Phonological deficits in specific language impairment and developmental dyslexia: towards a multidimensional model

An on-going debate surrounds the relationship between specific language impairment and developmental dyslexia, in particular with respect to their phonological abilities. Are these distinct disorders? To what extent do they overlap? Which cognitive and linguistic profiles correspond to specific language impairment, dyslexia and comorbid cases? At least three different models have been proposed: the severity model, the additional deficit model and the component model. We address this issue by comparing children with specific language impairment only, those with dyslexia-only, those with specific language impairment and dyslexia and those with no impairment, using a broad test battery of language skills. We find that specific language impairment and dyslexia do not always co-occur, and that some children with specific language impairment do not have a phonological deficit. Using factor analysis, we find that language abilities across the four groups of children have at least three independent sources of variance: one for non-phonological language skills and two for distinct sets of phonological abilities (which we term phonological skills versus phonological representations). Furthermore, children with specific language impairment and dyslexia show partly distinct profiles of phonological deficit along these two dimensions. We conclude that a multiple-component model of language abilities best explains the relationship between specific language impairment and dyslexia and the different profiles of impairment that are observed.

Language, Social Behavior, and the Quality of Friendships in Adolescents With and Without a History of Specific Language Impairment

Language is drawn on extensively in friendships but has received scant attention in the developmental literature. This study compared friendship quality in 16-year-old adolescents with and without specific language impairment (SLI), testing the extent it is predicted by individual differences in social behaviors and language ability. Participants were 120 adolescents with SLI and 118 typically developing (TD) adolescents. After considering the effects of nonverbal IQ and prosocial and difficult behavior, language measures were found to be associated with friendship quality. The TD participants enjoyed normal friendships, whereas the participants with SLI were more likely to exhibit poorer quality (although 60% experienced good quality of friendships). Longitudinal analyses identified early language difficulties as predictive of poorer friendship quality in adolescence.

Language development, literacy skills, and predictive connections to reading in Finnish children with and without familial risk for dyslexia

Discriminative language markers and predictive links between early language and literacy skills were investigated retrospectively in the Jyväskylä Longitudinal Study of Dyslexia in which children at familial risk for dyslexia have been followed from birth. Three groups were formed on the basis of 198 children's reading and spelling status. One group of children with reading disability (RD; n = 46) and two groups of typical readers from nondyslexic control (TRC; n = 84) and dyslexic families (TRD; n = 68) were examined from age 1.5 years to school age. The RD group was outperformed by typical readers on numerous language and literacy measures (expressive and receptive language, morphology, phonological sensitivity, RAN, and letter knowledge) from 2 years of age onward. The strongest predictive links emerged from receptive and expressive language to reading via measures of letter naming, rapid naming, morphology, and phonological awareness.

Children's understanding of monosyllabic nouns in quiet and in noise

A four-alternative, forced choice adaptive procedure was used to measure the lowest intensity at which children could identify monosyllabic nouns that had been standardized to be understandable (at comfortable listening levels) to inner city, 3-year-old children. Results showed no age-related performance changes when the words were presented against a 12-talker babble or against filtered noise. In quit, however, performance improved between the ages of 5 and 10 years. Performance of children with learning problems was poorer than performance of children achieving normal school progress, even though clinical measures of auditory sensitivity showed no differences. Results are discussed in terms of "semantic closure" skills of children.

Abnormal speech articulation, psychomotor retardation, and subcortical dysfunction in major depression

Psychomotor retardation, characterized by changes in speech, motility and cognition, is common in major depression. It is also a cardinal feature of subcortical disorders such as Parkinson's disease (PD). Based on this observation and other data it has been hypothesized that the retardation of depression is related to mesolimbic-nigrostriatal dysfunction. To further test this hypothesis, speech articulation in major depression was compared to that in PD, where disordered articulation is related to bradykinesia and rigidity caused by striatal dopamine depletion. Thirty subjects with major depression were compared with 30 patients with PD and 31 normal controls on 3 acoustic measures of articulation. Major depression and PD groups had significantly shortened voice onset time and decreased second formant transition compared to controls, and major depression also had increased spirantization. There were no differences between the depression and PD groups on any of the acoustic measures. These findings provide indirect support for the hypothesis that nigrostriatal dysfunction is related to psychomotor slowing in major depression.

Seven-year follow-up of speech/language impaired and control children: psychiatric outcome

This study examined the 7-year psychiatric outcome of 202 speech/language (S/L) impaired and control children selected from a community sample at age 5 years. Children with S/L at age 5 years were more likely to be psychiatric cases at age 12.5 years than were normal controls, even if their S/L improved. Controlling for concurrent psychiatric disorder, S/L impairment at age 5 years was still associated with an increased rate of psychiatric disorder at 12.5 years. Psychiatric disorder at age 12.5 years was more likely to co-occur with language disorder than with speech disorder.

Intervention for children with severe speech disorder: a comparison of two approaches

BACKGROUND

Children with speech disorder are a heterogeneous group (e.g. in terms of severity, types of errors and underlying causal factors). Much research has ignored this heterogeneity, giving rise to contradictory intervention study findings. This situation provides clinical motivation to identify the deficits in the speech-processing chain that underlie different subgroups of developmental speech disorder. Intervention targeting different deficits should result in a differential response to intervention across these subgroups.

AIMS

To evaluate the effect of two different types of therapy on speech accuracy and consistency of word production of children with consistent and inconsistent speech disorder.

METHODS & PROCEDURES

Eighteen children (aged 4;08-6;05 years) with severe speech disorder participated in an intervention study comparing phonological contrast and core vocabulary therapy. All children received two 8-week blocks of each intervention. Changes in consistency of production and accuracy (per cent consonants correct) were used to measure the effect of each intervention.

OUTCOMES & RESULTS

All of the children increased their consonant accuracy during intervention. Core vocabulary therapy resulted in greater change in children with inconsistent speech disorder and phonological contrast therapy resulted in greater change in children with consistent speech disorder.

CONCLUSIONS

The results provide evidence that treatment targeting the speech-processing deficit underlying a child's speech disorder will result in efficient system-wide change. Differential response to intervention across subgroups provides evidence supporting theoretical perspectives regarding the nature of speech disorders: it reinforces the concept of different underlying deficits resulting in different types of speech disorder.

Receptive Vocabulary, Expressive Vocabulary, and Speech Production of Boys With Fragile X Syndrome in Comparison to Boys With Down Syndrome

Boys with fragile X syndrome with (n = 49) and without (n = 33) characteristics of autism spectrum disorder, boys with Down syndrome (39), and typically developing boys (n = 41) were compared on standardized measures of receptive vocabulary, expressive vocabulary, and speech administered annually over 4 years. Three major findings emerged. Boys with fragile X without autism spectrum disorder did not differ from the younger typically developing boys in receptive and expressive vocabulary and speech production when compared at similar levels of nonverbal cognitive skills. Boys with fragile X without autism spectrum disorder and typically developing boys had higher receptive vocabulary and speech production than did boys with Down syndrome. There were mixed patterns of results for the boys with fragile X and characteristics of autism spectrum disorder.

Phonology and vocal behavior in toddlers with autism spectrum disorders

The purpose of this study is to examine the phonological and other vocal productions of children, 18-36 months, with autism spectrum disorder (ASD) and to compare these productions to those of age-matched and language-matched controls. Speech samples were obtained from 30 toddlers with ASD, 11 age-matched toddlers and 23 language-matched toddlers during either parent-child or clinician-child play sessions. Samples were coded for a variety of speech-like and nonspeech vocalization productions. Toddlers with ASD produced speech-like vocalizations similar to those of language-matched peers, but produced significantly more atypical nonspeech vocalizations when compared to both control groups. Toddlers with ASD show speech-like sound production that is linked to their language level, in a manner similar to that seen in typical development. The main area of difference in vocal development in this population is in the production of atypical vocalizations. Findings suggest that toddlers with ASDs do not tune into the language model of their environment. Failure to attend to the ambient language environment negatively impacts the ability to acquire spoken language.

Increasing speech intelligibility in children with autism

Accumulating studies are documenting specific motivational variables that, when combined into a naturalistic teaching paradigm, reliably influence the effectiveness of language teaching interactions for children with autism. However, the effectiveness of this approach has not yet been assessed with respect to improving speech intelligibility. The purpose of this study was to systematically compare two intervention conditions, a Naturalistic approach (which incorporated motivational variables) vs. an Analog (more traditional, structured) approach, with developmentally similar speech sounds equated within and across conditions for each child. Data indicate that although both methods effectively increased correct production of the target sounds under some conditions, functional use of the target sounds in conversation occurred only when the naturalistic procedures were used during intervention. Results are discussed in terms of pivotal variables that may produce improvements in speech sounds during conversational speech.

Linguistic abilities in children with Williams-Beuren syndrome

In recent studies children with Williams-Beuren syndrome (WBS) have been characterized as having a distinct neuropsychological profile with verbal abilities being superior to visuo-spatial and motor skills. An unusual command of language, including excessive use of verbal stereotypes, social phrases, and clichés has been noticed. The aim of this study is to establish whether the quality and quantity of verbal behavior, and the articulation and tonal quality of the voices of children with WBS differ from other children with nonspecific developmental disabilities. A group of 25 children with WBS and a control group of 25 children matched for age (4-10 years), sex (12 girls; 13 boys), and non-verbal reasoning abilities (mean IQ = 79) were investigated. The Heidelberg Language Development Test and a picture story were administered. The mothers were asked to answer a questionnaire to assess the articulation and the vocal characteristics of their children. The results show that children with WB syndrome do not differ in most qualitative and quantitative tasks with regard to verbal competence. They produce significantly more correct plural-singular formations than the control children (t = 2.49, P < 0.01) on a primitive level of grammatical competence. In general, their articulation was reported to be more exact and clear (t = -2.73, P < 0.006). More mothers of children with WBS noticed a production of stereotypes, the use of social phrases, and clichés than did mothers of the control children (Chi square = -6.67 P < 0.005). Children with WBS were less likely to lisp as compared to the control children (Chi square = 2.08, P = 0.074).(ABSTRACT TRUNCATED AT 250 WORDS)

Verbal and cognitive sequelae following unilateral lesions acquired in early childhood

Eight left-hemisphere lesioned children and eight right-hemisphere lesioned children between 18 months and 8 years of age were compared to control subjects on a battery of intelligence and language measures. Both left- and right-lesioned subjects had lower IQ scores than their controls, yet most functioned within the normal range or higher. Lexical comprehension and production were depressed in both subject groups and appeared to be depressed to a greater degree in right-lesioned subjects than in those with left lesions. In contrast, syntactic production in left-lesioned subjects was markedly deficient in comparison to controls as well as right-lesioned subjects. Although both subjects and controls included children with articulation errors, the number of misarticulating children and misarticulated sounds was greatest in the left-lesioned group. Finally, fluency disorders were observed in both right- and left-lesioned subjects but were not observed in controls. The study provides further evidence that the right and left hemispheres are not equipotential for language and that left-hemisphere lesions acquired early in childhood impair syntactic development to a greater degree than do right-hemisphere lesions.

Phonological working memory impairments in children with specific language impairment: where does the problem lie?

PURPOSE

The purpose of this study was to determine which factors contribute to the lexical learning deficits of children with specific language impairment (SLI).

METHOD

Participants included 40 7-8-year old participants, half of whom were diagnosed with SLI and half of whom had normal language skills. We tested hypotheses about the contributions to word learning of the initial encoding of phonological information and the link to long-term memory. Children took part in a computer-based fast-mapping task which manipulated word length and phonotactic probability to address the hypotheses. The task had a recognition and a production component. Data were analyzed using mixed ANOVAs with post-hoc testing.

RESULTS

Results indicate that the main problem for children with SLI is with initial encoding, with implications for limited capacity. There was not strong evidence for specific deficits in the link to long-term memory.

CONCLUSIONS

We were able to ascertain which aspects of lexical learning are most problematic for children with SLI in terms of fast-mapping. These findings may allow clinicians to focus intervention on known areas of weakness. Future directions include extending these findings to slow mapping scenarios.

LEARNING OUTCOMES

The reader will understand how different components of phonological working memory contribute to the word learning problems of children with specific language impairment.

Facilitating conversation through self-initiated augmentative communication treatment

We examined the conversational skills of 2 adult males with severe motor and speech deficits resulting from cerebral palsy. A multiple baseline design across subjects was used to determine the effectiveness of an intervention strategy designed to teach them to use an augmentative communication system (Touch Talker) independently. The dependent measure was the number of conversation initiations relative to conversation reactions during spontaneous communication across baseline and treatment. The treatment included specific training on using the augmentative system to participate in communication. Once the intervention began, the production of conversation initiations accelerated at a rapid rate. The treatment program was effective in training the subjects to use the augmentative system to increase conversation participation. These results demonstrate that training on the operation of the device alone is not sufficient to ensure improvement in conversation performance, and that it is important to incorporate direct conversational treatment when providing instruction on the use of augmentative communication systems for severely speech-impaired individuals.

Phonological processing skills of adolescents with residual speech sound errors

PURPOSE

Research has shown that young children with speech sound disorders may have weaknesses in phonological processing. However, such skills have not been thoroughly examined in adolescents with residual speech sound errors. Therefore, this study compared the phonological processing abilities of adolescents with residual speech sound errors to those of normally speaking peers.

METHOD

Two nonword repetition tasks, multisyllabic word repetition, spoonerisms, phoneme reversals, and an elision task were used to compare the phonological processing skills of 10-14-year-olds with residual speech sound errors that include rhotic phonemes (RE, n = 13) to those of normally speaking (NS, n = 14) adolescents of similar age and receptive vocabulary abilities.

RESULTS

The 2 groups were found to differ on 5 of the 6 phonological processing tasks. Discriminant analysis showed that 85% of the participants could be correctly classified into the RE and NS groups based solely on phonological processing skills.

CONCLUSION

The possible nature of the phonological processing impairment is discussed in the context of current theoretical understanding. It is recommended that when planning assessment and intervention for adolescents with residual speech sound errors, clinicians be cognizant of the fact that the adolescents may also have weaknesses in phonological processing.

Classification rules for basic phonological processing disabilities and nonverbal learning disabilities: formulation and external validity

Rules for the classification of two subtypes of learning disabilities (LD), namely, Basic Phonological Processing Disabilities (BPPD) and Nonverbal Learning Disabilities (NLD), are reported. These rules (refined as a result of application to two separate samples of children with LD) were used to select children from an entirely new sample who could be classified as having "definite" or "probable" BPPD or NLD. As a first step in the external validation of these rules, the patterns of psychosocial functioning exhibited by these two subtypes of LD were determined. As predicted, the vast majority of the BPPD subtype exhibited a pattern most consistent with normal or relatively normal psychosocial adjustment, and no appreciable increase in the incidence of significant psychosocial disturbance with advancing years. Also, as predicted, an increasing incidence of internalized psychosocial dysfunction (a form of significant psychosocial disturbance) was evident in the NLD subtype with advancing years. It is clear that children classified as having BPPD or NLD using these rules exhibit quite different, and predicted, relative patterns of psychosocial functioning. Thus, in this sense, the rules have concurrent validity. Finally, sets of rules/criteria for classification are presented that reflect their actual incidence in the two subtypes of LD generated for use in the validation phase of this investigation. These rules would appear to be useful for clinical purposes. It is also clear that they should be subjected to further validation studies in a broader age range for clinical and research purposes.

Speech perception in children with speech output disorders

Research in the field of speech production pathology is dominated by describing deficits in output. However, perceptual problems might underlie, precede, or interact with production disorders. The present study hypothesizes that the level of the production disorders is linked to level of perception disorders, thus lower-order production problems (such as childhood apraxia of speech; CAS) are linked to lower-order perception problems and higher-order production problems (phonological disorder; PD) are linked to higher-order perception problems. For this, various perception tasks were administered (non-word auditory discrimination task, word rhyming task, categorical classification, and discrimination task) in children with CAS, PD, or a mixture. The results show that children with PD only show higher-order perception problems, whereas children with CAS have difficulties on both lower- and higher-order perception tasks. In children with CAS, difficulties at lower-order processes might affect the higher-order processes in development. Furthermore, significant correlations were found between production and perception scores at different levels. Thus, a link between perception and production seems to be evident.

A Meme’s Eye View of Speech-Language Pathology

In this article, the reason why certain terms, labels, and ideas prevail, whereas others fail to gain acceptance, will be considered. Borrowing the concept of "meme" from the study of evolution of ideas, it will be clear why language-based and phonological disorders have less widespread appeal than, for example, auditory processing and sensory integration disorders. Discussion will also center on why most speech-language pathologists refer to themselves as speech therapists or speech pathologists, and why it is more desirable to have dyslexia than to have a reading disability. In a meme’s eye view, science and logic do not always win out because selection favors ideas (memes) that are easy to understand, remember, and copy. An unfortunate consequence of these selection forces is that successful memes typically provide superficially plausible answers for complex questions.

Stuttering, language, and cognition: a review and a model of stuttering as suprasegmental sentence plan alignment (SPA)

Extant models of stuttering do not account for the emergence of stuttering at the onset of productive language use; the greater incidence of stuttering during spontaneous speech, on complex sentences, and at sentence-initial positions; the greater incidence of stuttering in bilinguals' 2nd language; the apparent deficiency of stutterers in expressive and receptive language skills; the prevalence of spontaneous recovery from stuttering; and the lack of chronic physiological or articulatory deficits in stuttering children's fluent speech. The author presents a model of stuttering as points of suprasegmental sentence plan alignment (SPA). Such alignment processes occur when, due to on-line sentence production processes, SPAs adopted prior to utterance initiation need to be aligned with revised SPAs. This model parsimoniously accounts for the findings reviewed in the article.

Verbal short-term memory in Down's syndrome: an articulatory loop deficit?

BACKGROUND

Verbal short-term memory, as measured by digit or word span, is generally impaired in individuals with Down's syndrome (DS) compared to mental age-matched controls. Moving from the working memory model, the present authors investigated the hypothesis that impairment in some of the articulatory loop sub-components is at the base of the deficient maintenance and recall of phonological representations in individuals with DS.

METHODS

Two experiments were carried out in a group of adolescents with DS and in typically developing children matched for mental age. In the first experiment, the authors explored the reliance of these subjects on the subvocal rehearsal mechanism during a word-span task and the effects produced by varying the frequency of occurrence of the words on the extension of the word span. In the second experiment, they investigated the functioning of the phonological store component of the articulatory loop in more detail.

RESULTS

A reduced verbal span in DS was confirmed. Neither individuals with DS nor controls engaged in spontaneous subvocal rehearsal. Moreover, the data provide little support for defective functioning of the phonological store in DS.

CONCLUSIONS

No evidence was found suggesting that a dysfunction of the articulatory loop and lexical-semantic competence significantly contributed to verbal span reduction in subjects with DS. Alternative explanations of defective verbal short-term memory in DS, such as a central executive system impairment, must be considered.

Down syndrome and the phonological loop: the evidence for, and importance of, a specific verbal short-term memory deficit

Individuals with Down syndrome are thought to perform poorly on tests of verbal short-term memory, such as measures of word span or digit span. This review critically examines the evidence for a specific deficit in verbal short-term memory in Down syndrome, and outlines a range of possible explanations for such a deficit. The potential implications of a verbal short-term memory impairment for broader aspects of development are outlined, in particular with respect to vocabulary development. Possible intervention strategies, which might improve verbal short-term memory performance in Down syndrome are also considered. However, we argue that further research is needed to fully clarify the nature of a verbal short-term memory deficit in Down syndrome, before the merits of these various intervention approaches can be properly evaluated.

Accurate non-word spelling despite congenital inability to speak: phoneme-grapheme conversion does not require subvocal articulation

Previous work has shown that children with motor speech disorders (dysarthria) have no particular difficulty in spelling non-words containing sounds that they cannot produce accurately in their own speech. This suggests that subvocal articulation is not implicated in generating a graphemic representation from a phonological string. However, it could be argued that, although severely unintelligible, dysarthric individuals may be able to use their own articulation as a basis for translating between phonemes and graphemes. In this study we investigated spelling of words and non-words in cerebral palsied individuals, including speechless (anarthric) as well as dysarthric subjects. Although spelling abilities of these individuals were below control levels, there was no evidence that different processes were used, and one anarthric individual achieved perfect performance in spelling a list of non-words which included consonant clusters. It is concluded that spelling by the 'indirect' route can be achieved in the absence of any articulation.

Misarticulating and normally articulating children's identification and discrimination of synthetic [r] and [w]

In this study, 22 children, ages 6:0 to 6:11, who misarticulated word-initial [r] as [w], were compared to 13, age-matched normally articulating children for their ability to identify and discriminate seven synthetic stimuli representing an acoustic continuum between [we] and [re]. Discrimination was tested among 3-step continuum stimulus pairs using the 4IAX paradigm. All of the control children demonstrated a single, sharp phonemic boundary during identification and higher between-phoneme than within-phoneme discrimination ability. Most of the misarticulating children demonstrated abnormal identification functions, with many showing only chance-level responses. Discrimination ability of the misarticulating children was generally poorer than that of the normally articulating children. Furthermore, discrimination ability of children in both groups was largely predictable from their identification performance, assuming categorical perception of these stimuli. Results indicate that a majority of the 6-year-old [r]-misarticulating children have failed to phonemically distinguish /r/ from /w/. These results call into question the use of the liquid gliding process as a psychological processing description of the misarticulation of these children.

On the prediction of phonologic generalization learning patterns

The purpose of this study was to obtain information on six children's misarticulation of consonant clusters in order to illustrate how certain factors influence generalization learning patterns. While all subjects evidenced generalization, individual differences in learning patterns did emerge. These patterns were explained in terms of the following three factors: (1) information about the children's unique knowledge about the phonologic system, (2) the linguistic relationships among sounds, and (3) the interaction of these factors with the treatment target. The implications of this explanation are discussed as they relate to the selection of treatment targets that will facilitate generalization.