To what extent do orthographic units in print mirror phonological units in speech?

transcript

Journa l o f Psychol inguis t ic Research, Vol. 23, No. 1, 1994

To What Extent Do Orthographic Units in Print Mirror Phonological Units in Speech?

R e b e c c a T r e i m a n ~

Three exper iments were p e r f o r m e d to examine the degree to which the or thographic units in pr in ted syl lables reflect the phono log ica l units in speech. Two o f the experin,ents used a pronuncia t ion decision task in which subjects had to de termine whe ther a nonword sounded like a real w ord when pronounced . The third exper iment used a lexical decis ion task. In all three experiments , ev idence was obtained for or thographic units that correspond to onsets and rimes. The evidence was equivocal on whe ther the phonological category o f the consonant that f o l lows the vowel affects the internal s tructure o f the or thographic r ime as it does the s tructure o f the phonolog ica l rime. Tire results are d iscussed in terms o f the role o f l inguistic units in tire process ing o f print.

Linguist ic and psycholinguist ic evidence suggests that the English words are

more than simple linear strings of phonemes. Instead, the phonemes within

spoken words are organized into groups that are larger than a phoneme but smaller than a syllable. The two primary units in the spoken syllable are the

o n s e t and the r i m e . The onset is the initial consonant or consonant cluster. The rime is the vowel and any fol lowing consonants . Thus, /d r l f t /has the

This research was supported by NSF Grants BNS 8109892 and SBR 9020956. I thank Shellie Haut-Rogers, Peggy Ericson, Jennifer Gross, and Denise Berch for their assistance and Andrea Levitt, and Alice Healy for detailed comments on a draft of the manuscript. The manuscript was written, in part, while the author was on sabbatical leave at the MRC Applied Psychology Unit, Cambridge, England.

Address all correspondence to Rebecca Treiman, Department of Psychology, Wayne State University, 71 West Warren, Detroit, Michigan 48202 or via e-mail: treiman@math.wayne.edu.

0090-6905/94/0100-0091507.00/0 ~ 1994 Plenum Publishing Corporation

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onse t /d r / and the rime/lft/ . 2 Evidence for phonological onset and rime units comes from studies of speech perccption and speech production as well as studies of word games and short-term memory for speech (e.g., Claxton, 1974; Cutler, Butterfield, & Williams, 1987; Fo,vler, 1987; Fowler, Treiman, & Gross, 1993; MacKay, 1972; Treiman, 1983; Treiman & Danis, 1988; Yaniv, Meyer, Gordon, Huff, & Sevald, 1990; see Treiman, 1989, for a review). For example, when people are asked to listen to a list of CVC nonsense syllables (C = consonant; V = vowel) and repeat them back in order, they often produce errors that join the onset of one to-be-remembered syllable with the rime of another (Treiman & Danis, 1988). In this and other tasks, the initial consonant (or consonant cluster) behaves somewhat inde- pendently of tile following vowel. At the phonetic level, in contrast, the articulation of a consonant may vary depending on the identity of the vowel that follows it (see Ladefoged, 1982). The tasks that show evidence for onset and rime units tap a level of processing higher than the phonetic level.

Tile internal structure of the syllable 's rime appears to depend, in part, on the phonological category of the consonant that follows the vo,vel (Der- ,ring & Nearey, 1991; Derwing, Nearey, & Dow, 1987; Fowler, 1987; MacKay, 1978; Stemberger, 1983; Treiman, 1984; Treiman & Danis, 1988). When that consonant is a liquid, / r /o r /1 / , the vowel and the liquid form a strong unit. In a syllable such as /kwdt/, the rime contains the subunits/II / and /t/. The first of these units is called the syllable peak and the second is called the coda. The pattern is different when the consonant after the vowel is an obstruent such a s / f / , / s / , / p / , or/k/ . I n / d r i f t / , / f / a n d / t / f o r m a stronger unit than do /J/ and /ft. The vowel here constitutes the peak and the consonant cluster the coda. Thus, VCC rimes have the structure VC/C ,vhen the consonant after the vowel is a liquid and the structure V/CC when the consonant after the vowel is an obstruent. When the postvocalic consonant is one of the English nasals /m/, /n/, or/rj/, the results are somewhat variable. Neither type of unit appears to predominate in this case. These differences in the strength of the vowel--consonant bond may reflect the sonority or vowel likeness of the consonant. Liquids, which are high in sonority, form strong units with a preceding vowel. Nasals, which are lower in sonority, are less closely allied with vowels. Obstruents, which are the least sonorant type of consonant, show the weakest vowel--consonant bonds.

The evidence reviewed so far concerns the structure of spoken syllables. To what extent do the units in printed words mirror the units in spoken words? When reading the word DRIFT, for example, do people group the letters D and R, which correspond to the onset of the spoken syllable, and the letters I, F, and T, which correspond to the rime? Are F and T more

:/I/as in bit, /1]/ a s in sing.

Orthographic and Phonological Units 93

likely to behave as a unit than I and F, in line with the peak/coda structure of the spoken word? Similarly, do the I and L of QUILT form a stronger unit than the L and T, just as/II / is a more cohesive unit than /It/? These are the questions that motivated the present research. Answers to these questions should help illuminate the role of phonology in reading. In particular, they should help to show whether printed words are parsed into linguistically based units as part of the recognition or pronunciation processes.

For purposes of discussion, issues related to the role of syllable structure in the processing of printed words may be divided into two parts. First, are printed words parsed into orthographic units that correspond to onsets and rimes? Second, if onset/rime parsing occurs, does the internal structure of the orthographic rime mirror the internal structure of the phonological rime with respect to the effect of the type of postvocalic consonant? The evidence on each of these questions will be discussed in turn.

The Division Between Orthographic Onsets and Orthographic Rimes

Treiman and Chafetz (1987) asked whether printed words contain units that correspond to the onset and rime units of spoken words. T`,vo of their experiments involved an anagrams task in which subjects saw a display such as S K U N K PR OMP and had to determine as quickly as they could `,vhether a word was present. In this example, of course, the fragments make up the word SKUNK. The word has been divided into SK and UNK, that is, between the onset and the rime of its spoken form. In other trials, words were divided after the vowel, that is, within the rime of the spoken syllable. An example of such a trial is S K U N K PRO MP. Subjects responded faster ,,',,hen words such as SKUNK were divided into SK and UNK than when they `,vere divided into SKU and NK. With words such as SPREE, whose spoken forms have three-phoneme onsets, a SPR EE division was easier than a SP REE division.

The third experiment reported by Treiman and Chafetz (1987) used a lexical decision task. The stimuli were words and nonwords that were spelled with two consonant letters followed by a vowel letter followed by two final consonants. The stimuli were divided with two slashes either after the initial consonant cluster, the CC//VCC division, or after the vowel, the CCV//CC division. Subjects responded more quickly when the stimuli were presented as CC//VCCs than when they were presented as CCV//CCs. This was true for positive responses; subjects were faster to say that DR//IFT was a word than that DRI//FT was a word. It was also true for negative responses; subjects were faster to say that FL//UNT was not a word than that FLU//NT was not a word. Importantly, the superiority for CC//VCC parsing over CCV//CC parsing was as strong when the initial consonant cluster

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corresponded to two phonemes, as in DRIFI ' , as when it corresponded to a single phoneme, as in THING. These results suggest that initial consonant clusters behave as units in the lexical decision task whether they symbolize a single phoneme or a cluster.

Bowey (1990, 1993) used a partial priming technique in which a target word was briefly preceded by a masked bigram or trigram. For example, the target word HAIL was preceded by AIL (primed condition) or a string of asterisks (unprimed condition). Subjects were to pronounce the target word as quickly as possible. HAIL was named more quickly after the prime AIL than in the unprimed condition. Word-final trigrams that were not orthographic rimes, such as the LEW of BLEW, were relatively ineffective primes. These results suggest that orthographic rimes function as units of word recognition. Another study (Bowey, 1990) was designed to assess the importance of orthographic onsets. In this study, the prime was the first two letters of the target word. These letters corresponded to the word 's onset, as in the prime BR with the target BRAND, or the onset plus part of the rime, as in the prime BI with the target BIRCH. Significant priming occurred only when the prime corresponded to the onset.

In addition to the studies by Treiman and Chafetz (1987) and Bowey (1990, 1993), results of Taraban and McClelland (1987), Treiman, Goswami, and Bruck (1990), and Treiman and Zukowski (1988) also fit with the idea that orthographic units that correspond to onsets and rimes play a role in the processing of printed words. However, no such evidence was found by Levitt, Healy, and Fendrich (1991). These researchers presented words with an asterisk immediately preceding the word, as in *CRAFT, between the first and second letters, as in C ' R A F T , or after the second letter, as in CR*AFT. These stimuli were used in a lexical decision task, an oral naming task, and a silent reading task. In no case was performance on CR*AFT significantly better than that on C ' R A F T , as would have been expected if CR functioned as a unit. Given the failure of Levitt et al. to find evidence for the orthographic onset, it was considered important to reevaluate this issue. Toward this end, Experiments 1 and 2 were designed to examine the role of orthographic onsets and rimes in a pronunciation decision task. In this task, subjects decided whether a letter string, when pronounced, sounds like a real word.

The hzternal Structure of the Orthographic Rime

As discussed above, the internal structure of the phonological rime appears to vary with the sonority of the consonant that follows the vowel. If that consonant is high in sonority, as with /r/ or/1/, the vowel and the consonant together form the peak. If the consonant is lower on the sonority

scale, as w i t h / f / o r / p / , the vowel alone is the peak and the final consonant or consonant cluster is the coda. Do orthographic rimes in printed words show a parallel structure?

So far, the only researchers to have addressed this question were Levitt et al. (1991). Their studies included stimuli with an asterisk after the vowel, such as STO*RM, stimuli with an asterisk after the postvocalic consonant, such as STOR*M, and stimuli with an asterisk after the word, as in STORM*. The stimuli had either a postvocalic liquid, as in STORM, a postvocalic nasal, as in BLUNT, or a postvocalic obstruent, as in GRAFT. If the internal structure of the orthographic rime mirrors the internal structure of the phonological rime, asterisk position and type of postvocalic consonant should interact.

In the first experiment reported by Levitt et al. (1991), one group of subjects performed a lexical decision task and the other group performed a naming task. Both words and nonwords were used in these tasks, but Levitt et al. presented only the results for words. In a by-subjects analysis of errors to words in the lexical decision task, there was a significant main effect of asterisk position. The critical interaction between asterisk position and type of postvocalic consonant was marginally significant (p = . 0 6 ) . 3 The pattern of results gave partial support for the idea that the class of postvocalic consonant affects the cohesiveness of the vowel and the consonant. Specif- ically, breaks between the two final consonants were particularly disruptive when the postvocalic consonant was an obstruent. Such breaks were also disruptive, but to a lesser extent, for nasals. When the postvocalic consonant was a liquid, however, breaks between the vowel and the liquid did not yield more errors than breaks after the liquid, as the sonority hypothesis would lead one to expect. In this experiment, the critical interaction was not found in response times to words in the lexical decision task or in response times or errors to words in the naming task.

In the second experiment reported by Levitt et al. (1991), one group of subjects performed a lexical decision task and the second group performed a silent reading task. The main effect of asterisk position was again significant in a by-subjects analysis of latencies to words in the lexical decision task. The predicted interaction between asterisk position and type of postvocalic consonant was marginally significant (p = .054). For words with postvocalic obstruents and liquids, latencies were longer when the asterisk divided the two final consonants (BLUN*T or GRAF*T) than when the asterisk preceded the two consonants (BLU*NT or GRA*FT). For words with postvocalic liquids, latencies were longer when the asterisk was before

3 Levitt et al. (1991) did not analyze the results by items on the grounds that the stimuli were not randomly selected.

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the liquid (STO*RM) than when it was after the liquid (STOR*M). How- ever, the interaction was not found in errors in the lexical decision task or in the silent reading task.

The results of Levitt et al. (1991) provide some support for the idea that the internal structure of the orthographic rime mirrors the internal structure of the phonological rime. However, the evidence is not strong. As men- tioned earlier, Levitt et al. (1991) presented only the results for words. They stated that effects of syllable-internal structure and sonority were not found for nonwords. However, Treiman and Chafetz (1987) reported similar effects of stimulus division for words and nonwords in a lexical decision task. For nonwords, as well as for words, a CCV//CC division led to slower responses than a CC//VCC division. Had the results for nonvr been included in the analyses of Levitt et al., it is not known whether the interaction between asterisk position and consonant type would have been significant. Nor is it known whether asterisk position, consonant type, and lexical status would interact. This three-way interaction would be necessary to confirm that the pattern of results for nonwords in fact differed from the pattern of results for words. Even in the analyses restricted to words, the critical interaction between asterisk position and consonant type was only marginally significant. Given these concerns, Experiment 3 was designed to further test the hypothesis that the internal structure of the orthographic rime depends on the nature of the postvocalic consonant.

E X P E R I M E N T 1

For this experiment, a pronunciation decision task was developed. All of the stimuli for this task were nonwords. Half of the nonwords sounded like words when pronounced according to English spelling-to-sound correspondence rules. For example, PHELL sounds like FELL and FRUNT sounds like FRONT. Subjects were to answer yes to these stimuli because they sounded like words when read aloud. The other half of the nonwords did not sound like real words when pronounced. Examples are SHARR and TRISP, which do not sound like real words. Subjects were to respond no to these stimuli. The pronunciation decision task requires subjects to construct phonological representations from printed letter strings. One can ask whether onsets and rimes are involved in this process by determining whether people perform better when the stimuli are divided with two slashes at the orthographic onset/rime boundary, as in PH//ELL and TR//ISP, than when the stimuli are divided within the rime, as in PHE//LL and TRI//SP.

Method

Stimuli. All of the stimuli were orthographically legal and pronouncable nonwords. All had CCVCC spellings and all were presented in upper-case

letters. There were two condi t ions in the exper iment that differed in the number

of phonemes in the spoken forms of the st imuli . In the th ree -phoneme condit ion, the initial and final CCs of each s t imulus were d igraphs such as SH

or double ts such as RR that symbo l i zed a s ingle phoneme. Thus, the st imuli in the th ree -phoneme condi t ion conta ined three phonemes when pronounced, as in S H A R R . In the f ive -phoneme condi t ion, the initial and final CCs were clusters that co r responded to two phonemes . Examples are TR and SP. The s t imuli in this condi t ion thus contained five phonemes when pronounced , as in TRISP.

In each condi t ion , there were 24 i tems that sounded l ike words when pronounced accord ing to Engl ish spe l l ing- to -sound rules and 24 i tems that did not sound like w o r d s ? Each item was presented twice, once as a CC// V C C and once as a CCV/ /CC. There were four pract ice i tems for each condi t ion, each of which was presented with both types of division. Sample s t imuli are shown in Table I. A comple te list of s t imuli for this and the fo l lowing exper iments is p rovided in the appendix .

Procedure. The subject sat before a compute r screen and rested his or her index fingers on response keys labe led yes and no. Ha l f of the subjects used the left hand for yes and the right hand for no. These ass ignments were reversed for the other half of the subjects. Subjec ts were told that they would see a ser ies of nonsense words on the compute r screen. They were to press yes if the nonsense word sounded l ike a real word when p ronounced and no if it did not. Subjects were told to ignore the s lashes and respond as quickly and as accura te ly as possible . For each condi t ion, the pract ice st imuli were presented first, fo l lowed by the test s t imuli . The order of the s t imuli

was randomly chosen for each subject .

4 The number of unique stimuli in the list of nonwords that did not sound like real words in the five-phoneme condition was 23, as one nonword was inadvertently repeated.

Table I. Sample Stimuli for Experiments 1 and 2"

Lexieal status

Sounds like word

Condition CC//VCC CCV//CC

Doesn't sound like word

CC/NCC CCVHCC

Three-phoneme

Five-phoneme

"C = consonant; V = vowel.

PH//ELL PHE//LL WR//USH WRU//SH FR//UNT FRU//NT ST//EPT STE]/PT

KN//ANG KNA//NG WH//UCK WHU//CK TR//ISP TRI//SP KL//ARF KLA//RF

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Subjects. Twenty students attending classes at Indiana University, Bloo- mington, participated. All were native speakers o f English. Each subject served in both the three-phoneme and f ive-phoneme conditions, with order of conditions balanced across subjects.

Results

Table II shows the mean response times for correct responses and the mean proportions of errors. The data were analyzed using the factors o f condition ( three-phoneme vs. f ive-phoneme), division (CC/ /VCC vs. CCV// CC), and lexical status (sounds like a word vs. doesn ' t sound like a word). Only those results that reached the .05 level in both types of analyses are considered significant.

In analyses of response times, there was a main effect of division [FI(1 , 19) = 5.05, p = .034; F2(1, 91) = 9.33, p = .003]. Response times to CCV/ /CC divisions were longer than those to CC/ /VCC divisions. There was also a main effect of lexical status [FI (1 , 19) = 69.29; F2(1, 91) = 114.67; p < .001 for both]. Subjects took longer to respond that a nonword did not sound like a word than that a nonword did sound like a word. No other main effects or interactions were significant. In particular, although responses appeared to be faster in the three-phoneme condit ion than the five- phoneme condition, the effect o f condit ion was not significant in either the by-subjects or the by-i tems analysis.

Table II. Results of Experiment 1"

Lexical status

Sounds like word Doesn't sound like word

Condition CC//VCC CCV//CC CC//VCC CCV//CC

Response times in msec (standard deviations in parentheses)

Three-phoneme 1281 1363 1993 2120 (348) (417) (631) (789)

Five-phoneme 1381 1464 2106 2180 (462) (531) (734) (885)

Proportion of errors (standard deviations in parentheses)

Three-phoneme .13 .14 .16 .14 (.12) (.12) (.14) (.14)

Five-phoneme .18 .18 .12 .11 (.13) (.15) (.10) (.08)

The error data were analyzed in the same way as the latency data. No significant main effects or interactions were found. The error rate was relatively high overall, a mean of 14.4%.

Discussion

The results in this pronunciation decision task were very similar to the results in the lexical decision task of Treiman and Chafetz (1987). In the pronunciation decision task, as in the lexical decision task, printed stimuli that had two slashes between the initial CC and the VCC were responded to more quickly than printed stimuli that were divided after the V. In both studies, the advantage for CC//VCC divisions over CCV//CC divisions appeared whether the two initial consonant letters symbolized one phoneme, in the three-phoneme condition, or two phonemes, in the five-phoneme condition. Also, yes responses were faster than no responses in both tasks. Treiman and Chafetz found significantly more errors with three-phoneme stimuli than with five-phoneme stimuli but no such difference emerged in the present study.

The results of Experiment 1 suggest that orthographic onset and rime units are involved in the translation of printed letter strings into phonological forms. Subjects could more readily perform this translation when the orthographic onsets and rimes were intact, as in the CC//VCC condition, than when the orthographic rime was divided, as in the CCV//CC condition. These results add to the body of evidence reviewed earlier that orthographic onsets and rimes play a role in the processing of print. They suggest, more directly than does previous research, that this role extends to the translation of printed letter strings into phonological forms.

The error rate in Experiment 1 was fairly high. Indeed, several subjects had error rates of over 30%. These subjects had some difficulty in assigning phonological forms to the nonsense words and deciding whether these forms matched those of known words. These subjects' difficulties in performing the task mean that caution must be taken in drawing conclusions from the results of Experiment 1.

In Experiment 2, the pronunciation decision task was modified to allow subjects to perform better. To do this, a training phase was added in which all of the stimuli were presented without slashes. During the training phase, subjects practiced pronouncing the stimuli and telling whether they sounded like English words. The experimenter corrected any wrong responses. After

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completing the training phase, subjects performed the speeded pronunciation decision task. Given that subjects could pronounce the intact stimuli when they were presented without time pressure, performance in the speeded task could now be examined. Would subjects be faster and/or more accurate when stimuli were divided between the onset and the rime (the CC//VCC division) than when stimuli were divided within the rime (the CCV//CC division)?

Method

Stimuli. The stimuli for Experiment 2 were identical to those of Exper- iment 1.

Procedure. In the training phase, subjects were shown a printed list of the stimuli. The nonwords were printed without slashes and were arranged in a random sequence, which was the same for all subjects. Subjects were asked to pronounce each stimulus and tell whether or not it sounded like an English word. Errors were corrected. After going through the complete list of stimuli, subjects redid any items on which they had erred. When the training phase was completed, the practice and test stimuli were presented as in Experiment 1.

Subjects. Fifty subjects from the same pool as in Experiment 1 participated. Half of the subjects served in the three-phoneme condition and half in the five-phoneme condition.

Results

Table III shows the mean response times for correct responses and the mean numbers of errors. The data were analyzed as in Experiment 1.

The response times were very similar to those of Experiment 1. The results of the statistical analyses were also similar. As in Experiment 1, there was a main effect of division [F1(1, 48) = 7.84, p = .007; F2(1, 91) = 5.72, p = .019], with longer response times to CCV//CC stimuli than to CC// VCC stimuli. Also as in Experiment 1, there was a main effect of lexical status [F1(1, 48) = 45.97; F2(1, 91) = 207.23; p < .001 for both], with no responses taking longer than yes responses. Although responses in the three- phoneme condition appeared to be faster than responses in the five-phoneme condition, the effect of condition was not significant in the subjects analysis [F1(1, 48) < 1], although it was significant by items IF2(1, 91) = 19.96, p < .001].

The mean error rate was less than half that of Experiment 1 - -6 .2% in this experiment as compared to 14.4% in Experiment 1. There was a ten- dency for more errors on yes items than on no items, although this trend

Table III. Results of Experiment 2"

Lexieal status

Sounds like word Doesn't sound like word

Condition CC//VCC CCV//CC CC//VCC CCV//CC

Response times in msec (standard deviations in parentheses)

Three-phoneme 1234 1277 2006 2041 (331) (313) (1015) (1126)

Five-phoneme 1463 1531 2162 2279 (784) (859) (1415) (1560)

Three-phoneme .07 .08 .04 .06 (.06) (.07) (.06) (.06)

Fivc-phoneme .07 .08 .05 .05 (.06) (.08) (.08) (.07)

"C -~ consonant; V = vowel.

did not reach significance an the items analysis [F1(1, 48) = 4.51, p = .036; F2(1, 91) = 3.33, p = .071].

Comparison of Results of Experiments 1 and 2. Experiments 1 and 2 used the same stimuli and subjects from the same population. They differed primarily in the presence versus absence of a training phase. A training phase was provided in Experiment 2 but not in Exper iment 1. Thus, a combined analysis was carried out using the variables of condition ( three-phoneme vs. f ive-phoneme), division (CC/ /VCC vs. CCV//CC), lexical status (sounds like a word vs. doesn ' t sound like a word), and training (present or absent). The analysis was performed only by items, subject analysis being complicated by the fact that condition was a within-subject factor in Experiment 1 and a between-subjects factor in Experiment 2.

In the combined analysis of response times, a main effect was found for division [F2(1, 91) = 11.34, p = .001]. As in the individual analyses of Experiments 1 and 2, CCV/ /CC divisions yielded shorter response times than CCV/ /CC divisions. Division did not interact with any other factor. There was also a main effect of condition [F2(1, 91) = 9.04, p = .003]. Overall, responses were faster to five-letter nonwords that contained three phonemes than to five-letter nonwords that contained five phonemes. This difference was larger in Experiment 2 than in Experiment 1, as shown by the significant interaction between condition and training [F2(1, 91) = 5.74, p = .019]. Recall, however, that the difference between the three-phoneme and f ive-phoneme conditions was not significant in the subjects analysis of

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Experiment 2, although it was significant by items. The only other reliable effect in the combined analysis of responses times was the main effect of lexical status [F2(1, 91) = 185.80, p < .001]. No responses took longer than yes responses, as in the individual analyses of the two experiments.

In the combined analysis of errors, the only significant effect was that of training [F2(1, 91) = 74.50, p < .001]. This effect reflects the substantial decrease in errors from Experiment 1 to Experiment 2.

To summarize the results of the combined analysis, Experiments 1 and 2 showed similar patterns of results. In both cases, CC//VCC stimuli were responded to more rapidly than CCV//CC stimuli. The major difference was that there were fewer errors in Experiment 2, in which people practiced pronouncing the nonwords beforehand, than in Experiment 1, in which no such practice was provided.

Discussion

The practice that subjects received with the intact nonwords helped them to perform the speeded pronunciation decision task more accurately. However, the practice did not change the relative pattern of performance on CC//VCC and CCV//CC stimuli, nor did it change subjects' response times in the speeded task. Whether or not subjects had practiced pronouncing the intact nonwords, they still responded more slowly to stimuli that were divided within the rime (CCV//CC stimuli) than to stimuli that were divided between the onset and the rime (CC//VCC stimuli). For example, subjects who during the practice phase dealt errorlessly with an intact nonword such as PHELL responded more slowly during the test phase to PHE//LL than to PH//ELL. That the pattern of performance on CCV//CC and CC//VCC stimuli was not affected by practice with intact stimuli strengthens the view that onset and rime units are involved in the assignment of pronunciations to printed stimuli. The results support the idea that printed stimuli are parsed into linguistically defined units as part of the pronunciation process.

The question that motivated Experiments 1 and 2 was whether printed letter strings are parsed at a point that corresponds to the onset/rime boundary of the corresponding spoken stimuli. Such evidence was found for nonwords in both experiments. Experiment 3 moved to a more detailed level, the internal structure of the rime. The question was whether the phonological category of the postvocalic consonant affects the internal structure of the orthographic rime in the same way as it affects the internal structure of the

phonological rime. A lexical decision task was used to address this issue. The primary question was whether the pattern of performance on CC//VCC stimuli relative to CCV//CC stimuli would vary with the type of consonant after the vowel. Would the decrement in performance on QUI//LT versus QU//ILT (a word with a liquid after the vowel) be larger than the decrement in performance on FLI//NT versus FL//INT (a word with a nasal after the vowel)? Would the decrement in performance on FLI//NT versus FL//INT in turn be larger than the decrement on DRI//FT versus DR/tiFF (a word with an obstruent after the vowel)? A second question was whether CC// VCC divisions would generally lead to better performance than CCV//CC divisions. Such a difference was expected given the findings of Treiman and Chafetz (1987) with the lexical decision task.

Method

Stimuli. The stimuli were 60 words and 60 orthographically legal nonwords. All had CCVCC spellings and all were presented in upper-case letters. The number of phonemes in the spoken forms of the stimuli ranged from three to five. One-third of the stimuli had a liquid (R or L) after the vowel, one-third had a nasal (M, N, or NG) after the vowel, and one third had an obstruent (F, S, P, PH, SH, CK, or TH) after the vowel. The frequencies of the words in the liquid, nasal, and obstruent categories were as similar as possible (mean frequencies according to Ku~era & Francis, 1967, of 21.3, 17.2, and 27.3 for liquids, nasals, and obstruents, respectively). Each stimulus was presented twice, once as a CC//VCC and once as a CCV//CC. In addition, there were six practice stimuli, each of which was presented with both types of division. Sample stimuli are shown in Table IV.

Postvocalic consonant

Table IV. Sample Stimuli for Experiment 3 ~

Lexical status

Word Nonword

cc//vcc ccvHcc CC//VCC CCV//CC

Liquid

Obstrucnt

SC//ALP SCA//LP TH//ORN THO//RN BR//ING BRI//NG FI.J/INT FLI//NT SH//IFT SHI//FT CL//OTH CLO//TH

SN//ILD SNI//LD CH]/ARN CHA]/RN PR//UNK PRU//NK TH//OMP THO//MP BIJ/ISK BLI//SK GR//EPH GRE//PH

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Procedure. The procedure was like that of Experiment 1, except that subjects were told to press the yes key if the stimulus was a real word and the no key if it was not.

Subjects. Thirty-six students from the same population as Experiment 1 were run. The data of one subject had to be dropped due to a computer malfunction. The data of another subject were dropped because this person appeared not to understand the task, responding no to all but 17 of the 240 items. Thus, 34 subjects contributed data.

Resuhs

Table V shows the mean response times for correct responses and the mean proportions of errors. The data were analyzed using the factors of division (CC//VCC vs. CCV//CC), lexical status (word vs. nonword), and postvocalic consonant (liquid vs. nasal vs. obstruent).

In the analyses of response times, the main effect of division was significant [F1(1, 33) = 4.52, p = .041; F2(1, 114) = 4.06, p = .046]. As in the study of Treiman and Chafetz (1987), CCV//CC divisions led to longer responses than CC//VCC divisions. There was also a significant effect of lexical status [FI(1, 33) = 32.70; F2(1, 114) = 53.39; p < .001 for both].

T a b l e V. Results of Experiment 3 ~

Lcxical status

Word Nonword

Postvocalic consonant CC//VCC CCV//CC CC//VCC CCV//CC

Responsc times in msec (standard deviations in parentheses)

Liquid 904 957 1099 1100 (274) (279) (410) (406)

Nasal 920 926 1042 1094 (275) (27S) (322) (388)

Obstruent 857 864 1051 1066 (233)- (227) (343) (339)

Liquid .08 .07 .08 .07 (.09) (.07) (.10) (.I1)

Nasal .12 .i3 .09 .09 (.09) (.10) (.14) (.11)

Obstruent .03 .03 .07 .07 (.05) (.06) (.12) (.11)

"C = consonant; V = vowcl.

No responses took longer than yes responses, as usual in lexical decision experiments. In addition, there was a main effect of postvocalic consonant [F1(2, 66) = 11.22, p < .001; F2(2, 114) = 3.37, p = .038]. Overall, responses were fastest for stimuli with postvocalic obstruents and slowest for stimuli with postvocalic liquids.

If the relative size of the superiority for CC//VCC divisions over CCV// CC divisions varied systematically with the type of consonant after the vowel, type of postvocalic consonant should have interacted with division. However, the interaction between division and postvocalic consonant did not approach significance [F1(2, 66) < 1; F2(2, 114) < 1]. There was a three-way interaction of division, postvocalic consonant, and lexical status in the by-subjects analysis only [F1(2, 66) = 4.32, p = .017; F2(2, 114) = 1.74, p = .18]. For words, the superiority for CC//VCC divisions over CCV// CC divisions appeared to be larger for liquids (53 msec) than for nasals (.5 msec) or obstruents (7 msec). This is the pattern predicted under the hypothesis that vowels and liquids are more cohesive than vowels and other types of following consonants. For nonwords, however, the superiority for CC//VCC divisions over CCV//CC divisions appeared to be larger for nasals (52 msec) than for liquids (1 msec) or obstruents (15 msec), a pattern that has no clear interpretation.

In the analyses of errors, there was only a main effect of type of postvocalic consonant [Fl(2, 66) = 20.652, p < .001; F2(2, 114) = 3.179, p = .045]. Error rates were highest for stimuli with nasal consonants after the vowel and lowest for stimuli with obstruent consonants after the vowel, which could reflect the small frequency differences among the classes of stimuli.

Discussion

The results of Experiment 3 replicate the finding of Treiman and Chaf- etz (1987) that printed stimuli that are divided with two slashes within the orthographic rime (CCV//CC division) are responded to more slowly in a lexical decision task than printed stimuli that are divided at the onset/rime boundary (CC//VCC division). These findings suggest that the structure of printed words mirrors, to some extent, the structure of spoken words. In both cases, the major internal boundary is between the initial consonant or consonant cluster and the vowel. Just as the spoken word /drift/ contains the uni ts /dr / and/1ft/, the printed word DRIFT contains the units DR and IFT.

However, the results of Experiment 3 are equivocal on whether the internal structure of printed stimuli mirrors the internal structure of spoken stimuli at a more detailed level, in terms of the structure of the rime itself. For words, the pattern of results was as expected in that the superiority for

106 Tre iman

CC//VCC divisions over CCV//CC divisions appeared to be larger for liquids than for nasals or obstruents. For nonwords, the superiority for CC//VCC divisions over CCV//CC divisions appeared to be largest for nasals, a pattern that is difficult to interpret. However, because the interaction of division, postvocalic consonant, and lexical status was not significant by items, it may be premature to conclude that the pattern of results for words was different from the pattern of results for nonwords.

As discussed earlier, the results of Levitt et al. (1991) for words in a lexical decision task provide partial support for the idea that the internal structure of the orthographic rime mirrors the internal structure of the phonological rime. If the apparent differences between words and nonwords in the present study are real, the present results provide additional support for this claim, at least for real words. However, as discussed above, the apparent differences between words and nonwords in Experiment 3 may not be real. It is ironic that Experiment 3, which was motivated by the statistical weak- ness of the results of Levitt et al., has also yielded equivocal results.

G E N E R A L D I S C U S S I O N

The results of these experiments suggest that there is some correspondence between the units of print and the units of speech. Such a correspondence appears to exist at the level of onsets and rimes. Monosyllabic printed words and orthographically legal nonwords are parsed into an orthographic onset and an orthographic rime, paralleling the phonological onset/rime division. Evidence for an orthographic onset/rime boundary was found for nonwords in a task that required subjects to construct pronunciations (Ex- periments 1 and 2) and for words and nonwords in a lexical decision task (Experiment 3). This evidence adds to the existing support for orthographic onset and rime units that was reviewed in the Introduction. The results of Experiments 1 and 2, in particular, suggest that orthographic units corresponding to onsets and rimes are involved in the assignment of pronunciations to letter strings. When the orthographic rime is disrupted, as in FRU// NT, people take longer to work out the pronunciation of the letter string than when the orthographic rime is intact.

At a more detailed level, it is still not clear whether the units within orthographic rimes correspond to the units within phonological rimes. As discussed in the Introduction, the structure of the phonological rime has been found to vary with the category of the consonant that follows the vowel. When the consonant is a liquid, a VCC rime is composed of a VC peak and a C coda. When the consonant after the vowel is an obstruent, a VCC is composed of a V peak plus a final CC coda. The results of Experiment 3

and of Levitt et al. (1991) do not clearly show whether the structure of the orthographic rime varies in a similar manner. There are signs of a correspondence between orthographic rimes and phonological rimes for real words, but there are no such signs for nonwords. The apparent differences between words and nonwords must be followed up in future research.

The weak results of Experiment 3 and of Levitt et al. (1991) may reflect the lack of sensitivity of the tasks. The slashes used in the present research and the asterisks used by Levitt et al. may not have greatly disrupted the psychological integrity of letter groups. The lexical decision task itself may not be very sensitive to the effects of orthographic units, influenced as it is by postlexical factors. Naming latencies as used in the study of Levitt et al. may also be a less than ideal measure if people begin to say a word before they have fully processed it. If the weak results reflect the limitations of the tasks, one could argue that phonologically based units do form an integral part of the processes by which printed words are processed. If so, clear correspondences between the structure of orthographic rimes and the structure of phonological rimes should be found in research employing more sensitive tasks.

Alternatively, the orthographic units involved in reading may not nec- essarily mirror the phonological units that are used in the processing of spoken words. Precedent for this interpretation comes from the findings of Prinzmetal, Treiman, and Rho (1986). These researchers used an illusory conjunction task to examine the role of syllables in visual word perception. For some of their stimuli, syllables were defined orthographically. Thus, the syllable boundary in V O D K A must fall between D and K because these two letters cannot belong to the same syllable in English. Prinzmetal et al. found evidence for syllable units with such stimuli. Subjects were more likely to say that D was the color in which O (a letter in the same syllable) was printed than that D was the color in which K (a letter in the other syllable) was printed. However, Prinzmetal et al. did not find effects of phonological syllables with their task. Although words such as LAPEL and CAMEL have different phonological syllabifications, the two types of words showed similar patterns of illusory conjunction errors. The results of Prinzmetal et al. suggest that orthographic syllables are not isomorphic to phonological syllables. The same may hold for other types of units. In particular, orthographic rimes may not be isomorphic to phonological rimes.

Such a conclusion would fit with the idea that orthographic units arise not because of their relation to linguistic units but because of the properties of the orthography itself (Seidenberg, 1987; but see Levitt et al., 1991, foot- note 11, and Rapp, 1992, for some counterevidence). For example, E and T may be processed as a unit because these two letters often appear together in words such as WET, SET, and so on. E and M may function as a unit

108 Treiman

for the same reason. If E and M occur together no more often than E and T, E and M will not be a stronger unit. That the phoneme corresponding to M is higher in sonority than the phoneme corresponding to T is immaterial. In this view, what is important is the distributional patterns of letters and letter groups in print rather than the linguistic units to which the letters correspond. Readers' parsing of letter strings may depend on the identities of letters and on whether they are consonants or vowels but not on their other phonetic or phonological properties. Thus, linguistic units such as peaks, codas, onsets, rimes, and syllables may not be involved in lexical access and spelling-to-sound translation. To tile extent that they appear to do so, as with the onset/rime division, this may reflect the properties of tile orthography itself.

To distinguish between the possibilities just outlined, it ,.viii be necessary to develop experinaental methods that can more clearly illuminate the nature of orthographic units. In addition, it will be necessary to carry out careful studies of the distributional properties of print in order to disentangle the effects of orthographic structure and phonological struclure.

A P P E N D I X

Stimuli for Experiments 1 and 2

Three-phoneme condition, sounds like word: PHORR, KNE'IT, WHIPP, PHARR, PHATT, CHOPP, SHIPP, PHEDD, CHIPP, SHOPP, SHUTT, PHUSS, PHELL, WRANG, KNICK, PHANG, KNIT]', KNOTT', WRASH, WRUSH, WRICH, KNECK, PHECH, WRUFF

Three-phoneme condition, doesn't sound like word: PHUPP, PHEPH, PHESH, SHARR, PHOCK, PHUNG, SHASH, PHAPP, CHULL, SHANG, PHUSH, KNUSS, PHUCH, WREFF, KNANG, KNECH, WRELL, WRULL, WRUDD, KNESH, WRACH, CHESH, KNARR, WHUCK

Five-phoneme condition, sounds like word: FRUNT, BREST, DWORF, SWORM, KWORT, KWILT, SCUNK, SKARF, KRUST, KRISP, TRIPT, TRAKT, BLOC~, CROST, CLOKS, TWELV, STARV, TRIKT, KRANK, KWEST, SKALP, SLIPT, TRIMD, STEPT

Five-phoneme condition, doesn't sound like word: BRILT, DWUNT, SWORF, KWORM, KWUNK, SCORT, SKUST, KREMD, KLARF, KRUND, STtPT, TRISP, BLOST, CRELV, STEST, CLARV, TWAKT, STULP, TREPT, KRIMD, KWOKT, SKOKS, TRUPT

Stimuli for E.~periment 3

Postvocalic liquid, word: SWELL, SMELL, SPELL, SKULL, SCALD, SCALP, KNELT, STILT, CHILD, QUILT, SHARP, CHORD, THORN,

O r t h o g r a p h i c and P h o n o l o g i c a l Uni t s 109

SNARL, STORK, STORM, WHARF, SCORN, SPORT, DWARF Postvocalic liquid, nonword: SNELL, SKELL, SMULL, SWULL,

GNALP, QUELT, SNILD, SCILT, SPALT, SHALD, THORD, SMORD, SCARN, SPORL, STORP, THORK, SHORM, CHARN, STORF, DWARP

Postvocalic nasal, word: STING, BRING, THONG, FLING, CLIMB, THUMP, CHUNK, FLINT, GRUNT, SKUNK, BLIND, TRUNK, DRANK, THANK, PRINT, BLANK, TRUMP, BLOND, FLUNK, CRANK

Postvocalic nasal, nonword: BLANG, SKING, BRONG, GRING, FLIMB, THOMP, PRUNK, THUNT, PLINT, BLONK, CLIND, TRANK, STENK, CHANK, DRINT, GRUNK, PRUMP, THOND, CRUNK, FLONK

Postvocalic obstruent, word: SHIFT, CRUST, WHISK, BRISK, BLAST, GRAPH, FRESH, CRACK, WRIST, TWIST, CHEST, SLEPT, TRUST, SWEPT, CREST, DRIFT, CRISP, CROSS, CLOTH, STUFF

Postvocalic obstruent, nonword: CRIFT, WHAST, BLISK, TWISK, TRAST, GREPH, CLOSH, FRECK, CHIST, SLEST, TREST, CHEPT, BRUST, DWEPT, WRAST, DRISP, CREFT, STUSS, DRATH, CLUFF

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To what extent do orthographic units in print mirror phonological units in speech?

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