Transcript Phonological working memory in Spanish

Phonological working memory in SpanishEnglish bilingual children with and without
specific language impairment
Dolors Girbau and Richard G. Schwartz
Journal of Communication Disorders 41
(2008)
124-145
37-975-Challenges to Language Acquisition: Bilingualism and Language
Impairment
December 2010
Introduction
 The identification of Specific Language Impairment
continues to be a challenge for clinicians, even in older
children (e.g., Spaulding, Planto, & Farinella, 2006).
 Many children’s language impairments still go
undiagnosed and, instead, intervention often focuses
on poor academic achievement and reading
disabilities, which are more readily identified.
 There is, therefore, a need for further examination of
measures that can reliably identify SLI in school-aged
children.
Specific Language Impairment in Spanishspeaking children
 The number of undetected children with SLI who
speak languages other than English might be
larger, even with recent attempts to improve the
accuracy of this diagnosis (e.g., Crespo-Eguilaz &
Narbona, 2003).
 There are relatively few Spanish language
assessment tools, despite the significant number of
Spanish speakers in USA and worldwide (with
more speakers than English).
 This population has greater incidence of poverty
and less education than the national average (Suro,
2005).
 Bilingual proficiency varies across the sequential
bilingual Hispanic population living in USA
depending on many variables, such as language
instruction at school, language spoken at home
and with friends, years of residence in countries
with L1 and L2, history of language deficits,
socioeconomic status, length of exposure to the
English, and how similar the two languages are.
 English and Spanish have significant phonological,
morphological and syntactic differences.
 In Spanish, words are usually morphologically
marked. Spanish-speaking children’s errors with verb
morphology tend to be substitutions, unlike in English
speakers who are more likely to omit verb inflections
(Bedore and Leonard, 2000).
 The transparent orthography of the Spanish language
contrasts with the deep asymmetrical English
orthography-phonology correspondence.
 English has more vowel sounds than Spanish (five
vowels).
Phonological Working Memory and SLI
 Non-word repetition (NWR) is one of several tasks
used by clinicians for distinguishing SLI children
from their TLD peers.
 Several studies have indicated that this task, which
involves a shorter time than other language
measures, is a reliable identifier of language
impairment and the risk for language impairment
in pre-school (e.g., Bishop, Adams, & Norbury, 2004) and
primary-school children (e.g., Archibald & Gathercole,
2006a).
 In NWR tasks, the child listens to a non-word, temporarily
stores the novel phonological representation, and then
produces it. The task involves the phonological loop which
is a specialized subsystem of working memory with two
components. The first component, phonological short-term
storage maintains the incoming auditory sequence as a
phonological code and the second component, subvocal
rehearsal, holds this phonological representation avoiding
its decay.
 Children with SLI have an apparent deficit in phonological
working memory(PWM) as exhibited by poorer repetition
of non-words, particularly as the length of the non-words
increases (e.g., Gathercole, 2006a, 2006b).
Aims of the study
 The present study examined the performance of sequential
bilingual children with and without SLI on the Spanish nonword repetition task developed by the researchers.
 The researchers’ main goal was to determine the success with
which that task can distinguish children with and without SLI
in this bilingual context.
 They also aimed to analyze the errors made by these children,
and examine the relationship between NWR and scores from
two language tests (one for each language).
 The same task was administered to a subset of these children’s
mothers as a pilot study, to determine whether the mothers of
SLI children perform more poorly than the mothers of TLD
children.
Method
Participants:
 Most of the study participants were recruited from a dual
language (English/Spanish) public school in NY. The rest
were recruited through speech-language pathologists and
by postings on internet and news papers.
 Spanish was their L1 and English their L2.
 They all came from Spanish-speaking homes in NY with
low/low-middle socio-economic status.
 Both parents were monolingual speakers of Spanish (with
some exposure to English), and were born in Latin
American Spanish-speaking countries.
 The study population included 11 children with SLI and
11 age-matched children with TLD (7;6-10;10): 5 boys
and 6 girls in each group.
 SLI children were initially identified by speech
pathologists. The presence of language impairments was
further confirmed by the judgments of their teachers and
parents. All were receiving intervention, except two
children.
 Each participant with SLI was matched on age (in years
and months) and gender with a child with TLD, as closely
as possible.
 All children performed within normal limits on the Test of
Nonverbal Intelligence (TONI-3; Brown et al., 1997), and
passed a hearing screening.
 A parent questionnaire was used to
determine:
1. The extent to which Spanish was the primary
language
2. Their socioeconomic status
3. The family and child history for language deficits
4. That the child did not have
a history of neurological disorders,
behavior characteristic of autism.
The Primary English/Spanish language measures
 The English CELF-3 Screening test (Semel, Wiig, &
Secord, 1996) was administered as the primary English
language measure.
 The Spanish version of the Illinois Test of
Psycholinguistic abilities (ITPA; Kirk et al., 2001) was
the primary Spanish language measure. The researchers
applied the ITPA with norms from Spain due to the scarce
availability of Spanish tests with norms from USA for this
age. It consisted of 11 individually administered subtests,
which all were administered to the children, but only 4
subtests were selected as criteria for SLI: Auditory
Comprehension, Auditory Association, Verbal Expression,
and Grammatical Integration.
 Twelve of the children’s mothers agreed to participate in the
study. Seven of them had a child with SLI and five had a child
with TLD.
 Almost all mothers of children with SLI (6 out of 7) reported to
have one or more relatives with language and/or learning
disabilities.
 The English and Spanish versions of the Peabody Picture
Vocabulary Test were administered to these mothers to get a
comparative language measure in both languages (PPVT-III,
Dunn & Dunn, 1997; TVIP, Dunn, Padilla, Lugo, & Dunn,
1986).
The Non-word repetition task
 The task followed the phonotactic patterns in the syllable structure, stress,
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and the segments.
It included 20 non-words, four at each of five syllable lengths (1,2,3,4,and 5
syllables).
All the non-words began with consonants.
They had a total of 184 segments: 14 in 1- s nw, 25 in 2and-s nw, 38 in 3-s
nw, 48 in 4-s nw, and 59 in 5-s nw.
60 medium-low frequent different syllables were selected from a sample of
1148 syllables produced by 6-10 year old children and 1156 syllables
produced by 6-13 year olds and from a list of more than 2500 Spanish
syllables.
Each syllable contained only one vowel.
None of the non-words contained any diphthongs.
Twelve non-words included at least one cluster. The clusters were frequent
in Spanish words.
Only one syllable in each word was stressed.
All the Spanish sounds were included in the task.
Procedure
 The sessions were audio-recorded.
 The non-words were presented to the participants individually
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through a computer with headphones so that they were seated
on a side of the table without seeing the screen but the
microphone of their recording.
Immediately after listening to each non-word, they had to
repeat it.
An interstimulus interval was increased as the length of the
non-word increased, which permitted sufficient time for the
child’s repetition.
Each non-word was presented only one time.
The entire task lasted approximately 3 min.
Instructions
 “I am going to say some funny made-up words. Your
job is to say them back to me, exactly the way you hear
them. Some of the words are short, and others are
longer. Listen carefully, because I can say the words
once. Here comes the first word!”
Transcription and scoring
 The participants’ productions were transcribed by the
experimenter. A second judge independently
transcribed the non-word productions of nine
randomly selected children. The percentage of
agreement between the two judges was 98.53%.
 The number of correct words, the accuracy of the
stress pattern as well as the frequency and types of
overall consonant, consonant singleton, consonant
cluster, and vowel errors were examined.
Each segment produced was categorized as
one of the following:
Correct
• the child’s production matched the adult target
or involves a minor distortion in pronunciation.
Substitution
• the child substituted a segment for the adult target
in the same serial position within the syllable.
Omission
• a consonant or vowel in the adult target did not
appear in the child’s production.
Addition
• a segment that was not present in the matching
target syllable was produced.
•For the mothers, the analysis focused only on the overall accuracy of
non-word production and the accuracy of 3-4-5 syllable non-words.
Their errors were not further analyzed.
Results
ITPA
CLEF-3
Auditory
Comprehension
Auditory
Association
Verbal
Expression
Grammatical
Integration
Overall M
Total
SLI
-3.73 (2.44)
-2.15 (1.50)
-1.71 (0.75)
-4.34 (1.85)
-2.95 (1.09)
-2.42 (0.67)
TLD
-0.04 (0.66)
-0.05 (0.51)
-0.24 (0.67)
0.04 (1.16)
-0.07 (0.55)
-0.19 (1.42)
Mean standard deviations, in relation to mean scores from the norms (and
Standard Deviations) for the Spanish ITPA and the English CELF-3
Screening Tests scores
Mean Number of Correct Nonwords
•Fig.1 illustrates that the number of non-words produced correctly decreases with
increases in the number of syllables. The graph includes the mean number of
correct non-words and S.D. for each of five syllable lengths in both language groups
of children.
(0.65)
(0.83)
(0.75)
(0.50)
(0.83)
(0.93)
(0.65)
(1.18)
(0.67)
(0.60)
Syllable Length of Nonwords
 The reproduction of the stress pattern for the non-
words was almost always correct for the two groups of
children, except for 5 non-word productions by
children with SLI.
 Thus the analysis focused on the percentage of correct
non-words and correct segments, and the frequency of
various error types.
 Most of the errors occurred on the non-words that were
3,4, and 5 syllables in length. Therefore, a combined
score for these non-words was examined as well.
Total non-words
3-4-5 syllable non-words
SLI
TLD
SLI
TLD
Non-words
37.27 (8.76)
55.91 (8.61)
18.94 (13.48)
42.42 (9.47)
Consonants
73.31 (10.17)
87.46 (3.96)
70.53 (12.08)
86.31(4.57)
Vowels
91.06 (9.08)
98.18 (2.03)
90.06 (10.39)
98.14 (2.07)
Clusters
73.33 (17.33)
83.64 (9.12)
68.69 (23.84)
80.20 (11.65)
Substitutions
14.88 (6.57)
9.16 (3.84)
15.73 (7.81)
9.48 (4.28)
Omissions
10.85 (6.91)
3.52 (2.08)
12.66 (7.93)
4.28 (2.66)
Additions
4.64 (2.87)
3.18 (1.78)
4.27 (2.80)
2.73 (1.49)
Correct Items
Errors in
consonants
Mean (Standard Deviation) accuracy for non-word repetition
Relation to other Spanish and English language skills
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Likelihood ratios for the percentage of correct non-words from the
subgroup of 3-4-5 syllable non-words in children with SLI and TLD
SLI
Number
TLD
Proportion
Number
Likelihood
ratio
Proportion
Children
from USA
<33.0%
9
9/11=0.8182
1
1/11=0.0909
0.8182/0.0909
=9.00
≥33.0%
2
2/11=0.1819
10
10/11=0.0909
0.1819/0.9091
=0.20
≤50.0%
11
11/11=1
1
1/11=0.0909
1/0.0909=11.0
>50.0%
0
0/11=0
10
10/11=0.0909
0/0.0909=0
Children
from Spain
Mean (Standard Deviations) accuracy for non-word repetition in a
subgroup of children with SLI and TLD and their mothers: percentage of
correct numbers
Total non-words
SLI
3-4-5 syllable in non-words
TLD
SLI
TLD
Mothers
39.29 (13.36)
51.00 (4.18)
23.81 (16.96)
36.67 (7.46)
Children
34.29 (7.87)
57.00 (7.58)
15.47 (10.31)
43.33 (6.97)
Spanish Test: Mothers of TLD children: M=96.60;
Mothers of SLI children: M= 90.5.
English Test: Mothers of TLD children: M= 52.4;
Mothers of SLI children: M=45.5.
Discussion
The NWR Task
 The NWR task identified language status with high
degree of accuracy in bilingual Spanish L1
children.
 The difference between the two groups was greater
in longer non-words beginning with the threesyllable length.
 These findings are similar to previous findings for
children speaking other languages (e.g., Le Foll et
al., 1995), including English and Spanish.
Error Analysis
 The two groups diverged significantly in the percentage of
consonant errors.
 The most frequent errors were consonant substitutions. This
finding is similar to previous findings for children of
similar ages ( e.g., Marton & Schwartz, 2003).
 The SLI group made significantly more substitution and
omission errors.
 Although they made less vowel errors, the SLI children did
not approach the ceiling scores reached by the TLD group.
This could be due to the limited vowel inventory of Spanish
(only 5), and the fact that vowels are fully acquired earlier
in development than the complete consonant inventory. But
it also might indicate that vowels are preferentially
preserved in this PWM task in SLI and TLD children.
The relation between the NWR task and the two
standardized language tests ( CELF-3 and ITPA)
 NWR was highly correlated with three of the four ITPA
subtests. The reason might be that these tasks have auditory
working memory demands similar to the NWR task.
 The Verbal Expression task did not correlate significantly
with the NWR task, because this subtest makes more
demands on long-term memory than on working memory.
 There was no significant correlation between the NWR task
and CELF-3, maybe because it assesses L2 skills in these
children. The correlation, however, approached significance
because two of the CELF-3 tasks make direct demands on
working memory.
The SES Factor
 In the present study, the likelihood ratios led the
authors to set a 33% correct non-word repetition cutoff, whereas in a previous study they conducted in
Spain, with a higher SES population, the cut-off was
50%.
 There is evidence that SES has some effect on
language development and academic achievement
(e.g., Schuele, 2001). It may have an even greater
impact on the fragile language and working memory
abilities of children with SLI.
Performance of the mothers
 The mothers with SLI children performed more poorly than
the mothers of TLD children for the set of 20 non-words
and for the subset of 3-4-5 syllable non-words.
 Future research is needed with a larger number of parents
(mothers and fathers) to examine the potential use of this
NWR task in parents as another marker of SLI.
 It may be possible to identify parents whose children are at
risk of SLI at an earlier age than the children might be
testable.
 It might also provide further information about the
heritability of NWR deficit as a clinical marker of SLI.
Conclusions
 The NWR task following the phonotactic patterns
of Spanish is an accurate identifier of SLI for
Spanish-speaking children from 8 to 10 years of
age.
 Length effects were found in 3-4-5 syllable nonwords.
 Phonological working-memory abilities, as
measured by NWR, were strongly related to
comprehension and production skills in the
children’s native language.