treatment of irregular word spelling in developmental ... - CiteSeerX

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COGNITIVE NEUROPSYCHOLOGY, 2005, 22 (2), 213–251

TREATMENT OF IRREGULAR WORD SPELLING IN DEVELOPMENTAL SURFACE DYSGRAPHIA Ruth Brunsdon Macquarie University and Children’s Hospital at Westmead, Sydney, Australia

Max Coltheart and Lyndsey Nickels Macquarie University, Sydney, Australia

An increasing number of cognitive neuropsychological treatment studies of acquired dysgraphia have been published in recent years, but to our knowledge there are no corresponding studies of developmental dysgraphia. This paper reports a cognitive neuropsychological treatment programme designed for a child with developmental surface dysgraphia. The treatment aim was to improve functioning of the orthographic output lexicon, and so treatment methods targeted irregular word spelling. Treatment methods were based on previous successful treatments employed in cases of adult acquired surface dysgraphia (Behrmann, 1987; De Partz, Seron, & Van der Linden, 1992; Weekes & Coltheart, 1996). Results showed a significant treatment effect for both spelling and reading of irregular words that was largely stable over time and that generalised partially to spelling of untreated irregular words. Homophone words were not treated but some aspects of homophone reading and spelling also improved, though homophone confusion errors remained. Comparison of treatment effectiveness with and without mnemonics suggested that the mnemonic cue itself was not necessary to achieve treatment success for irregular word spelling. Analyses revealed that untreated irregular words whose spellings became correct as a result of treatment generalisation were those whose original misspellings were closest to being correct prior to treatment. Results also provided preliminary evidence that the mechanism underlying treatment generalisation involved improved access to orthographic representations, resulting in an increased tendency to employ orthography for spelling attempts and reduced reliance on phoneme to grapheme conversion.

INTRODUCTION In the field of cognitive neuropsychology, dysgraphia has received far less research attention than dyslexia. In addition, most research has focused on theoretical aspects of dysgraphia and

has neglected investigation of treatment options (e.g., Bub & Kertesz, 1982; Ellis, 1988; Friedman & Alexander, 1990; Katz & Deser, 1991; Miceli & Silveri, 1985; Patterson, 1988; Rapcsak, 1997; Robinson & Weekes, 1995; Roeltgen & Heilman, 1985; Roeltgen & Tucker, 1988; Romani, Ward,

Correspondence should be addressed to Ruth Brunsdon, Rehabilitation Department, Children’s Hospital at Westmead, Locked Bag 4001, Westmead, NSW 2145, Sydney, Australia (Email: [email protected]). The authors are grateful to Alan Taylor for statistical advice. We are indebted to our client MC and his family for their enthusiastic participation throughout the project. Lyndsey Nickels was supported by an Australian Research Council QEII Fellowship and Max Coltheart by an Australian Research Council Federation Fellowship during the preparation of this paper. The authors also wish to thank Assistant Professor Argye Hillis and two anonymous reviewers for their very helpful comments on a previous version of this paper. © 2005 Psychology Press Ltd http://www.tandf.co.uk/journals/pp/02643294.html

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& Olson, 1999; Temple, 1988, 1990; Weekes, 1994). However, a small but growing number of treatment studies for acquired dysgraphia have been published (e.g., Beeson, 1999; Beeson, Hirsch, & Rewega, 2002; Behrmann & Byng, 1992; Carlomagno & Parlato, 1989; Conway et al., 1998; De Partz et al., 1992; Hatfield, 1983; Hillis & Caramazza, 1986; Luzzatti, Colombo, Frustaci, & Vitolo, 2000; Pound, 1996; Rapp & Kane, 2002; Seron, Deloche, Moulard, & Rousselle, 1980), but we are unaware of any published single case treatment studies of developmental dysgraphia. The current paper reports on the treatment of spelling in a 12-year-old child with developmental surface dysgraphia and developmental surface dyslexia, and is theoretically based on cognitive neuropsychological dual-route models of reading and spelling (Coltheart, 1987; Ellis, 1982; Ellis & Young, 1988; Patterson & Shewell, 1987).

Cognitive neuropsychological dual-route models of reading and spelling Cognitive neuropsychological dual-route models of reading and spelling (see Figure 1) propose two main processing routes for spelling to dictation and reading aloud: the lexical and sublexical processing routes. Spelling For spelling to dictation (i.e., converting a spoken stimulus into its written form), the lexical procedure relies on the retrieval of whole-word orthographic information from the orthographic output lexicon and allows efficient spelling of familiar words (both regular and irregular). Skilled readers first recognise the heard word through activation of its entry in the phonological input lexicon, and then access its associated meaning from the semantic system. Finally, the word’s written form is retrieved from the orthographic output lexicon 1

and is made available for the process of writing via the graphemic output buffer (see Figure 1, route shown by arrows 1, 2, 3, 4). The graphemic output buffer is proposed to store ‘whole-word’ representations temporarily while the physical process of writing (or oral spelling) is completed. In contrast, the sublexical spelling procedure (see Figure 1, route shown by arrows 5, 6, 7, 8) allows spelling of unfamiliar words and nonwords, and regularly spelled familiar words, by applying rule-based phoneme to grapheme conversion. Some authors have also proposed a third ‘lexical nonsemantic’ spelling route that links the phonological input lexicon to the orthographic output lexicon via the phonological output lexicon bypassing the semantic system (see Figure 1, route shown by arrows 1, 9, 10, 4) (Ellis & Young, 1988; Patterson, 1986).1 Post-graphemic processing includes conversion of abstract graphemic representations to visual letter shapes or letter stroke features (often referred to as allographic conversion) (Goodman & Caramazza, 1986a, 1986b; Rapp & Caramazza, 1997), and more peripheral writing includes coordination of motor processes allowing sequences of strokes to be formed into each written letter (Goodman & Caramazza, 1986a, 1986b). Reading Most theories of reading also make the distinction between lexical and sublexical processing routes (Coltheart, 1985, 1987; Coltheart, Curtis, Atkins, & Haller, 1993; Coltheart, Rastle, Perry, Langdon, & Ziegler, 2001; Ellis, 1982; Ellis & Young, 1988; but also see Seidenberg & McClelland, 1989; Plaut, Seidenberg, McClelland, & Patterson, 1996, for discussion of alternative theoretical viewpoints). The lexical reading route relies on visual word recognition through access to an internal store of learned familiar words (see Figure 1, route 13, 14, 12, 11) and the sublexical reading procedure involves rulebased grapheme to phoneme conversion, which

There are also several other possible routes that could be employed for spelling to dictation, including: direct route through lexical phonology and then phoneme-to-grapheme conversion (shown by arrows 1, 9, 11, 7, 8); lexical phonological route via the semantic system and then grapheme-to-phoneme conversion (shown by arrows 1, 2, 12, 11, 7, 8); lexical route via the semantic system and then output orthography (shown by arrows 1, 2, 12, 10, 4).

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Figure 1. Cognitive neuropsychological dual-route model of reading and spelling (adapted from Ellis & Young, 1988).

allows the skilled reader to ‘sound-out’ unfamiliar words and nonwords (see Figure 1, route 16, 17). As with spelling, some authors also argue for a lexical nonsemantic processing route in reading (e.g., Ellis & Young, 1988), which allows for processing of irregular words without access to their meaning (see Figure 1, route shown by arrows 13, 15, 11).

Patterns of impairment in dysgraphia Reported cases of dysgraphia vary enormously in terms of the nature of the impairment and the resultant functional spelling difficulties (for a concise summary of the nature of dysgraphia, see

Rapcsak & Beeson, 2000). In brief, cases of both phonological dysgraphia (specific difficulties with nonword spelling, in the context of relatively unimpaired word spelling; e.g., Campbell & Butterworth, 1985; Iribarren, Jarema, & Lecours, 2001; Marien, Pickut, Engelborghs, Martin, & De Deyn, 2001; Ogden, 1996; Shallice, 1981; Snowling, Stackhouse, & Rack, 1986) and surface dysgraphia (difficulties with irregular word spelling in the context of relatively intact nonword spelling; e.g., Behrmann & Bub, 1992; Hanley, Hastie, & Kay, 1992; Roeltgen & Blaskey, 1992; Temple, 1985, 1986) have been reported. Other cases of dysgraphia have been reported with specific impairments COGNITIVE NEUROPSYCHOLOGY, 2005, 22 (2)

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(single or multiple) involving other components of the spelling system such as the graphemic output buffer (Bonazzi, 1996; Caramazza, Miceli, Villa, & Romani, 1987; Piccirilli, Petrillo, & Poli, 1992; Posteraro, Zinelli, & Mazzucchi, 1988; Rapp & Kane, 2002; Schiller, Greenhall, Shelton, & Caramazza, 2001), post-graphemic processes (Goodman & Caramazza, 1986a; Hanley & Peters, 2001; Zesiger, Martory, & Mayer, 1997), or more peripheral aspects of writing such as selection of motor programmes, motor planning, or handwriting (Cubelli, Guiducci, & Consolmagno, 2000; Destreri, Farina, Alberoni, Pomati, Nichelli, & Mariani, 2000; Ellis, Young, & Flude, 1987; Silveri, Misciagna, Leggio, & Molinari, 1997; Venneri, Cubelli, & Caffarra, 1994).

Remediation of lexical spelling impairment This paper will hereafter focus on the treatment of dysgraphia and specifically treatment programmes designed to treat lexical spelling impairments. Interested readers are also referred to Rapcsak and Beeson (2000) and/or Beeson and Hillis (2001) for a recent overview of published spelling treatment studies, including those with a treatment focus on other aspects of spelling. As there are no known published cognitive neuropsychological treatment studies of developmental dysgraphia, the following review refers solely to studies of the treatment of acquired lexical dysgraphia in adults. Some treatment studies of lexical spelling impairments have focused on direct remediation of impaired functions, while others have focused on the strengthening of compensatory skills. Direct remediation methods have predominantly aimed to strengthen representations in the orthographic output lexicon (or improve access to them) and also facilitate lexical-semantic connections (Aliminosa, McCloskey, Goodman-Schulman, & Sokol, 1993; Beeson, 1999; Beeson et al., 2002; Behrmann, 1987; Carlomagno, Lavarone, & Colombo, 1994; De Partz et al., 1992; Rapp & Kane, 2002; Weekes & Coltheart, 1996). Compensatory techniques are often targeted at sublexical or phonological skills

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in order to support lexical processing, such as improving the use of phoneme to grapheme conversion in order to cue whole-word lexical retrieval (Hillis & Caramazza, 1994; Hillis Trupe, 1986). A more recent study capitalised on residual oral spelling skills and employed a compensatory treatment method involving a letter-by-letter oral to written spelling relay technique (Mortley, Enderby, & Petheram, 2001). The current treatment study has a direct remediation methodology so only those studies reporting direct remediation of lexical impairments will be reviewed, with a focus on three studies particularly relevant to the current study (Behrmann, 1987; De Partz et al., 1992; Weekes & Coltheart, 1996). Other studies that have employed subjects with very severe dysgraphia affecting multiple components of the writing system and/or groups of aphasia patients with different underlying impairments (e.g., Aliminosa et al., 1993; Beeson, 1999; Beeson et al., 2002; Carlomagno et al., 1994) will not be discussed further here. Behrmann (1987) reports a homophone spelling treatment study for CCM, a case of acquired surface dysgraphia without dyslexia. The treatment aim was to help CCM link homophone words with their meanings and to improve homophone spelling. During each weekly training session CCM was required to examine the spelling of both words in each homophone pair and to memorise the difference between them. Each word was presented with a pictorial representation of its meaning. Other training activities included: matching each homophone word to its corresponding picture; writing each homophone word when given a pictorial cue; and writing each homophone word to dictation. Homework practice included a number of forcedchoice activities such as written word to picture matching, written homophone naming in response to picture cues, and sentence completion tasks (e.g., “After Christmas the shops have a big . . . [sale/sail]”). Behrmann conducted four assessments prior to treatment to establish stable pretherapy performance; however, each stimulus homophone word was only given once, so baseline stability was not established for individual

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treated words.2 Treatment resulted in an improvement in overall homophone spelling (from a total of 49% correct responses at pretest to 67% at post-test); however, there was not a reduction in the number of homophone confusions.3 In contrast, there was a significant decrease—from 36% (35/70) to 18% (8/45)—in the number of nonword errors. In sum, it seems that treatment resulted in an improvement in spelling of homophone words but not in assigning each homophone to the correct semantic context. There was no generalisation to untreated homophone pairs (though only 20 untreated homophone words were evaluated) but generalisation to a list of untreated irregular words was apparent. Behrmann (1987) postulates that untreated homophone spelling failed to improve because homophones require word-specific training so, unlike irregular words, do not benefit as a result of general improvements in lexical processing. Finally, a group of 68 untreated homophone words that were written correctly pretreatment were evaluated post-treatment and the total number spelled correct actually decreased from 100% to 85%. Given that each homophone word was only administered once pretreatment, this may simply represent regression to the mean. The statistical phenomenon of regression to the mean refers to the tendency for lower pretest scores to be higher on post-test and higher pretest scores to be lower on the post-test. That is, the tendency for scores at the extremes to revert toward mean levels upon repeated testing (Heiman, 2001; Kazdin, 1982; Shaughnessy & Zechmeister, 1990). Regression to the mean effects are not often evaluated in treatment studies, but in fact should be carefully considered when evaluating treatment outcome, particularly when selection of items is not random and is based on extremes of performance. In

treatment studies target items are most often selected on the basis of incorrect responses at baseline (i.e., the lower extreme of performance), and thus regression to the mean must be considered as a possible factor in any increase in performance on subsequent assessments. It is therefore important for researchers to statistically separate those improvements related directly to treatment from those resulting from regression to the mean. Weekes and Coltheart (1996) employed a similar technique to Behrmann (1987) for treatment of NW’s difficulties with homophone spelling. NW had acquired his surface dysgraphia following a traumatic brain injury. During treatment, words were always presented in their homophone pairs and with a pictorial mnemonic. NW was asked to examine the spelling of each word in the homophone pair, to notice the differences in their spelling, and to associate the mnemonic cue with the appropriate spelling. Treatment results indicated overall improvement in homophone spelling of target words (29% → 74%) but no generalisation to spelling of untreated homophone words, replicating the findings of Behrmann (1987). Weekes and Coltheart do not discuss the nature of spelling errors at baseline or change in error type with treatment. De Partz et al. (1992) targeted high-frequency word spelling in their treatment of LP, a Frenchspeaking patient with acquired surface dysgraphia. For lexical treatment LP was first familiarised with a general visual imagery technique, then an imagery strategy was used to reteach the writing of words. The target set of words consisted predominantly of words spelled incorrectly by LP from a list of high-frequency written words. For each target word a mnemonic was devised that was both semantically related to the word and also linked specifically to misspelt letters. For example, the

2

Berhmann (1987) assessed a total of 138 homophone words (69 pairs) prior to treatment. However, only 34 words were given at pretest one, 35 at pretest two, 34 at pretest 3, and 35 at pretest 4—with 50%, 46%, 59%, and 43% correct responses respectively. Behrmann argues that because performance was stable over the four assessments a stable baseline was established. However, each individual homophone word was only assessed once prior to treatment, so word-specific effects were not measured at baseline. 3 The overall proportion of homophone confusion errors increased from 57% to 82% but absolute number barely changed (i.e., a change from 40/70 errors at pretest to 37/45 at post-test).


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mnemonic devised for a misspelling of pathologie as patologie was a drawing of a hospital bed (i.e., a semantically related cue) and was incorporated into the letter h (i.e., the defective letter) on the training card. In each therapy session LP was required to copy the word with the drawing, reproduce the written word and drawing from memory after a delay of 10 seconds, and finally reproduce the written word and drawing in response to the spoken word. Treatment resulted in a dramatic improvement in trained words (0% → 91%) and also a smaller but significant improvement in untrained words (0% → 30%). De Partz et al. also used the Beauvois and Derouesne (1981) list of irregular, regular, and ambiguous words as a control list that was not treated and there was no generalisation of treatment to this control list.4 It is important to note that these generalisation results cannot be directly compared with those of Behrmann (1987) or Weekes and Coltheart (1996) as the target words were not restricted to homophones but were simply a mixed list of high-frequency written words. De Partz et al. (1992) conducted a second treatment study that contrasted the effectiveness of the mnemonic cue with a purely didactic verbal relearning technique (simple copying of the word with no mnemonic). Results indicated a significant therapy advantage for the imagery technique.

Generalisation of treatment effects to untreated stimuli The finding of treatment generalisation to untreated items in cognitive neuropsychological treatment studies is now well established. Lexical treatment studies of acquired dysgraphia that have employed treatment methods focused on homophone spelling have demonstrated treatment generalisation to spelling of untreated irregular words (Behrmann, 1987), but no treatment generalisation to spelling of untreated homophones (Behrmann, 1987; Weekes & Coltheart, 1996). There is a similar trend in results for surface dyslexia. Coltheart and

4

Byng (1989) and Weekes and Coltheart (1996), whose treatments focused on irregular word reading, found generalisation to the reading of untreated irregular words. Scott and Byng (1989) focused on the treatment of homophone reading, and results indicated mixed generalisation results with improvement of untreated items on one task, a forced-choice sentence discrimination task, but not on the more difficult homophone definition task. In sum, results of lexical treatment studies provide evidence that treatment generalisation can occur for untreated irregular words in both reading and spelling. In contrast, results suggest that untreated homophone words do not consistently benefit from treatment generalisation. The reason for treatment generalisation has not been unequivocally established. Weekes and Coltheart (1996), while discussing generalisation in surface dyslexia treatment, propose two effects from item specific training. They propose that: one must be word-specific (since treated words benefit more than untreated words) and the other must be more general (since untreated words benefit). The specific effect we take to be . . . restoration of the ability to use local word-representations in the visual word recognition system; restoration that occurs only for words that are part of the treatment programme. We speculate that the general effect has to do with the general procedure by which entries in the visual word recognition system are accessed; if this procedure is damaged in these patients, and if treatment improves how well the procedure works, all words, not just treated words will benefit (p. 305). The same could be argued to account for findings of generalisation in treatment of surface dysgraphia. That is, improvements in spelling of untreated irregular words could simply represent treatment effects on the general process by which entries in the orthographic output lexicon are retrieved. So, in addition to individual word restoration, general retrieval from the orthographic output lexicon is

This discrepancy may have related to differences in frequency between the two lists as LP’s spelling was significantly affected by word frequency in pretreatment testing (it is not clearly indicated whether the untrained word list and the control lists were matched).

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improved, so both treated words and untreated words benefit, but treated words more so. With regard to homophones, Behrmann (1987) speculates that they require word-specific training so do not benefit from this more general effect on the orthographic output lexicon. Weekes and Coltheart (1996) have proposed that, in treatment of acquired reading impairments, some untreated irregular words may benefit more than others, depending on their level of pretreatment activation and whether the words were available to the patient premorbidly or not.5 More specifically, they have proposed that generalisation occurs for those words with premorbidly available orthographic representation whose entries (or access to them) have been degraded. In contrast, generalisation will not occur for lower-frequency words that were not premorbidly available to the patient. Therefore, in simple terms, one might theorise that those words with orthographic entries that are relatively inaccessible or degraded may be more susceptible to generalisation than words whose orthographic entries are completely absent. Although treatment generalisation effects have been clearly documented in previous studies, researchers have failed to investigate possible underlying mechanisms in any detail. In contrast, the current treatment study was carefully designed to enable detailed exploration of the reasons why treatment generalisation occurs. That is, the current study investigated which factors or variables predict treatment generalisation through analyses of differences between those untreated words that improved and those that did not. This study evaluated a lexical treatment programme designed for MC, a child with developmental surface dyslexia and dysgraphia, and was theoretically based on cognitive neuropsychological dual-route theories of spelling. The aim of treatment was to improve the functioning of the orthographic output lexicon and targeted irregular word spelling. Treatment design enabled an objective assessment of treatment efficacy, stability of

treatment effects over time, generalisation of treatment to spelling of untreated stimuli (irregular and homophone words), and also generalisation of treatment to reading performance.

CASE HISTORY MC, a 12-year-old boy, was in his first year of high school at the time of treatment. He was referred by his mother for assessment and intervention. There had been concerns about his progress in reading and spelling since early primary school, and as a result MC received extra assistance (both through school and privately organised tuition) in Years 3, 4, and 5 of primary school. Detailed developmental history revealed no prenatal or postnatal risk factors and early developmental milestones were within normal limits (if not a little advanced). There was no history of neurological damage or dysfunction. Intellectual assessment conducted at age 7 years indicated superior intellectual skills. There were also no concerns regarding general cognitive, language, or behavioural development other than MC’s specific difficulties with reading and spelling. The following excerpt from a letter written by MC’s school teacher illustrates this well. I have found [MC] to be a perceptive, intelligent student who possesses excellent oral skills. He organises his thoughts and opinions effectively and expresses himself in a clear and confident manner. He is able to listen to presentations and summarise main points [and] he also possesses an excellent general knowledge of current affairs issues. [He] is, however . . . currently reading at a level below his chronological age. Furthermore, he finds it extremely difficult expressing himself on paper. Despite his best efforts, [MC] cannot spell most common words correctly. Recent intellectual assessment using the WISC-III (Wechsler, 1991) revealed skills in the

5 For their case study of NW, premorbidly available words were irregular words that NW could define when presented in spoken form (and were therefore presumed to have been readable by him prior to his acquired brain injury) and premorbidly unavailable words were low-frequency irregular words that he could not define when presented aurally.


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Table 1. Intellectual assessment resultsa Scaled score Information Similarities Arithmetic Vocabulary Comprehension Digit Span

12 15 5 11 12 7

Scaled Score Picture Completion Coding Picture Arrangement Block Design Object Assembly Symbol Search

12 4 17 16 13 4

Standard score VIQ PIQ FSIQ

106 116 112

a

Wechsler Intelligence Scale for Children–3rd revision (Wechsler, 1991).

above-average range, though MC’s pattern of subtest weaknesses suggested specific difficulties with working memory (see Table 1). On an initial screening of academic skills (Wide Range Achievement Test-Revision 3) (Wilkinson, 1993) MC achieved standard scores of 90 for word reading, 75 for word spelling, and 90 for arithmetic. Of most interest, however, was the striking nature of MC’s errors on the spelling subtest (e.g., circle → circel, reasonable → resanerball, surprise → serpries, explain → exsplaen). Nearly all of his errors were phonologically plausible nonword responses, which immediately suggested the possibility of surface dysgraphia with or without dyslexia (reading errors on this word set were less conclusive). These preliminary test results and review of MC’s prose writing prompted further investigation of reading and spelling skills. Two samples of prose writing taken from MC’s school exercise books are shown in Figures 2 and 3 and illustrate other interesting aspects of MC’s written output including incorrect use and/or absence of punctuation and capitalisation.

Single letter processing MC was able to name (26/26) and sound (24/26) single letters (errors: e → /i:/, u → /jə/). He was also able to write letters when provided with their names (26/26) or their sounds (26/26).

Visual lexical decision Visual lexical decision was assessed using the visual lexical decision task from PALPA (subtest number 27, Kay, Lesser, & Coltheart, 1992). This task contains an equal number of exception words, regular words, pseudohomophones (e.g., wich)

FURTHER ASSESSMENT AND FUNCTIONAL LOCALISATION OF IMPAIRMENT Pretreatment testing included assessment of reading, spelling, and phonological skills and also included a screen of picture naming and semantics. Assessment results (described below) revealed a pattern confirming a diagnosis of developmental surface dyslexia and dysgraphia.

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Figure 2. Sample of MC’s pretreatment prose writing.

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Phonological processing General phonology skills were assessed using phonological segmentation of initial and final sounds (PALPA subtests 16 and 17), word rhyme judgements-auditory version (PALPA subtest 15), the Children’s Test of Nonword Repetition (CNRep; Gathercole & Baddeley, 1996) and Phonological Processing (a phonological segmentation task) from the NEPSY (Korkman, Kirk, & Kemp, 1997). MC’s performance on the PALPA segmentation of sounds tasks was error free. He also performed well on the other phonological processing tasks, with scores of 58/60 on PALPA word rhyme judgements, an age-scaled score of 10 on NEPSY phonological processing, and 36/40 on nonword repetition (CNRep).

Naming and semantics Semantic knowledge and naming were screened using spoken word–picture matching, written word–picture matching, and spoken picture naming (PALPA subtests 47, 48, and 53). MC’s performance on all three tasks was virtually errorfree with scores of 40/40, 40/40, and 39/40 respectively.

Figure 3. Sample of MC’s pretreatment prose writing.

and nonhomophonic nonwords (e.g., plit). Although no normal control data exists for 12year-olds, comparison with data for a small group of normal 9–10-year-olds certainly suggests that MC’s lexical decision skills were below age expectations (see Table 2) and that he made more irregular (exception word) and pseudohomophonic word errors than normal.

Reading and spelling of regular and irregular words MC was first asked to read aloud and write 30 irregular and 30 regular words from the Coltheart and Leahy (1996) word/nonword test (see Appendix A). He was also required to read and spell a list of 308 monosyllabic irregular words (all with a written

Table 2. Visual lexical decision (PALPA, subtest number 27) MC age 12 Test Total (n ⫽ 60) Regular words (n ⫽ 15) Exception words (n ⫽ 15) Pseudohomophones (n ⫽ 15) Nonhomophonic nonwords (n ⫽ 15)

Normal controls age 9 and 10 (n ⫽ 6)

Raw scores

Mean (SD)

Range

43 11 9 10 13

55.5 (3.02) 14.7 (0.82) 13.2 (0.75) 13.7 (0.82) 14.0 (1.26)

53–59 13–15 12–14 13–15 12–15


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frequency greater than 100). The list was obtained by removing all homophones, plurals, and past-tense word variations and words with a written frequency of ⬍ 100 from an original list of 1396 monosyllabic irregular words. This original list consisted of all the monosyllabic words in the CELEX lexical database (Baayen, Piepenbrock, & van Rijn, 1993) that are irregular according to the set of grapheme to phoneme correspondences listed by Rastle and Coltheart (1999). Reading Using the Coltheart and Leahy (1996) stimuli, reading performance on regular words (25/30, z ⫽ ⫺1.67) was better than with irregular words (15/30 correct, z ⫽ ⫺2.41) (see Table 3), though both fell below an expected level based on MC’s level of intellectual functioning. Note that the z-scores were calculated using developmental normative data provided by Edwards and Hogben (1999), and indicate MC’s level of performance relative to other children of his age. Predominant error type for irregular word reading reflected the attempted (mostly but not invariably correct) application of grapheme to phoneme correspondence rules (e.g., bouquet → /bəυkεt/, soul → /səυl/, also see Appendix A). Regular word reading errors, however, were more visual in nature (e.g., peril → “pearl”, also see Appendix A).

Table 3. Total number of correct responses on the Coltheart and Leahy (1996) word and nonword lists (n ⫽ 30) Task Reading Regular words Irregular words Nonwords Spelling Regular words Irregular words Nonwords

6 7

Total correct

z-score

25 15 21

⫺1.67 ⫺2.41 ⫺1.26

20 12 27

For the longer list of 308 irregular words, MC read a total of 210 correctly. A regression analysis including the variables spoken frequency and, written frequency,6 word length (number of letters), and number of orthographic neighbours7 was conducted to determine which had a significant impact on reading accuracy. The analysis revealed that the only stimulus variables which made independent contributions to irregular word reading accuracy were written frequency (Wald ␹2 ⫽ 12.056, p ⫽ .001), and number of orthographic neighbours (Wald ␹2 ⫽ 5.362, p ⫽ .021). Irregular words read correctly (when compared to those read incorrectly) were significantly higher in written frequency and had more orthographic neighbours (see Table 4). The predominant error type involved the attempted application of grapheme to phoneme correspondence rules, though a number of visual errors were also evident.

Spelling Using the Coltheart and Leahy (1996) stimuli, regular word spelling (20/30) was better than irregular word spelling (12/30) (refer to Table 3; z-scores are not provided as developmental normative data was not available). As with reading, most errors were phonologically plausible nonword responses (e.g., choir → quwiyer, colonel → cernal, also see Appendix A). For the longer list of irregular words, MC spelled 120/308 correctly. A regression analysis including the variables spoken frequency, written frequency, word length, and number of orthographic neighbours was again conducted to determine which variables had a significant impact on spelling accuracy. The only stimulus variables that made independent contributions to spelling accuracy were number of orthographic neighbours (Wald ␹2 ⫽ 23.937, p ⫽ .000), written frequency (Wald ␹2 ⫽ 23.536, p ⫽ .000), and spoken frequency (Wald ␹2 ⫽ 7.862, p ⫽ .005) (see Table 4). The predominant error type again

Taken from the CELEX (Centre for lexical information) database (Baayen et al., 1993). Log frequency was used for all analyses. Number of orthographic neighbours determined using the definition of Coltheart, Davelaar, Jonasson, and Besner (1977).

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Table 4. Variables affecting reading and spelling of irregular words at baseline

Reading Incorrect responses Mean SD Correct responses Mean SD Spelling Incorrect responses Mean SD Correct responses Mean SD

Length

Number of orthographic neighboursa,b

Spoken frequencyb

4.95 0.94

4.41 3.86

72.01 298.13

1573.52 7041.40

4.50 0.95

6.72 5.24

1237.43 5287.40

16,540.68 81,696.54

4.88 0.89

4.65 4.32

153.15 377.46

2184.37 6097.94

4.22 0.96

8.37 5.16

2135.46 7145.85

28,812.69 110,888.10

Written frequencya,b

a

Variables that significantly affected reading accuracy. Variables that significantly affected spelling accuracy.

b

involved the attempted application of phoneme to grapheme rules.

Reading and spelling of nonwords Reading

Reading and spelling of homophones MC was required to read and write 96 homophone words (48 homophone pairs) (see Appendix B). Forty-two of the homophone words had an irregular spelling (e.g., queue) and the remainder had regular spellings (e.g., brake).

MC was asked to read aloud and write 30 nonwords from the Coltheart and Leahy (1996) word/nonword test. In reading, 21/30 nonwords were read aloud correctly (z ⫽ ⫺1.26, see Table 3) (Edwards & Hogben, 1999), with 5 errors reflecting visually similar real-word responses (e.g., boril → “boil”, also see Appendix A). Nonword reading was also assessed using the Graded Nonword Reading Test (Snowling, Stothard, & McLean, 1996). On this test MC read 14/20 nonwords correctly, which placed him at the 25th percentile for his age.

For assessment of homophone reading, MC was asked to read the homophone word aloud and then form a sentence using the target word. He read aloud a total of 77/96 homophone words correctly (i.e., pronounced the word correctly), but for 13 of these correct responses he made a homophone confusion error when forming the sentence (e.g., pear → “pairs of them,” tale → “there is a tail on a dog”) (also see Appendix C).

Spelling

Spelling of homophones

In contrast, nonword spelling was almost perfect. When required to write the 30 nonwords from Coltheart and Leahy (1996), MC spelled 27/30 correctly (see Appendix A and Table 3).

For assessment of homophone spelling, MC was required to listen to the target word both in isolation and in context (in a sentence) prior to writing it. Sixty-six per cent (63/96) of homophonic words

Reading of homophones


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were misspelled. Nineteen per cent of errors (12/63) were homophone confusions (i.e., in response to “maid, the maid cleaned the house” MC wrote made). Sixty per cent (38/63) of errors were phonologically plausible nonword errors (i.e., in response to “prays, he prays everyday before going to sleep” MC wrote praes), and 21% of errors (13/63) consisted of other error responses that were not phonologically plausible (i.e., eight → etaght, their → thir) (also see Appendix D).

Summary of pretreatment assessment In summary, MC’s reading and spelling were characteristic of surface dyslexia and dysgraphia. That is, sublexical processing was relatively preserved (although not perfect), as shown by his better performance on regular words and nonwords for both reading and spelling. In contrast, MC displayed significant difficulties with irregular word reading and spelling, homophone reading comprehension, and homophone spelling (with frequent homophone confusion errors), and overall his error pattern was characterised by a large number of phonologically acceptable attempts, or regularisation errors. We acknowledge that MC’s reading impairment did not represent ‘pure’ surface dyslexia. It is not argued that sublexical reading processes (i.e., nonword reading) were entirely normal, only that lexical reading skills were clearly impaired.8

Functional localisation of impairment With respect to models of reading and spelling, MC’s dyslexia and dysgraphia can primarily be explained by specific difficulties with lexical orthographic processing. We can determine the level of impairment more specifically using pretreatment assessment results and the theoretical framework of the dual-route model of reading and spelling shown in Figure 1.9

First, intact processes will be discussed. Relatively good nonword reading suggests a relatively intact (though not perfect) sublexical reading route (visual analysis, grapheme to phoneme conversion, phonological output buffer, linked by arrows 16 and 17). Good nonword spelling to dictation suggests intact sublexical spelling processes (including auditory analysis, acoustic to phonological conversion, grapheme to phoneme conversion, and the graphemic output buffer, linked by arrows 5, 6, 7, and 8). Intact expressive language and comprehension of spoken language suggests intact language processing routes and semantics (including the phonological input and output lexicons, and semantic system, linked by arrows 1, 2, 12, 11, and arrow 9). Reading MC’s lexical reading impairment can therefore be explained by specific difficulties with lexical orthographic processes. MC had difficulty with visual lexical decision (see Table 2), which suggested difficulties with access to and/or entries in the orthographic input lexicon. So when unable to access the entry for an irregular word in input orthography MC was forced to rely on grapheme to phoneme correspondences (shown by arrows 16 and 17, Figure 1), leading to regularisation errors. This was apparent with irregular word reading tasks (especially the longer list of irregular words), on which MC made a large number of phonologically plausible nonword responses. Can we be more specific regarding MC’s theoretical level of impairment in reading and, in particular, can we determine whether MC also had additional deficits affecting connections from orthographic lexicon to semantic system (as shown by arrow 14)? We will argue that MC’s connections between orthography and semantics were not fully developed.

8 The terms intact and impaired (when used in reference to MC’s abilities) refer to MC’s performance relative to normal age expectations. 9 We note that MC’s pattern of impairment can be explained adequately by either the two lexicon or the single lexicon theoretical viewpoints. Data from the current case was unable to definitively adjudicate between the two theoretical viewpoints, and therefore this theoretical debate and relevant analyses are not discussed in the current paper.

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MC was able to read aloud correctly a small number of irregular homophone words, which suggested that he was able to access their entries in the orthographic input lexicon and was not relying on sublexical grapheme to phoneme conversion for pronunciation. However, even with these irregular homophone words he still made homophone confusion errors (e.g., MC was able to read the word queue correctly but provided the wrong semantic context “the actor needed a cue,” see Table 5 for other examples). This suggested that for some words MC was able to access their orthographic entries but that connections from these to semantics were faulty, forcing MC to use the direct route to the phonological output lexicon but preventing word-specific semantic activation (route shown by arrows 13, 15, 11, Figure 1). Homophone confusion errors with irregularly spelled homophones are rarely investigated or reported in developmental cases. One exception, however, is a developmental case (CD) reported by Coltheart, Masterson, Byng, Prior, and Riddoch (1983) who also made a small number of such errors in reading. So, in summary for MC’s reading, it seems that impairments were evident both at the level of representations in the orthographic

input lexicon or access to them, as well as in their connections to semantics. Spelling MC’s spelling to dictation performance can also be explained by difficulties with orthographic processes. However, it is more difficult to determine his exact level of impairment in this area than it is for reading. MC’s homophone spelling, akin to reading, revealed an interesting pattern of responses. For some homophones, MC produced a homophone confusion response, which had an irregular spelling and which he spelled correctly (e.g., when provided with the context “they bred the cattle carefully” he produced the homophone confusion bread, but spelled it correctly despite it being an irregular word; see Table 5 for more examples). This suggested that he was able to successfully access the response word’s representation in the orthographic output lexicon and write the word, but was unable to access the stimulus word’s orthographic output representation correctly from semantics. So, referring to Figure 1, we assume, based on his intact auditory comprehension skills, that when asked to

Table 5. Reading and spelling of irregular homophones (examples from baseline 1 and 2) (a) Reading Target

Read correctly

Homophone confusion: Definition provided by MC

Queue Pear Whole Their Steak

Yes Yes Yes Yes Yes

“the actor needed a cue” “socks . . . pairs of them” “there is a hole in the ground” “there is a ball” “I stuck a stake into the ground”

Target

Context provided

Homophone confusion: MC’s written response

Bred Bare Pair Lock Quay Their

‘They bred the cattle carefully . . . ’ ‘The desert landscape was bare’ ‘He wore a pair of black shoes’ ‘The gate had a lock’ ‘The boat sailed into the quay’ ‘They were washing their clothes’

bread bear pear loch key there

(b) Spelling


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spell a homophone (e.g., “bred”) after hearing the semantic context in a sentence (e.g., “they bred the cattle carefully”), MC was able to access the semantic system normally (route shown by arrows 1 and 2).10 We also know he was able to retrieve the correct spelling of the homophone confusion response from the orthographic output lexicon because he correctly wrote bread, which has an irregular spelling.11 The homophone confusion must therefore arise from MC’s inability to access output orthography directly from semantics. He is instead forced to access the orthographic representation of the word via the phonological output lexicon (shown by arrows 12 and 10), which gives rise to the homophone confusion. This suggests impairment in connections between the semantic system and orthographic output lexicon (shown by arrow 3 in Figure 1). MC’s irregular word spelling performance (i.e., his spelling of irregular words that are not homophones) suggests additional deficits. MC made a large number of phonologically plausible nonword errors when spelling irregular words to dictation. His phonologically plausible nonword spelling errors most probably resulted from him relying on the processing route through the phonological lexicons and semantic system and then sublexical phoneme to grapheme correspondences (shown by arrows 1, 2, 12, 11, 7, 8). He would be forced to employ this compensatory strategy if entries within the output lexicon were poorly formed and/or if unable to access the orthographic output lexicon from semantics (arrow 3) and the phonological output lexicon (arrow 10). In summary, using evidence from both irregular and homophone words, it is proposed that MC’s spelling impairments resulted from deficits in semantic to orthography

connections (shown by arrow 3) and deficits either at the level of entries in the orthographic output lexicon or access to those entries from the phonological output lexicon (shown by arrow 10). It is important to note that we do not propose that affected components of the reading and spelling system are abolished. For MC, a developmental case, we would propose that entries in the orthographic lexicons and/or access to them were poorly formed, immature, or unreliable. It is important to note, however, that MC could read and spell some irregular words correctly. He could also read and spell some homophones correctly and access their correct semantic representation. So, he did have some complete entries in his orthographic lexicons and he could access them and retrieve correct semantic information consistently for some words; however, he certainly had not reached a normal level of efficiency in functioning for his age.

TREATMENT OF THE SPELLING IMPAIRMENT General treatment aims Treatment was focused on spelling, as this was perceived by MC and his family to be the major functional difficulty. His family were very aware of MC’s poor irregular word spelling as it was evident in his written work, even with very highfrequency words. Assessment results suggested that MC’s spelling difficulties resulted from impairments in access to output orthography and most probably additional deficits in actual word representations in the orthographic output

10 Although semantic knowledge was not assessed for target words at an individual word level, the authors feel confident that words were semantically represented and that access to these from spoken language was intact, especially given the target words’ high written and spoken frequency. MC had normal language and semantics (as tested using PALPA 47, 48, and 53 and standard VIQ assessment). He had no history of developmental language or semantic difficulties and no reported current difficulties in these areas. In fact, he was described by his school teacher as highly articulate and intelligent, with good listening skills, good spoken expression and good general knowledge (as quoted on p. 219). 11 It is interesting to note that MC’s homophone confusion responses that were correctly spelled irregular words did not simply reflect a tendency for him to produce the higher-frequency homophone of the homophone pair. Some of these responses were the lower-frequency member of the homophone pair.

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lexicon. Therefore, treatment focused on irregular word spelling and aimed to add new ‘whole irregular word’ entries in his output lexicon. Because MC’s semantic representations of target irregular words were presumed intact, it was also hoped that treatment would facilitate his ability to access output orthography directly from semantics. It was anticipated that a focus on irregular word spelling would result in the best functional outcome for MC (when compared to a focus on homophone spelling). The treatment study was also carefully designed to enable detailed post hoc investigation of the mechanisms underlying treatment generalisation to untreated stimuli, which to our knowledge has not been investigated in such detail previously. In addition, treatment design enabled evaluation of the efficacy of employing mnemonics in lexical treatment studies. In summary, the treatment study aimed to: 1. Improve MC’s irregular word spelling. 2. Determine factors underlying treatment generalisation to untreated items. 3. Determine the contribution of the specific mnemonic cue to the effectiveness of treatment.

Target stimuli Two baseline assessments of reading and spelling were conducted using 308 irregular words (the same list that was used for assessment of irregular word reading and spelling above). The 222 target stimuli were then selected. They included all those words for which MC’s spelling response was incorrect on at least one of two baselines. The 222 target irregular words were then divided into three sets of 74 words (Sets 1, 2 and 3). The sets were matched as closely as possible on written frequency (Kruskal Wallis ␹2 ⫽ 0.69, p ⫽ .71), spoken frequency (␹2 ⫽ 2.05, p ⫽ .36), length (␹2 ⫽ 3.93, p ⫽ .14), and number of orthographic neighbours. Although the word sets did differ significantly in terms of number of orthographic

neighbours12 (␹2 ⫽ 7.71, p ⫽ .021), all further analyses comparing word sets 1, 2, and 3 controlled for this difference. The words sets were also matched according to the total number of words read and spelled incorrectly on both baselines and the total number that were incorrect on just one baseline (also matched for the number incorrect on only the first baseline and only the second baseline). Word set 4 consisted of 86 words that were spelled consistently correctly over two baselines.

Baseline assessments MC’s performance on the 222 target irregular words did not vary across pretest assessments for spelling (overall, McNemar ␹2 ⫽ 1.82, p ⫽ .178; Set 1, p ⫽ .481; Set 2, p ⫽ .648; Set 3, p ⫽ .481) (see B1 vs. B2 in Figure 5) or reading (overall, McNemar ␹2 ⫽ 2.327, p ⫽ .127; Set 1, p ⫽ .804; Set 2, p ⫽ .481; Set 3, p ⫽ .238) (see B1 vs. B2 in Figure 7). There was no change in total correct for Set 4 spelling (see B1 vs. B2 in Figure 6). Two baseline assessments were also conducted for reading and spelling of the 48 homophone pairs (as described in assessment section above). Spelling performance was recorded in terms of total errors, total homophone confusion errors (total HCE), total phonologically plausible nonword errors (total PPNE), and total other errors (total OE). Other errors were those spelling attempts that were nonwords but not phonologically plausible (see Appendix D for error examples). Homophone spelling was consistent across baselines for total errors (McNemar, p ⫽ 1.0), total PPNE (p ⫽ .359), total OE (p ⫽ .388) but not for total HC errors (p ⫽ .039) (see B1 vs. B2 in Figure 8). MC made significantly more HCE errors on the second baseline. Homophone reading performance (see Figure 9) was recorded in terms of total errors in reading aloud and total homophone confusion errors (total HCE). MC’s homophone reading performance

12

Word set 2 (mean 5.74, SD 4.23), had a higher mean number of orthographic neighbours than Sets 1 (mean 4.05, SD 4.23) and 3 (mean 4.9, SD 4.3). COGNITIVE NEUROPSYCHOLOGY, 2005, 22 (2)

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was consistent across baseline assessments (total correct, McNemar, p ⫽ 1.0; total HCE, p ⫽ .424).

1 were Set 1 words, for training session 2 were Set 2 words, and for training session 3 were Set 3 words.

Treatment design Overall treatment design is shown in Table 6. Treatment was conducted over a period of 1 month and focused on each irregular word set in turn. There were three training sessions, one for each word set (see italics, Table 6). There were seven assessments—two baseline assessments, three post-treatment assessments (post-treatment phase 1, 2, and 3), and two follow-up assessments (2 months and 4 months post-treatment). Each included assessment of both reading and spelling of all homophone and irregular words (with the exception of the post-treatment phase 1 and the second follow-up assessment, when only spelling was assessed). Assessments were conducted over two testing sessions to avoid repetition of stimuli (that is, assessment of reading and spelling of the irregular word set was conducted on separate days, as was assessment of reading and spelling of the homophone word set).

Treatment method As mentioned above, there were three treatment phases with each phase targeting a different set of irregular words. Target words for training session

Stimuli All stimuli consisted of flash cards containing the target word written in lower case (size 48 arial font). Set 2 words were also assigned a mnemonic cue (a semantically related picture cue; see Figure 4). Mnemonic cues were devised by the first author and drawn beside the target word on each flash card. Only Set 2 words were assigned a mnemonic and, aside from this, treatment method and training sessions were identical for all word sets.

Training sessions Training sessions were conducted by the first author. Only one training session was conducted for each word set. In the training sessions each target word was trained in turn and was trained only once. For each target word MC was shown a flash card displaying the correct spelling. He was first asked to copy the word (the word was also read aloud by the first author). The word was then removed from view and MC was asked to write the word again after a 10-second delay. If his

Table 6. Treatment design Testing session 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

228

Date 1/3/01 10/4/01 13/4/01 18/4/01 30/4/01 10/5/01 14/5/01 26/5/01 27/5/01 27/5/01 12/6/01 13/6/01 20/8/01 21/8/01 23/10/01

Testing Baseline 1 Baseline 1 cont Baseline 2 Baseline 2 cont Word Set 1 training Session Post-treatment 1 testing Word Set 2 training session Post-treatment 2 testing Post-treatment 2 testing cont Word Set 3 training session Post-treatment 3 testing Post-treatment 3 testing cont Follow-up 1 (2 mths post-treatment) Follow-up 1 cont Follow-up 2 (4 mths post-treatment)


Tasks Irregular word spelling and homophone reading Irregular word reading and homophone spelling Irregular word spelling and homophone reading Irregular word reading and homophone spelling Irregular word spelling Irregular word spelling and homophone spelling Irregular word spelling Irregular word spelling and homophone reading Irregular word reading and homophone spelling Irregular word spelling Irregular word spelling and homophone reading Irregular word reading and homophone spelling Irregular word spelling and homophone reading Irregular word reading and homophone spelling Irregular word spelling and homophone spelling

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in a different order) MC’s parents were instructed to: 1. Read aloud the word and ask MC to write the word down. 2. Tell MC whether his response was correct or incorrect. 3. If incorrect, show MC the corresponding flash card with the correct spelling. Show him for 5 seconds and then ask him to rewrite the word from memory. Provide no further help if his second attempt was also incorrect. 4. Move on to the next word.

RESULTS All comparisons between baseline and posttreatment results employ the highest baseline result for establishing improvements in total correct or increase in error responses and the lowest baseline for establishing a reduction in errors.13

Irregular word spelling Figure 4. Examples of mnemonic cues employed for irregular words.

response was incorrect he was shown the flash card again for a few seconds. Finally, he was required to write the word to dictation. Again, he was shown the flash card containing the correct spelling if his response was still incorrect. Home practice In between training sessions MC was required to conduct home practice. Detailed instructions were provided for his parents, who supervised all home practice sessions. Home practice was discontinued when MC spelled at least 90% of the words correctly for 2 consecutive days. Duration of treatment was 8 days for Set 1, 6 days for Set 2, and 7 days for Set 3. For each word (once a day

General treatment results Results for irregular word spelling are shown in Figure 5. There was a significant increase in the total number of irregular words spelled correctly from pretreatment baseline (33/222 at B1) to post-treatment phase 3 (149/222) (overall, McNemar ␹2 ⫽ 148.30, p ⫽ .000; Set 1, p ⫽ .000; Set 2, p ⫽ .000; Set 3, p ⫽ .000). As expected all individual word sets improved dramatically after they were specifically targeted for spelling treatment. That is, Set 1 words improved after treatment phase 1 when compared to baseline (McNemar ␹2 ⫽ 57.02, p ⫽ .000), Set 2 improved after treatment phase 2 when compared to posttreatment phase 1 (McNemar ␹2 ⫽ 40.20, p ⫽ .000), and Set 3 words improved after treatment phase 3 when compared to post-treatment phase 2 (McNemar ␹2 ⫽ 39.02, p ⫽ .000).

13 For example, for irregular word spelling (see Figure 5) baseline one is employed for all comparisons and for homophone reading (see Figure 9) baseline two is used for total error comparisons and baseline one is used for total homophone confusion error comparisons.


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Figure 5. Percentage correct for irregular word spelling at baseline, during treatment and at post-tests.

At 2 months post-treatment (follow-up 1) a total of 134/222 words were spelled correctly indicating a significant decline from post-treatment phase 3 (overall, McNemar ␹2 ⫽ 41.07, p ⫽ .000; Set 1, p ⫽ .004; Set 2, p ⫽ .004; Set 3, p ⫽ .000), though this still represented a significant improvement when compared to pretreatment baseline performance (overall, McNemar ␹2 ⫽ 93.458, p ⫽ .000; Set 1, p ⫽ .000; Set 2, p ⫽ .000; Set 3, p ⫽ .000). There was no difference between the three word sets in degree of decline from

post-treatment to assessment at follow-up 1 (Generalised Estimating Equation [GEE] analysis, ␹2 ⫽ 3.15, p ⫽ .21).14 No further decline was evident at 4 months post-treatment (follow-up 2) (overall, McNemar ␹2 ⫽ .078, p ⫽ .78; Set 1, p ⫽ 1.0; Set 2, p ⫽ .424; Set 3, p ⫽ 1.0). Post hoc analyses were conducted to investigate possible reasons for the decline in performance between post-treatment phase 3 and the first follow-up assessment. A logistic regression analysis was conducted to determine which variables were significant in differentiating between words that changed from correct to incorrect and words that remained correct. Target words for the analysis were responses for word sets 1–3 at the posttreatment 3 assessment. Variables investigated included word frequency, spoken frequency, length (number of letters), and number of orthographic neighbours. The only variable that made a significant independent contribution was number of letters, with longer words more likely to drop off with time (Wald ␹2 ⫽ 7.162, p ⫽ .007), though number of orthographic neighbours did also approach significance (Wald ␹2 ⫽ 3.03, p ⫽ .082) (those words with fewer orthographic neighbours were more likely to drop off with time). Total number of words spelled correctly in Set 4 (i.e., words that were consistently correct pretreatment) was significantly lower post-treatment, as measured at post-treatment phase 3 and followup 1 assessments, when compared to baseline two (PT3: McNemar, p ⫽ .000; follow-up 1: p ⫽ .031) (see Figure 6). Accuracy declined from 100% at baseline to 86% at post-treatment phase 3 and 93% at follow-up. However, this degree of change (i.e., 14% and 7% respectively) was no greater than a regression to the mean effect as measured over baseline (i.e., a regression to the mean effect of 28%)15 and thus will not be discussed further.

14 GEE is an approach to the analysis of correlated response data, which is particularly useful when the responses are binary. It takes account of the correlations between observations and uses them when calculating both parameter estimates and their standard errors. Interested readers can refer to Hanley, Negassa, Edwardes, and Forrester (2003) for more information. 15 This regression to the mean effect was calculated by determining the percentage of correct responses at baseline 1 (from all word sets) that were incorrect at baseline 2.

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Figure 6. Percentage correct for irregular word Set 4 (irregular words that were spelled correctly on both baselines and were never treated) at baseline and post-treatment.

Generalisation to untreated words Significant generalisation (of treatment effects) to untreated irregular words was also apparent. After treatment phase 1 (which targeted Set 1 words only) the number of words spelled correctly for the untreated Set 2 improved significantly when compared to baseline 1 (McNemar, p ⫽ .023). Although Set 3 words had not significantly improved following treatment phase 1 (p ⫽ .383), generalisation was evident after treatment phase 2 (i.e., improvement occurred before Set 3 words were trained) (p ⫽ .000). It was important to demonstrate that this effect was not a result of regression to the mean but a true treatment generalisation effect. We examined the extent of variability across baseline testing in order to predict the size of the likely effects of regression to the mean: Of all those words incorrect at the first baseline, 11.7% were correct at the second baseline (i.e., a regression to the mean effect of 11.7% prior

to the commencement of treatment). In contrast, after treatment phase 1, untreated words from sets 2 and 3 that were spelled incorrectly on the second baseline improved, with 21.1% becoming correct. This represented a significantly larger proportion of words than the 11.7% regression to the mean effect (␹2 ⫽ 4.58, p ⫽ .032). Therefore, we argue that at least part of the improvement in untreated words was a true treatment generalisation effect. Similarly, for Set 3, 27.6% of words that were wrong after treatment phase 1 became correct after treatment phase 2 (again significantly more than the 11.7 regression to the mean effect, ␹2 ⫽ 7.487, p ⫽ .006), even though they had not yet received any treatment. Again, this indicates that improvements in spelling of untreated words cannot be explained entirely by regression to the mean but in fact reflects (at least in part) a treatment generalisation effect.16 Post hoc analyses were conducted to investigate possible predictors of generalisation. The analyses conducted compared characteristics of those untreated words that improved prior to their treatment (i.e., those affected by treatment generalisation) and those that didn’t improve. Target words for the analysis included error responses for word sets 2 and 3, taken from the second baseline assessment. A logistic regression analysis was used to determine which variables significantly differentiated between untreated words that improved with generalisation and those that didn’t. The dependent variable ‘generalisation’ was a binary outcome variable. Predictor variables included were written word frequency, spoken word frequency, length (number of letters), number of orthographic neighbours, and a binary variable ‘error vs. stimulus length,’ which represented whether the error response was the same length as the stimulus. It was also considered that generalisation could possibly depend on how close the error response was to being correct prior to treatment. It was hypothesised that those words whose error responses were closer or more similar to the correct response prior to treatment may respond

16 Given that the improvements in spelling of untreated irregular words was significantly greater than regression to the mean effects, we can conclude that the larger improvement evident in spelling of treated irregular words following treatment was also significantly greater than any regression to the mean effect.


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to treatment generalisation more readily. To investigate this possibility, five variables representing a series of ‘match’ values were also included in the analyses. These match variables essentially represent a measure of how similar an error response is to the correct stimulus (i.e., how closely the error matches the correct spelling) in five different ways according to different coding schemes. The five different coding schemes and their match values will be referred to as match 1, match 2, match 3, match 4, and match 5, where the match value is based on the measure of overlap between the stimulus and error response divided by the number of letters in the stimulus (resulting in a match value between 0 and 1). An in-depth review of coding schemes is beyond the scope of this paper; however, a brief description of each match variable employed in the current study will follow (for match values 1–4 also refer to Table 7).17

vowel slot with the remaining consonants assigned from left to right. For match 3, surrounding consonants are assigned positions from right to left surrounding the vowel. Match 4. For match 4, the position of each letter is coded relative to the first and last letters and the middle letters are then compared for similarity (so, in a way, the first half of the word is coded according to absolute letter position, while the second half is coded relative to the final letter). Match 5. This is a form of spatial coding devised by Davis (1999), in which the comparison between stimulus and error response is based on the spatial pattern of activity across the stimuli within the SOLAR computational model of reading rather than direct comparison of letters according to letter position. Briefly, in this scheme words are not anchored according to letter position; letter order is coded by relative activation of letters and resultant spatial patterns of activation are position-invariant. This enables recognition of similarity between a stimulus and response when letters are transposed (or when the correct letters are employed but in the wrong order (e.g., “weight”–wiehgt). For the current analyses, the default parameters employed for match 5 placed slightly more weight on exterior letters. For the above examples of target and error response (i.e., “strap”–spat) this coding scheme results in a match value of 0.41. For a comparison of match values 1–5 for a sample of MC’s actual spelling error responses, refer to Table 8.

Match 1. The variable match 1 is based on a simple comparison of letters according to absolute letter position, in which the stimulus and error response are aligned according to the leftmost letter. Match 2 and 3. Match 2 and 3 are ‘vowelcentred’ schemes in which the stimulus and error response are aligned using the first vowel as an anchor. Match 2 and 3 use slightly different methods for aligning the surrounding consonants. For match 2, surrounding consonants are assigned positions from left to right. Consonants preceding the vowel are assigned to slots until a vowel is reached; this is then assigned to a designated

Table 7. Match variable 1–4 for stimulus “STRAP” and error response SPAT Matching scheme

S

T

R

A

P (Stimulus)

Overlaps *

Match value

1 2 3 4

S* S*

P P S P

A

T A* A* A*

T T T

1/5 2/5 1/5 2/5

.2 .4 .2 .4

S*

P

17

For a discussion of the various orthographic coding schemes, see Davis (1999, pp. 77–81). We thank Colin Davis for making available to us his program for calculating these various kinds of match values.

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Table 8. Match values for a selection of MC’s spelling errors Error Stimulus response Yield Phase Clerk Pearl Ward Heart Built Path

Yiald Faes Clarc Perl Word Hart Biult Parth

1

2

3

.80 .20 .60 .40 .75 .20 .60 .50

.80 .40 .40 .60 .25 .20 .60 .50

.80 .40 .40 .60 .50 .40 .60 1.0

4

5

.80 .00 .60 .80 .75 .60 .60 1.0

.84 .44 .58 .76 .80 .77 .89 .90

Analyses investigating the nature of generalisation First, point-biserial correlation analyses were conducted to investigate the intercorrelation between the match variables, the ‘error vs. stimulus length’ variable, the word characteristic variables (spoken frequency, written frequency, number of orthographic neighbours, word length), and also the binary outcome variable ‘generalisation.’ All of the match variables were highly correlated with each other (correlations ranged from .508 to .832). Match variables 3, 4, and 5 were significantly correlated with number of orthographic neighbours and match 4 was also significantly correlated with word length. None of the match variables were significantly correlated with word frequency. The variable ‘error vs. stimulus’ length was significantly correlated with match 1, written frequency, and word length. All of the word characteristic variables were highly correlated with each other. The variable of interest, ‘generalisation,’ was significantly correlated with the match variables 1, 3, 4, and 5 (correlations ranged from .189 to .242) as well as spoken frequency, written frequency, and number of orthographic neighbours. Then, a logistic regression analysis including word frequency, spoken frequency, length and number of orthographic neighbours, ‘error vs. stimulus’ length, and the match variables was conducted. Results indicated that no stimulus variable made a significant contribution that was independent of the other variables. This was not a surprising result given the high degree of correlation between predictor variables.

Because of the significant correlation between the match variables, additional regression analyses were conducted for each match variable in turn (with word characteristics and ‘error vs. stimulus’ length also included in the analysis) to examine the difference in their predictive powers when included alone. In this analysis, match 1, 3, 4, and 5 were all significant predictors of generalisation (match 1, p ⫽ .038; match 3, p ⫽ .048; match 4, p ⫽ .016; match 5, p ⫽ .022). Finally, regression analyses were conducted for pairs of match variables to determine whether any individual match variable could predict generalisation independent of the other (word characteristic variables were also included as predictor variables). Match 4 was a significant predictor of generalisation independent of match 2 (p ⫽ .043), with a trend for prediction independent of match 1 (p ⫽ .089). Match 5 also approached significance for prediction of generalisation independent of match 2 (p ⫽ .055). No other comparisons between pairs of match variables were significant. Finally, a backwards logistic regression was conducted to determine the best model of prediction for generalisation. All of the match variables and word characteristic variables were included as predictors. The best model for predicting generalisation consisted of match 4 (Wald ␹2 ⫽ 7.235, p ⫽ .007), and written frequency (Wald ␹2 ⫽ 4.678, p ⫽ .031). As the degree of match between the error responses and stimuli increased (where the position of each letter was coded relative to the first and last letters) and written frequency increased, the likelihood of improvement with generalisation also increased. In summary, results suggest that match variables 1, 3, 4, and 5 are all strong predictors of generalisation. However, match 4 is consistently the strongest or best predictor of generalisation, and the best model for prediction includes both match 4 and written frequency. Mean match values (at baseline 2) for those words that improved prior to treatment and those that didn’t are shown in Table 9. Analyses of how errors changed during treatment Analyses were also conducted to investigate the nature of changes in error characteristics for COGNITIVE NEUROPSYCHOLOGY, 2005, 22 (2)

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Table 9. Match values for irregular words (spelling) that improve prior to treatment and those that do not Match 1 Words that improve Mean 0.62 SD 0.19 Words that do not improve Mean 0.53 SD 0.21

2

3

4

5

0.67 0.19

0.75 0.18

0.69 0.22

0.77 0.15

0.59 0.23

0.64 0.25

0.56 0.26

0.68 0.19

untreated words during treatment. This interest arose from an observation that error responses for some words appeared to gradually change and improve in orthographic accuracy as a result of treatment generalisation but prior to becoming totally correct. For example, the stimulus word “tough” (from treatment set 3) was an untreated word that benefited from treatment generalisation. However, there appeared to be a gradual increase in the use of orthography from baseline 2 (taf ), to post-treatment phase 1 (taugh), prior to the correct response at post-treatment phase 2 (tough) (also see Appendix E). This raised the possibility that treatment generalisation might actually result in a gradual improvement in spelling of untreated words, rather than a sudden all-or-none change from incorrect to totally correct. This possibility was formally investigated in more detail and is discussed below. The analyses focused only on words from Set 3, those words treated last. Limiting the focus to Set 3 words enabled an examination of error characteristics at four points prior to their treatment (i.e., at baseline 1, at baseline 2, after treatment phase 1 and after treatment phase 2: B1, B2, PT1, PT2). This provided an opportunity to analyse how the misspellings of words changed during treatment rather than simply focusing on the identification of which words benefited most from treatment generalisation. The analyses were conducted in two stages (described below). Comparison of error characteristics at baseline 2 and post treatment phase 1. The data used for the first

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set of analyses included all error responses (from Set 3) made at baseline 2 and post-treatment phase 1, for those words that were correct prior to treatment (i.e., were correct after treatment phase 2). We were interested in determining whether their misspellings were closer to being correct after treatment phase 1 when compared to baseline. Results indicated that there was a significant increase in match 2 (Mann Whitney, p ⫽ .016), match 3 (p ⫽ .009), and match 5 (p ⫽ .015) values between baseline 2 and post-treatment phase 1. This suggests that the nature of the error responses was changing and that misspellings of words were improving with treatment generalisation prior to becoming totally correct. Interestingly, it was the two vowel-centred match schemes (match 2 and 3) that improved significantly, possibly suggesting a gradual improvement in interior vowel patterns during treatment. The analyses below further examine the role of match schemes 2 and 3 in error change. Examination of error characteristics at four testing points during treatment. The second analyses examined a smaller subset of words in more detail to allow specific examination of gradual changes in error responses for untreated words during treatment, with a focus on match schemes 2 and 3. The stimuli for these analyses were those Set 3 words that were consistently incorrect at baseline 1, baseline 2, and post-treatment phase 1 (B1, B2, PT1). These target stimuli were divided into two groups for the analyses: words that benefited from generalisation (i.e., incorrect at B1, B2, and PT1 but correct at PT2, N ⫽ 10; see Appendix E) and words that failed to benefit from generalisation (incorrect at B1, B2, PT1, and PT2, N ⫽ 37). Mean match values for coding schemes 2 and 3 were calculated for both groups for words at each testing point. Analyses revealed a very strong trend for an increase in match 2 (Wilcoxon, p ⫽ .066) and 3 (p ⫽ .066) values between baseline 2 and posttreatment phase 1 for words that benefited from treatment generalisation (i.e., were correct at post treatment phase 2). In contrast, there was no significant increase in match 2 (p ⫽ .688) or match

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3 (p ⫽ .478) values from B2 and PT1 for errors that failed to benefit from treatment generalisation (i.e., remained incorrect at PT2). This supports the observation that errors gradually increase in degree of correctness (e.g., “tough” → taf → taugh example described above) as a result of treatment generalisation and that this improvement predominantly involves interior letters.18 Finally, analyses were conducted to determine whether the misspellings of words that do not benefit from generalisation (those misspelled at posttreatment phase 2) ever increase in accuracy. The match values for this group of words did actually eventually improve between post-treatment phase 1 and 2 (but still prior to being targeted for treatment) (match 2, p ⫽ .025; match 3, p ⫽ .04). So, even those words that did not become correct as a result of treatment generalisation did actually show a treatment generalisation effect. Again it was interior letters that appeared to improve most.

had received spelling treatment, improved significantly when compared to pretreatment (baseline 2) (Set 1, McNemar ␹2 ⫽ 12.90, p ⫽ .000; Set 2, p ⫽ .000). In contrast, reading of irregular words for Set 3 (untreated at this stage) did not significantly improve, suggesting no treatment generalisation to reading of untreated words (McNemar, p ⫽ .302). Reading of Set 3 words, however, did improve after treatment phase 3 when compared to baseline and post-treatment phase 2 (baseline, McNemar p ⫽ .000; PT2, p ⫽ .000).

Homophone spelling Results for homophone spelling are shown in Figure 8.

Irregular word reading Results for irregular word reading are shown in Figure 7. Irregular word reading was assessed at baseline 1 and 2, after treatment phase 2 and 3, and at 2 months post-treatment (follow-up 1). There was a significant increase from baseline (baseline 2) to post-treatment phase 3 in the total number of irregular words read correctly (overall, McNemar ␹2 ⫽ 58.53, p ⫽ .000; Set 1, p ⫽ .000; Set 2, p ⫽ .000; Set 3, p ⫽ .000). At 2 months post-treatment (follow-up 1) this improvement was maintained, with no significant change in total correct from post-treatment phase 3 to the first follow-up assessment (overall, McNemar p ⫽ .210; Set 1, p ⫽ 1.0; Set 2, p ⫽ .250; Set 3, p ⫽ .727). At assessment post-treatment phase two, reading of both Set 1 and Set 2 words, which

Figure 7. Percentage correct for irregular word reading at baseline, during treatment, and at post tests.

18 It is important to note that neither group of words significantly changed in match values from baseline 1 to baseline 2 (match 2, p ⫽ .688; match 3, p ⫽ .478). So, there were no changes in error characteristics during baseline and therefore any changes that occurred during treatment were due to treatment generalisation effects.


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Total errors The total number of homophone spelling errors was reduced during treatment, with significantly fewer errors evident after treatment phase 3 than at baseline 2 (McNemar p ⫽ .031), suggesting treatment generalisation to homophone spelling. This treatment effect was maintained at 2 and 4 months post-treatment, when compared to Posttreatment 3 (follow-up 1, McNemar ␹2 ⫽ 0.30, p ⫽ .584; follow-up 2, p ⫽ 1.0). Interestingly, the predominant change occurred after treatment phase two and the use of mnemonics, with the difference between post-treatment phase 1 and 2 for total correct approaching significance (p ⫽ .053). Homophone confusion errors As mentioned above, total homophone confusion errors (HCE) for spelling increased between

initial baselines. No further significant changes were evident during treatment or at follow-up, when compared to baseline 2 (PT1, McNemar p ⫽ .804; PT2, p ⫽ .607; PT3, p ⫽ .804; follow-up 1, p ⫽ .629; follow-up 2, p ⫽ 1.0). When compared to baseline 1, the total homophone confusion errors post-treatment 3 was significantly higher (p ⫽ .041) (NB. no other comparisons were significant), though this result is difficult to interpret in the context of unstable baselines.

Phonologically plausible nonword errors The total number of phonologically plausible nonword errors (PPNE) was reduced during treatment, with significantly fewer errors after treatment phase 3 than at baseline 2 (McNemar ␹2 ⫽ 16.7, p ⫽ .000), suggesting a change in the nature of errors made as a result of treatment. There was a significant decrease in PPNE between baseline 2 and post-treatment phase 1 (p ⫽ .023), between post-treatment phases 1 and 3 (p ⫽ .019), but not between treatment phases 1 and 2 (p ⫽ .541). This treatment effect was maintained over time with no change between the end of treatment and the two follow-up assessments (follow-up 1, p ⫽ 1.0; follow-up 2, p ⫽ 1.0).

Other errors

Figure 8. Percentage of responses that were errors for homophone spelling at baseline, during treatment, and at post-tests.

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The total number of other errors (OE) increased significantly after treatment phase 1 when compared to baseline 1 (McNemar, p ⫽ .012) but there were no further significant changes during treatment or at follow-up. These errors were responses that were incorrect and were not phonologically plausible (see Appendix D for examples). Post hoc analyses were conducted to compare the nature of homophone spelling errors before and after treatment. This analysis included all homophone error responses (both nonword errors and homophone confusion word errors) and was conducted to investigate whether error responses moved closer to the target with treatment. In other words, even though the responses were still incorrect after treatment, were they closer to being

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correct as a result of the irregular word spelling treatment. The degree of match (using the match variables described previously) between error responses and the correct spellings were calculated for errors at baseline 2 and the first follow-up assessment and then compared. First, at baseline (baseline 2), there was not a significant interaction between error type and match values for coding schemes overall (match 1, Kruskal Wallis ␹2 ⫽ 4.719, p ⫽ .094; match 2, p ⫽ .339; match 3, p ⫽ .411; match 4, p ⫽ .259; match 5, p ⫽ .060). This indicated that the match variables did not distinguish significantly between the three error response classifications (e.g., HCE, PPNE, and OE) in homophone spelling. In other words, HCE, PPNE, and OE were similar in how closely they matched the stimulus word (or correct response). A simple overall comparison of the errors made at baseline with those made at follow-up assessment indicated that there were significantly fewer phonologically plausible (p ⫽ .000) and significantly more other (p ⫽ .001) errors at follow-up (see Table 10). There was no difference according to stimulus regularity (p ⫽ .096), number of HCE (p ⫽ .568), or any match values (match 1: p ⫽ .202, match 2: p ⫽ .447; match 3 p ⫽ .418; match 4, p ⫽ .154; match 5, p ⫽ .407). A regression analysis was then conducted to further investigate differences between the errors at baseline and those at follow-up (i.e., to determine what was different about the errors after treatment). Predictor variables included match values 1–5, error type (i.e., PPNE, HCE, or OE), whether the stimulus was irregular or regular, and

Table 10. Total number of homophone errors at baseline 2 and follow-up assessment Errors Total HCE Total PPNE Total OE Total errors

Baseline

Follow-up

20 33 9 62

18 9 21 48

HCE: homophone confusion errors; PPNE: phonologically plausible nonword errors; OE: other errors.

whether the error response was the same length as the stimulus. The binary outcome variable represented time of testing (baseline vs. post-treatment) for all error responses. Results indicated that error type was the only variable that differentiated significantly between errors made before treatment and those made post-treatment. Errors at followup were less likely to be phonologically plausible (Wald ␹2 ⫽ 7.4, p ⫽ .006), than at baseline. There was also a trend for errors at follow-up to be more likely to be ‘other’ errors (Wald ␹2 ⫽ 3.246, p ⫽ .072), consistent with results reported above (again see Table 10). Finally, a regression analysis was conducted to investigate the difference between errors at baseline that were correct at follow-up (N ⫽ 17) and those that were not (N ⫽ 45) (i.e., to determine differences between those untreated homophone words that improved and those that didn’t). The same predictor variables were included. Results indicated that no variable was able to predict improvement in homophone words over and above the other variables included; however the power of the analyses is limited due to the small number of homophone errors that improved (N ⫽ 17).

Homophone reading Results for homophone reading are shown in Figure 9. Total words read correctly The total number of homophone reading errors decreased during treatment, with significantly fewer read incorrectly at post-treatment phase 3 and follow-up 1 assessments when compared to baseline 2 (PT3, p ⫽ .035; post follow-up 1, p ⫽ .002), suggesting some treatment generalisation to homophone reading. It is interesting to note that, of those words that improved (i.e., changed from incorrect to correct), 77% (10/13) were irregular homophonic words. Results indicated a significant increase in the total number of homophone words read correctly during treatment but, as with spelling, there was no consistent COGNITIVE NEUROPSYCHOLOGY, 2005, 22 (2)

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Set 2 irregular words but not for treatment of words in Set 1 or Set 3. There was no significant difference between the word sets in terms of duration of treatment required to reach ceiling (i.e., efficiency of treatment). Duration of treatment for Set 1 was 8 days, for Set 2 it was 6 days, and for Set 3 it was 7 days. There was also no difference between the three word sets in degree of decline from post-treatment to assessment at follow-up 1 (Generalised Estimating Equation [GEE] analysis, ␹2 ⫽ 3.15, p ⫽ .21). The only relevant change was a reduction of errors in homophone spelling, which predominantly occurred after treatment of Set 2 (and the use of mnemonics), but this change only approached significance (p ⫽ .053). Thus there was no consistent evidence that the use of mnemonics contributed to the efficacy of treatment. Figure 9. Percentage of responses that were errors for homophone reading performance at baseline, during treatment, and at post-tests.

change in the number of homophone confusion errors. Homophone confusion errors The total number of homophone confusion errors (made with those words read correctly) decreased significantly following treatment phase 3 when compared to baseline 2 (binomial p ⫽ .035) but not baseline 1 (p ⫽ .118), but this decline was transitory and errors had increased by follow-up 1 (p ⫽ .000) back to baseline level (B2, p ⫽ .210; B1, p ⫽ .063).

Mnemonics The efficacy of employing mnemonics in lexical spelling treatment was evaluated according to efficiency of treatment (speed at which target word spelling improved) and stability of treatment (how resistant the words were to decline following treatment). Note: As mentioned in the Method section, mnemonics were used for treatment of

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Overview of results 1. The treatment method used in this case of developmental surface dysgraphia was highly efficacious, since spelling of treated words improved significantly as a direct result of treatment. 2. Although there was some reduction in total words spelled correctly at 2 months posttreatment (indicating some loss of accuracy with time), spelling of treated words remained significantly improved at 4 months post cessation of treatment when compared to baseline. 3. The treatment method employed resulted in a significant generalisation effect, since spelling of untreated words also improved with treatment, though not as dramatically as spelling of treated words. 4. Untreated words whose spellings became correct as a result of treatment generalisation (as compared to untreated words whose spellings remained incorrect) were those whose errors were closer to being correct prior to treatment and those with a higher word frequency. The degree of correctness (or degree of match to the correct spelling) was best characterised by a coding scheme that placed relatively more weight on exterior letters than interior letters.

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5. A close examination of error characteristics during treatment revealed that untreated words improved gradually as a result of treatment generalisation and that this improvement predominantly involved interior letters. Even those untreated words that did not become correct prior to their treatment showed some improvements in spelling. 6. There was no evidence that the use of mnemonics contributed to the efficacy of treatment. 7. Although reading was not specifically treated, those words whose spelling had been treated also showed an improvement in reading accuracy. 8. The total number of error responses made in homophone reading and spelling was also significantly reduced, but the number of homophone confusions did not change. However, there was a significant reduction in phonologically plausible spelling errors and an increase in other errors (i.e., orthographically based spelling attempts) during treatment. 9. In addition, a close examination of error characteristics (from both irregular word and homophone word spelling) provided preliminary evidence that the mechanism underlying treatment generalisation involved a general improvement (that was not word-specific) in the ability to access and use output orthography for spelling attempts.

DISCUSSION The current study adds to the small number of cognitive neuropsychological case studies reporting successful treatment of surface dysgraphia, and is the first study we are aware of to focus on the cognitive neuropsychological treatment of developmental surface dysgraphia. The results have implications for current theoretical proposals about lexical processes in reading and spelling, as well as clinical methods used for treatment of surface dysgraphia.

Theoretical implications The current results provide support for a number of theoretical proposals, including the following.

1. Weekes and Coltheart’s (1996) proposal that two treatment effects can occur as a result of item-specific training: a word-specific treatment effect and a more general treatment effect impacting on access to orthography. 2. Behrmann’s (1987) speculation that homophone comprehension difficulties require itemspecific training and that homophone comprehension does not improve as a result of general improvements in orthographic processing. 3. Weekes and Coltheart’s (1996) prediction that some untreated irregular words may benefit more than others depending on their level of pretreatment representation. 4. The empirical proposal that exterior letters are particularly important for orthographic processing (Humphreys, Evett, & Quinlan, 1990; Jordan, 1990; Perea, 1998). 5. The theoretical proposal that a direct nonsemantic route is required in models of normal reading and spelling. Each of these proposals will be discussed in turn. Orthographic processing difficulties can result from two different levels of impairment; from word-specific impairment or from a general impairment or inefficiency in access to stored lexical representations. The current study adds weight to previous research findings that treatment focused on improving orthography (in this case irregular word spelling) can benefit both forms of impairment. This is consistent with Weekes and Coltheart’s (1996) proposal that two treatment mechanisms arise from item-specific training: a word-specific effect (which results in improvement for target words) and a more general effect on access to orthography (which results in generalisation to untreated irregular words). This explanation makes sense for cases of acquired dysgraphia, but can it be applied to MC, a developmental case? Adults with acquired dysgraphia will have had a normal store of lexical representations prior to their injury (assuming they were literate) and thus can benefit from treatments that improve general access to those orthographic representations that remain relatively intact. But can a child with long-standing poor or unreliable COGNITIVE NEUROPSYCHOLOGY, 2005, 22 (2)

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access to orthography actually form adequate word-specific representations that would then enable them to benefit from generalised improvements in access to orthography? We would argue in the affirmative, for the following reason. It is conceivable that a child with poor access to orthography could gradually build up correct (or partially correct) representations of individual words via multiple exposures to the correct spelling, though presumably the formation of orthographic representations would be delayed. The child could then continue to have difficulty accessing (or retrieving) these representations (resulting in ongoing severe reading and spelling difficulties) but would show significant improvements as a result of treatment generalisation, as seen in the current case MC. For MC, significant treatment generalisation did occur, which provides additional evidence that MC had a developmental impairment in general access to orthography and not just impairment at the level of orthographic representation.19 The current results also provide strong support for Behrmann’s (1987) speculation that homophones require word-specific training (presumably in orthography-semantic association) so, unlike irregular words, do not benefit from a general orthographic treatment effect. In the current study, the benefits of treatment generalisation did not extend to orthography-semantic connections for untreated homophones. Although homophone spelling improved, the improvement was only evident in the total number of homophone stimuli spelled correctly. There was no reduction in the number of homophone confusion errors. Of most interest, in the current study, were the results of the novel investigation into mechanisms underlying treatment generalisation, analyses that have been lacking in previous research. Weekes and Coltheart (1996) propose that some untreated irregular words may benefit more than others,

19

depending on their level of pretreatment representation. More specifically, words with partial representation prior to treatment will benefit more than those with little or no orthographic representation (Weekes & Coltheart, 1996). In order to investigate this proposal the current study analysed the characteristics of untreated words that improved as a result of treatment generalisation and examined how they differed from those untreated words that didn’t improve. Pretreatment representation was measured using the degree of match (or similarity) between the error response and correct spelling prior to treatment. In addition, an attempt was made to investigate the actual mechanism underlying treatment generalisation through analyses of changes in error characteristics as a result of treatment. Overall and in combination, the results of these investigations provide some support for the proposals of Weekes and Coltheart (1996). First, the current results indicate that, in general, untreated irregular words whose errors are closer to being correct prior to treatment (i.e., have a closer match to the correct spelling) are more likely to improve as a result of treatment generalisation. However, the coding schemes and match values employed in the analyses did not distinguish between error type prior to treatment; that is, both phonologically plausible nonword spelling errors and nonphonological spelling errors (which often contained partial orthographic information) had similar match values. This is because both phonologically and orthographically based errors can be highly similar to the correct response (e.g., phonological attempts: soul → sowl, won → wun; nonphonological orthographic attempts: eight → etaght, their → thir). In addition, phonologically plausible nonword errors are also often orthographically similar to the correct response, so there may have also been some overlap between error classifications. Therefore, all we can conclude from this finding is that untreated irregular words

This is based on the assumption that the generalisation effects in the current study were due to improvements in orthographic processing. An anonymous reviewer made the valid point that generalisation effects can occur following improvement in other aspects of the spelling system, such as the graphemic buffer. However, in the current case, this would be unlikely as no such other impairments were detected in assessment.

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that improve with treatment generalisation have a closer match to the correct spelling prior to treatment. This does not provide definitive support for a proposal that these words have partial orthographic representations prior to treatment. However, investigation into changes in error characteristics during treatment provided some evidence for an underlying treatment mechanism of an improved ability to access and use orthographic representations for spelling attempts. Observation of untreated irregular words that improved over multiple testing points during treatment revealed that many showed gradual improvement in degree of similarity to target orthography. In addition, for homophone spelling (all untreated) there was a reduction in phonologically plausible nonword errors, which is consistent with incomplete but improved access to representations in orthography resulting in less reliance on sublexical processing. There was also a co-occurring increase in the number of ‘other’ errors, which essentially reflected an increase in attempts that were not phonologically plausible but more often represented incomplete orthographically mediated attempts. In the current study, extensive analyses were conducted to determine the best predictors of treatment generalisation. The main focus of the analyses were the coding schemes (and match values) to determine not only whether degree of pretreatment ‘correctness’ could predict generalisation (as discussed above), but also whether one method of coding ‘correctness’ was superior to another. Overall, the results suggest that the best way to determine how correct an error response is prior to treatment, in order to predict treatment generalisation, is to use a coding method where the position of each letter is coded relative to the first and last letters—that is, a coding method that places relatively more weight on exterior letters. The best statistical model for predicting generalisation for untreated irregular words included this particular method of coding combined with written frequency. However, given the very high correlation between all of the coding methods employed (match variables), the authors would hesitate to argue definitively that one matching method was significantly superior to the others. It would seem

reasonable, however, given the consistent findings of various analyses, to suggest that some matching methods (or coding schemes) may be better than others for predicting which untreated words will improve with treatment. In the current study, matching methods for coding schemes 4 and 5 (which both emphasised the exterior letters) seemed consistently superior for predicting which untreated irregular words would benefit from treatment generalisation. A post hoc examination of the nature of MC’s actual error responses for untreated words was also highly consistent with this finding, particularly for the relative importance of exterior letter positions. For those irregular words that improved with treatment generalisation, a large proportion of the errors at baseline (75%) contained correct letters in the first and last letter position. In contrast, for those untreated words that failed to improve, less than half of the error responses (46%) contained correct first and last letters. For interior letters, this effect was not present: Interior letters were correct in 15% of untreated words that improved and 9% of untreated words that did not improve. This finding makes theoretical sense as previous research has also indicated the importance of exterior letters (over internal letter positions) in orthographic processing (Humphreys et al., 1990; Jordan, 1990; Perea, 1998). Most previous studies have investigated letter position effects in visual word recognition, but the current results provide some preliminary evidence that exterior letters may also be important in spelling. It is interesting to consider how the results for predicting which untreated words will benefit most from generalisation (as just discussed) relate to results describing the nature of error change during treatment. That is, can we speculate not only about which words will improve but also about how they will improve? As discussed above, error responses with a closer match (particularly involving exterior letter positions) to the correct response will benefit most from treatment generalisation. So at baseline, those words with correct initial and final letter positions are more likely to become correct as a result of treatment generalisation (many of these words would therefore have errors affecting COGNITIVE NEUROPSYCHOLOGY, 2005, 22 (2)

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interior letter positions). Interestingly, an examination of how error responses change during treatment (prior to becoming correct) indicated a highly significant change in vowel-centred match schemes (match 2 and 3), possibly indicating a gradual improvement in interior vowel patterns during treatment. This was apparent for both words that became correct as a result of treatment generalisation and those that didn’t, though the latter took longer to respond to treatment generalisation effects. Finally, in regard to theoretical implications, homophone confusions with irregularly spelled homophones are rarely investigated or reported in cases of surface dyslexia and more particularly in developmental surface dyslexia. As Coltheart et al. (1983) discuss, these errors are of theoretical importance as they provide additional evidence for the existence of the direct nonsemantic route in reading connecting the orthographic input lexicon to the phonological output lexicon. When an irregular homophone is read aloud correctly but a homophone confusion is made in comprehension (e.g., reading the word ‘queue’ correctly but providing the wrong definition “the actor needed a cue,” see Table 5 for other examples) the theoretical explanation must be as follows. The correct word entry is successfully accessed in the orthographic input lexicon but word-specific communication with the semantic system fails. As a result, output phonology is obtained via the direct route linking the orthographic input lexicon to the phonological output lexicon, which prevents word-specific semantic activation (route shown by arrows 13, 15, 11, Figure 1), giving rise to the homophone confusion error. Documentation of multiple examples of such errors in the current developmental case, in addition to the case of Coltheart et al. (1983), requires current models of reading and spelling to include not only the lexical-semantic and sublexical reading routes, but also the third nonsemantic reading route.

Clinical implications The current results also have clinical implications for management of dysgraphia, particularly

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developmental dysgraphia. Results suggest the following. 1. Carefully designed theoretically based treatment methods for developmental dysgraphia can be highly efficacious. 2. Lexical treatment of developmental surface dysgraphia can result in dramatic improvements in target word spelling but also significant improvements in spelling of other untreated words. 3. Further improvements in efficiency of treatment may be achieved by targeting particular subsets of words, specifically those that are less likely to benefit from treatment generalisation. 4. Lexical spelling treatment methods can result in substantial improvements in reading of target words. 5. It must not be assumed that mnemonics always increase efficacy in treatment of irregular word spelling in developmental dysgraphia. Each of these clinical implications will be discussed briefly. The theoretically based lexical treatment method used in the current study was highly successful in improving irregular word spelling in a child with long-standing delays in the development of orthographic word reading and spelling. The treatment improvements were dramatic, occurred rapidly, and were also maintained over time. This study shows that treatments previously used successfully in cases of adult-acquired surface dysgraphia can be very effective for treatment of developmental surface dysgraphia. It is hoped that this case study will encourage further research into treatment of childhood reading and spelling disorders (a research area that remains extremely limited), especially given the potentially dramatic benefits for the child. The lexical treatment methods used in the current study not only resulted in dramatic improvements in the specific words chosen for treatment but also resulted in better spelling of other untreated words. Essentially, clinically, this implies that the benefits of treatment can reach well beyond the small set of target words and that treatment focused on single words can also benefit other words in the system that are not fully developed. In addition, the current results suggest that it may be possible to predict, prior to treatment,

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which words will benefit most from treatment generalisation by examining the nature of errors at baseline. This may therefore allow increased efficiency in treatment by allowing the separation of target words into two groups prior to treatment. The first group would contain those words least likely to benefit from treatment generalisation, that is, those words with a low written frequency and with spelling errors that are not close to being correct prior to treatment (i.e., spelling errors that do not have a high degree of match with the correct spelling). These errors would be targeted for word-specific treatment. The second group would contain those words most likely to benefit from treatment generalisation, those words with a high written frequency and with spelling errors that are close to being correct prior to treatment. These words could be deliberately excluded from the treatment group as we might predict that they would improve during treatment as a result of treatment generalisation. This proposal, that treatment planning could potentially maximise efficiency of treatment, requires further investigation and research, however. Treatment of irregular word spelling in the current case also resulted in significant improvement in reading of treated words. The improvement in reading of treated words is not an unexpected finding as, although treatment focused on output orthography and spelling, the treatment method also involved constant visual exposure to target words. In clinical terms this result implies that in developmental dysgraphia and dyslexia treatment targeted at spelling is also likely to benefit reading. Mnemonics are commonly used as a treatment tool in treatment of surface dyslexia and dysgraphia and are also employed for teaching beginner readers early in primary school. However, the efficacy of mnemonics is not often empirically evaluated (Behrmann, 1987; Byng & Coltheart, 1986; Coltheart & Byng, 1989; Weekes & Coltheart, 1996). De Partz et al. (1992) evaluated the efficacy of mnemonics (compared to writing to dictation and simple copying of the word with no mnemonic) in their treatment of spelling in an adult, LP, with acquired dysgraphia, which targeted high-frequency words. They found a

significant therapy advantage for the mnemonic technique. It is important to note that LP reportedly had semantic deficits. In contrast, a recent treatment study focused on improving visual word recognition in developmental dyslexia (also focused on high-frequency words) questions the efficacy of mnemonics when compared to ‘wordonly’ treatment methods (Brunsdon, Hannan, Coltheart, & Nickels, 2002). In the current study, mnemonics were used for treatment stage two (word Set 2 only) and, in general, results suggested no additional benefit from use of mnemonics. Neither of these developmental cases benefited from mnemonics and neither presented with semantic deficits. Overall, it would be reasonable to suspect that the use of mnemonics may be beneficial when the treatment aim is specifically to train orthography-semantic connections, as in specific homophone reading and spelling treatment programmes, where the individual demonstrates impaired access to semantic information for target words (though, even in this instance, a verbally mediated orthography-semantic association treatment may be equally effective). In contrast, mnemonics may not offer any treatment advantage when treatment simply targets irregular word reading or spelling, when the individual already knows the meaning of target words. Finally, with regard to clinical implications, surface dyslexia and dysgraphia are still commonly overlooked or misdiagnosed in children. MC’s case provides a typical example of this. His reading and spelling difficulties were apparent from early in primary school. He had undergone numerous reading assessments and as a result received extra reading tuition during primary school. Despite this, the exact nature of his reading and spelling disorder was not precisely diagnosed until the current investigation, when MC was 12 years old and in high school. Although it is certainly never too late to begin treatment, appropriate treatment earlier in primary school would obviously be better. It is hoped that the current case will provide a timely reminder of the importance of theoretically based assessment early in primary school for identification and then treatment of lexical spelling (and reading) disorders. COGNITIVE NEUROPSYCHOLOGY, 2005, 22 (0)

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Theoretically based assessment and diagnosis is fundamental to treatment planning and design. To devise a successful treatment programme targeted at a particular impairment, the fundamental requirement is to first determine the nature of that impairment. Although the treatment design (including the intensive nature of treatment and repeated exposure to target stimuli) is important, if treatment is not targeted specifically at the impairment, success is likely to be limited. The current case MC had undergone numerous special education programmes, including some periods of intensive daily training. However, given that his surface dyslexia and dysgraphia had not previously been diagnosed it must be suspected that treatment was not targeted appropriately at irregular words.

Final comments In summary, the current study demonstrates successful application of cognitive neuropsychological theories and methods to the assessment and remediation of developmental spelling difficulties. Treatment was highly successful and resulted in a dramatic improvement in spelling and reading of irregular words that was stable over time. Treatment also generalised to spelling of untreated irregular words. Novel analyses indicate that untreated words that improved were closer to being correct prior to treatment than untreated words that failed to improve. Results also suggest that, prior to treatment, it may actually be possible to predict which words will benefit most from treatment generalisation. There is also preliminary evidence that the actual mechanism underlying treatment generalisation involves improved access to orthographic representations, resulting in an increased tendency to attempt to employ orthographic knowledge and a reduced tendency to rely entirely on phoneme to grapheme conversion. Results have both theoretical and clinical implications and raise a number of interesting proposals worthy of future research. Manuscript received 8 April 2003 Revised manuscript received 3 October 2003 Revised manuscript accepted 16 February 2004 PrEview proof published online 15 December 2004

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APPENDIX A MC’s errors for irregular, regular, and nonword reading and spelling (using the Coltheart & Leahy, 1996, word and nonword lists) Regular words 1. bed 2. brandy 3. chance 4. check 5. chicken 6. context 7. cord 8. curb 9. drop 10. flannel 11. free 12. hand 13. life 14. long 15. luck 16. market 17. marsh 18. middle 19. mist 20. navy 21. need 22. nerve 23. peril 24. plant 25. pump 26. stench 27. tail 28. take 29. weasel 30. wedding Irregular words 1. blood 2. bouquet 3. bowl 4. break 5. brooch 6. ceiling 7. choir 8. colonel 9. come 10. cough 11. eye 12. friend 13. gauge 14. give 15. good

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Reading response ✓ ✓ “change” ✓ ✓ ✓ ✓ ✓ ✓ /flntεl/ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ /n:vi:/ “pearl” ✓ ✓ ✓ ✓ ✓ /wɒzli:/ ✓

Spelling response ✓ ✓ carns ✓ ✓ contexs corwd cerb ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ navey ✓ nerv peral ✓ pamp staench ✓ ✓ ✓ weding

Reading response

Spelling response

/blυd/ /bəυkεt/ ✓ ✓ ✓ ✓ “chore” /kɒləυnel/ ✓ “caught” ✓ ✓ /g:rd/ ✓ ✓

✓ bowckay ✓ braek browtch cilling quwiyer cernal ✓ cofe ✓ ✓ gaeg ✓ ✓


Irregular words

Reading response

Spelling response

✓ ✓ ✓ /ləυz/ “merging” /pnt/ /prεti:/ /raυtn/ ✓ /səυl/ /ʃu::/ /tɒmb/ ✓ ✓ /jtʃt/

haed iorne ✓ lowes merrag pient pritte rooten ✓ ✓ shore ✓ ✓ werk yote

Nonwords

Reading response

Spelling response

1. aspy 2. baft 3. bick 4. bleaner 5. boril 6. borp 7. brennet 8. brinth 9. crat 10. delk 11. doash 12. drick 13. farl 14. framp 15. ganten 16. gop 17. grenty 18. gurve 19. hest 20. norf 21. peef 22. peng 23. pite 24. pofe 25. rint 26. seldent 27. spatch 28. stendle 29. tapple 30. trope

/sfiə/ ✓ “bike” /bεnə/ “boil” ✓ /brεnt/ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ “gentle” “gravy” ✓ ✓ /pəf/ “peg” ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓

✓ ✓ ✓ ✓ (blener) ✓ (boral) ✓ ✓ (brenet) ✓ ✓ ✓ (delck) ✓(dowsh) ✓ ✓ ( farll ) ✓ ✓ ✓ granty ✓ ( girv) ✓ ✓ ✓ pag ✓(piet) ✓(powf ) ✓ ✓(selldent) ✓ ✓ (stendell) ✓ (tapell ) trop

16. head 17. iron 18. island 19. lose 20. meringue 21. pint 22. pretty 23. routine 24. shoe 25. soul 26. sure 27. tomb 28. wolf 29. work 30. yacht

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APPENDIX B Homophone stimuli Irregular key quay loch stalk pear break bury seize suite son prays build know some steak heir great

Regular

Irregular

ring wring lock stork pair brake berry sees sweet sun praise billed no sum stake air grate

sure bear heard none bread waste raise soul queue earn two to their there would wood watt what

Regular shore bare herd nun bred waist rays sole cue urn male mail fair fare ate eight hire higher

Irregular

Regular

one won aisle isle where wear whole

plane plain seen scene missed mist hole knead need tax tacks sail sale tail tale maid made cruise

APPENDIX C Homophone confusion errors in reading at baseline 1 Target word wring pear mist brake tale prays steak mail male their whole queue crews

Read aloud correctly?

Spoken definition provided by MC

yes yes yes yes yes yes yes yes yes yes yes yes yes

“the telephone rings” “socks. . . . pairs of them” “I missed the ball” “I break the vase” “there is a tail on a dog” “a cat preys on a bird” “I stuck a stake in the ground” “the male toilet” “the mail came. . . . was delivered” “there is the ball” “there is a hole in the ground” “the actor needed a cue” “a boat cruise. . . . a cruise ship”


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APPENDIX D Homophone errors in spelling at baseline 1 Target homophone quay loch stalk wring whole knead scene hire maid fare sum heard pear missed tax brake break sail tale tail bury berry prays Praise steak stake mail male heir there watt grate great sure shore bear bare build won waist raise rays soul sole cruise crews aisle earn

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MC’s written response

Homophone confusion errors

key lock stork ring hole need seen higher made fair some herd pare mistd taxs braek braek sayal taile taile berrey berrey praes praes staek staek maile maeal airr thair whot graet graet shor shor bair bair biuld wun waest raes raes sowl sowl croos croos ieal ern


Phonologically plausible nonword errors

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

Other errors

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APPENDIX D (continued) Homophone errors in spelling at baseline 1 Target homophone where wear tacks seize sweet suite plain higher eight their none queue cue isle bred

MC’s written response

Homophone confusion errors

whair whair taxes sesy swety swets plan highter etaght thir nune qu qu lias breaed

Phonologically plausible nonword errors

Other errors

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

Phonologically plausible nonword errors refer to those errors for which MC employed plausible sound to letter conversion in his spelling response (this classification was not restricted to the most common phoneme to grapheme rules).

APPENDIX E Irregular word responses (from Set 3): Those responses that are incorrect at baseline 1, baseline 2, and after treatment of Set 1 words but are correct after treatment of Set 2 words Target irregular word want kind move range staff rise clothes tough draft soup

At baseline 1

At baseline 2

wont ciend more rang starf ries cloths taph drarft soop

wont cind moov rang starf riess clows taf drarft soop

Post-treatment 1 wont cind morve* raeng starf ries clouthes* taugh* drarft soupe*

*Untreated words with gradual increase in orthographic knowledge with treatment generalisation (Note: All of these untreated words were spelled correctly at the next assessment).


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