The representation of geminate consonants: Evidence from the phonological errors of an aphasic patient

Pergamon

J. Neurolinguistics, Vol. 9, No. 3, pp. 219-235, 199516 Copyright 0 1996 published by Ekvier Science Ltd !mll-4044(96)ooo10-3 All rights reserved

Wll-60441% $15.00+0.al

THE REPRESENTATION OF GEMINATE CONSONANTS: EVIDENCE FROM THE PHONOLOGICAL ERRORS OF AN APHASIC PATIENT CRISTINA ROMANI*

and ANDREA

CaLABRRsEt

*University of Birnktgham, U.K.; tHarvard University, U.S.A. Abstract-In this paper, we report the phonological errors made by an Italian patient on geminate consonants. DB’s geminate errors provide evidence for phonological representations of the type suggested by autosegmental phonology. In particular, they provide evidence for a timing tier that encodes the length of phonological segments and is separate from a melodic tier that encodes the phonological quality of the segments. The distribution of DB’s phonological errors is contrasted with the distribution of spelling errors reported in the literature in some forms of dysgraphia. The results suggest differences in the orthographic and phonological representation of geminate consonants.

INTRODUCTION

The representation of geminate consonants has been the subject of a great deal of debate in phonology, and what appeared to be contradictory results bearing on their representation have played an important role in determining the rise of autosegmental phonology as the dominant approach in theoretical phonology. Recent papers in neuropsychology have debated the representation of geminate consonants in the orthography [ l-51 . It has been suggested that in the orthography, as in the phonology, one needs to hypothesize a distinction between a level that represents segment identities and a level that represents their length or quantity. Different authors, however, have endorsed different views on the correspondence between phonological and orthographic representation. Caramazza and Miceli [ 1] have suggested a different representation in the orthography and in the phonology, while McCloskey et al. [ 21 have suggested a correspondence between the two. The debate over the representation of geminates in the orthography is part of the more general debate on the relationship between phonological and orthographic representations. On the one hand, orthographic representations could be nothing more than a shallow sequence of symbols that translates the phonology (e.g. refs [6,7]). On the other, they could be as structured as their phonological counterparts. In this last case, however, a crucial question is whether this structure comes from the phonology, or from more abstract linguistic principles encompassing phonology and orthography, or whether it enjoys some degree of independence (e.g. refs [ 1,8 ] ). The purpose of the present paper is twofold. First, we want to present the pattern of geminate errors made by a dysphasic patient in the spoken modality. We will argue that this pattern supports an autosegmental representation of geminate consonants. Secondly, we want to compare the phonological errors made by our patient with the orthographic errors made by the dysgraphic patients reported in the literature. Differences in the phonological and orthographic Address for correspondence: Cristina Romani, Ph.D., School of Psychology, Birmingham Bl5 2TT, U.K. 219

University of Birmingham, Edgbaston,

220

C. ROMANI and A. CALABRESE

error patterns would suggest differences in the representation of geminates in the two modalities and, therefore, would support some degree of independence of orthographic from phonological representation. We will now, briefly introduce issues related to the representation of geminates in the phonology. We will, then, discuss their representation in the orthography. In Italian, as in other languages, there is a contrast between short and long consonants (also called geminate consonants). Thus, Italian can distinguish words by means of the length of one of their consonants: for example, the word /pala/ with a short /l/ means ‘spade’; the word /pal:a/ with a long /l/ means ‘ball’. English has geminate consonants in the orthography, but not in the phonology. Until recently, the representation of geminate consonants was a puzzle. Two possible representations were debated: (a) a single consonant bearing the feature ‘long’, or (b) two identical, adjacent consonants. Neither of these two representations was entirely satisfactory since, according to some phonological rules, geminates behave as a single segment, while according to other phonological rules they behave as two distinct segments (for examples and a more extensive discussion, see refs [9, lo]). The puzzle was solved by the introduction of autosegmental representations. Autosegmental phonology represents phonological segments and the prosodic structure of these units on different planes or tiers. For example, scheme (1) shows the autosegmental representation of the Italian word ‘fretta’ (hurry) which contains a geminate consonant:

0 /\ xxx

I f Scheme 1.

N C 0 N I I ! I xx x

I I r e

\/ t

I a

prosodic tier skeletal tier melodic tier

o = syllable, 0 = onset, N = nucleus, C = coda. The units on the melodic tier represent the phonemes of traditional

linguistics,

but, more properly,

are bundles of distinctive

features.

In an autosegmental representation, phonological segments are linked to the corresponding syllabic positions through an intermediate layer of timing units (the Xs) . Since units at one level do not need to be in a one-to-one correspondence with units at another level, it is possible to represent a geminate consonant by linking nyo timing units to one phonological segment. This representation not only explains why geminate consonants sometimes behave as two units and other times as one unit, but also predicts the contexts in which they will behave one way or the other. They should behave as a single unit for the purpose of rules that look at the melodic tier, but they should behave as two units for the purpose of rules that operate on the skeletal tier (e.g. stress placement rules). This is exactly what has been found for a number of different languages. Note that in scheme (l), the two units making up the geminate are heterosyllabic: one is in coda position, the other in onset position. A representation of geminates as a heterosyllabic cluster is supported by the fact that the syllable preceding a geminate behaves as a closed syllable (that is, as a syllable with a consonant in the coda) for the purpose of rules of stress assignment. In Italian, if the penultimate syllable is closed, it is stressed. Penultimate syllables followed by a geminate are always stressed (e.g. corre’tto, carte’ggio, arme’ggio, affe’tto). An autosegmental analysis of geminates has been supported not only by traditional linguistic arguments, but also by some analyses of speech errors made by normal speakers. Stemberger

REPRESENTATION OF GEMINATE CONSONANTS

221

[ 111 has presented some evidence from Swedish and German corpora of speech errors that, when a segment moves to a new position, it assumes the length of the segment originally in this position. This supports the autosegmental hypothesis that length and segments are independently represented. Recently, a number of papers have investigated the issue of how geminates are represented in the orthography. These studies have looked at the spelling errors made by brain-damaged patients and have concluded that in the orthography, like in the phonology, information about a segment’s identity and information about its quantity (whether it is single or double) are represented independently [ 1,2,4] . The main evidence for this conclusion is that dysgraphic patients make many errors that shift the position of a geminate in the word (e.g. caress > carres; [ 1,2] ). In these errors, the information about ‘quantity’ is preserved, but not information about identity. McCloskey et al. [2] demonstrate that errors of this type occur in a proportion that is clearly higher than what would be expected by chance. Tainturier and Caramazza [4], moreover, describe a patient who spells words containing a geminate with a geminate, even if little else of the target word is preserved (in particular, neither the identity nor the position of the geminate). The results discussed above suggest that information about letter identities and information about letter quantities are represented independently, as suggested by autosegmental phonology. This is one way of explaining how spelling errors can preserve information about doubling a letter, but not information about the identity of the letter to be doubled. However, while McCloskey et al. [ 21 have suggested that geminates are represented in the orthography through the same formalism used by the phonology, Caramazza and Miceli [ 1 ] have suggested a different representation. Scheme (2) shows the orthographic representation of the Italian word ‘mattone’ (brick) according to Caramazza and Miceli (a) and according to an autosegmental representation (b) .

(a)

(b) 0

7, /=, /T

0

cvcvcv I

I

I

m

a

tone

I

II

:,

Scheme

2. (a) Orthographic

representation

0

/I\

with a feature ‘double’. representation.

NC

/I

ON

ON

III

IIll

xxx

xx

I

I

m

a

\/

(3

/I

xx I

t

I

I

one

(b) Phonological/orthographic

autosegmental

The representation argued for by Caramazza and Miceli has some similarity with the original proposal in the phonology that geminates are represented as a single phoneme linked to a feature ‘long’. Note that, in this representation, the skeletal tier is constituted by consonant/ vowel (C/V) symbols and not by neutral timing units. Caramazza and Miceli adopt this formalism as that minimally required to explain the errors of their dysgraphic patient LB. LB’s substitutions always replace vowels with vowels and consonants with consonants. Moreover, since LB’s errors tend to preserve the number of syllables of the target word, the C/V symbols are linked to syllable units.

C. ROMANI and A. CALABRESE

222

The representations shown in scheme (2) have different strengths and weaknesses in explaining spelling errors made on geminates. Caramazza and Miceli argue that errors commonly made by dysgraphic patients, where a geminate shifts position in the word (e.g. sorella > sorrela), are better explained by a representation where a single grapheme is linked to a feature ‘double’ than by an autosegmental representation. Scheme (3) shows how the error sorella > sorrela can be produced from a representation with the feature ‘double’ (a) and from an autosegmental representation (b). In (a), the error is produced simply by separating the feature ‘double’ from the segment ‘1’and by reattaching it to the segment ‘r’. To produce the same error in (b) one needs more complex transformations: several links between the segments and the timing units have to be changed and then syllabic positions have to be reassigned to the timing units. Errors involving shifts of geminates, therefore, should be quite rare if one hypothesizes autosegmental representations, but not if one hypothesizes representations with a feature ‘double’.

(a)

17cv,Ycv/p

cv I

I

I

I

sore

,Y /Y /Y

cvcvcv

I

I

I

la

>

I

II

I

I

sorela

A

d

@) 0 I x I

N I x I

ONC I I I xxxx : I \/

ON I I x I

sore1

a

ON I II X I

l\/lII

III

XXXY

c

Scheme 3. (a) Orthographic

e

I

I

S

ore

I

I I xx

>

I

I

ONCONOY I I I I

ON I

xx

so

>

ONONCON I I I I xx x xx

a

1

I

I

e

1

I

>

1 a

representation with a feature ‘double’.

xI xIx\;xI; r s 0

;

(b) PhonologicaUautosegmental

a

representation.

It is to be noted that shift errors involve complex transformations only if the segments involved are not adjacent to one another and if the representations are syllabified, as in scheme (3). The majority of shift errors in HE, the patient described by McCloskey et al., do involve adjacent shifts (e.g. sorella > soreela). These errors can be easily explained by an

REPRESENTATION OF GEMINATECONSONANTS

223

autosegmental representation provided that the timing units are not linked to syllable positions. If the connection between one of the two timing units and the letter corresponding to the geminate is lost, the timing units can be reassociated to an adjacent letter as shown in scheme (4): xxxx

xxxx

II\/ ba

xx

II/

>

>

ba

1

1

xx

I \I

I

b

1

a

Scheme 4.

The assumption that orthographic representations are not syllabified, however, is problematic. HE’s errors preserve not only consonant-vowel sequence as LB’s, but also orthographic constraints. Since it is much easier to encode orthographic constraints in terms of syllable structure than in terms of letter sequences-only certain letters are possible in certain syllabic positionsorthographic or phonotactic constraints are often cited as evidence for syllable structure.* McCloskey et al. [2] argue in favour of an autosegmental representation mainly on the basis of errors where a geminate is replaced with a sequence of two distinct segments (e.g. sorella > sore&a). McCloskey er al. call these errors pseudosubstitutions. Both an autosegmental representation and a representation with a feature ‘double’ represent the identity of the phoneme or letter in the double consonant with a single unit. However, only in the autosegmental representation is the double consonant represented by two units at other levels in the representation. Therefore, errors where a geminate is replaced by a different two-letter sequence are difficult to explain given a representation with a feature ‘double’, since there is no level of representation where the geminate corresponds to two segments, but should be more common given an autosegmental representation. Scheme (6) shows how the error sorella > sorelta can be produced from an autosegmental representation (a) and from a representation with a feature ‘double’ (b). In (a) the segment ‘l’, corresponding to the geminate, loses its link with one of the two timing units and a new segment is inserted in the position which has become free. A representation with a ‘double feature’ can explain this error only as a casual cooccurrence of two independent errors: a deletion of the feature ‘double’ and an insertion of a segment in an adjacent position. This, in turn, results in a complex restructuring of the original representation. McCloskey et al. have shown that pseudosubstitutions occur in their patient, HE, much more often than expected given the hypothesis of the combination of two adjacent unrelated errors.

*To account both for the presence of shift errors and the preservation of CV structure, McCloskey et al. assume representations as in scheme (5). To account for shift errors, the skeletal tier consists of neutral timing units not linked to syllable positions. To account for the preservation of consonant-vowel structure, each letter is associated with a feature that identifies it as a consonant or as a vowel. It is not clear, however, whether this representation predicts a systematic preservation of C/V structure. If a grapheme unit is lost together with its associated C/V specification it could well be replaced by a grapheme unit with a different C/V specification. Moreover, it is not clear whether C/V specifications without syllabic structure would be able to account for the general preservation of orthographic constraints beyond consonant-vowel structure. x

x

x

I

I

\/II

C:m V:a

.;

C:t

x

x

x I

V:o

Scheme 5.

C:n

V:e

224

C. ROMANI and A. CALABRESE

(a) ON I x I s

I x I 0

ONC I I xxx I I r e

ON I I xx \/ I 1 a

ON I I xx I I s 0

I

>

ONC I I x x I I r e

ON I I I xx x I 1

I t

I a

(b)

cv I

cv

cv I

sore

I

I

I

cvcvccv

I

la

>

I I sore1

I

I

I

I ta

I

:, Scheme 6. (a) Autosegmental

representation.

(b) Representation

with a feature ‘double’.

The representations of orthographic geminates discussed so far have opposite strengths and weaknesses in explaining shifts and pseudosubstitution errors. In addition, they face a common problem. In an autosegmental representation (phonological or orthographic) as well as in a representation with a feature ‘double’, the identity of the geminate is represented by a single unit on the melodic tier. Given this characteristic, one should expect that geminate substitutions (e.g. sorella > soremma) should occur as often as single phoneme/letter substitutions since nothing on the grapheme tier distinguishes a unit representing a single phoneme/letter from a unit representing a geminate. Dysgraphic patients, however, make very few geminate substitution errors. In this study, we will show that the phonological errors made by DB are as would be expected given an autosegmental representation of geminate consonants. These results in favour of an autosegmental representation add to evidence from other domains. The phonological errors made by our patient, however, also bear on the issue of the representation of geminates in the orthography. If the representation of geminates is the same in the orthography and in the phonology, as claimed by McCloskey et al., we have no reason to expect different patterns of error in the two modalities. We will discuss how differences between DB’s error pattern and those reported for dysgraphic patients bear on the nature of orthographic representations.

CLINICAL

CASE

DB is a 45-year-old Italian patient who suffered a CVA 6 years before we started testing. He has a high school diploma and was employed as a clerk before his illness. A CT scan showed an extensive left fronto-parietal lesion. DB’s speech output is severely reduced and limited mainly to content words. Inflectional and phonological errors are often produced in spontaneous speech and in single word repetition. However, in Romani, Semenza and Grana’ (in preparation) we argue that both morphological and phonological errors are the consequence of a phonological impairment. DB’s capacity for phonological discrimination is unimpaired. Comprehension of single words is quite good. In word-picture matching tasks, including semantic and phonological distracters, DB was 39/40 correct with spoken words and 36/40 correct with written words. However, DB has problems comprehending syntactically reversible

REPRESENTATION OF GEMINATE CONSONANTS

225

sentences and performing grammaticality judgements. On a sentence-picture matching task including semantic, morphological and syntactic disorders, he was 77% correct overall (63% correct with syntactic distracters). In judging sentences including different kinds of ungrammatical constructions, he was 65 % correct with spoken sentences and 42 % correct with written sentences. Since DB’s phonological impairment has been described extensively in Calabrese and Romani [ 121 and in Romani and Calabrese [ 131, we refer the reader to these papers for further information. Here, we will only say that DB’s speech production errors are for the most part substitutions, deletions, insertions and transpositions of single phonemes. Most of these errors result in simplifications of syllable structure. DB’s error pattern has been used to argue in favour of a sonority-based notion of syllabic complexity. It has been proposed that the optimal syllable type is one where sonority increases maximally and steadily from the margin of the syllable to the peak (e.g. ref [ 141). DB’s deletion errors concentrate on those syllable types that are more complex according to this notion. Moreover, both his deletions and his substitution errors show a strong tendency to produce syllable types that are simpler in terms of sonority. DB’s reading and writing are mildly impaired. In both tasks, performance is better with words than with non-words. A frequency effect is significant with the reading lists (highfrequency words: lo/94 = 11% errors; low-frequency words 20/94 = 21% errors); but not with the writing lists (high-frequency words: 8/40 = 20% errors; low-frequency words 9/4O = 23% errors). In writing, like reading, the great majority of errors can be characterized as substitutions, deletions, insertions and transpositions of single phonemes/letters. Table 1 shows the proportion of different kinds of errors made by DB in a reading and in a writing task. DB has an output problem and makes similar errors in any task that requires a spoken response (reading, repetition, spontaneous speech). However, he also makes the same kinds of errors in reading and writing. This similarity is more surprising. One has to consider, however, that Italian is a transparent language where most words can be written successfully by applying local phoneme-grapheme conversion rules. DB’s writing, moreover, is accomplished in a slow, piecemeal fashion. It takes him on average 15 Set to write a four-letter word, 38 Set to write a six-letter word and 43 Set to write an eight-letter word. The similarity between the errors made in the spoken and written modality, therefore, can be explained considering that DB is subvocalizing the word while writing it and converting his faulty phonological output into corresponding spelling mistakes. Our analyses concentrate on DB’s spoken output. Although DB made a few errors on geminates in the written modality, they were too few for a comparison with the spoken modality.

Table 1. Proportions

of error types made by DB in a reading and in a writing task

Error type Errors involving Substitutions Deletions Insertions Transpositions Total

a single letter

Errors involving Total

two letters

Errors

one or two letters

involving

Total number of errors

Reading

Writing

70% 5% 2% 0% 78%

48% 5% 4% 1% 58%

12%

16%

90%

74%

101

85

C. ROMANI and A. CALABRESE

226

EXPERIMENTAL

INVESTIGATION

All the errors discussed in this paper were produced while repeating single words. DB was given a large corpus of words to repeat (N = 7537), including words of different frequency, grammatical class and phoneme length. The general distribution of DB’s errors is reported in Table 2. The majority of errors (79%) involve the substitution, deletion, insertion, or transposition of a single phoneme (for more details, see ref [ 131). The analyses presented in this paper, however, concentrate on a comparison of the different kinds of geminate errors made by DB. Overall, DB made 78 errors with target geminate consonants; a complete listing of these errors is reported in the Appendix. They were of five different kinds. (1) Deletions: a geminate is replaced by the corresponding short consonant (e.g. /fretta/ > /freta/); N = 17/78; 22% of geminate errors. DB also made 15 errors of the opposite kind: a single consonant is geminated. Three of these errors are morphological. (2) Substitutions: a geminate is substituted for another geminate (e.g. /fretta/ > /fredda/); N = 44178; 56% of geminate errors. (3) Identity exchanges: the phonological value of a geminate is exchanged with that of a single consonant (e.g. /surreale/ > /sulleare/); N = 4/78; 5% of geminate errors. (4) Pseudosubstitutions: a geminate is replaced by a sequence of two distinct consonants (e.g. /fretta/ > /frenta/, /kontJesso/ > /kontJesto/). DB made 25 errors of this type. Twelve, however, were morphological (e.g. adottasse (he adopted, conjunctive) > adottaste (you-plural adopted, conjunctive). Excluding these errors, pseudosubstitutions amount to 13/78 = 17% of geminate errors. DB also made 29 errors of the opposite kind: two different consonants are replaced by a geminate (e.g. konserve > kosserve). Of these errors, one was morphological and 18 were palatalizations (that is, a liquid or a nasal consonant followed by a palatal glide was replaced by a geminate palatal consonant; e.g. komunyone > komuppone; elyo > eMo; note that p or d is always geminated in Italian). Table 2. Distribution of DB’s errors in repeating 7537 words Errors involving Substitutions Deletions Insertions Transpositions Total

a single phoneme 865 299 96 68 1328

Errors involving two phonemes d+s i+s i+d t+s t+d double substitutions double deletions double insertions double transpositions Total

191

Other phonological Fragments Omissions

126 39 2

errors

(51%) (18%) (6%) (4%) (79%)

38 7

^L 8

9: 29 13 1

(11%)

Total Proportions

of total errors are shown in parentheses.

REPRESENTATION OF GEMINATE CONSONANTS

227

(5) Full exchanges: a double phonological segment is transposed. DB made only one error of this kind: dissotjatsione > di.tJossatsione; l/78 = 1.3% of geminate errors. As for other linguistic phenomena, DB’s errors cannot be easily explained either by the hypothesis that geminates are represented by a single segment plus a feature ‘long’, or by the hypothesis that they are represented by a sequence of two identical units. The hypothesis that geminates are represented by a single segment plus a feature ‘long’ can easily explain four out of five of the kinds of errors made by DB. The first kind of error (e.g. /fretta/ > /freta/) can occur when the feature ‘long’ is lost (or mistakenly added); the second kind (e.g. /fretta/ > /fredda/) can occur when a segment is changed, but the feature ‘long’ is preserved; the third kind (e.g. /surreale/ > /sulleare/) can occur when a segment is exchanged with another, but the feature double remains in its original position; finally, the fifth kind (dissotJatsione > di.tJossatsione) can occur when a segment moves together with the attached feature double. This hypothesis, however, has difficulty explaining the fourth kind of error (e.g. /fretta/ > /frenta/). Given a representation with the feature ‘long’, there is no level where the geminate corresponds to two units. These errors would require two separate changes: reduction of the geminate and insertion of a different phoneme. The hypothesis that geminates are represented by two identical segments can easily explain the first kind of error made by DB (e.g. /fretta/ > /freta/) by hypothesizing that one of the two identical segments making up the geminate is deleted. It can also explain the fourth kind of error (e.g. /fretta/ > /frenta/) by hypothesizing that one of the two segments has been substituted. However, it has difficulty explaining the second and third kinds of errors (e.g. /fretta/ > /fredda/; /surreale/ > /sulleare/) since it will have to assume that, by chance, the same substitution has occurred on two adjacent segments. This hypothesis also finds it difficult to explain the fifth kind of error, ‘full exchanges’, since we have to assume that two independent segments move together. DB, however, makes only one error of this kind (dissotjatsione > di.tJossatsione). The two-segment hypothesis, therefore, correctly predicts the rarity of these errors. While both kinds of representations discussed above have difficulty explaining all five kinds of errors made by DB, an autosegmental representation can easily account for all of them. The first type of error (fretta > freta) results from the loss of one of the two timing units; the second kind (fretta > fredda) results from the substitution of the phonological segment; the third kind (surreale > sulleare) results from the exchange of two phonological segments; the fourth kind /fretta > frenta) results from breaking the link between the phonological segment and one of the two timing units and from associating a new phonological segment to the timing unit which was freed. Finally, this representation correctly predicts the rarity of full exchanges. An autosegmental representation can also account for an additional characteristic of DB’s errors. As described above, DB makes errors where a geminate consonant is replaced by a sequence of two different consonants, and vice versa. In these substitutions, the original consonant of the geminate is produced, plus a new consonant (e.g. /innaltsare/ (to rise) > /intaltsare/). It is interesting that in the case of pseudosubstitutions DB’s errors replace the geminate consonant with heterosyllabic clusters, but not with tautosyllabic clusters (e.g. fret.ta > fren.ta, but not fret.ta > fre.tra). That is, the two consonants replacing the geminates are one in coda position, and the other in the onset of the following syllable. In the whole corpus, there is only one case where the geminate is replaced by a sequence of two onset consonants (e.g. kom.mis.sa.rya. > kom .mi.sya. rya. to). This pattern would be predicted by an autosegmental representation where

C. ROMANI and A. CALABRESE

228

one to the timing unit of the geminate is linked to a coda position, and the other to an onset position. * A possible objection to the autosegmental interpretation of pseudosubstitutions proposed above stems from the fact that DB has a general tendency to avoid complex onsets (as shown in refs [ 12,131). The fact that he never repiaces a geminate consonant with a tautosyllabic sequence (e.g. two consonants in the onset), therefore, could stem from a tendency to avoid complex onsets, as well as from a tendency to preserve syllabic structure. DB, however, does make a few insertions that complicate syllable structure by replacing a single consonant with a cluster. In these cases, DB does not show any tendency to avoid tautosyllabic clusters. In fact, 48 of his insertion errors create a tautosyllabic cluster (e.g. fo.to.gra.fo > fro.to.gra.fo; le.o.par.do > le.o.par.dyo), and only 10 a heterosyllabic cluster (e.g. fer.ma.va.te > fer.ma.val.te). This is in striking contrast with errors where a cluster replaces a geminate. Finally, an autosegmental representation is consistent with a lack of shift errors in DB’s corpus. The phonological content of a geminate may be changed, but its position in the word remains unaltered. A similar result has been reported by Stemberger [ 111 for German and Swedish-but not English-corpora of speech errors: when a segment moves, it takes the length of the segment it replaces; length, however, moves much more rarely. These results suggest a greater stability of the skeletal tier than of the segmental tier. This is possibly due to the fact that changes at the skeletal tier would result in complex changes at the syllabic and prosodic tiers, as shown in scheme (3) above. Comparison

with dysgraphic

patients

DB’s error pattern on geminates shows some important differences from the error pattern shown by dysgraphic patients. Table 3 compares DB’s errors with those of LB reported by Caramazza and Miceli [ 1] and HE reported by McCloskey et al. [ 21. The most salient difference between DB and the dysgraphic patients is in the proportion of errors where a geminate consonant changes position in the word (e.g. exchanges, shifts, and duplications) that are made by the dysgraphic patients but not by DB. As discussed in the Introduction, these errors are most easily explained in terms of a representation with a feature ‘double’ and they have been the primary motivation for this representation. In the case of shifts, the feature ‘double’ is linked to the wrong consonant. In the case of duplications, it is linked to more than one consonant. In the case of exchanges, it exchanges position along with the linked letter. These errors are much more difficult to explain with an autosegmental representation unless one wishes to adopt the problematic assumption that representations are not syllabified (complex transformation of syllabic structure would thus be avoided). While DB does not make errors that are problematic for an autosegmental representation, he makes quite a few errors that are difficult to explain if geminates are represented with a feature ‘double’. These are errors where a geminate consonant is replaced by a sequence of two consonants (fretta > frenta). LB, the patient described by Caramazza and Miceli [ 1 I , makes only 7% pseudosubstitutions among geminate errors. Caramazza and Miceli explain them as complex errors arising as a combination of a deletion and an insertion. HE, the patient

*In the case of the converse kind of error either a heterosyllabic or a tautosyllabic cluster is replaced, by assimilation, with a geminate consonant (e.g. /markate/ > /makkate/; or elyo > eMo). In the case of a tautosyllabic clusters, most of DB’s errors are palatalizations where a liquid or a nasal followed by glide is replaced by a geminate palatal consonant (e.g. komunyone > komuppone; N = 18; see Appendix). These errors can be explained by DB’s general tendency to avoid complex onsets and, in particular, consonant-glide onsets.

REPRESENTATIONOF GEMINATECONSONANTS

229

Table 3. Comparison of different kinds of geminate errors in the phonology (DB) and in the orthography (LB and HE) DB

LB

HE

Type of error

N

%

N

%

N

%

1. Deletions sorella > soreia

17

22

9

13

159

52

2. Substitutions sorella > soremma

44

56

6

9

2

0.07

3. Segment exchange sorella > solerra

4

5

IO

14

0

0

4. Pseudosubstitution sorella > sorelta

13

17

5

7

28

9

39

56

97

32

1

0

0

97

32

I

1

Full exchanges sorella > sollera

I

1

Shifts sorella > sorrela

0

0

25

36

0

0

13

19

0

0

0

0

0

0

18

6

5. Changes

in position

Duplications sorella > sorrella 6. Others Total

64

1

69

304

described by McCloskey et al. [ 21, does not make many more pseudosubstitutions (9% of geminate errors), but McCloskey et al. argue that they cannot be explained as mixed errors. Since HE very rarely inserts a segment after a geminate (without deleting one of the two letters making up the geminate), it is difficult to claim that pseudosubstitutions result from two independent errors. * Pseudosubstitutions provide even stronger evidence in favour of an autosegmental phonological representation in the case of DB. HE’s pseudosubstitutions could still be errors where a consonant is inserted by chance after a geminate. One of the two letters making up the geminate could then be deleted to avoid the production of an illegal sequence (e.g. happen > hapren produces a legal sequence, but happen > happren is illegal). This explanation is more problematic in the case of DB since he makes a higher rate of pseudosubstitutions (17% vs 9%), and a lower rate of insertion errors (6% vs 17%). In fact, DB’s rate of pseudosubstitutions is much higher than his rate of consonant insertions, creating a cluster in an intervocalic context (e.g. VCV > VCCV). His rate of pseudosubstitutions is 28/2267 = 1.2% ; his rate of consonant insertions is 44/11364 = 0.4% (continuity adjusted x2 = 23.7; P < 0.001). This clearly indicates that the source of pseudosubstitutions is different from that of simple insertions. As noted above, moreover, consonant insertions creating clusters often produce tautosyllabic sequences (considering only intervocalic clusters, 39 insertions produce a tautosyllabic cluster, i.e. a complex onset, and only five a heterosyllabic cluster, i.e. a coda). This pattern is in sharp contrast with pseudosubstitutions that, instead, result systematically in heterosyllabic clusters. An autosegmental representation seems, clearly, to be the appropriate one for the spoken modality. DB’s errors can be explained by an autosegmental representation, and he makes no

*Note that, at least from the examples given by the authors, these errors are different from the equivalent errors produced by DB. As noted, when DB substitutes a geminate with a sequence of two consonants, one is in coda and one in onset. HE does not seem to respect this constraint (e.g. happen > hapren).

230

C. ROMANIand A.

CALABRESE

errors that are problematic for this account. It is less clear which is the correct representation in the written modality. The presence of shift errors suggest a representation with a feature ‘double’. The presence of pseudosubstitutions suggests an autosegmental representation. A comparison between DB and the dysgraphic patients, moreover, highlights still another problematic aspect of any of the proposed orthographic representations. Both an autosegmental representation and a representation with a feature ‘double’ predict that the rate of geminate substitutions should be identical to the rate of single-letter substitutions. In both representations, in fact, the identity of the geminate is represented by a single grapheme that is in no way different from a grapheme representing a single letter. Dysgraphic patients, however, make a puzzlingly low rate of geminate substitution errors (e.g. attuale > appuale). This in spite of the fact that, in all of these patients, substitutions are the most common error in the general corpus, and in contrast with DB, whose geminate errors are in rough proportion to the kinds of errors in the general corpus (e.g. a substitution is the most common error in the general corpus and with geminates). For example, in the total corpus of errors, HE made about the same number of substitution and deletion errors. With geminates, however, he made 52% deletions and only 7% substitutions. Given HE’s overall rate of substitution errors, McCloskey ef al. note that one should expect six times more geminate substitution errors. More substitution errors should also be expected in LB. This low error rate is particularly surprising when compared with the pseudosubstitution rate. According to Caramazza and Miceli’s account, substitutions are simple errors. They should, therefore, occur much more often than pseudosubstitutions which are interpreted as complex errors involving two unrelated, adjacent errors. LB, instead, makes almost the same proportion of substitution and pseudosubstitution errors (0.09 and 0.07%). A third dysgraphic patient reported by Miceli et al. [ 31, SFI, shows the same striking lack of geminate substitution errors. Most of SFI’s errors in writing words and non-words can be characterized as substitutions, deletions, insertions and transpositions of single letters. Substitutions are the most common errors in the general corpus but, in spite of the fact that the patient makes numerous geminate errors, he does not make a single geminate substitution.* A comparison with the phonology (DB) makes the low rate of geminate substitution errors even more problematic for existing accounts of orthographic representations. One could think that linking a graphemic unit to two timing units or to a feature ‘double’ protects it from damage. This hypothesis, however, is made implausible by the fact that no such protection is shown in the phonology: in fact, most of DB’s errors with geminates are substitutions. The rarity of geminate substitutions in writing would be explained if geminates are represented by two identical, adjacent segments. Identical, independent substitutions on adjacent segments should be quite rare. Given this representation, however, it is difficult to explain errors where a geminate changes position in the word.

*While SF1 does not make a single ‘pure’ geminate substitution, he produces some mixed errors where the geminate is both deleted (produced as a single consonant) and substituted (e.g. pubblico > puplico; N = 4). Miceli CI al. find that the rate of these errors is not different from the rate of single consonant deletions in non-geminate clusters and take this result as evidence that, at the graphemic level, geminates are represented as single letters. This conclusion appears to be based on the assumption that the mixed errors involve a geminate substitution plus deletion of the feature double. However, since only one of the two letters making up the geminate is substituted, we cannot be sure that this is the case. It is possible, for example, that the patient may first delete one of the two letters making up the geminate, and then makes a substitution, on the remaining letter; or that he may substitute one of the two letters making up the geminate first and then delete the remaining one. In both of these cases, the error does not involve a geminate substitution, but a substitution on single letters.

REPRESENTATION OF GEMINATE CONSONANTS

Phonological

vs orthographic

231

representations

A comparison between the phonological and the orthographic errors suggests that different representations are involved in the two modalities. Not only is the pattern of errors clearly different (55 % of LB’s errors and 32 % of HE’s errors with geminates are never produced by DB) , more crucially those features of the orthographic pattern that are problematic for an autosegmental representation do not show up in the phonology: DB shows a high rate of geminate substitutions and no geminates shifts. However, he shows a fair number of pseudosubstitutions. Given what has been discussed above, we think it likely that orthographic representations include a feature that says ‘repeat’ or ‘double’ (see ref [ 151 for a similar proposal in the typing domain). However, we agree with McCloskey et al. [ 21 in finding the rate of HE’s pseudosubstitution too high, given this representation. We noted, moreover, that the rate of double substitutions is surprisingly low in dysgraphic patients. A last resort could be to consider that geminates are represented differently at different orthographic levels. Geminates may be represented as a sequence of two letters at an abstract orthographic level. This would explain a low rate of substitution errors as well as the existence of pseudosubstitution errors. The representation that immediately precedes the motor level, however, may include a feature that gives the instruction to repeat the same motor pattern twice (therefore, something analogous to a feature ‘double’). This would explain the high rate of errors where the geminate changes position in the word. The hypothesis that geminates are represented differently at different levels explains the whole error pattern, but at the price of locating geminate shift errors at a different level to the other geminate errors. Not only is this inelegant, but it also has no independent support in the case of LB’s and HE’s errors. Recent studies, however, have provided evidence that the doubling information can be selectively affected by brain damage [ 3,5] , and that doubling information is represented at a level more peripheral than that of the most abstract orthographic representations [ 5 ] . SFI, the patient reported by Miceli et al. [ 31, makes mostly geminate deletions (e.g. leggo > lego) and very few other geminate errors. As suggested by the authors, this pattern is best explained in terms of loss of a doubling feature. RT, the patient reported by Venneri et al. [ 51, makes a large number of geminate perseveration errors in spelling (e.g. corteccia > corteeccia). These errors are best explained in terms of damage to the “doubling information” that acts “as a multiplier command without any specification for the number of repetitions”. Interestingly, RT’s geminate perseverations occur in handwriting, but not in oral spelling or spelling using wooden blocks. This suggests that the problem is not at the level of abstract orthographic representations, but at a more peripheral level of programming motor patterns for writing. Since autosegmental representations do not include a feature ‘double’, we expect that patterns where the doubling information is selectively affected, like those reported by Miceli et al. [ 31 and Venneri et al. [ 51, should not arise in the phonology. Clearly, more evidence is necessary to decide on the right orthographic representations. In particular, more evidence is necessary to decide at which level(s) the doubling information is represented. Taken together, however, the results we have discussed suggest that different representations are involved in the phonology and in the orthography. This has a bearing on the general issue of the relation between phonological and orthographic representations. At least in the case of the representation of geminates, there is evidence that orthographic representations are neither a direct translation of phonological representations nor the result of abstract principles encompassing both. The representation of geminate with a feature ‘double’, instead, seems to result directly from the different nature of orthographic representations.

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An orthographic geminate is easy to define: it is a letter (consonant or vowel) which is repeated twice. To define a phonological geminate is harder. It can be defined only by comparison with the corresponding short segment: it is longer and sometimes more tense. Length and tenseness, in their turn, are not easy to define. For example, it is the vowel preceding the geminate that is characteristically much shorter than the vowel preceding a short consonant. Thus, the production of an orthographic geminate (in handwriting, oral spelling, or typing) requires carrying out an identical motor gesture twice. For example, in spelling, the same graphic pattern is carried out twice in a row. The production of a spoken geminate, instead, in no way requires repetition. The same gesture instead is prolonged in time compared to a single consonant. These differences can very well affect the nature of the representation that controls motor implementations-a doubling feature may be involved in orthographic, but not in phonological representations-and, therefore, the likelihood of different kinds of errors.

CONCLUSION A proportion of DB’s errors involves the replacement of a geminate consonant with a sequence of two different consonants. Moreover, DB never changes the position of the geminate in the string. This pattern is not compatible with a representation of geminates in terms of a single phoneme linked to a feature ‘double’. This is in contrast to the pattern shown by dysgraphic patients which, instead, has lent support to a representation in terms of such a feature. Just as some of DB’s errors cannot be interpreted by a representation that has a single unit linked to a ‘double feature’, so other errors are not easily explained by a representation in terms of fwo separate consonants. DB often substitutes a geminate for another geminate (and there are some errors where the phonological value of the geminate is exchanged with the phonological value of another segment in the string). Again, this is in contrast with the pattern that has been reported for dysgraphic patients, who make very few geminate substitution errors. Overall, DB’s pattern is best explained by hypothesizing a representation of geminates that links a single phonological segment to two units of time. The fact that this pattern is so different from those reported for dysgraphic patients suggests differences in the format of phonological and orthographic representations. Acknowledgemenrs-This work was supported by a fellowship from the Human Frontier Science Program Organization (HFSPO) to Dr Cristina Romani and by INH grant n. 23836 to Prof. Alfonso Caramazza. We are indebted to Gabriele Miceli who provided access to the patient and to both Gabriele Miceli and Alfonso Caramazza for making some data available. We would also like to thank Andrew Olson for his helpful comments on the manuscript.

REFERENCES 1. Caramazza,

2. 3. 4. 5. 6. 7. 8.

A. and Miceli, G. The structure of graphemic representations. Cognifion 37, 243-297, 1990. McCloskey, M., Badecker, W., Goodman-Schulman, B. and Aliminosa, D. The structure of graphemic representations in spelling: evidence from a case of acquired dysgraphia. Cognitive Neuropsychology 11, 341-392, 1994. Miceli, G., Benvegnu’, B., Capasso, R. and Caramazza, A. Selective deficit in processing double letters. Cortex 31, 161-171, 1994. Tainturier, M. and Caramazza, A. The status of double letters in graphemic representations. Journal of Memory and Language, in press. Venneri, A., Cubelli, R. and Caffarra, P. Perseverative dysgraphia: a selective disorder in writing double letters. Neuropsychologia 32, 923-93 1, 1994. de Saussure, F. Course in General Linguistics. C. Bally and A. Sechehaye (Editors). McGraw Hill, New York, 1914/1959. Bloomfield, L. Language. Henry Holt, New York, 1933. Prinzmetal, W., Treman, R. and Rho, S. How to see a reading unit. Joumd of Memory and Language 25, 461-475, 1986.

REPRESENTATION OF GEMINATE CONSONANTS

233

9. Kenstowicz, M. Phonology in Generarive Grammar. Blackwell, London, 1994. IO. Goldsmith, J. Aurosegmenraal Phonology. Garland, New York, 1990. 11. Stemberger, J. P. Length as a suprasegmental feature: evidence from speech errors. Language 60, 895-913, 1984. 12. Calabrese, A. and Romani, C. Syllable structure in aphasia: a case study. In Cermmen Phonologicum II, P. Bettinetto, M. Kenstowiz and M. Loporcaro (Editors). Rosenberg & Sellier, Torino, 1991. 13. Romani, C. and Calabrese, A. Syllabic constraints in the phonological errors of an aphasic patient, submitted. 14. Clements, G. N. The role of the sonority cycle in core syllabification. In Papers in Lzborarory Phonology I, J. Kingston and M. Beckmann (Editors). Cambridge University Press, Cambridge, 1989. 15. Rumelhart, D. and Norman, D. Simulating a skilled typist: a study of skilled cognitive-motor performance. Cognirive Science 6, l-36, 1982.

APPENDIX Listing of DB Deletions:

s errors

involving geminate consonants

a geminate is produced as a single consonanl

arrabbyatura rabbyoso picnjone sbokkare skokkare fyankeddSrtre somitintse soomifiantse fallimentare intollerante annuntJare adoleJJentsa dijjiplina kojjentsa avviato avvyene ovviato

arrabyatura rabyoso pitjione sbokare skokare fyanked3are somilantse somilantsa falimentare intolerante anuntjare adolesenta disiplina kosentsa aviato avyene oviato

Geminations: a single consonant abbrutire karbonayo maniko

kwestionario ginokkyo pyumino pompeyani anormalita’ kanoro pipata ferirei gratn_fjano trattjeremo blokkeremo brutjeremo Pseudosubstitutions: abbondante att_fehi (NW) sofferto eleggo abbondantsa innotJentsa innaltsare

abbruttire karboppayo mappiko kwestoppario gippokkyo PyumipJto PompeaJmi allormalita’ kannolo pippata feril(ei grammaLfano trattjeremmo blokkeremmo brutjeremmo

bb>b bb>b kk>k kk>k kk>k dd3 > d3 M>I Lb>1 11>1 II>1 nn>n IS>s IS>s JS>s vv>v vv>v vv>v is produced as a geminate t > tt n>Jm n>Jm n>Jm n>pp n>Jtp n>Jm n>ll n>nn P>PP r>K m>mm m>mm m>mm m>mm

morphological morphological morphological

a geminate is produced as a sequence of two consonants ambondante altjelti sorferto erergo ammottantsa indotentsa intahsare

bb>mb tt$ > 1tJ ff>ti gg>rg nd>tt nn>nd nn>nt

C. ROMANI and A. CALABRESE

234

apportate distasse kontlessero kontjesso avvold3ere kommissariato adottasse adottassi domandassi d3ovasse d3urasse d3urassi mandasse mandassi nwotasse sperasse abitasse d3ovassi Pseudosubstitutions: balneare konserve markate subnormale dorsale avverarsi pastittJ0 trottskista ammainare kolonyale opinyoni alyeno allyetare allyevo immobilyare curvilineo erroneo estraneo omod3enei sotterraneo Anyene kalunnyare kantsonyere tjernyera tJiminyera komunyone estranyare matrimonii tokkaste

arportate distaste kontJestero kontJesto alvolgere kommisiariato adostaste adottasti domandasti d3ovaste d3uraste dgurasti mandaste mandasti nwotaste speraste abitasti dgovasti

PP>rp ss>st ss>st ss>st vv>lv ss>sy ss>st ss>st ss>st ss>st ss>st ss>st ss > St ss>st ss>st ss>st ss>st ss>st

morphological morphological morphological morphological morphological morphological morphological morphological morphological morphological morphological morphological

a sequence of two phonemes is produced as a geminate balleare kosserve makkate sublommale dossale avverassi pastiJ$o trottista ammappare kolonnae opipponi aLLen a.Metare aLr(evo immobiMayo curvilippo erroppo estrappo omod3eppi sotterrappo Appene kaluppale kantsoppera tlerppyera tlimippera komuppone estrappare matrimoppi tokkassi

In>ll ns>ss rk>kk rm>mm rs>ss rs>ss ttJ > I.f tts > tt in>pp ny>nn ny>pp ly>LL ly>M ly>Kb ly>bl( ne>pp ne>pp ne>pp ne>pp ne>pp ny>pp ny>pp ny>pp ny >pp ny>pp ny >pp ny>pp ny>pp st>ss

palatalization palatalization palatalization palatalization palatalization palatalization palatalization palatalization palatalization palatalization palatalization palatalization palatalization palatalization palatalization palatalization palatalization palatalization morphological

Substitutions: a geminate is produced as another geminate uJJugaman0 abbondantsa abbondantsa sbuttjare ragattsattjo addyanJo addyetro distruddse gaMarbi 0rgoMosi ipporanti

assugamano ammottantsa ammontantsa sbuJJare ragattsatsio aggyattlo aggyetro distrutte galliarbi orgollosi innorantsi

JJ>ss bb>mm bb>mm tt.l> SJ ttJ > ns dd > ggh dd > ggh dd3 > tt 6L>ll ‘ib>ll pp>nn

word

REPRESENTATIONOF GEMINATECONSONANTS

inseppanti reflnare folli autunnali kapodanno soprannome suattjennato kolonnelli appurare adoleJIente ajjugamano a_fJugare konoJIentsa konoJJentse lajjato PastaJIum pastaJIutta pastajjutta projjutto projjutto scrollare suJ$ti scrisse tjivettwolo attuale tjertettsa doltjettsa ragattsattJ0 singyottso moralittsare utilittsatsione d3eneralittsare

rennare foM0 autuppali kapodaPPo dFppaio sopprappome suattjeppato kolollelli accurare

assugare konossentsa lassato pastassutta pastassyutta pastassyutta prossyutto prossutto scrossare sussiti scri$$e tJivekkwol0 tJertJettJa doltJettJa ragattjattjo singyokkyo moraliddare

Exchanges: the phonological single segment kolonnello surrealism0 irreale birteka (NW)

m>nn m>nn ll>bd nn>pp nn>Pp nu>pp nn>pp nn>pp nn>ll PP>kk s.f>ss JJ>ss I.f>ss s.r>ss I.r>ss ss>ss s.r>ss JJ>ss IJ>ss

.I-P-ss

ss>ss j$>ss

.f.r>ss ss>ss tt> kk tt’PP tts > tt$ tts > tt$ tts>ttJ tts>kk tts > dd tts>dd tts > ddg

value of the geminate is exchanged with that of

konollello sullarismo illeare birketta

I-nn > n-II IT-I > 11-r IT-I > 11-r t-kk > k-tt

Shijis: the geminate changes position in the word dissotjatsione

ditjossatsione

SS-t > tJ-ss

235