure a full developmental acquisitional sequence is obtained. It

is important not only to investigate the language abilities of older participants with WS, but

also to include younger school-aged children with WS.

The relationship, however, between age and linguistic performance is not a simple one

and the age differences across the studies may not be a sufficient enough explanation for the

differences in results observed. The correlations obtained in this study across CA and PIQ

and the linguistic measures indicate that the relationship between age and syntactic ability

is more complex. Whilst there was a positive significant correlation between PIQ and

performance on both passives and wh-question tasks, a correlation which remained robust


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even after the effects of CA were removed, this was not the case for CA. There were

significant negative correlations between CA and performance with passives and wh-

questions, although these fell away once PIQ was partialled out. It is also the case that the

older participants with WS did not obtain the best scores either for passives or wh-

questions. The two oldest participants with WS (mean CA of 13;10 and 12;9 years, mean

MA: 6;3 and 5;8 years) obtained scores of 33% and 0% respectively on the interpretation of

passives and scores of 0%, 18.7% and 56.2% and 31.2%, 37.5% and 68.7% respectively for

wh-question elicitation, comprehension and repetition. Therefore, it is not the case that the

older participants with WS will necessarily perform better on language tasks than the

younger participants. In fact, the stronger more enduring correlations between

performance IQ and performance on measures of passives and wh-questions reinforce

the associations between verbal and non-verbal abilities and do not provide support for

marked discrepancies between verbal and non-verbal performance at this age level in the

WS cohort. We would need to follow up these participants into adolescence to observe

whether any such discrepancy becomes more marked at a later point in development,

perhaps as a result of differential rates of development in verbal and non-verbal

performance (see Jarrold, Baddeley, & Hewes, 1998).

Since we find impaired morphosyntax and syntactic processing in young school-aged

participants with WS and DS, even when compared to a very much younger mental aged-

matched control group, it is important to consider the possible intervention strategies that

may be used in the education context to enhance syntactic performance. There is an

important need for targeted intervention studies to be set up which focus on specific

syntactic phenomenon with the aim of enhancing syntactic understanding in individuals

with WS and DS. There are already some positive reports on improving the understanding

of passives in young TD children (Baker & Nelson, 1984) as well as with SLI children

(Ebbels, 2007; Ebbels & van der Lely, 2001) and in enhancing understanding and

production of wh-questions in young typically developing children (Nelson, 1977; Valian &

Casey, 2003). These positive results are pleasing and should encourage intervention studies

to be conducted to improve the language abilities, and in particular, syntactic processing, of

individuals with WS and DS and build a stronger evidence base for effective and

differentiated interventions for these populations.

Acknowledgments

The authors are grateful for the support of the UK Williams Syndrome Foundation, the

UK Down’s Syndrome Association, all the WS, DS and TD participants and their families

for their willingness to participate and the main research assistant of the project, Amy

Riddett, who collected most of the data. Appreciation is also due to some additional pump

priming research funding to the first author from City University. The study was funded by

an ESRC grant to both authors (RES-000-22-0656).

Notes

1. This is the same cohort of participants reported on in Joffe and Varlokosta (2007).

2. Mental ages were derived from performance IQ from the WISC III or WPSSI-R.

3. More recent evidence though suggests that 3;6 to 5;5-year-old English-speaking children understand actional

passives (full and short) 100% of the time (Fox & Grodzinsky, 1998).

4. But Cairns and Hsu (1978) report no significant difference in the comprehension of subject and object wh-

questions.


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5. The low scores for wh-question elicitation in the younger TD group were surprising in light of the

developmental norms available. Although we are not sure why this is the case, it is important to bare in mind

that the TD cohort includes only 10 participants, a number which certainly cannot be representative of the

developmental norms.

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patterns of syntactic development in children with williams syndrome and down's syndrome:...

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