Reading, why not? Literacy skills in children with motor and speech impairments.
Keywords: auditory discrimination; literacy; motor disability; phonological awareness; speech impairment
Literacy is crucial for children with severe speech impairments. It is their gate to more unlimited communication and to a more independent acquisition of knowledge and information (Blischak, 1994; Foley, 1993; Light & Kelford Smith, 1993; Smith, 2005). Accordingly, one of the main questions for researchers in this field is the following: Which skills are important for children with severe speech impairments to acquire to reach a functional level of literacy?
Most research in the area of literacy has been carried out with participants without speech impairments. This body of research provides an important basis from which the factors that influence literacy in the motor- and speech-impaired population can be identified. This might, however, not be sufficient to explain the specific difficulties that children with severe speech impairments encounter. The limited research with this small group of people suggests that a multiple factor explanation of the problems with literacy that children with severe speech impairments encounter is required. Several studies have explored social factors contributing to low literacy among congenitally anarthric and dysarthric children (Koppenhaver, Evans, & Yoder, 1991; Light & McNaughton, 1993). Smith (2001) listed several social factors, such as home and school experiences, competition with medical or therapy appointments during school hours, and physical limitations that restrict the degree of independent learning. Social factors are important for understanding the context of literacy development in children with severe speech impairments; however, an understanding of the linguistic and cognitive profiles of these children is also important (Snowling, Bishop, Chipchase, & Kaplan, 1998). This study will focus on a comprehensive assessment of the cognitive and linguistic skills of a group of children with severe speech impairments, with social background variables taken into account.
Literacy in the Population With Typical Speech
Reading ability is commonly seen as the composite skill of word decoding and reading comprehension (Hoover & Gough, 1990). Decoding refers to the ability to transform written words into their corresponding sounds, and reading comprehension refers to the process of gaining meaning from text (Gustafson, 2000). These fundamental skills can be seen from two different perspectives. Reading can be seen as a bottom-up process (i.e., connecting smaller discriminating units to create more complex semantically understandable units) or as a top-down process (i.e., starting from semantically meaningful material to predict the meaning of a text; Alderson, 2000; Stanovich, 2000). These processes are combined in the connectionist model by Plaut, McClelland Seidenberg, and Patterson (1996) to a more holistic view where both processes have to be active for the child to reach full reading competence.
In the current study, we focus on five fundamental linguistic and cognitive skills related to word decoding and reading comprehension. Numerous studies of the typical-speaking population have stressed these variables and are the logical foundation for exploring these variables in the population with speech impairments. The variables are letter knowledge (Adams, 1990; Foulin, 2005; Naslund & Schneider, 1996; Snowling, Gallagher, & Frith, 2003), phonological processing (Lundberg, Frost, & Petersen, 1988; Perfetti, 1995; Snowling et al., 2003; Wagner & Torgesen, 1987), linguistic ability (Catts, Fey, Zhang, & Tomblin, 1999; Naucler & Magnusson, 2000), working memory (Alloway, Gathercole, Willis, & Adams, 2004; Baddeley, 2002; Bayliss, Jarrold, Leigh & Baddeley, 2005) and general cognitive ability (Jacobson & Jacobson, 1996; Maughan, Collishaw, & Pickles, 1999). These variables represent the processing of small linguistic and cognitive units to the more complex ones.
Letter knowledge has been found to be a strong predictor of emerging reading. Foulin (2005) described letter knowledge as developing phonemic sensitivity through letter-sound knowledge. Gallagher, Frith, and Snowling (2000) stressed that the problems in learning letter names and sounds that children with literacy delays often encounter seem to reflect a specific verbal learning difficulty.
Phonological processing has been shown to be an important factor in the development of early literacy in children with typical speech (Wagner & Torgesen, 1987). Simmons and Kameenui (1998) found evidence in the research literature showing that phonological processing ability explains significant differences between good and poor readers. They also concluded that the specific phonological processing skill of phonological awareness is important in literacy but has a reciprocal relation to reading acquisition. Additionally, they found that phonological awareness is necessary but not sufficient for reading acquisition. The importance of phonological awareness in relation to literacy has been frequently stressed in the literature (Burt, Holm, & Dodd, 1999; Lundberg et al., 1988; Mody, 2003; Perfetti, 1995).
Linguistic ability is an essential ability for literacy. Linguistic ability includes vocabulary that gives the child a possibility for semantic matching of phonologically intriguing and irregular words (Raman & Baluch, 2001). It also gives the child readiness to handle morphologic and syntactic features in text (Cooper, Roth, Speece, & Schatschneider, 2002), such as subject, predicate and object, suffixes and prefixes, word sequencing, and subordinate clauses. Others argue that even though linguistic ability might not be important in the beginning of reading, linguistic ability at least is needed for developing elaborated comprehension of text later in reading development (Hirsch, 2003).
Working memory is often mentioned in the literature as a correlate to literacy (Alloway et al., 2004; Bayliss et al., 2005; Passenger, Stuart, & Terrell, 2000). Picketing and Gathercole (2004) found deficits in all areas of working memory in children having problems with literacy. In their study, they compared the reading impaired group with a language deficit group. The participants with reading impairments had a low working-memory profile. The group with language impairments had average levels of visuospatial memory, but otherwise, low working memory. Thus, working memory seems to be important in dealing with both the auditory phonological entities and the visual orthographic entities that are connected with text processing.
Finally, general cognitive ability is of importance to literacy. In studies of literacy, general intelligence is often used as a matching variable to be held constant or, as a variable, used as covariate to predictions of reading ability (Harlaar, Hayiou-Thomas, & Plomin, 2005; Tiu, Thompson, & Lewis, 2003; Vellutino, 2001). Torgesen (2000) notes that word-reading difficulties often have been assumed to be caused by low general intelligence, but that the difficulties rather can be found in the phonological language domain. We have also found this in our research (Gustafson, 2000); however, many of the studies concluding this have been conducted with children within normal ranges of intelligence. There are limited numbers of studies with more specific testing of reading ability and reading-related variables in children with intellectual impairments. Reading disability has been found to be more pronounced and common in people with mental retardation (Jacobson & Jacobson, 1996; Maughan et al., 1999). For this, it does not appear that the independency of word decoding from IQ in this group has been fully investigated. Therefore, nonverbal intelligence is included in the test battery as a complement to the phonological tests to further study this issue.
These correlates of literacy are also of importance in the speech-impaired population. They may serve the same, elaborated, or different purposes to the person with severe speech impairments. The severe speech impairment can also serve as a strategic sample that gives us additional, comparative information of specific skills related to literacy that cannot be found in the typically-speaking population. This is also the main motivation for the study.
Literacy in the Population With Speech Impairment
Research has shown that children with severe speech impairments face numerous barriers in their efforts to become literate (Berninger & Gans, 1986; Dahlgren Sandberg, 1996; Koppenhaver & Yoder, 1993; Light & Kelford Smith, 1993; Vandervelden & Siegel, 2001). Basically, these are the same fundamental areas for bottom-up and top-down processes that can be found in the typically-speaking population. There are also additional areas uniquely connected to speech impairment in the population that have to be explored. The areas that we find interesting in this population are articulation, the internal speech sound system, letter knowledge, phonological processing, linguistic ability, working memory, and general cognitive ability.
First, the most obvious aspect is that these children cannot articulate. They lack speech or at least fully intelligible speech. Consequently, these children have fewer opportunities to train speech sounds and their relations to letter symbols. The oral sounding of written text, common among other beginning readers, is hard or impossible to master without functioning speech. There have even been early claims that reading ability is directly correlated with speech and articulation (Barsch & Rudell, 1962; Liberman, Cooper, Shankweiler, & Studdert-Kennedy, 1967). This is hardly a viewpoint nowadays. But even though Foley and Pollatsek (1999) emphasized the role of the ability of children with speech impairment to make phonological coding, they described the articulatory element of the phonological coding as "not essential ... (although it certainly may be helpful)" (p. 170). Following this, as a measure of articulation, the speech impairments of the children in our study have been graded by one of the authors, who is trained as a speech and language pathologist.
The internal speech sound system can also be affected in children with speech impairments. Speech impairments come in different forms. Grunwell (1987) described two fundamental forms, the phonetic and the phonological. Children with phonetic impairments traditionally talk with nondistinct and blurry speech sounds. Dysarthria is defined by its phonetic impairment component (i.e., physical troubles with articulation). Children with phonological impairments, however, have problems with speech sounds at a higher cognitive level. Their auditory discrimination for speech sounds is distorted. The distinction between speech sounds is less phonologically developed than in the adult, and normally developed system and systematic errors occur. These errors can be paradigmatic or syntagmatic (Trask, 1995). Paradigmatic speech errors refer to errors where single speech sounds compete for a position, such that speech sounds become replaced by other speech sounds in a systematic way (e.g., /r/ is replaced by /l/). Paradigmatic errors are often based on phonological features (e.g., voiced speech sounds become voiceless). Syntagmatic errors refer to more context-dependent errors where, for example, speech sounds get assimilated by other speech sounds within a word or sentence or when speech sounds become transposed. This often affects children's speech production but frequently also their speech perception (Grunwell, 1987). The child's internal speech sound system also provides the limits of the arena in which their phonological awareness skills can be operating. If I do not know that /r/ and /l/ are different phonemes, I will also be less accurate in manipulating these speech sounds. The distinction between phonetic impairments and phonological impairments is not as clear cut. Many children with dysarthria also have phonological impairments, although it is hard to detect in speech output because of the phonetic impairments. In this study, however, we tested the auditory discrimination of our participants to find phonological problems with distinction of speech sounds at a perceptual level.
The letter knowledge of children with speech impairment is lower than in the typical population (Raitano, Pennington, Tunick, Boada, & Shriberg, 2004). Insufficient phoneme awareness and auditory as well as visual perception deficits could be possible explanations for this. The lower expectations from the environment for literacy development in these children (Light & Kelford-Smith, 1993) can also contribute to less alphabetic and orthographic instructions for them, thus leading to deficits in letter knowledge. Letter knowledge is tested by letter sounds in this study.
Children with severe speech impairments have been shown to have poorer phonological skills (Blischak, 1994; Dahlgren Sandberg, 1996). Foley and Pollatsek (1999) divided these phonological-processing abilities into three component skills that have been identified as critical to the development of skilled reading: (a) phonological awareness, (b) phonological recoding in identification of written words, and (c) phonological coding to maintain information in working memory. Phonological awareness is often developed in spite of severely distorted speech (Dahlgren Sandberg, 1996; Foley, 1993), but studies still have shown that children with severe dysarthria or anarthria have troubles reaching the phonological awareness levels of their typically-speaking peers. Vandervelden and Siegel (1999) found a significantly lower performance in the AAC group on practically all their phonological awareness and phonological recoding tasks. Therefore, to chart these possibilities, this study includes different tasks testing phonological awareness.
The overall linguistic ability among children with speech impairments is often poor. Foley (1993) concluded that linguistic ability, as opposed to speech production ability, appeared to be the more critical factor. This linguistic deficiency can affect all linguistic levels of language (Naucler & Magnusson, 2000), such as vocabulary, morphology, syntax, complex narratives, and pragmatics. This includes production as well as perception. Many children with speech impairments lack an elaborated AAC system to produce language. The AAC system might also have drawbacks in itself (Higginbotham, 1989), such as not being able to stimulate the child in all the literacy-related areas that oral language can (Dahlgren Sandberg, 1996). Linguistic ability is addressed in this study through assessment of receptive vocabulary, grammar, and narratives.
In close relation to phonological processing, working memory is often suggested as limited in the populations with severe speech and motor impairments. The phonological processing skills used in working memory have often been connected with oral speech, for example, in the articulatory loop of Baddeley's (1986) classical model of working memory. Later, Gathercole and Baddeley (1990) stressed the importance of more primary phonological processing through reducing the prominence of the articulatory component in phonological coding, changing the articulatory loop in Baddeley's (1986) working memory model to the more sophisticated phonological loop. Baddeley and Wilson (1985) found strong evidence for the fact that subvocal rehearsal and phonological coding could operate without feedback from pure articulation. Nevertheless, children with speech impairments children often fail in working-memory tasks. Dahlgren Sandberg (2001) found it reasonable that lack of speech may indeed limit the ability to manipulate the sound structure of language. Working memory is tested by digit span in this study.
Finally, Blischak (1994) called our attention to the fact that children with congenital speech impairments also may have cognitive impairments that could contribute to poor literacy skills. Cognitive ability is tested nonverbally in this study.
Aims of the Study
The aim of this study is to investigate the cognitive and linguistic components that contribute to reading in a population of children with congenital speech impairments in combination with motor deficits. In contrast to studies of acquired speech impairments (Baddeley & Wilson, 1985), congenital difficulties give us information about reading in the light of undeveloped cognitive and linguistic functions, compared to the effect of lost functions.
Twelve children (seven girls and five boys) ages 8 to 14 participated in the study. The inclusion criteria were children 8 to 14 years old, with a congenital impairment including speech impairment and motor disability of varying degrees and causes, who participated in literacy instruction in their schools. The exclusion criteria were children with any documented severe visual or auditory impairment (including cerebral impairment), children with no alphabetic knowledge, and children with severe mental retardation. General information about the participants and speech and language information are provided in Table 1a and Table 1b.
The children were included on the basis of recommendations from several habilitation centers and a few schools in Sweden. Overall, 10 schools participated in the study. Two pupils attended a special class for children with language disabilities. Two attended a special class for children with motor disabilities. Four followed the curriculum for pupils with learning disabilities, but in different school settings. Four attended ordinary compulsory school. The different school situations primarily reflect practical, local considerations rather than individual factors.
The present study was designed as a multiple case study with subgroups based on a posteriori median split of their ability to read, measured by the composite scores of the two reading tests. A comparison across cases was deemed more interesting for the study than comparison with typical controls. The study offers a broad scope with a comprehensive assessment of the dimensions of cognition, language, phonological awareness, and reading. The assessment includes adapted tests with a range of task difficulty.
Materials: Test Battery
The test battery consisted of 15 components: standardized tests and tests specifically constructed for the study. Various tests of reading, speech and linguistic, and cognitive ability were included. Eight composite variables were created, and each test was categorized into one of these eight variables. The composite variables were the following: reading, letters, speech, auditory discrimination, phonological awareness, language, digit span, and nonverbal intelligence. The test results of all the included test components in the composite variables were summed, for reliability.
Word reading 0S64 (Nielsen, Kreiner, Poulsen, & Soegard, 1997a). Eight items were chosen from the standardized Swedish word-reading test, OS64. A written word was presented to the participants together with four black-and-white drawings. The participants were asked to read the word and point to the corresponding drawing. The maximum score was 8.
Sentence reading SL60 (Nielsen, Kreiner, Poulsen, & Soegard, 1997b). Eight items were chosen from the standardized Swedish sentence-reading test, SL60. A written sentence was presented to the participants together with five black-and-white drawings. The participants were asked to read the sentence and point to the corresponding drawing. The maximum score was 8.
Letter knowledge. The 29 letters of the Swedish alphabet with their corresponding sounds were presented to the participants. They were asked to point to the orthographic representation of this sound on an alphabet board. The maximum score was 29.
Speech intelligibility. The participants articulated 19 words with varying first phonemes and up to two syllables. Their performance was video recorded, and their level of speech was graded on a scale from one to seven by one of the authors with a background as a speech and language pathologist. Interrater reliability was computed as percentage of agreement with another speech and language pathologist with experience with children with severe speech impairments. The percentage of agreement was 80%. The judgments differed 1 point on the scale for one participant (P06) and 2 points for another participant (P07). The difference can be explained by the differences in the participants' performance in fluent speech and pronunciation of separate words. The head judge had experienced the participant in both settings, whereas the interrater reliability was computed only for separate words.
Auditory discrimination (phonological auditory discrimination). There was auditory discrimination of two different phonological settings: 12 nonsemantic pairs (nonsense words) and 12 semantic pairs (words). The test procedure was the following: The pairs were presented auditorily to the participants, and the participants were asked to judge whether the units of this pair were the same or different. Maximum score for each subtest was 12.
Phonological awareness (rhyme judgment). The participants were shown one photographic picture at the top of a sheet of paper and three at the bottom. The participants were asked to point to the picture at the bottom that rhymed with the picture at the top of the paper. The test leader presented the first eight items audio visually. The last eight items were only presented visually, and the children needed to come up with the picture names themselves. If needed, they were given semantic cues. One of the two lures in this task was phonologically related, and one was semantically related. The maximum score per subtest was 8.
Nonsense rhymes judgment. Twelve pairs of nonsense words were presented orally to the participants. The participants were asked to judge if the words rhymed and give a yes or no reply. The maximum score was 12.
Synthesize. Photographic pictures were shown, and the picture names were presented to the participants. The phonemes of the word were then sounded, and the participants were asked to synthesize these and point to the picture that corresponded to the sounded link of phonemes. The maximum score was 8.
Compound words. Four photographic pictures were shown to the participants. The test procedure was the following: A compound word was orally presented, and the participants were asked to judge what was left when the first part of the compound word was deleted (e.g., "What's left in the word sunflower if I take away sun?). The child answered by pointing to the corresponding picture. The maximum score was 8.
Syllable reduction. A word was orally presented, and the participants were asked to judge what was left when a defined part of the word was deleted (e.g., "What's left in the word crocodile if I take away cro?). The child answered by pointing to one out of four written as well as orally presented nonsense words. The maximum score was 8.
Test of reception of grammar (TROG; Bishop, 1983). Nine blocks of the syntactic items in the Swedish version of TROG were used (Blocks 8, 11, 12, 14, 15, 17, 18, 19, and 20). The four color drawings were shown to the participants, a sentence was read aloud by the test leader, and the participants were asked to point to the corresponding picture. The scores are presented both in blocks and as raw scores. The maximum score of raw was 36; the maximum score of blocks was 9.
Test of receptive vocabulary, PPVT-III (Dunn & Dunn, 1997). A partial testing of the unofficial Swedish translation of PPVT, set 5 to 8, was used. The four black-and-white drawings were shown to the participants, a word was read aloud by the test leader, and the participants were asked to point to the corresponding picture. The maximum score was 48.
Pricken (complex reception of narratives). A short story was presented from a CD. After each three sentences, the participants were asked to fill in a word or answer a question from three multiple-choice answers. The maximum score was 30.
Digit span (probed digit recall). The participants were tested on eight items of 2 to 5 digits each. After a digit sequence, they were asked to remember if a certain digit was in the sequence. The results on the level of 5 digits were registered. The maximum score was 8.
Nonverbal intelligence (Raven 's, 1965, colored matrices): Visual-perceptual reasoning. The complete book version of the test was used. The participants were shown a puzzle and were told that they were supposed to point to the correct missing piece out of six. The maximum score was 36.
The tests were administered to each of the participants individually; most of them were tested in separate rooms in their home schools. A few test rounds were administered in the homes of the participants for time-saving reasons. The testing took an average of 8 hours per child, and to avoid effects of exhaustion or lack of motivation, the tests were completed in several separate sessions. Personal assistants or parents were allowed in the room with clear instructions not to interrupt the test procedure. A single primary test order was set for not creating a confounding variable. However, the test order was frequently individually adjusted, according to concentration and needs for variation during the test situation. Tests could be interrupted and resumed after a pause or after a diverting maneuver consisting of another test. Some thresholds were used, primarily for ethical reasons; if a participant could not perform on the word-reading test, he or she did not have to take the sentence-reading test. If they persisted in claiming or showing they did not understand what to do on a test after adapted instructions, they were not forced to do the test. Each test round had an individual duration. The modes for answering were individually adapted as oral answers, pointing to answers, or indicating the correct answer when the test leader pointed to the reply items. The example items of the tests were used to clarify instructions as well as to find a functioning way to communicate the test responses.
Statistical analyses and graphs were made using SPSS 12.0.1 for Windows and Microsoft Excel. Mean values and medians for the clustered variables are presented as percentage of correct answers, because maximum raw scores differ between tests. In the test results, a zero performance or a discontinued performance is handled as a chance performance. The participants received a chance value for not-completed items. After subdivision of composite reading skill, group effects were analyzed by one-tailed t tests. Analyses of nonparametric correlations were made with Spearman's rank correlation coefficient.
The sample was divided into two subgroups based on a median split of their reading skills (i.e., the composite variable of word and sentence reading). In general, the study showed that the high-level readers subgroup performs high on most tests, whereas the low-level readers subgroup performs low on most tests (see Table 2). The only variable that seemed to break this pattern is the test of working memory (i.e., the digit span test), where the groups performed equally.
The performance of the participants in these subgroups was analyzed by one-tailed t tests. Statistically significant group effects were only found for reading, t(10) = 3,81, p < .05; auditory discrimination, t(10) = 2,61, p < .05; and language, t(10) = 2,00, p < .05, where the low-level readers performed significantly lower than the high-level readers. The groups also differed significantly from each other in speech level, t(10) = 1,89, p < .05.
Schools. No significant differences in school type were found between the subgroups.
Low-level readers. In this sample, the low-level readers attended all school settings except for special language classes.
High-level readers. The high-level readers in this sample came from all types of schools.
Age. Because the age range in the material was substantial (i.e., from 8.0 to 14.6), age differences could be concealing actual differences in skills. However, this is not the case in this study. No significant differences were found, neither at the group level nor through analyzing individual data.
Correlations. Spearman's rank correlation coefficients are presented in Table 3. Significant correlations (p < .05) were found between reading--the main criterion variable--and letters ([r.sub.s] = 0, 76), reading and auditory discrimination ([r.sub.s] = 0, 85), reading and phonological awareness ([r.sub.s] = 0, 64), reading and language ([r.sub.s] = 0, 73), and reading and nonverbal IQ ([r.sub.s] = 0, 60). Significant intercorrelations (p < .05) were also found between speech level and letters ([r.sub.s] = 0, 81), auditory discrimination and letters ([r.sub.s] = 0, 71), auditory discrimination and speech level ([r.sub.s] = 0, 58), auditory discrimination and phonological awareness ([r.sub.s] = 0, 62), language and phonological awareness ([r.sub.s] = 0, 77), phonological awareness and nonverbal IQ ([r.sub.s] = 0, 69), language and nonverbal IQ ([r.sub.s] = 0, 91), and nonverbal IQ and digit span ([r.sub.s] = 0, 64).
Additional analyses. Other theoretically interesting subdivisions of the material could be made, such as subgroups based on articulation gradings and mobility, but this would partially remove the focus from the main interest of the study (namely, literacy) and would not further investigate the contributions to reading skills in the population with speech and motor impairments. However, for the sake of completeness, these additional analyses were conducted, and no systematic findings were revealed by these subgroupings.
Summary of general findings. The general findings suggest that auditory discrimination and language play an important role in literacy within the sample. Significant rank correlations were also found for letters, phonological awareness, and nonverbal IQ. Additionally, statistically significant differences among the subgroups, but no rank correlation, were found for speech level. School type, age, and digit span skills did not differ between low-level readers and high-level readers.
The heterogeneity of the sample was characteristic for the group. The sample included participants who found many of the tests easy and participants who did not understand how to solve some of the tasks at all. Many of the composite variables showed a high variance. Specific findings are therefore presented. The data can be found in Tables 4a and 4b.
Reading (low-level readers). In this group, there were two fundamentally different types of participants: those who read and those who did not read. Two participants in the group (P01 and P09) did not read at all and were more similar to each other than any other participants in the sample.
High-level readers. The concept of "high" is relative. The reading level of the participants in this group were not at the same high functional level as the reading level of good readers in the nondisabled conditions. Most of them did not read very fast, and long sentences were more troublesome to read. Simple sentence reading worked well for some children in the group, whereas others had tendencies to guess when they thought they had enough information from their reading.
Letters. Six of the participants recognized all the letters and their sounds. An additional four scored better than 90% on the letter measure. The failures were mostly on infrequent letters in the alphabet, like w, q, and z, which are very rarely used in the Swedish orthography. Although most participants in the sample knew pretty much the whole alphabet, one low-level reading participant (P01) had fundamental problems with her alphabetic knowledge and received a score below 20% (17.24%).
Speech level (low-level readers). There were two participants with anarthria in the sample, and they both fit into this subgroup. The best speaker in the group had, in addition to her dysarthric speech, a severely impaired phonological speech sound system.
High-level readers. Three of the high-level readers had the highest speech level, and they were also the only three participants who did not have cerebral palsy as their diagnosis. They could be understood by strangers and in unfamiliar contexts. Their speech impairments were systematic and limited. The best reader in the sample, though, was diagnosed with cerebral palsy and had a low speech level. She could be understood by family in most situations but was hardly intelligible to strangers in unfamiliar contexts.
Auditory discrimination (low-level readers). Except for P03, who made an impressive ceiling performance on the auditory discrimination task, considering her severe dyspraxia, the low-level readers all performed below 85% on the auditory discrimination tasks.
High-level readers. All the high-level readers performed above 85% correct on the auditory discrimination tasks, and the three highest ranked readers made ceiling performances on the auditory discrimination tasks. Their systems were well developed relative to the sample.
Phonological awareness, including rhyme (low-level readers). The phonological skills fundamentally differentiate the readers from the nonreaders in this subgroup. The nonreaders had severe problems understanding the tasks included in this composite variable. Focusing on the form of the language and not the meaning and content was very difficult, and the difficulty was increased with the inclusion of phonological and semantic lures. None of the participants in this group appeared to understand the rhyme task. They appeared to be guessing throughout the rhyme task, focusing more on the onset than the rhyme.
High-level readers. The three best readers had phonological skills in correlation with their high-level reading; this includes rhyme as well as other phonological elements. Among the other participants in this group, two of the participants (P02 and P10) had not cracked the code of rhyme.
Language (low-level readers). The two nonreaders in this group had a low level of language performance.
High-level readers. Two participants (P04 and P12) in the high-level group had the highest level of language skills. But these were also two of the best speakers in the sample, which could have had an effect on their reading skills. However, another good speaker (P05), included in the high-level reading group, performed only in the lower to medium range of language performance. The best reader in the sample (P06) had unexpectedly high language skills considering the fact that she had severe dysarthria and no actual functioning communication in unfamiliar situations.
Digit span. The performance on digit span seemed to have no relevance to the ability to read. The skill was equally distributed throughout the whole sample.
Nonverbal intelligence. The participants in this study all performed below their age level on nonverbal intelligence. This will have to be interpreted with caution because no Swedish standardizations are available. It does indicate a low intelligence in the sample, though. The results are presented as raw scores in percentages because no IQ equivalent for the oldest children is available in the norm data. It should be noted that the raw scores should increase over age, which gives older children with the same raw scores a lower percentile.
Low-level readers. The performance on the nonverbal intelligence test was very low in this subgroup. The exception is the oldest participant in the group (P08), who had a higher result, but this should be the case with his age and is no real difference in nonverbal IQ.
High-level readers. Three of the participants in this subgroup had a nonverbal intelligence highest in the sample. The oldest participant in the subgroup (P02) had a very low percentage correct on the test but should have had the highest scores because of her age; thus, she was performing extremely low. Yet another of the participants (P05) in the subgroup had a very low nonverbal intelligence. Nonverbal intelligence did not seem to be explanatory at the group level.
Summary of specific findings. The specific findings highlight the proficiency in the three best reading participants. They had good letter knowledge and phonological awareness, including rhyme and language skills. Their nonverbal intelligence was highest in the sample. The two nonreaders, on the contrary, scored low on phonological awareness and language, and one of them even had a fundamental problem recognizing the letters in the alphabet.
The study covers a continuum of literacy skills within the population with speech and motor impairments that goes from nonreading to functional reading and maybe to even high-level reading. This is in line with many clinical observations. The population is heterogeneous, and literacy skills often surprisingly occurred in individuals we did not believe had a cognitive profile to become future readers. While children we had reason to believe should become readers, given their overall cognitive profile, never cracked the alphabetic code. What is the explanation for this? This study suggests no single explanation for impairments in literacy. But the results that are interesting to address in this discussion are:
1. Differences between subgroups concerning auditory discrimination and language skills.
2. No differences between subgroups concerning digit span.
3. Individual differences.
4. Differences that generate new hypotheses.
Skills That Differ Between Subgroups
The results suggest an integrated literacy model even for basic literacy. Literacy is a complex skill, and to master it, the child with motor and speech impairments needs instructions to improve both complex, high-level, top-down skills, such as general language ability, and more specifically, low-level, bottom-up skills, such as auditory discrimination.
The most important skill related to reading in this sample was auditory discrimination. Auditory discrimination significantly differentiated the low-level readers from the high-level readers; it was also significantly rank correlated to reading skill. The internal speech sound system of several of the participants seemed distorted. Their ability to discriminate between speech entities, both at the phonemic level, shown in the auditory discrimination tasks of phoneme, and at the syllable level, seen in the rhyming tasks, was clearly impaired. This is a fundamental problem for children in relation to reading because their clearly impaired internal speech sound system is the base for the phoneme--grapheme conversion. The phonological knowledge included in the internal speech sound system is also the limit for what phonological entities can manipulate in the phonological awareness tasks (Rvachew & Grawburg, 2006).
The other important factor related to reading in this sample was language skills. Language skills significantly differentiated the low-level readers from the high-level readers, and it was also significantly rank correlated to reading skill. It is essential to stress the importance of well-developed linguistic abilities as a base for literacy. Every individual needs a receptive and expressive language to become good readers (Catts et al., 1999). Children with speech and motor impairment might need augmentative or alternative communication to reach these goals. It is important to see that literacy cannot be an alternative to language (Sturm & Clendon, 2004). Children with speech and motor impairments require strong support for their language skills to develop their general cognitive abilities and important linguistic features used in communication and text. Language is often found to be an important factor in reading comprehension (Bishop & Adams, 1990; Rankin, Harwood, & Mirenda, 1994; Snyder & Downey, 1991). Vocabulary and higher language skills, such as grammatical skills, are essential to be able to reach higher levels of reading, including sentence reading and text reading. For children with speech and motor impairments, there is often room for much improvement in the expressive language area, which would promote their literacy development. Furthermore, this study indicates that high language skills are important even for simple written word identification. It is striking how a low level of vocabulary tended to affect the cohort of words available for matching the phonological entities the reader had identified.
Overall, the study points to the importance of both auditory discrimination skills and general language skills to reach functional levels of literacy.
Skills That Do Not Differ Between Subgroups
The difficulty that children with motor and speech disabilities have in reaching even basic literacy skills has been seen before (Foley & Pollatsek, 1999; Smith, 2001; Sturm et al., 2006). Working memory has been offered as an explanation as to why many of these children do not develop literacy skills beyond a basic level (Dahlgren Sandberg, 1996). In this study, no differences between subgroups could be found concerning working memory measured with digit span. The capability to keep single digit units in mind seems to be unconnected to reading ability. There are several explanations for this result:
1. Working memory differences might not affect degrees of reading ability. Complete disposal of working memory as an important variable for reading ability among people with speech impairments is contrary to several studies (Dahlgren Sandberg, 2001; Smith, 2001). It contradicts clinical findings in which the inability to articulate words seemed to put a higher pressure on working memory in these children. We will therefore not claim this as our main explanation for this result.
2. Digit material might not be relevant for verbal material. Digits have been questioned (Just & Carpenter, 1992) as material specific and not relevant for verbal working memory. Digit span has actually also been found to be unrelated to verbal short- and long-term memory earlier (Larsson et al., 1989). This might very well be the case also in this study, because no correlations between digit span and any verbal skills could be found.
3. Digit span with probed recognition is a too-rough measurement of working memory. Digit span was used to measure working memory in this study. The digit span task required participants to respond with yes or no in recognition of digits that matched the test items. The task minimizes the motor energy required by the participants in this study, but most researchers would actually not define the test as a working memory test, because the demand for serial order is absent. They would classify it as a short-term memory test (Baddeley, 1986; Conway, Cowan, Bunting, Therriaulta, & Minkoff, 2002; Larsson et al., 1989). However, it is a delicate mission to find working memory tasks that measure pure working memory but do not demand verbal responses and that consider time and energy consumption in response modes. This discussion of validity is applicable to our study where memory testing has not been found to be connected to reading, as well as to those studies that have found such a connection.
The most proficient of the high-level readers in this sample had no special high-level skill but did have a high level of most skills tested (see Table 4b). They knew their alphabet, their auditory discrimination skills were good, phonological skills, including rhyming skills, were relatively well developed, their language skills were relatively high, and their nonverbal intelligence was highest in the sample. The nonreaders, on the other hand, scored low on most skills tested: low phonological skills, low language skills, and in one case even a fundamental problem recognizing the letters in the alphabet (see Table 4a). Thus, it seems necessary to have both language skills and phonological skills for efficient reading (Catts, 1993).
But the literature also offers other explanations for this phenomenon. Literacy might simply be the cause of all these skills. Reading develops one's vocabulary and sense of grammar, and alphabet skills in combination with good decoding skills improves one's phonological skills. For example, phonemic awareness has been described as being improved by literacy in itself (Burr et al., 1999; Ehri & Wilce, 1980; Read, Zhang, Nie, & Ding, 1986). This has been observed in literacy development (Stanovich, 2000) as a perpetual motion of being well equipped and therefore becoming even more equipped. Hence, reading helps one to read. But this effect applies to the outliers of this sample; what is more challenging is that our sample also included less-equipped individuals who still had cracked the code of reading. What are the mechanisms behind this?
The medium readers on both sides of the median split still seemed to score well on the skills tested (Tables 4a and 4b). They knew most of the letters, they had medium language skills, and their phonological skills were relatively good except for some individual shortcomings concerning rhyme. They seemed to have sufficient skills to crack the alphabetic code, but something was hindering them from reaching a higher level. One explanation could be that the word readers preferably used sight word strategies. This might have been the case with P08. Observation suggests that his word reading seemed to be based on sight-word reading in combination with identification of initial phoneme and a decent level of phonological awareness. It did not look like he was using a full knowledge of the alphabetic code to support his word reading. There is indeed a need for further research to find the factors connected with achieving word-reading skills above basic levels.
Differences That Generate New Hypotheses
This study has also provided us with results that generate new hypotheses. The sample size puts limitations to the extension of explorations possible. Hence, some results are theoretically interesting and need to be further investigated. The results referred to in this discussion are group differences that did not give significant rank correlations or on the other hand, had significant rank correlations, without corresponding subgroup differences.
Speech. Speech cannot be ignored as a factor for reading success. Speech gives an opportunity for rehearsal and for self-generated auditory feedback (Blischak, 1994). Thus, speech gives accompanying articulatory coding to the phonological processes involved in literacy. This rehearsal is not exclusively dependent on articulation, but the articulatory coding seems to support the subvocal rehearsal process (Foley & Pollatsek, 1999). Dysarthric speech can be of great importance to the reader in the process of acquiring reading skills: even a distorted speech can generate auditory feedback (Heister-Trygg & Sigurd Pilesjo, 1997). Anarthric speech, however, is of less functional assistance for the reader in the reading process, leaving the speaker to rely on other abilities (Foley & Pollatsek, 1999). Dowden (1999) mentioned limited spelling ability as a limitation for an individual to advance to independent communication. It is valuable to mention, however, that even though full functional literacy might not be attainable for people with anarthria, even partial reading and writing skills can be of tremendous importance for their communicative competence. Anarthria is an essential obstacle for reaching sufficient reading skills, but severely dysarthric speech also makes reading a difficult task to perform (Smith, 2001).
In this study, significant differences in speech level were found between the low-level readers and high-level readers. Although severe speech impairment does not have a simple relation to reading impairment in the sample, there were participants who read well but still had severe problems with articulation (e.g., P06).
During the test sessions, some children who read out loud with highly distorted dysarthric speech seemed to be disturbed by their own speech errors (e.g., P03 and P07), while children with equally distorted speech who chose to read the text silently without any visible signs of articulation were much less disturbed (e.g., P06), as were children with milder dysarthria, naturally. This can serve as an explanation of the poor sentence reading of P07. She read the words in the sentences, but she was so slow and used so much articulation energy in reading the words out loud that understanding at the sentence level was lost. Perhaps improved phonological awareness in combination with teaching her silent reading would improve her sentence reading. This is an observation that would be challenging to investigate further. Reading research has often studied children reading words and nonwords aloud and equalized this kind of reading with reading in general (Compton, 2000; Miller-Shaul, 2005; Rack, Snowling, & Olson, 1992). Few studies have explored the mechanisms of silent reading and the differences that might be detectable between silent reading and reading aloud.
Thus, it would be theoretically fruitful to test the hypothesis that using impaired articulation actively when reading will impair reading performance compared to not using impaired speech actively when reading. Of course, silent reading can be an effect of reading development. It would therefore be interesting to explore the relationship between articulation usage and literacy development from an equal baseline.
Letter knowledge. Letter knowledge was highly rank correlated with reading in this study. Knowing the sounds of the letters is a basic skill for readers, and it is not surprising that the participant with low letter knowledge in this sample was not a reader. There were small differences regarding letter knowledge in the rest of the sample. Only the knowledge of the rarely used letters differentiated the high-level readers from most of the others. It appears that many teachers often refrain from teaching these letters to children who are struggling orthographically and phonologically. But it can also be the case that through continuous reading, children learn the uncommon letters.
Phonological awareness. Phonological awareness was rank correlated to reading in this study, as has been seen in many other studies (Blischak, 1994; Dahlgren Sandberg, 1996; Foley & Pollatsek, 1999; Vandervelden & Siegel, 1999). Phonological awareness skills are rewarding to clinically study further since they are highly teachable (Simmons & Kameenui, 1998), and they have been found to be strongly related to reading. It is important to investigate the hypothesis that phonological awareness can be taught to individuals with speech and motor impairments, especially among children with anarthria or severe dysarthria.
Nonverbal IQ. Intelligence is a variable that many schools lean on to judge who will benefit from basic education in literacy and who will not. In this study, no differences between subgroups could be found at the group level concerning nonverbal IQ, but it was rank correlated. Thus, it does look like intelligence might be involved in hindering some participants from reaching higher levels of reading. The picture is more complex, however, because good reading performance could be connected to very low nonverbal intelligence in the sample (e.g., P05). Overall, the study does not support the importance of high nonverbal IQ for literacy development in people with motor and speech disabilities. The nonverbal intelligence in the sample was low. The levels of performance in the entire group of participants never exceeded 55% correct responses, in correspondence to the norm, they never exceeded the 25th percentile. Clinically, this is not surprising since expressive language skills have been limited through development; some of the participants had reduced motor skills to take their own initiatives for sensomotoric learning; the school situation for many of the children has been problematic; and the limits of time decrease the opportunities for learning when motor training, ADL issues, and the like compete with education for time. Even though the children may have had a primary intelligence equal to their peers, as a secondary consequence their intelligence might have been affected over the years (Conti-Ramsden, Botting, Simkin, & Knox, 2001) as an effect of lack of life experiences, language skills, and education to support their general cognitive skills.
A hypothesis worth further investigation is that there might be a threshold that involves nonverbal intelligence to reach higher levels of reading such as text reading and comprehension of complex text. This would also serve as an important clarification the research that discusses reading and intelligence without including participants with IQs below 70.
The study has stressed the importance of auditory discrimination skills and general language skills as a fundamental base for literacy in the sample. Children with motor and speech impairments will need instructions to improve both complex, high-level, top-down skills, such as general language ability, and more specific, low-level, bottom-up skills, such as auditory discrimination, to reach proficient literacy skills.
The study also generates new hypotheses that will need to be investigated further. It supports earlier studies in that reading correlates with letter knowledge and phonological awareness, and further intervention studies are proposed in these areas. The study shows that speech, which these children have limited or no access to, indeed has relevance for reading. A hypothesis about the effect of impaired articulation usage during reading is presented. The nonverbal IQ in the sample was low, but because reading correlated with it, a hypothesis about a threshold for reaching higher levels of reading is suggested.
Authors' Note: This article was supported by the Swedish Agency for Innovation Systems, VINNOVA, which has contributed financially and was patient with this research, as the study changed a great deal from the original application. The authors would like to thank teachers, assistants, and pupils at the attending schools and other personnel at local habilitation centers for their collaboration. Please address correspondence to Janna Ferreira, The Swedish Institute for Disability Research (SIDR), IBL, Linkoping University, 581 83 Linkoping, Sweden; e-mail: firstname.lastname@example.org.
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Linkoping University, Sweden
Lund University, Sweden
Janna Ferreira is a certified speech and language pathologist with a PhD in disability research. She is currently involved in research with a focus on speech and language impairments, phonological awareness, literacy, nonspeaking children, and alternative communication.
Jerker Ronnberg is a full professor of psychology, specializing in disability research, at Linkoping University, Sweden. He is manager and director of research at the Swedish Institute for Disability Research. His research interests include cognitive and communicative disabilities, in particular for persons with hearing impairment, deafness, dyslexia, or intellectual disability or for nonspeaking children.
Stefan Gustafson is a senior lecturer in developmental psychology at Linkoping University. His research is focused on reading disabilities and developmental dyslexia.
Asa Wengelin is a research fellow at the department of linguistics, Lund University, and a senior lecturer of special education at Karlstad University. Her current research interests include psycholinguistic and educational aspects of reading and writing and reading and writing difficulties.
Table 1a The Participants, General Information Motor Participants Age Diagnosis Transportation P01 Hedwig 11.8 CP Wheelchair P02 Jamie 14.6 CP Walking P03 Linn 8.5 CP Walking P04 Nora 10.0 Dyspraxia Walking P05 Norman 9.7 Dyspraxia Walking P06 Sussi 8.4 CP Wheelchair/Wheel walking frame P07 Erina 8.2 CP Walking P08 Bob 14.0 CP Wheelchair P09 Stella 8.0 CP Wheelchair P10 Steven 9.1 CP Wheelchair P11 Umberto 10.0 CP Wheelchair P12 Uno 9.8 MMC Wheelchair Participants School Form P01 Hedwig Segregated room in compulsory school; curriculum for pupils with learning disabilities P02 Jamie Education for pupils with learning disabilities P03 Linn Compulsory school P04 Nora Special class for children with language disabilities P05 Norman Special class for children with language disabilities P06 Sussi Compulsory school P07 Erina Compulsory school P08 Bob Special remedial class, learning disabilities, and behavior P09 Stella Special class for children with motor disabilities P10 Steven Special class for children with motor disabilities P11 Umberto Segregated room in education for pupils with learning disabilities P12 Uno Compulsory school Table 1b The Participants, Speech and Language Information Speech Participants Speech Disorder Intelligibility Level (a) P01 Hedwig Anarthria No 1 P02 Jamie Severe dysarthria Seldom speaks, hardly 2 intelligible, echo-speech P03 Linn Severe dyspraxia Spontaneous speech is 2 rare but medium intelligible, produces little on command P04 Nora Dyspraxia Fully intelligible speech 6 with phonological errors P05 Norman Dyspraxia Fully intelligible speech 5 with phonological errors P06 Sussi Severe dysarthria Weak voice, medium 2 intelligible in context P07 Erina Severe dysarthria Speaks a lot, medium 4 intelligible P08 Bob Anarthria No 1 P09 Stella Severe dysarthria Medium intelligible in 2 context P10 Steven Severe dysarthria Medium intelligible in 2 context P11 Umberto Severe dysarthria Speaks rarely, hardly 2 intelligible in context P12 Uno Mild dysarthria Fully intelligible speech 5 with articulatory errors Participants Yes/No Expressions Communication Modes P01 Hedwig Eye pointing right/left PCS-symbols, eye pointing, gestures, facial expressions P02 Jamie Oral, gestures, signs Signs, symbols (PCS and photos), gestures, facial expressions P03 Linn Oral, gestures Speech, signs, gestures P04 Nora Oral Speech P05 Norman Oral Speech P06 Sussi Oral, gestures Speech, symbols (PCS and gestures, facial expressions P07 Erina Oral Speech, signs, gestures P08 Bob Gestures, facial Eye pointing, gestures, expressions facial expressions, bliss P09 Stella Oral Bliss, gestures, facial expressions, speech P10 Steven Oral Bliss, speech, gestures, facial expressions P11 Umberto Oral, gestures Gestures, speech, facial expressions P12 Uno Oral Speech (a.) Judged by speech language pathologist on a scale from 1 to 7 (1 = anarthric, 7 = normal). Table 2 Means and Standard Deviations for Subgroups on All the Composite Variables Reading Level Low High Variable M SD M SD Reading 47.50 (19.48) 84.38 (13.55) Letters 82.18 (32.01) 99.43 (1.41) Speech level 2.00 (1.10) 3.67 (1.86) Auditory discrimination 81.95 (11.08) 95.14 (5.54) Phonological awareness 55.90 (17.85) 68.87 (20.09) Language 57.37 (14.61) 71.15 (8.47) Digit span 66.67 (12.91) 66.67 (20.41) Nonverbal IQ 39.35 (12.84) 45.83 (13.00) Age 9.86 (2.40) 9.88 (2.14) Table 3 Nonparametric Rank Correlations for People With Speech and Motor Impairments Speech Auditory Variable Reading Letters Level Discrimination Reading 1.00 Letters .76 ** 1.00 Speech level .57 .81 ** 1.00 Auditory discrimination .85 ** .71 ** .58 * 1.00 Phonological awareness .64 * .42 .30 .62 * Language .73 ** .44 .39 .57 Digit span .24 .06 -.04 .12 Nonverbal IQ .60 * .23 .11 .46 Phonological Digit Nonverbal Variable Awareness Language Span IQ Reading Letters Speech level Auditory discrimination Phonological awareness 1.00 Language .77 ** 1.00 Digit span .55 .57 1.00 Nonverbal IQ .69 * .91 ** .64 1.00 * p < .05. ** p < .01. Table 4a Individual Test Results in the Low-Level Reading Subgroup on All the Composite Variables Low-Level Readers P01 P09 P11 Variable Hedwig Stella Umberto Reading 22.50 22.50 56.25 Letters 17.24 93.10 96.55 Speech level 1 2 2 Auditory discrimination 83.34 66.67 83.34 Phonological awareness 36.11 (a) 34.72 (a) 80.56 Language 40.97 37.14 62.55 Digit span 62.50 50.00 62.50 Nonverbal IQ 38.89 25.00 25.00 Age 11.08 8.00 10.00 Low-Level Readers P07 P08 P03 Variable Erina Bob Linn Reading 60.00 61.25 (a) 62.50 Letters 100.00 89.66 96.55 Speech level 4 1 2 Auditory discrimination 83.34 75.00 100.00 Phonological awareness 57.64 67.36 59.03 Language 66.85 72.27 64.45 Digit span 87.50 75.00 62.50 Nonverbal IQ 44.44 58.33 44.44 Age 8.02 14.00 8.05 (a.) Contains chance values because of noncompletion of test. Table 4b Individual Test Results in the High-Level Reading Subgroup on All the Composite Variables High-Level Readers P02 P10 P05 Variable Jamie Steven Norman Reading 68.75 68.75 81.25 Letters 100.00 96.55 100.00 Speech level 2 2 5 Auditory discrimination 91.67 87.50 91.67 Phonological awareness 63.06 67.04 63.01 Language 48.61 56.25 48.61 Digit span 33.33 44.44 27.78 Nonverbal IQ 37.50 87.50 50.00 Age 14.06 9.01 9.07 High-Level Readers P04 P12 P06 Variable Nora Uno Sussi Reading 93.75 93.75 100.00 Letters 100.00 100.00 100.00 Speech level 6 5 2 Auditory discrimination 100.00 100.00 100.00 Phonological awareness 83.89 78.05 71.85 Language 81.25 84.03 94.45 Digit span 58.33 52.78 58.33 Nonverbal IQ 62.50 75.00 87.50 Age 10.00 9.08 8.04
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|Author:||Ferreira, Janna; Ronnberg, Jerker; Gustafson, Stefan; Wengelin, Asa|
|Publication:||Communication Disorders Quarterly|
|Date:||Jun 22, 2007|
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