Reading and spelling acquisition in Thai children

SPENCER BONNETTE

Thai, a tonal language, has its own distinctive alphabetic orthography. The study investigates reading and spelling development in Thai children, with an aim of examining the grain size that is predominantly used when reading and spelling. Furthermore, word and nonword lists were developed to examine the acquisition of the complex system of vowels and tone rules in Thai. Reading and spelling of words and nonwords were assessed in 60 Thai children ranging in age from 7 to 9 years 8 months from Grade(s) 1, 2, and 3. A lexicality effect was found for both reading and spelling. Spelling lagged behind reading in the Grade 1 children. Development rapidly increased between the youngest Grade 1 children and the older Grade 2 and 3 children. For word reading there were significantly more lexical errors than phonological errors. Beginning readers appear to predominantly use a larger lexico-syllabic grain size to read Thai.

Read Writ (2010) 23:1021–1053 DOI 10.1007/s11145-009-9194-6 Reading and spelling acquisition in Thai children Heather Winskel Æ Kanyarat Iemwanthong Published online: 24 July 2009 Ó Springer Science+Business Media B.V. 2009 Abstract Thai, a tonal language, has its own distinctive alphabetic orthography. The study investigates reading and spelling development in Thai children, with an aim of examining the grain size that is predominantly used when reading and spelling. Furthermore, word and nonword lists were developed to examine the acquisition of the complex system of vowels and tone rules in Thai. Reading and spelling of words and nonwords were assessed in 60 Thai children ranging in age from 7 to 9 years 8 months from Grade(s) 1, 2, and 3. A lexicality effect was found for both reading and spelling. Spelling lagged behind reading in the Grade 1 children. Development rapidly increased between the youngest Grade 1 children and the older Grade 2 and 3 children. For word reading there were significantly more lexical errors than phonological errors. Beginning readers appear to predominantly use a larger lexico-syllabic grain size to read Thai. Keywords Development Grain size Reading Spelling Thai Lexicality effect Introduction The basic aim of learning to read is a process of matching the visual symbols of the particular orthography with the phonology of the language. The characteristics H. Winskel (&) School of Psychology, University of Western Sydney, PO Box 1767, Penrith South, NSW 1767, Australia e-mail: [email protected] K. Iemwanthong Center for Research in Speech and Language Processing (CRSLP), Chulalongkorn University, Phaya Thai Road, Pathumwan, Bangkok 10330, Thailand 123 1022 H. Winskel, K. Iemwanthong of the orthography and the language that it maps onto, pose different challenges to beginning readers, and influences the developmental pathways observed in reading development. The psycholinguistic grain size theory formulated by Ziegler and Goswami (2005) suggests that the way the phonology of a language is represented by its orthography, affects the psycholinguistic grain size that is primarily accessed by beginning readers. The relative consistency of mapping between phonology and orthography is a crucial contributing factor to the reading acquisition process and the relative ease with which beginning readers acquire an alphabetic orthography. In transparent orthographies such as German, acquisition is rapid and children appear to have ready access to small grain size units, grapheme-phoneme correspondences, whereas in other less consistent orthographies such as English, children can take several years to gain a similar level of competence, and appear to use a mixed or flexible grain size strategy (Goswami, 2000, 2003; Seymour, Aro, & Erskine, 2003; Goswami, Ziegler, Dalton, & Schneider, 2003). Another characteristic that can affect reading and spelling development is the degree of balance between the mapping of phonemes to graphemes and graphemes to phonemes in different orthographies. For example, when there is consistent mapping between phonemes and graphemes but there are multigrapheme to phoneme correspondences, then spelling development generally lags behind reading (e.g. French, Hebrew, Portuguese, and Persian; Geva, Wade-Woolley, & Shany, 1993; Rahbari, Sénéchal, & Arab-Moghaddam, 2007; Pinheiro, 1995; SprengerCharolles, Siegel, & Bonnett, 1998). Thus, predictions can be made about reading and spelling development based on the characteristics of the orthography and the language it maps onto. Thai, a tonal language, forms an interesting case study, as it has its own unique orthography, which has several interesting, distinctive characteristics worthy of further investigation. Thai has an alphabetic script, which also has shared properties with syllabic scripts, as it has implicit vowels for some consonants. In addition, the syllable is a highly salient unit in the spoken language, as it has clear syllable boundaries and words are predominantly monosyllabic. Thai consonants are written in a linear order, but vowels can be written non-linearly above, below, or to either side of the consonant, and commonly combine across the syllable to produce a single vowel or dipthong. These hybrid characteristics of Thai give us an opportunity to investigate the influence that features commonly associated with alphabetic scripts (e.g. linearity, phonemic prominence) and syllabic scripts (e.g. non-linearity, syllable prominence) have on reading development (Vaid & Padakannaya, 2004). Furthermore, lexical tone is a neglected area in reading research, but is important to investigate as it plays a crucial role in tonal languages throughout the world (e.g. Mandarin Chinese, Cantonese, and Vietnamese). Little is known about how beginning readers of Thai learn to read or write Thai, and how development is influenced by the characteristics of the orthography. The current study investigates reading and spelling development in Thai children, with an aim of examining the grain size that is predominantly used when reading and spelling. Furthermore, the tasks are designed to focus on vowels and tones when reading and spelling Thai, so that the developmental pathways involved in learning these 123 Reading and spelling acquisition 1023 subsystems can be traced. Reading and spelling of words and nonwords was assessed in 60 Thai children ranging in age from 7 to 9 years 8 months from Grades 1, 2, and 3. First, more detailed information about the Thai language and its orthography will be reviewed, followed by relevant background literature, and the research aims and questions of the current study. Characteristics of Thai language and its orthography Thai is a tonal language that has an alphabetic orthography with 44 basic consonants plus 4 archaic consonants1 for 21 consonant sounds. Thai initial consonants are listed in Appendix 1. Thai is predominantly monosyllabic but it also has polysyllabic words, which have been borrowed mainly from Khmer, Pali, or Sanskrit. Spoken Thai has clearly defined syllable boundaries (Hudak, 1990). Possible syllable structures are V, VC, CV, CCV, CVC and CCVC [e.g. vowel (V), vowel-consonant (VC)]. In Thai script there are no spaces between words; instead, spaces in Thai text may indicate the end of a clause or sentence. Thai has a high degree of consistency in mapping between phonemes and graphemes but there are multigrapheme to phoneme correspondences for some consonants (e.g. for /ph/, /th/, /kh/, /s/, /t h/; refer to the list of initial consonants in Appendix 2). In addition, there is a change in grapheme-phoneme correspondences of consonants when they occur in final position. Thai has only nine final consonant phonemes, /p/, /t/, /k/, / /, /m/, /n/, / /, /w/, /t h/, and other consonants occurring in /a:ha:r/ food becomes final position have to take one of these sounds (e.g. /a:ha:n/). There are 15 initial consonant clusters, which all start with stop consonants and are followed by laterals, trills, or bilabials; kr , kl , kw , khr , khl , khw , khr , khl , khw , tr , pr , pl , or phl , phr . In addition, there are orthographic class-change clusters, in which the first consonant of the cluster, or is silent, and is used to change the class of consonant to a high or / middle class expression with a corresponding change in tone, for example,2 na:w0/ becomes /na:w42/ cold or /ja:k2/ becomes /ja:k1/ want. Thai does have additional irregularities, which include silent consonants and vowels that in week is not are not pronounced, for example the final consonant expressed, which in this case is explicitly marked by the diacritic . Another characteristic of Thai is that many word forms have multiple functions, which change depending on their position in a clause or sentence. For example, paj0, ma:0, or daj2 can act as different function words such as prepositions or verbs. 1 There are 4 archaic letters; , which are rarely used. 2 Tones are marked in the Thai examples cited in this paper as follows; 0 = mid, 1 = low, 2 = falling, 3 = high, 4 = rising. This system is based on the system that was developed at the Linguistics Research Unit (LRU) of Chulalongkorn University (Luksaneeyanawin, 2004). IPA transcription is used for the transcription of all other Thai text. 123 1024 H. Winskel, K. Iemwanthong When reading languages with many multifunction words, we can expect sentence context and top down processes to play a crucial role. Vowels Vowels are placed vertically above, or below, or to either side of the consonant, and can combine to produce a large additional number of vowels, as illustrated in Table 1. Vowel length is linguistically significant and Thai has both short and long vowels. In addition, vowels are not always explicitly specified. Instead, inherent vowels can occur with the consonant; an a is usually found in words of Sanskrit, Pali, or Khmer origin, whereas an o is found in native Thai words. However, these type of vowels are not used in the present study. Thai vowel expressions can be classified into the following categories based on the combination of letters that produce the vowel or dipthong: (1) single vowel expressions, (2) simple vowel combinations that consist of two vowel letters, and (3) complex vowel combinations that result from the combination of three or more vowel letters (see Table 1). In the simple and complex vowel combinations, the reader has to combine vowel orthographic units across the syllable to form a single vowel phoneme or dipthong. There are also five commonly used vowels that precede the consonant and yet operate or combine across the syllable, as illustrated in Table 1 (i) Single vowel expressions. Thai vowels are complex graphemically in their expression, but have consistent grapheme to phoneme mapping. Tones Tone forms an integral element of the syllable in Thai, and serves an essential function in distinguishing meanings of syllables and words with identical phonological structure. There are five tones in Thai conceptualised as high, mid, falling, rising, and low. However, there are only four tone markers; which occur above the consonant. The tone determination of a syllable is complex, as it is influenced by a combination of the class of initial consonant, the type of syllable (open or closed), the tone marker, and the length of the vowel. In Table 2, it can be seen that the different tone markers interact with the class of the consonant to produce particular tone realizations. Typically, the zero marked tone marker produces a mid level tone, the tone marker, a low level tone, and a falling tone. However, it can be seen that there are exceptions or irregularities to the rule (marked in bold). The low tone marker produces a low level tone in both high and mid class consonants, but with a low class consonant it produces a falling tone. A high class consonant with mid level zero marking produces a rising tone, which again is an exception to the rule. A falling tone in combination with high and mid class consonants produces a falling tone, however, with a low class consonant a high tone is produced. Furthermore, the final ending of the syllable also interacts with vowel length and again there are inconsistencies or irregularities in tone expression (marked in bold). We can see from this review that the expression of tone in Thai 123 Reading and spelling acquisition 1025 Table 1 Thai vowel expressions classified in terms of vowel combinations (adapted from Schoknecht 2000) 123 1026 H. Winskel, K. Iemwanthong Table 2 Lexical tone is determined by an interaction between tone markers, class of consonant and syllable ending Class of initial consonant High class consonant Mid class consonant Low class consonant Rising Mid Mid Low Low Falling Falling Falling High Any ending except k, p, or t, or short vowel Rising Mid Mid k, p, or t after a long vowel Low Low Falling Short vowel, or k, p, or t after short vowel Low Low High Tone marker Ending The irregular tone realizations are marked in bold involves complex rules that can be inconsistent, and that combine and operate at the syllable level. The prominence of grain size used when learning to read and spell in Indo-European orthographies There has been much debate about what grain size beginner readers and spellers use across different orthographies when learning to read and spell; whether beginners use whole words or phonemes or intermediate sub-syllabic units such as onsets and rimes, body and coda, or syllables (e.g. Duncan, Seymour, & Hill, 2000; Kim, 2007; Treiman & Zukowski, 1996; Ziegler & Goswami, 2005). The consistency of the orthography affects the grain size used by children learning to read different orthographies. In English, a notoriously irregular orthography, children initially appear to adopt a whole word lexical approach in learning to read (Frith, 1985). Seymour and Elder (1986) and Stuart and Coltheart (1988) found that reading errors made by English beginning readers involved reading one word for another and substituting visually similar words for the target word, which gives evidence for the use of a lexical (whole-word) reading strategy. In contrast, children learning to read German, a relatively transparent orthography, produce predominantly nonwords that share letter-sound correspondences with the target sounds. This indicates that German beginning readers are using a sublexical, phonemic level of processing (Wimmer & Hummer, 1990). Similarly, Spencer and Hanley (2003) found that English-speaking children’s reading errors were predominantly real-word substitutions, whereas children learning to read Welsh, 123 Reading and spelling acquisition 1027 a relatively consistent orthography, produced more phonologically based reading errors. Similar to reading most models of spelling have assumed that people rely on two procedures when engaging in spelling: a lexical look-up procedure and a nonlexical procedure that uses phoneme–grapheme rules (e.g. Perry, Ziegler, & Coltheart, 2002). For spelling in German, it has been argued that similar to reading, the nonlexical phonemic level takes precedence (Wimmer & Hummer, 1990). In English it has also been found that small grain size is important for beginning spellers (Caravolas, Hulme, & Snowling, 2001; Cassar, Treiman, Moats, Pollo, & Kessler, 2005). However, other researchers have argued that sublexical units other than phonemes, such as rimes and consonant–vowel clusters, are also important in spelling (e.g. Bruck & Treiman, 1990; Treiman, Kessler, & Bick 2002; Treiman & Zukowski, 1988). Perry and Ziegler (2004) concluded that phoneme–grapheme units are predominantly used by skilled readers when spelling English words, but larger grain sizes are also used. In transparent orthographies, it has been widely found that word recognition skills develop rapidly with relatively few errors by the end of first year of formal instruction. In contrast, in English, due to its relatively irregular or non-transparent orthography, children can take several years to gain a similar level of competence (Goswami, 2000, 2003). Seymour et al. (2003) found that reading accuracy after 1 year of learning to read was greater than 90% in consistent orthographies such as Dutch, Finnish, German, Greek, Italian, Norwegian, Swedish and Spanish, whereas children reading English showed only 34% accuracy for word reading. Similar results were found for Greek children, who read an average of 90% of real words correctly and 89% nonwords by the end of Grade 1 (Porpodas, Pantelis, & Hantziou, 1990). This contrasts with children learning to read English, who at the end of Grade 2 on average could read correctly 70% of the real words and only 45% of the nonwords (Frith, Wimmer, & Landerl, 1998). Reduced levels of accuracy in reading have been found to be dependent on the relative degree of consistency of orthographies, for example Danish (71%), French (79%), and Portuguese (73%) lagged behind the more transparent orthographies, but were more accurate than English (Seymour et al., 2003). Eventually, in order to become a competent or skilled reader in any alphabetic orthography, children need to progress beyond processing individual letters in a word to automatically processing groups of letters using well developed orthographic skills (Ehri, 1992; Ziegler & Goswami, 2006). Recent research on the grain size used when learning to read and spell in Asian orthographies Recent research on Asian languages has highlighted the syllable as an important additional processing unit when learning to read and write. Research investigating children acquiring Kannada, a semi-syllabic Indo-Dravidian script, indicates that the optimal unit for beginners is the syllable, although more proficient readers and spellers can also manipulate phonemes (Padakannaya, Rekka, Vaid, & Joshi, 2002). Research on spelling in Malaysian children (Rickard Liow & Lee, 2004), reading 123 1028 H. Winskel, K. Iemwanthong and spelling in Indonesian children (Winskel & Widjaja, 2007), and reading in Korean children (Cho & McBride-Chang, 2005; Kim, 2009), has also highlighted the syllable as a prominent processing unit. As discussed previously, Thai vowels can precede the consonant in writing but follow it in speech; hence there is a mismatch between how the word is spoken and how it is written. There are two types of misaligned vowels, one that operates within the syllable (e.g. :t o:m/ watermelon is spoken as : mo:/), and a more :ml / insect severely misaligned vowel that operates across the syllable (e.g. is spoken /m(a)l : /). This misalignment of vowels allows us to examine whether the phoneme or syllable is the more prominent processing unit when reading and spelling Thai. In a recent study, Winskel (2009) collected eye movement data of adults reading words with and without misaligned vowels in sentences in comparison with aligned control words (the written and spoken order corresponds, e.g. /mamua / mango), reaction times of adults rapidly naming the three different types of words (the two types of misaligned words and the aligned control words), and reading and spelling comparable words in children. Results revealed a processing cost due to the more severely misaligned words where the vowel operates across the syllable, and gives support for the prominence of the syllabic level rather than the phonemic level of segmentation for reading and spelling in Thai adults and children. It was also found that Grade 1 children could read more words (Grade 1 82%, Grade 2 96%) than they could spell (Grade 1 70%, Grade 2 94%), which reflects the multigrapheme-phoneme imbalance. However, in this study nonwords were not utilized for the reading and spelling tasks. Reading and spelling of nonwords Reading and spelling of nonwords is a particularly useful assessment tool to use with children learning to read and spell, as it requires children to assemble or decode word pronunciations, and thus assesses children’s phonological knowledge and ability to map sublexical units onto graphemes. In transparent orthographies such as German, children use a similar sublexical approach in reading familiar words as they do when reading nonwords (Wimmer & Goswami, 1994). Furthermore, the performance of German first grade children in nonword reading correlated highly with their reading of familiar words (r = .85), which gives additional evidence that a similar approach is used by German beginning readers to read both nonwords and familiar words (Wimmer & Hummer, 1990). It appears that, due to the transparency of the orthography, German beginning readers have ready access to graphemephoneme correspondence rules, and after only 6 months of instruction were able to read and write nonwords with considerable success. In contrast, English beginning readers experience difficulty reading nonwords (and have a corresponding high refusal rate), as they appear to be relying predominantly on a whole word or lexical strategy, and do not yet have sufficiently well developed alphabetic knowledge and skills for reading the nonwords (Wimmer & Goswami, 1994). English children appear to utilize reading by analogy strategies for rimes to aid word recognition, as they are a relatively consistent unit in English orthography. Hence, it appears that 123 Reading and spelling acquisition 1029 English children develop a variety of recoding or grain size strategies due to the irregularity or inconsistency of the orthography (Wimmer & Goswami, 1994; Ziegler & Goswami, 2005). The relationship between reading and spelling A commonly held view is that there are shared representations that underlie both the reading and spelling acquisition process (Curtin, Manis, & Seidenberg, 2001; Holmes & Carruthers, 1998). Similar predictors for reading and spelling have been found in various orthographies, for example in both Turkish and German, relatively transparent orthographies, letter knowledge and phonemic awareness have been found to be significant predictors of both spelling and reading (Öney & Durgunoğlu, 1997; Wimmer & Hummer, 1990). In transparent orthographies such as Italian, Spanish, or Greek, there is an approximately balanced bidirectional regular mapping between graphemes and phonemes and vice versa (Borzone de Manrique & Signorini, 1994; Cossu, Gugliotta, & Marshall, 1995; Porpodas et al., 1990). In contrast, English has a bidirectionally inconsistent orthography; it is orthographically inconsistent both in terms of phoneme-grapheme and grapheme-phoneme correspondences (although it is more inconsistent, in terms of spelling than reading; Ziegler, Stone, & Jacobs, 1997). It has been found in English that children can read more words than they can spell (Treiman, 1997), whereas in the more consistent orthographies such as Italian and Spanish, children can spell most of the words that they can read, and can even spell words that they can not read (Borzone de Manrique & Signorini, 1994; Thorstad, 1991). In other languages the mapping relationship can be less balanced, for example when there is consistent mapping between phonemes to graphemes but there are multigrapheme to phoneme correspondences. Hence, phonemes can be spelled in multiple ways, which is one of the main reasons why spelling lags behind reading in languages such as French, Hebrew, Portuguese, and Persian (Geva et al., 1993; Pinheiro, 1995; Rahbari et al., 2007; Sprenger-Charolles et al., 1998). Reading and spelling error analysis contributes to our understanding of the different cognitive strategies that children utilise when learning to read and spell, and how they acquire the specific rules of the written language they are learning (Abu-Rabia & Taha, 2004; Worthy, 1990). In general, spelling is considered to reveal more about a child’s phonological knowledge than reading, as a greater awareness of orthographic units is required in spelling than in the reading process (Alcock & Ngorosho, 2003; Lennox & Siegel, 1993). In order to spell effectively, children need to be able to retrieve well developed orthographic lexical representations (Abu-Rabia & Taha, 2004). The current study In the current study, word and nonword reading and spelling are utilized to investigate how reading and spelling develops in Thai children and to gain insight 123 1030 H. Winskel, K. Iemwanthong into what particular challenges Thai orthography poses to beginning readers. Furthermore, the tasks are designed to focus on reading and spelling of vowels and tones in Thai, which allows us to examine the developmental pathways involved in the acquisition of these subsystems. A number of predictions can be made based on previous research in conjunction with the characteristics of Thai language and its orthography: The relative degree of prominence of grain size used in reading and spelling Based on prior research (Winskel, 2009), we expect a larger grain size, the syllable, to play a prominent role in word recognition in Thai, which in turn will be reflected in the errors made. As monosyllabic words were used in the current study, the syllable level also corresponds to the lexical level. On this basis we can expect more lexico-syllabic errors than phonological errors when reading and spelling words in Thai. If Thai children also primarily use a larger lexical or syllabic grain size when reading nonwords, then this should result in difficulty in reading the nonwords, as they are attempting to use a grain size that is not directly compatible with the requirements of the nonword reading task. This should result in a lexicality effect whereby real words are read more effectively than the corresponding nonwords. In contrast, if children predominantly read alphabetically using grapheme-phoneme correspondence rules, then reading errors should primarily be phonological and consist of nonwords beginning with the first letter of the target word, as occurs in German, Welsh, or Indonesian (Wimmer & Hummer, 1990; Wimmer & Goswami, 1994; Spencer & Hanley, 2003; Winskel & Widjaja, 2007). Furthermore, nonword reading would not be expected to substantially lag behind word reading. The relationship between reading and spelling Previous research indicates that in languages in which phonemes can be spelled in multiple ways, spelling is likely to lag behind reading (Geva et al., 1993; Rahbari, Sénéchal, & Arab-Moghaddam, 2007; Sprenger-Charolles et al., 1998). As Thai has multigraphemic consonants as well as graphemically complex vowel and tone expressions dependent on well developed, stored orthographic knowledge, we can predict that spelling will lag behind reading in beginning readers. This trend has also been found in a previous study on Thai (Winskel, 2009). Vowel development Due to the complex graphemic representation of Thai vowels, we can expect beginning readers to have particular difficulty with the complex vowel combinations, as they require the memorization of a complex combination or pattern of vowels. We can expect this to be reflected in the number of correct responses and substitution errors made by children, and in their substitution of less complex vowel 123 Reading and spelling acquisition 1031 expressions for more complex ones (Table 1). Hence, we can predict that children will give more correct responses for single vowel expressions than simple vowel combinations, and in turn more correct responses for simple vowel combinations than complex vowel combinations. In relation to errors, we can expect the children to substitute less complex vowel expressions for more complex ones. Hindi, like Thai, has a complex system of vowels placed non-linearly above, below, and to the left or right of the consonant. It has been found that Hindi children have specific problems in reading and spelling vowels, short and long vowels in particular (Gupta, 2004). Tone development As the rules associated with the expression of tone in Thai are complex and can be inconsistent or irregular, we can expect tone-related errors to be potentially problematic for children learning to read. For example, in reading and spelling, the incorrect interpretation or selection of homophonous consonant or tone marker can result in the incorrect tone realization. Based on prior research, we can also expect that orthographically visually similar letters to be a source of confusion and consonant clusters to be potentially problematic, as has been found in other languages (Sprenger-Charolles & Siegel, 1997; Stuart, 2005; Treiman & Weatherston, 1992). Methods Participants A total of 60 Thai children ranging in age from 7 to 9 years 8 months were recruited from a public school in a town located in the outskirts of Bangkok. Twenty children were recruited from each of the following grades: Grades 1, 2, and 3. Grade 1 children (9 boys and 11 girls) ranged in age from 7 to 7 years 8 months with a mean age of 7 years 2 months (SD = .20); Grade 2 children (9 boys and 11 girls) ranged in age from 8 to 8 years 10 months with a mean age of 8 years 3 months (SD = .30); Grade 3 children (12 boys and 8 girls) ranged in age from 8 years 10 months to 9 years 8 months with a mean age of 9 years 3 months (SD = .30). All children were native speakers of Thai and had no known reading or learning difficulties as evaluated by their teachers. Thai children typically begin school in Grade 1 when they are 6 or 7 years of age. Prior to that, the majority of children attend Kindergarten where they are taught the letters of the alphabet; the consonants and single vowel letters are taught first. Initially, they are taught how to read real words or syllables composed of a consonant and simple vowel (e.g. /ma:0/ come) without final consonants, then easy words with final consonants are introduced. At the next stage, both monosyllabic and bisyllabic words are typically presented to the children. Gradually, children are taught to read words with more complex combinations of vowels (e.g. or ). 123 1032 H. Winskel, K. Iemwanthong Simple sentences are subsequently introduced to the children. When children begin to learn to read Thai they are given spaced text, but then unspaced text is introduced in Grade 2 (around 7 or 8 years of age). In Thailand the school year starts in May. Children in the current study were tested in September of the school year, so children had been in their current grade for approximately 4 months. Parental permission was obtained, and standard ethical guidelines, both, were adhered to. Stimuli and procedure The test stimuli consisted of two lists of monosyllabic words to be read or written by the children. Words were selected on the basis that they were very common familiar monosyllabic words and also tested children’s knowledge of the vowels and the tone rules in Thai. The words also occurred in the children’s school readers. The first list consisted of 28 vowel-related words and the second list consisted of 29 tone-related words (see Appendices 2 and 3). The vowel word list was designed to assess children’s knowledge of the different vowels and vowel combinations that exist in Thai. The vowel word list consisted of (1) eight single vowels either preceding, following, or occurring above or below the consonant, (2) six simple vowel combinations consisting of any two vowels listed in (1), and (3) fourteen complex vowel combinations consisting of more than two vowels (see Table 1). The tone word list was designed to assess children’s knowledge of the range of tone rules in Thai. In the tone list, eight of the words had class-change clusters in which the first consonant of the cluster, or is silent and is used to change the class of consonant to a high or middle class expression with a corresponding change in tone (e.g. /na:w4/ cold). The other words consisted of representative words with initial consonant selected from each of the three different consonant classes combined with an open or closed syllable, and either a tone marker or zero marked tone marker and short or long vowel. Four tasks were administered to the children: (a) reading words, (b) reading nonwords, (c) spelling words, and (d) spelling nonwords for both the vowel and tone word lists. Nonwords were created by changing the first consonant of the corresponding monosyllabic word, for example the word :an/ month :an/ (both test stimuli were included in either the became the nonword word or nonword task). The consonant that was substituted was selected from the same class of consonant, so that the tone realization remained the same. As homophonous consonants are a potential source of phonological error, particularly for spelling and tone realization, care was also taken to select a similar number of commonly used homophonous consonants for the word and nonword lists; vowel words had ten homophonous consonants and vowel nonwords had eleven; for the tone list there were thirteen homophonous consonants for the word list and fourteen for the nonword list. It is important to note when judging correctness of response in the nonword spelling task that any of the homophonous consonants were acceptable as long as the tone was not affected, whereas in the spelling word 123 Reading and spelling acquisition 1033 task the exact homophone had to be selected. This means that the criterion for judging correctness of responses in the spelling word task were more stringent than in the nonword spelling task. Children were tested on the reading and spelling tasks individually in a quiet room. The order of presentation of the reading and spelling tasks as well as the presentation of the real words and nonwords was counterbalanced across children, as they were asked to read and spell the same words and corresponding nonwords. In addition, the order of presentation of the real words and nonwords was counterbalanced. Children were given practice items to familiarize them with each of the tasks. Children read or spelled the real words separately from the nonword reading or spelling task, and the vowel list was tested prior to the tone list. For the reading task, the words or nonwords were displayed on a laptop screen in a fixed random order. Children read the words and nonwords aloud. For the nonwords, children were told that the words were not real but could be read. Children’s responses were audio-recorded, transcribed and later analyzed for errors. All mispronunciations were noted by a research assistant, a native speaker who was unaware of the purpose of the study. In the spelling task, children were asked to spell the words dictated by the experimenter. Children were all praised for their efforts, regardless of whether they gave the correct response or not. Scoring of responses and error analysis The number of correct responses for all tasks was recorded. In addition, errors were classified as either phonological or lexical errors based on Defior, Martos, and Cary’s (2002) classification system. Phonological errors involved producing another nonword which is incorrect in some way as it involved a deletion, substitution, or inversion of some part of the target nonword (e.g. for /khian4/ write the child responded with /sian4/). Lexical errors involved producing a real word for the /khian4/ write the child responded with / word or nonword (e.g. for khiaw4/ green). An additional more detailed error analysis was conducted. Errors were further classified into the following categories: 1. 2. 3. Unrelated word or nonword. This error response was when children made either a lexical or phonological response that was completely unrelated to the target word or nonword (e.g. for a 0/ town children produced :n0/ money). These types of errors occurred predominantly in the youngest, Grade 1 children. Initial consonant only. This error response was when a child either gave a lexical or phonological response but only used the initial consonant of the target word or nonword in the response they made (e.g. for /plaw1/ empty they produced /paj0/ go). These types of errors also occurred predominantly in the Grade 1 children. Segmentation error. Segmentation errors were when children incorrectly segmented the word. In general, this occurred with words with consonant 123 1034 4. H. Winskel, K. Iemwanthong clusters including the class-change clusters (e.g. for /plaw1/ empty children /pe:0-la:2/). These types of errors responded with a bisyllabic response were only observed in the reading task. Minus one errors. These types of errors consisted of the correct monosyllabic lexical or phonological response except for one error, either an incorrect consonant, vowel, or tone marker (e.g. instead of /khiaw4/ green children /khiaw0/ or for /plaw1/ empty read or wrote / either read or wrote plaw0/), which is similar to the ‘‘minus one errors’’ cited by Sprenger-Charolles et al. (1998) and Fernandes, Ventura, Querido, and Morais (2008). Vowel errors. Reading and spelling errors specific to vowels in the vowel word list were further categorised into the following categories. 1. 2. 3. Substitution for simpler vowel expression. In this case the child substituted a simpler vowel for a more complex vowel combination (e.g. instead of / /pla:0/ fish, or for /t h a2/ believe plaw1/ empty children read or wrote /t h 2/ name). they produced Vowel length error. In these type of examples the child made an error in relation to the vowel length (e.g. for 0/ curly children read or wrote / aw0/ shade or for /phu/ rotten produced /phu:/). Incorrect vowel. In these examples the child made a mistake when either reading or writing one of the vowels or vowel components. Typically, they would confuse vowels that are graphemically similar (e.g. instead of /haj4/ /pr : 0/ brush children produced jar children read or wrote /ho:4/, or for /pre: 0/), or for the complex vowel combinations children made a mistake /gl a0/ salt children produced in one of the vowel components (e.g. for /gl :0/). Tone errors. Reading and spelling errors in the tone word list for the minus one errors were further classified as either adhering to the same tone profile as the target /fa:k2/ bank children word or using a different tone to the target word (e.g. for /fa:k1/ deposit with a different tone profile or either read or spelled the word as with the same tone profile as /pa:k2/, or for /yaw4/ produced / aw4/ /yaw0/). The reason lonely with the same tone profile or with a different profile for this analysis was to assess the awareness of tone when reading and spelling words by the children in the different grades. It is expected that older children will have developed a greater awareness of tone, and hence produce more same tone error responses than different tone responses. Results Comparison of performance across the different tasks and grades In order to compare performance in the word and nonword reading and spelling tasks in the different age groups (see Fig. 1), an analysis of variance was conducted. 123 Reading and spelling acquisition 1035 100 Grade 1 Grade 2 Grade 3 90 80 % correct 70 60 50 40 30 20 10 0 Reading words Reading nonwords Spelling words Spelling nonwords Fig. 1 The percentage of correct responses for reading and spelling of words and nonwords across grade The effect of literacy task (reading, spelling) by word type (word, nonword) on correct responses produced by the children from the three different grades (Grades 1, 2, 3) was analysed using a repeated measures analysis of variance (ANOVA). Literacy task and word type were within-subjects factors and grade level was a between-subjects factor. There was a significant main effect of literacy task, F(1, 57) = 4.24, P = .044, gp2 = .069, as reading performance was superior to spelling performance. There was a significant main effect of word type, F(1, 57) = 455.50, P \ .001, gp2 = .889, as reading or spelling of words was superior to nonwords. There was also a significant main effect of grade, F(2, 57) = 62.99, P \ .001, gp2 = .689 (refer to Fig. 1). There was a significant interaction effect between literacy task and grade, F(2, 57) = 5.53, P = .006, gp2 = .162, and between word type and grade, F(2, 57) = 12.77, P \ .001, gp2 = .309. There were no other significant effects. Post-hoc comparisons were conducted for grade using a Bonferroni adjusted a of .017 to avoid familywise error (Howell, 2002). This revealed that the Grade 1 children scored significantly lower than Grades 2 and 3 children (P \ .001), which were not significantly different. Planned contrasts were conducted. They revealed that both word reading and word spelling had significantly higher correct responses than nonword reading and nonword spelling, respectively, for Grade 1 (reading t(59) = 9.72, P \ .001; spelling t(59) = 6.92, P \ .001), Grade 2 (reading t(59) = 10.82, P \ .001; spelling t(59) = 14.57, P \ .001), and Grade 3 (reading t(59) = 9.14, P \ .001; spelling t(59) = 8.92, P \ .001) children. For the Grade 1 children, the number of correct responses for word reading was significantly higher than word spelling (t(19) = 4.50, P \ .001), and nonword reading was significantly higher than nonword spelling (t(19) = 2.25, P = .04). However, for both the Grades 2 and 3 children, word reading and word spelling, and nonword reading and nonword spelling were not significantly different. There was a high correlation between word and nonword reading for the Grade 1 children (r = .92), which declined with age, although still significant in the older children (Grade 2 r = .78; Grade 3 r = .60). There was also a high correlation 123 1036 H. Winskel, K. Iemwanthong between spelling words and spelling nonwords (Grade 1 r = .77; Grade 2 r = .87; Grade 3 r = .77). High correlations suggest that similar strategies are being utilized for reading words and nonwords, and for spelling words and nonwords (Wimmer & Hummer, 1990; Wimmer & Goswami, 1994). Lexical and phonological error responses Reading. In order to examine the effect of word type (word, nonword) on error type (lexical, phonological) produced by the children from the three different grades (Grades 1, 2, 3) for reading was analysed using a repeated measures analysis of variance (ANOVA) was conducted (see Fig. 2). Word type and error type were within-subjects factors and grade was a between-subjects factor. There was a significant main effect of word type, F(1, 57) = 287.49, P \ .001, gp2 = .835, with more errors made for nonword reading than word reading. There was a significant main effect of error type, F(1, 57) = 5.34, P = .024, gp2 = .086, as there were more lexical errors made than phonological errors. There was also a significant main effect of grade, F(2, 57) = 43.21, P \ .001, gp2 = .603. In addition, there was a significant interaction effect between word type and grade, F(2, 57) = 8.08, P \ .001, gp2 = .221. There were no other significant effects. Post-hoc comparisons were conducted for grade. For the Grade 1 children, more lexical errors were produced than phonological errors for word reading (t(19) = 2.57, P = .019), but there was no significant difference for the Grade 2 and 3 children. For nonword reading for all grades, there was no significant difference between the number of lexical and phonological errors made. Spelling. The effect of word type (word, nonword) on error type (lexical, phonological) produced by the children from the three different grades (Grades 1, 2, 3) for spelling was analysed using a repeated measures analysis of variance 80 Correct Lexical error Phonological error 70 % response 60 50 40 30 20 10 0 Reading words Reading nonwords Spelling words Spelling nonwords Fig. 2 The proportion of correct responses, lexical errors and phonological errors made to the reading and spelling tasks 123 Reading and spelling acquisition 1037 (ANOVA; see Fig. 2). Word type and error type were within-subjects factors and grade was a between-subjects factor. There was a significant main effect of word type, F(1, 57) = 222.01, P \ .001, gp2 = .796, with more errors made for nonword spelling than word spelling. There was a significant main effect of error type, F(1, 57) = 22.34, P \ .001, gp2 = .282, as there were more phonological errors made than lexical errors. There was also a significant main effect of grade, F(2, 57) = 78.94, P \ .001, gp2 = .735. There was a significant interaction effect between word type and grade, F(2, 57) = 8.41, P \ .001, gp2 = .228, and between error type and grade, F(2, 5 7) = 9.15, P \ .001, gp2 = .243. There were no other significant effects. Post-hoc comparisons were conducted for grade. For Grade 1 children, there were more phonological errors than lexical errors for spelling words and nonwords (t(19) = 4.12, P \ .001; t(19) = 3.86, P \ .001, respectively). For the older children, the Grade 2 and Grade 3 children, the effect was not so apparent as there was only a significant difference for spelling words (Grade 2 t(19) = 3.20, P = 005; Grade 3t(19) = 2.18, P = .04), but not for nonwords. In summary, there was a lexicality effect for both reading and spelling, as reading and spelling of words was more accurate than the corresponding nonword reading and spelling tasks in all age groups. Furthermore, it was found that performance in general was better on reading than spelling. This was more pronounced in the Grade 1 children than in the older children. There was rapid development in literacy skills between Grade 1 and the older Grade 2 and 3 children. For reading it was found that there were more lexical error responses made than phonological errors, however, the reverse trend was apparent for spelling. Developmental pathways in reading and spelling Reading. Unrelated and initial consonant only errors predominantly occurred in the youngest Grade 1 children with a rapid reduction in these types of errors in the older Grades 2 and 3 children (refer to Fig. 3). These types of errors indicate that the children are having difficulty reading. Furthermore, these types of errors in Grade 1 children were predominantly real word errors rather than phonological errors for word reading and nonword reading for both the unrelated errors (reading: words 84% lexical, 16% phonological; nonwords 97% lexical, 13% phonological) and initial consonant errors (reading: words 67% lexical, 33% phonological; nonwords 80% lexical, 20% phonological). So when reading, the youngest Thai children commonly responded with either an unrelated word or with a word that had the same initial consonant only as the target word. Refusals were not apparent in the Thai children; however, this could be a product of the role of the child, the Thai education system, and the emphasis in Thai culture on obedience and compliance. A common error response in all grades, but particularly the older children, was to produce minus one errors (a correct syllabic response except for one error). This type of error was primarily a phonological error due to the use of the incorrect consonant, vowel, tone marker (e.g. instead of /khiaw4/ green children produced ‘‘ /khiaw0/’’), which in turn lead to the incorrect tone realisation. 123 1038 H. Winskel, K. Iemwanthong 400 unrelated initial consonant only segmentation error minus one errors 350 frequency 300 250 200 150 100 50 0 word noword reading reading word nonword word spelling spelling reading GRADE 1 noword reading word nonword word spelling spelling reading GRADE 2 noword reading word nonword spelling spelling GRADE 3 Fig. 3 Developmental patterns in error type across task and grade Segmentation errors were mainly made to the words that had complex consonant /plaw1/ clusters with the preposed vowels occurring prior to the consonant (e.g. /pe:-0la:2/), or with a silent class-change consonant (e.g. empty was read as / aw4/ lonely was read as /he0- a:0/). Spelling. Similar to the reading task the unrelated and initial consonant only errors were predominantly found in Grade 1 children (refer to Fig. 3). Due to the characteristics and demands of the task, there were more phonological than lexical errors made to the spelling task than the reading task. A common error response, similar to the reading task, was to produce a minus one error with either the incorrect consonant, vowel or tone marker. This was primarily due to children using the incorrect homophonous consonant or tone marker. The use of homophonous consonants in nonword spelling was acceptable as long as the tone of the word was not changed, however, when spelling words the exact homophonous consonant for that particular word had to be used to be deemed correct. This may account for the larger number of phonological errors found in spelling words than spelling nonwords. Vowel development It was predicted that there would be more correct responses for the single vowel than the simple vowel combination, and in turn more correct responses for the simple vowel combination than the complex vowel combination. In order to 123 Reading and spelling acquisition 1039 examine the effect of vowel type (single, simple combination, complex combination) on proportion of correct responses produced by the children from the three different grades (Grades 1, 2, 3) a repeated measures analysis of variance (ANOVA) was conducted. Vowel type was a within-subjects factor and grade was a betweensubjects factor. There was a significant main effect of vowel type, F(2, 57) = 57.54, P \ .001, gp2 = .502, and a significant main effect of grade, F(2, 57) = 52.54, P \ .001, gp2 = .648. In addition, there was a significant interaction effect between vowel type and grade, F(2, 57) = 14.40, P \ .001, gp2 = .336. Bonferroni post hoc analysis at .05 level revealed that Grade 1 responses were significantly lower than Grade 2 which in turn were lower than Grade 3. There was a significant interaction between vowel type and grade, F(2, 57) = 14.40, P \ .001, gp2 = .336. The proportion of single vowel responses were significantly higher than the simple vowel combinations (t(59) = 2.42, P = .02), which in turn were significantly higher than the complex vowel combinations (t(59) = 7.85, P \ .001). For the Grade 1 children the proportion of single vowel responses were significantly higher than the simple vowel combinations (t(19) = 3.61, P = .002), which in turn were significantly higher than the complex vowel combinations (t(19) = 6.79, P \ .001). For Grades 2 and 3 only the simple vowel combinations were significantly higher than the complex vowel combinations (t(19) = 4.76, P \ .001; t(19) = 3.33, P = .004), as the single vowel and simple vowel combinations were not significantly different (Table 3). For spelling the effect of vowel type (single, simple combination, complex combination) on proportion of correct responses produced by the children from the three different grades (Grades 1, 2, 3) was analysed using a repeated measures analysis of variance (ANOVA). Vowel type was a within-subjects factor and grade was a between-subjects factor. There was a significant main effect of vowel type, F(2, 57) = 39.62, P \ .001, gp2 = .410, and a significant main effect of grade, F(2, 57) = 123.62, P \ .001, gp2 = .812. Bonferroni post hoc analysis at .05 level revealed that Grade 1 was significantly lower than Grade 2, which in turn was lower than Grade 3 (P \ .001). There was a significant interaction between vowel type and grade, F(2, 57) = 7.51, P \ .001, gp2 = .208. The proportion of single vowel responses were significantly higher than the simple vowel combinations (t(59) = 4.06, P \ .001), which in turn were significantly higher than the complex vowel combinations (t(59) = 4.09, P \ .001). For the Grade 1 children the proportion of single vowel responses were significantly Table 3 The proportion of correct responses to the different vowel types for reading and spelling Grade 1 Grade 2 Grade 3 Reading Spelling Reading Spelling Reading Spelling Single vowel 0.66 (.23) 0.48 (.12) 0.89 (.19) 0.94 (.12) 0.88 (.14) 0.93 (.09) Simple vowel combination 0.46 (.24) 0.37 (.23) 0.89 (.15) 0.83 (.17) 0.90 (.13) 0.88 (.15) Complex vowel combination 0.15 (.21) 0.11 (.16) 0.74 (.21) 0.81 (.19) 0.79 (.16) 0.81 (.21) 123 1040 H. Winskel, K. Iemwanthong higher than the simple vowel combinations (t(19) = 2.20, P = .04), which in turn were significantly higher than the complex vowel combinations (t(19) = 4.97, P \ .001). For Grades 2 and 3 only the single vowel responses were significantly higher than the simple vowel combinations (t(19) = 2.74, P \ .01; t(19) = 2.44, P = .03), as the simple vowel and complex vowel combinations were not significantly different. From error analysis, it was also found that the Grade 1 children in particular had a tendency to substitute simpler vowels for more complex vowel combinations (Grade 1 19%, Grade 2 10%, Grade 3 9%). In addition, there were incorrect vowel errors (Grade 1 6%, Grade 2 18%, Grade 3 14%) and vowel length errors (Grade 1 5%, Grade 2 4%, Grade 3 7%) made by all children. Incorrect vowel errors were due to selecting visually similar vowels (e.g. /o/ for /aj/), or in the complex vowel was produced combinations one of the component vowels was incorrect (e.g. instead of ). Tone development For reading and spelling of the tone words and nonwords, the minus one errors were further classified as either adhering to the same tone profile as the target word or using a different tone to the target word. Children when reading words tended to respond with a different tone to the target word rather than retaining the same tone profile. There were significantly more different than same tone responses for all grades (Grade 1 t(19) = 5.55, P \ .001; Grade 2 t(19) = 3.36, P = .003; Grade 3 t(19) = 6.02, P \ .001). Similar significant results were found for nonword reading (Grade 1 t(19) = 6.2, P \ .001; Grade 2 t(19) = 7.63, P \ .001; Grade 3: t(19) = 10.11, P \ .001). For spelling words there were only significantly more different than same tone responses for the Grade 1 children (t(19) = 5.65, P \ .001), but not for the Grade 2 or 3 children. However, for the nonword spelling task, similar to the reading task, there were significantly more different than same tone responses for all grades (Grade 1 t(19) = 5.89, P \ .001; Grade 2 t(19) = 4.13, P = .001; Grade 3 t(19) = 5.57, P \ .001). For spelling words in the older children, the same and different tone responses were not significantly different, which could be interpreted as indicating that the older children have an enhanced awareness of tone for spelling in comparison to the younger children (Table 4). Discussion In the current study, we examined the development of reading and spelling of words and nonwords in Thai children from Grade(s) 1, 2, and 3. We were interested in the particular challenges that this distinctive orthography poses to beginning readers. One of the major aims was to investigate the prominent grain size used when reading and spelling words and nonwords in Thai, an orthography which shares common characteristics with both alphabetic and syllabic scripts. A lexicality effect, 123 Reading and spelling acquisition Table 4 The same and different error tone responses made to the reading and spelling tasks Reading Spelling Words Same tone Nonwords Different tone Words Nonwords Same tone Different tone Same tone Different tone Same tone Different tone Grade 1 2.40 (1.96) 6.15 (3.51) 2.70 (2.36) 10.40 (5.39) 2.90 (2.22) 7.00 (3.34) 3.30 (2.00) 9.05 (5.77) Grade 2 0.80 (.95) 2.25 (1.92) 1.55 (1.43) 7.75 (4.06) 1.15 (1.39) 1.90 (2.36) 4.15 (1.53) 7.40 (3.84) Grade 3 0.80 (.89) 2.70 (1.30) 1.90 (1.92) 9.50 (2.84) 1.05 (1.43) 2.00 (2.64) 2.70 (2.43) 6.30 (4.01) 1041 123 1042 H. Winskel, K. Iemwanthong a word-advantage was apparent for both reading and spelling, as children performed substantially better on the word reading and spelling tasks than on the corresponding nonword reading and spelling tasks. After 4 months of school, the Grade 1 children achieved 42% correct for reading words and 24% for reading the corresponding nonwords, and 32% correct for word spelling and only 17% for nonword spelling. It was noticeable that reading and spelling performance rapidly increased between the youngest Grade 1 children and the Grades 2 and 3 children, which concurs with results found in a previous study conducted on Thai (Winskel, 2009). However, even for the oldest children, the Grade 3 children, nonword reading and spelling still significantly lagged behind word reading and spelling (86% correct for word reading, 59% for nonword reading, 87% for word spelling, and 62% for nonword spelling). These results are more comparable with results found for children learning to read relatively inconsistent orthographies such as English, rather than more transparent orthographies such as German. Children learning to read German do not have difficulty reading nonwords as they have ready access to grapheme-phoneme conversion rules, which is compatible with the requirements of the nonword reading task in German, whereas English children have difficulty reading nonwords due to the inconsistency of the orthography as well as apparently being overly reliant on using a larger grain size, whole word or lexical strategy, and ‘‘having a rather underdeveloped alphabetic strategy’’ to read the nonwords (Wimmer & Goswami, 1994, p. 100). The lexicality effect, the better performance by the Thai children on reading and spelling of words than nonwords, suggests that a larger grain size (lexical or syllabic) is being utilised when reading and spelling Thai. If we examine the proportion of lexical and phonological errors made to the different tasks, we can make additional inferences about the grain size being used. For word reading across all the children, there were significantly more lexical errors (59%) than phonological errors (41%). For reading nonwords, there were still a relatively high but slightly reduced proportion of lexical errors (lexical: 53% and phonological: 47%). In the Grade 1 children, the effects were more pronounced with 61% lexical errors and 39% phonological errors for word reading; 56% lexical errors and 44% phonological errors for nonword reading. The relatively high proportion of lexical errors in conjunction with the relatively poor performance on nonword reading and the high correlation between word and nonword reading, suggests that Thai children, particularly the youngest Grade 1 children, were predominantly using a larger grain size (syllabic or lexical) to read both words and nonwords. For spelling, in contrast to reading, there were significantly more phonological errors (words 64% and nonwords 57%) than lexical errors (words 36% and nonwords 43%). This trend was more pronounced in the Grade 1 children than the older children, as there were 64% phonological errors and 36% lexical errors for spelling words and 63% phonological errors and 37% lexical errors for spelling nonwords. The relatively higher proportion of phonological errors in the spelling than reading tasks reflects the particular demands of the task and the characteristics of Thai orthography; the multigrapheme-phoneme mapping and the complex graphemic expression of the vowel and tone subsystems. Effective spelling is 123 Reading and spelling acquisition 1043 dependent on the retrieval of stored orthographic representations; hence well developed orthographic knowledge for spelling is required, which is particularly under-developed in the youngest, inexperienced beginning readers (Rahbari & Sénéchal, 2009). Furthermore, in order to become a proficient speller, additional orthography-specific contextual and linguistic knowledge (besides those for reading) is required, which includes grammatical and morphological knowledge (Alcock & Ngorosho, 2003; Cossu et al., 1995; Rahbari & Sénéchal, 2009; Rickard Liow & Lee, 2004). The rapid increase in children’s spelling performance in Grade 2 reflects children’s developing orthographic skills and knowledge. The high correlation between word and nonword spelling in conjunction with the relative proportion of phonological and lexical errors made in both tasks, suggests that similar strategies are being utilized by Thai children when spelling words and nonwords. However, results are somewhat contradictory for spelling, as there was a lexicality effect but in addition more phonological than lexical errors were made by the Grade 1 children. In the older Grade 2 and 3 children, there were more phonological than lexical errors for spelling words but not for spelling nonwords. This difference between the phonological errors for spelling words and nonwords in the older children could be due to the effect of homophonous consonants. In the nonword spelling task any of the homophonous consonants were deemed as correct as long as the tone was not affected, whereas in the spelling task the exact homophone needed to be selected. In transparent regular orthographies, word recognition skills develop rapidly with relatively few errors for both word and nonword reading and spelling by the end of the first year of formal instruction (Seymour et al., 2003). However, similar levels of competence for children learning to read less regular orthographies, such as English, Danish, or French takes a prolonged time to develop. In comparison to these other orthographies, Thai reading and spelling development is also relatively delayed, as although children scored 86% correct by Grade 2 for reading and spelling words, they still lagged behind in nonword reading and spelling with only approximately 60% correct in Grade 2 and Grade 3. Thai children are quite competent in word reading and spelling by Grade 2, but nonword reading and spelling is still problematic even for the Grade 3 children. This is particularly surprising considering that the only difference between the monosyllabic words and nonwords was the initial consonant. The prediction that Thai children would perform better on reading than on spelling was supported. It was found that the youngest Thai children were more accurate in reading than spelling words, and in turn read accurately more nonwords than they could spell. This is similar to results found in a previous study on Thai (Winskel, 2009), as it was also found that Grade 1 children could read correctly more words (Grade 1 82%, Grade 2 96%) than they could spell (Grade 1 70%, Grade 2 94%). Children in that study had been in their current grade for 9 months, whereas in the present study children had been in their current grade for only 4 months. The lower performance on spelling and the relatively high proportion of phonological errors than lexical errors on the spelling tasks, in particular the spelling of words, reflects the relative imbalance between phoneme-grapheme (PG) 123 1044 H. Winskel, K. Iemwanthong and grapheme-phoneme (GP) mapping and the complex graphemic expressions for vowels and tones in Thai. Notably, in both these studies, the Grade 1 children lagged substantially behind in word spelling in comparison with word reading ability, but by Grade 2 this disparity had dissipated. It appears that difficulties associated with learning to spell Thai words were to a large extent overcome by Grade 2. The differences in performance in the two studies on Thai are presumably due to the length of time (in months) children had spent in their current grade and the types of word stimuli used to assess the children’s reading and spelling ability. In the current study, the words selected were designed to assess children’s knowledge of the complex vowel and tone subsystems. More detailed error analysis can contribute to our understanding of the different cognitive strategies that children utilize and the particular challenges that the orthography poses to beginning readers, as well as the developmental pathways involved in acquiring the specific rules of the written language they are learning (Abu-Rabia & Taha, 2004; Worthy, 1990). The youngest children, the Grade 1 children, made a high proportion of unrelated and initial consonant errors, which reflects their poorly developed phonological and orthographic skills, and inability at this stage to decode or encode the words and nonwords. These errors were also predominantly lexical errors for reading, which supports the notion that these children are using predominantly a lexical strategy when reading. The youngest children when reading also had a tendency to incorrectly segment the monosyllabic words with consonant clusters, including the class-clusters, into two syllables. These types of errors, however, rapidly declined in the older children as their phonological and orthographic skills developed. Children acquired the single vowels prior to the simple vowel combinations, and the more complex vowel combinations were acquired later (as reflected by the number of correct responses). Additional evidence supporting this order of acquisition was that Grade 1 children, in particular, frequently substituted simpler vowels for more complex vowel combinations. This confirms that beginning readers do find the complex Thai vowels challenging when learning to read and write Thai. In addition, children had difficulty as reflected in the errors produced, with vowel length and visually similar vowels, which concurs with results found in Hindi (Gupta, 2004). However, by Grade 2, children had largely acquired the complex system of vowels and made relatively few vowel-related errors. The graphemic expression of Thai vowels is complex, but there is consistent mapping between phonemes and graphemes. A common error response in all children was to produce the correct response apart from one error, termed ‘‘minus one errors’’. These errors were primarily due to the incorrect selection of consonant, vowel, or tone marker. Tone errors were still apparent in the older children, which were largely due to selection of the incorrect homophonous consonant or tone marker, which affected the tone realisation of the syllable. As expected the complex rules associated with the expression of tone proved problematic for Thai children. Furthermore, children in general tended to produce ‘‘minus one errors’’ with an incorrect rather than correct tone profile for reading, which suggests that tone expression takes a secondary role to the expression of consonants and vowels when reading. In relation 123 Reading and spelling acquisition 1045 to spelling words, this effect was only apparent in Grade 1 children but not Grade 2 or 3 children, which suggests that the older children have an enhanced awareness of tone particularly when spelling real words in comparison to the younger children. As predicted, children tended to make errors on the words involving consonant clusters; when reading they either tended to not pronounce the second consonant in the cluster or segment the word incorrectly, or when spelling they tended to drop the second consonant. This difficulty with consonant clusters is similar to results found in other studies (Sprenger-Charolles & Siegel, 1997; Stuart, 2005; Treiman & Weatherston, 1992; Treiman, 1993). Specific to Thai, the younger children had difficulty with the orthographic class-change clusters, in which the first consonant of the cluster, or is silent. When reading children tended to pronounce the silent / aw4/ was pronounced consonant and segment the word inappropriately (e.g. /he:4- a:0/) and when spelling, these silent class-change consonants were as often omitted. We were particularly interested in the errors that persist in the older children as this gives us additional clues about the specific challenges Thai orthography poses to the child. The persistent errors found in the current study for Thai children predominantly involved the incorrect selection or usage of homophonous consonants and the incorrect expression of tone. Older children’s errors typically had the correct vowel expression but the consonant and/or tone was incorrect. The tone rules for Thai are complex and irregular, and hence these persistent errors confirm that tone rules are problematic for beginning readers. However, it is important to consider that in the tasks used in the current study, children were required to read and spell single words in isolation, whereas when reading words more naturally in continuous text, readers use contextual cues and top-down processing to aid in the recognition of words. As Thai also does not have interword spaces and has multifunction words that change function dependent on context, we can expect Thai readers to be fairly reliant when reading continuous text on top–down processes to both segment the text into words and for word identification. Thai readers may not need to have detailed knowledge of the tone rules and use bottom–up processes for identifying lexical tone on a syllable when reading continuous text, as instead, they can use contextual cues to assign the correct tone to the word or syllable. In Hebrew, it has been found that the cost of reading words without vowels (as occurs in adult text) in isolation disappears once readers are presented with sentences or continuous text, as they are then able to use morphological information that is available in full sentences (Frost, 2006). This could also be the case for reading lexical tone by Thai readers. There is a commonly held view that there are shared representations that underlie both the reading and spelling acquisition process (Curtin et al., 2001; Holmes & Carruthers, 1998), however, maybe we need to modify this claim at least in relation to orthographies that are more irregular or unbalanced in terms of PG and GP correspondence rules. The difference in proportions of lexical and phonological errors made in the spelling and reading tasks suggests that there are qualitatively different strategies and processes being utilized for reading and spelling by 123 1046 H. Winskel, K. Iemwanthong beginning readers of Thai, which changes with age as orthographic and phonological knowledge develops. In Persian orthography, which is also more inconsistent in terms of phoneme-grapheme correspondences than grapheme-phoneme correspondences, it has been found that different processes are involved in reading and spelling. Persian adults relied more on lexical processes to read words, whereas phonological processes were more dominant for spelling words (Rahbari & Sénéchal, 2009), which is similar to results found for Thai. Different orthographies have unique linguistic characteristics that pose different challenges to beginning readers and affect the reading and spelling developmental process (Abu-Rabia & Taha, 2004). Thai has its own distinctive orthography, which has complex graphemic expressions, particularly in relation to non-linear vowel combinations and for the expression of tone that operates at the syllable level, and requires the memorisation of a complex combination of vowels and diacritics. In the current study, it was found that in comparison to more transparent orthographies such as German, Welsh, or Indonesian, a relatively high proportion of lexical errors were produced by the Thai children, particularly by the youngest Grade 1 children. Nonword reading and spelling proved problematic to even the oldest children, the Grade 3 children. It appears that children are predominantly using a larger lexical or syllabic grain size to read both words and nonwords. This is particularly apparent in the youngest children, but declines in the older children as their reading skills develop. Spelling was found to lag behind reading in the youngest children, which reflects the PG mapping imbalance, the multigrapheme to phoneme mapping of consonants in conjunction with the complex graphemic representation of Thai vowel and tone expressions. However, these problems were largely overcome by Grade 2 with relatively few of these error types persisting. The main errors that persisted were related to homophonous consonants and the expression of tone. Larger grain size, lexico-syllabic as well as phonemic grain size appears to be important when reading. This reflects the hybrid characteristics of the orthography. In order to become a skilled reader of Thai, it appears that a mixed strategy and ability to use both larger and smaller phonological units is advantageous. In future studies, it is important to extend this line of research to investigate in greater depth how the relative imbalance between PG and GP mapping in different orthographies as well as orthographic-specific characteristics, affects the developmental patterns and strategies used by children learning to read and spell typologically distinct orthographies. Appendix 1 See Table 5. 123 Reading and spelling acquisition 1047 Table 5 Thai initial consonants (IPA symbols are in parenthesis) Place of articulation Bilabial Labio- Alveola dental r Palatal Velar Glottal Manner of articulation Voiceless aspirated (ph) (tçh) (th) Stop (kh) Voiceless unaspirated (p) (t) (b) (d) (m) (n) (tç) (k) (?) Voiced Nasal ( ) Fricative (f) (h) (s) Lateral (l) Trill (r) Approximant (w) (j) 123 1048 H. Winskel, K. Iemwanthong Appendix 2 See List 1. 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