Adults’ knowledge of phoneme–letter relationships is phonology based and flexible

Despite the importance of phonemic awareness in beginning literacy, several studies have demonstrated that adults, including teacher trainees, have surprisingly poor phonemic skills. Three experiments investigated whether adults’ responses in phonemic awareness and spelling segmentation tasks are based on units larger than single letters and phonemes. Responses often involved large units, and they were influenced by sonority and syllable structure. Participants who performed a phoneme counting task before a spelling segmentation task produced significantly more phoneme-based responses and fewer onset–rime responses than participants who first counted words in sentences. This training effect highlights the flexibility of adults’ strategies. Although adults are capable of phoneme-based processing, they sometimes fail to use it. One of the best documented findings in the study of literacy development is the importance of phonological awareness, particularly phonemic awareness, in the learning of alphabetic writing systems (e.g., Bradley & Bryant, 1983; Caravolas, Hulme, & Snowling, 2001). Beginning readers often have problems conceptualizing words as sequences of phonemes (e.g., Liberman, Shankweiler, Fischer, & Carter, 1974), and illiterate adults and readers of nonalphabetic writing systems also perform poorly in phonemic awareness tasks (e.g., Morais, Cary, Alegria, & Bertelson, 1979; Read, Zhang, Nie, & Ding, 1986). Because a degree of phonemic awareness appears necessary for the acquisition of alphabetic literacy, and because learning to read and spell in turn improves phonemic awareness, skilled readers have been assumed to possess good phonemic skills. However, several studies have revealed that adults do not always perform well in tasks of phonemic knowledge (e.g., Scarborough, Ehri, Olson, & Fowler, 1998; Scholes, 1993). Some of these studies have tested teacher trainees (e.g., Mather, Bos, & Babur, 2001; Moats, 1994; Serrano, Defior, & Martos, 2003), and their poor performance is especially worrisome. If literacy teachers are to foster children’s phonemic skills, as research (e.g., Bryant, MacLean, Bradley, & Crossland, 1990; Hatcher, Hulme, & Ellis, 1994) suggests that they should, then the results suggest that teachers may not © 2007 Cambridge University Press 0142-7164/07 $12.00 Applied Psycholinguistics 28:1 96 Lehtonen & Treiman: Adults’ knowledge of phoneme–letter relationships be as phonemically aware as they should be in order to teach and evaluate young children. If adults do not always use phonemes as their response units in phonemic awareness tasks, what do they do instead? Some researchers have claimed that adults often respond to oral phonemic awareness tasks on the basis of letters. Ehri (1985, p. 342) suggested that “the visual forms of words acquired from reading experiences serve to shape learners’ conceptualizations of the phoneme segments in those words.” Thus, the spelling of a word could increase the salience of one phoneme or depress the prominence of another. Studies using several different tasks and participant populations support the notion of letter-based responding. The teacher trainees tested by Moats (1994) made a number of errors that appeared to reflect use of letters rather than phonemes. For example, participants probably counted two phonemes instead of three for ox because this word is spelled with two letters. Letter-based responses were also found by Ehri and Wilce (1980), who reported that fourth graders more often detected a /t/ in words such as pitch and catch, which include a t in their spellings, than in words such as rich or much, and by Ventura, Kolinsky, Brito-Mendes, and Morais (2001), for Portuguese speakers. Adults’ errors in phonemic awareness tasks are not always explained by use of letters, however. Sometimes adults use units that are larger than single phonemes. Scarborough et al. (1998) reported that eighth graders’ errors in phoneme deletion and counting tasks almost always consisted of removing a portion larger than a single phoneme and undercounting phonemes. In a task in which participants had to underline the letters or letter groups that represented individual “sounds” in written words, Scarborough and colleagues (1998) found that adults did not systematically use either a letteror a phoneme-based strategy. Rather, participants often marked as a unit letters that represented two or more phonemes. These responses appeared to respect such linguistic structures as onsets (initial consonant clusters) and rimes (vowel + final consonant units). When Connelly (2002) administered a similar task to university students, he found that a group that received 10 min of training on phoneme–grapheme correspondences beforehand made significantly more phonemic responses than an untrained control group, although neither group was close to ceiling. This result suggests that, although adults often prefer to use units larger than single phonemes and single letters, their strategies are flexible. The research to date suggests that adults sometimes use units larger than single phonemes when linking sounds to spellings, but it has not systematically examined the linguistic factors that might explain these large-unit responses. At least two types of phonological attributes could be influential. The first is sonority, which refers to the loudness or vowel likeness of phonemes. Vowels are the most sonorant phonemes, followed in descending order by liquids (/r/, /l/), nasals (/m/, n/, /N/), and obstruents (fricatives, stop consonants; see International Phonetic Association, 1999, for a key to the phonemic notation). Several researchers (e.g., Stemberger, 1983; Treiman, 1984) have suggested that postvocalic liquids, such as the /l/ of milk, are linked with the vowel of the syllable. An obstruent, such as the /f/ of gift, is more strongly bound to the following consonant. Thus, because of the way in which sonority organizes the syllable, a final consonant cluster is most likely to be processed as a unit when its first consonant is an obstruent. Postvocalic nasals are intermediate in their affinity with the phonemes preceding and following them. The studies mentioned above dealt with spoken words, however, and they do not answer Applied Psycholinguistics 28:1 97 Lehtonen & Treiman: Adults’ knowledge of phoneme–letter relationships our questions about adults’ knowledge of phonological units that correspond to spellings. A second phonological factor that could contribute to adults’ large-unit responses involves the names of letters. People may be especially likely to treat as units phonemes such as /ε/ and /l/ that make up the name of a letter. Supporting this view, Treiman and Cassar (1997) found that adults were more likely to judge that a two-phoneme sequence consisted of only one phoneme when that sequence was a letter name than when it was not. In the first of the experiments reported here, we examined adults’ performance in several tasks of phonemic knowledge, asking whether their responses were based on individual phonemes, individual letters, or larger units. One task we used was a spelling segmentation task modeled after that of Scarborough et al. (1998) and Connelly (2002). This task investigated adults’ understanding of the links between the letters in printed words and the phonemes to which they correspond. We used monosyllabic words that varied in the sonority of the preand postvocalic consonants and in whether they contained letter-name segments. We hypothesized that liquids and nasals would be grouped with preceding vowels more often than obstruents and that letter-name sequences such as /εl/ would sometimes be treated as units. Such results would suggest that adults do not always conceive of letters in printed words as representing individual phonemes. They group phonemes into larger units in ways that are systematically influenced by phonological factors. The participants in Experiment 1 also performed two oral phonemic awareness tasks: phoneme deletion and phoneme counting. The stimuli, which were spelled with initial and final digraphs, were designed to test the idea that adults’ errors in phonemic awareness tasks are primarily based on use of letters. If so, all phonemes spelled with digraphs would often be treated as made up of two units. If phonology is important, however, the different phonological characteristics of the phonemes spelled by the digraphs may lead to different patterns of performance across digraphs.