Dissociations among functional categories in Korean agrammatism

Brain and Language 84 (2003) 170–188 www.elsevier.com/locate/b&l

Dissociations among functional categories in Korean agrammatism Miseon Lee Department of Communication Sciences and Disorders, Aphasia and Neurolinguistics Research Laboratory, Northwestern University, 2299 North Campus Drive, Evanston, IL 90802-3570, USA Accepted 30 April 2002

Abstract This study investigated the hypothesis that the syntactic trees formed by individuals with agrammatic aphasia cannot be constructed any higher than an impaired node as suggested by the tree-pruning hypothesis (Friedmann, 1994; Friedmann & Grodzinsky, 1997) and HagiwaraÕs (1995) hypothesis. It also examined their following implication that the members of a certain functional category are subject to the same degree of impairment. Two experiments were conducted to investigate a Korean agrammatic patientÕs use and understanding of three functional categories—Mood, Tense, and Complementizer. The results showed a dissociation among functional categories that preserves the higher node while leaving the lower node impaired both in production and comprehension. Another dissociation was found among members of the same category depending on their linear position in the clause. These results contrast with the predictions of the tree-pruning hypothesis, suggesting that the nearer to the end of the clause a functional element is located, the better it is preserved in Korean agrammatism. Ó 2002 Elsevier Science (USA). All rights reserved. Keywords: Agrammatism; Tree-pruning hypothesis; Functional categories; Korean agrammatism

1. Introduction The omission or substitution of grammatical morphemes and inflected forms has generally been taken to be the defining feature of agrammatism (Adams & Victor, 1993; Albert, Goodglass, Helm, Rubens, & Alexander, 1981; Berndt & Caramazza, 1980; Goldstein, 1948; Goodglass, 1976, 1993; Howes & Geschwind, 1962; Jones & Wepman, 1965; Marshall, 1986; Obler, 1988; Tissot, Mounin, & Lhermitte, 1973). A variety of theoretical accounts have been proposed concerning the sources of the loss of functional elements in agrammatic speech production; some phonological (Kean, 1977), some lexical (e.g., Bradley, Garrett, & Zurif, 1980; Bates & Wulfeck, 1989), and some syntactic (e.g., Caplan, 1983). Despite the ongoing controversies on the question of which linguistic level is impaired, many researchers now view agramE-mail address: [email protected]. 0093-934X/02/$ - see front matter Ó 2002 Elsevier Science (USA). All rights reserved. PII: S 0 0 9 3 - 9 3 4 X ( 0 2 ) 0 0 5 1 5 - 1

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matism as a disturbance of syntactic knowledge representations. The syntactic proponents can be divided into two groups—those that claim complete loss of syntactic knowledge (e.g., Caplan & Futter, 1986; Caramazza & Zurif, 1976; Goodglass, 1976; Jakobson, 1964; Saffran, Schwartz, & Marin, 1980), and those that claim a partial deficit in syntax (e.g., Goodglass & Hunt, 1958; Grodzinsky, 1984; Hagiwara, 1995; Saffran & Martin, 1990). Earlier work on agrammatism took the position that all functional elements are impaired to the same degree, whichever level of linguistic representation is considered to be disrupted. More recent studies, however, seem to support the view of partial impairment, drawing upon the crosslinguistic data that not all functional elements are equally impaired (e.g., de Roo, 1995; Menn & Obler, 1990; Miceli, Silveri, Romani, & Caramazza, 1989; Nespoulous et al., 1988; Saffran et al., 1980). The tree-pruning hypothesis (hereafter, TPH) proposed by Friedmann (1994) was the first attempt to account for this dissociation among functional elements. Based on the finding that tense but not agreement is impaired in the speech of a Hebrewspeaking patient, the TPH proposes that agrammatics produce trees that are intact up to the tense node and are pruned from this node and up. Along the same lines, Hagiwara (1995) has argued that the site of the deficit is not uniformly restricted to the Tense (T) node in all agrammatic sentence structures, but rather varies in accordance with the degree of severity of impairment. She proposed that the higher a functional node is in the syntactic representation, the more susceptible it is to impairment in cases of agrammatic aphasia. According to her claim, a patient who can handle the elements in the Complementizer (C) node should always perform well on the elements in the T node. She reported that no Japanese aphasics tested so far has performed well on the elements in C while performing badly on those in T. Friedmann and Grodzinsky (1997) and Friedmann (2001) confirmed that not all inflectional morphemes are equally impaired. Their Hebrew- and Palestinian Arabicspeaking agrammatic patients showed difficulties with verbal tense while they had an intact agreement system. Along with this result, Friedmann and Grodzinsky also considered other empirical facts suggesting that either T and Agreement (Agr) (along with C) are impaired or that only C is impaired in some agrammatics (Hagiwara, 1995). They proposed the revised TPH in (1) in order to account for these discrepancies. (1) The tree-pruning hypothesis (Friedmann & Grodzinsky, 1997, p. 420) (a) C, T, or Agr is underspecified in agrammatism. (b) An underspecified node cannot project any higher. According to this hypothesis, whenever a node is impaired, the tree cannot be constructed any higher, as shown in Fig. 1. This dissociation between tense and agreement inflectional morphemes has also been reported in other studies. For example, Benedet, Christiansen, and Goodglass (1998) report that their seven Englishspeaking agrammatics preserved agreement better than tense in spontaneous speech (42% versus approximately 15% correct). Nadeau and Gonzalez-Rothi (1992) also found that an English-speaking agrammatic made only 2% person agreement violations in spontaneous speech while making 17% tense violations and 40% complementizer omissions. An advantage of the TPH (including HagiwaraÕs hypothesis) is that it accounts within a particular syntactic framework for the dissociation among inflectional morphemes observed across languages. Another merit is that it accounts for individual variation among agrammatics in terms of the severity of impairment: that is, if a patient produces a tree that is pruned from a lower node, s/he suffers from a more severe impairment.

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Fig. 1. Degrees of severity in agrammatic impairment determined by pruning location (Friedmann & Grodzinsky, 1997, p. 421). The arch represents the site of the deficit.

However, there is some crosslingusitic evidence that compromises the TPH. Arabatzi and Edwards (2000) found in English agrammatic speech that tense was more severely impaired than wh words which are located in the higher node CP. Bastiaanse and van Zonneveld (1998) also showed that Dutch agrammatic subjects made no tense errors when their third person singular forms were not correctly inflected. Furthermore, Penke (2000) reported that functional categories including even the CP node were all preserved in German agrammatic speech. This finding suggests that agrammatic deficits in at least German are not due to the pruned syntactic tree. Moreover, the TPH does not explain the observed dissociations among elements belonging to the same inflectional node since it implies that pruning a functional node causes the same disruption to all the elements in the node. Therefore, when contrasts in the degree of impairment among elements belonging to the T category (i.e., copulas, auxiliaries, and verbal tense) were observed in two Japanese agrammaticsÕ speech (Sasanuma, Kamio, & Kubota, 1990), Friedmann and Grodzinsky (1997) proposed that the elements in question are located in different nodes in Japanese. The goal of the present study is to use experimental data from a Korean agrammatic aphasic to further investigate the dissociation among functional morphemes in agrammatic production. Given that earlier hypotheses took the position that all functional morphemes are impaired to the same degree in agrammatism, this paper focuses mainly on examining the validity of the TPHÕs claim that the syntactic

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tree cannot be constructed any higher than an impaired node. It also examines the further implication that members of the same functional category are subject to the same degree of impairment. In order is the second experiment on agrammatic comprehension of the same functional morphemes, which was designed to see if there is a modality dissociation between production and comprehension. Before proceeding to the experiments, a sketch of the functional categories in Korean that were tested in this study is presented.

2. Functional categories in Korean In Korean, a verb-final, agglutinating language, a clause typically ends with a verb inflected with several suffixes. The inflectional morphemes on the verb occur in the fixed order Ôverb stem-voice-subject honorific-tense/aspect-modal-addressee honorific-mood markerÕ (Sohn, 1994, pp. 299–300), as exemplified in (2). (2) ku pwun-i cap-hi-si-ess-keyss-sup-nikka? the person-N O M catch-P A S S -S U B H on-P S T -may-A D D H on-I N T R 1 ÔDid you feel that he was caught?Õ In (2), the verb stem cap Ôto catchÕ is inflected with six suffixes: passive –hi, subject honorific –si, past –ess, conjectural modal –keyss Ômay,Õ addressee honorific -sup, and interrogative mood marker –nikka.2 2.1. Mood markers (M) Although other inflectional suffixes are optional, a mood marker must occur at the end of a matrix sentence, as shown in (3). This is because a verb stem is a bound morpheme and thus cannot stand alone in Korean. (3) Mina-ka wus-ess-ta. Mina-N O M laugh-P S T -D E C L ÔMina laughed.Õ The mood markers indicate the clauseÕs modality and/or register, that is, declarative (DECL), interrogative (INTR), imperative (IMPR), and propositive (PROP). In Korean, unlike in English, it is the mood marker that determines the modality of an embedded clause while the complementizer (Comp) or a matrix verb cannot. For example, a complementizer or matrix verb identifies the modality of the embedded clause and the controller of PRO in English sentences, as seen in (4). On the other hand, in Korean sentences, such as in (5), mood markers identify the modality and the controller since the matrix verbs and the complementizers are identical. (4) (a) Mina believed that Minswu passed the exam. (b) Mina wondered whether Minswu passed the exam. (c) Minswui promised Mina [PROi to go]. (d) Minswu ordered Minai [PROi to go].

1

Abbreviations: ACC, accusative case; AddHon, addressee honorific; COMP, complementizer; DECL, declarative mood; HON, honorific suffix; IMPR, imperative mood; INTR, interrogative mood; NOM, nominative case; NPST, non-past tense; PASS, passive; PROP, propositive mood; PST, past tense; SubHon, subject honorific; TOP, topic; VOC, vocative. 2 The mood marker -nikka is in fact a combination of two suffixes -ni and -kka: -ni indicates the indicative interrogative and -kka indicates the sentence type of interrogative (Sohn, 1999, p. 234). In this paper, however, I will consider the two as the Ômood markerÕ to indicate the type of sentence, putting aside further discussion of this matter, which is beyond the goal of this paper.

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(5) (a) Minswui -nun Minaj -eykey [proiþj , ka-ca-ko] Minswu-T O P Mina-to [ go-P R O P -C O M P ] ÔMinswu suggested to Mina that they should go.Õ

hay-ss-ta. do-P S T -D E C L

(b) Minswu-nun Minai -eykey [proi ka-la-ko] hay-ss-ta. Minswu-T O P Mina-to [ go-I M P R -C O M P ] do-P S T -D E C L ÔMinswu ordered Mina to go.Õ For this reason, the mood marker is generally considered an independent functional category that heads its own projection Mood phrase (MP) in Korean (Ahn, 1991; Cho, 1994). 2.2. Complementizers (COMP) In an embedded clause, the mood marker is followed by a complementizer such as the quotative -ko Ôthat,Õ as exemplified in (6). This quotative complementizer is grammatically optional and, thus, can be omitted almost anywhere (Sohn, 1999, p. 325). (6) Minswu-nun Mina-eykey [khukey wus-ula(-ko)] malhay-ss-ta. Minswu-T O P Mina-to loudly laugh-I M P R -C O M P say-P S T -D E C L ÔMinswu told Mina to laugh loudly.Õ Other complementizers have different properties. For example, the conjunctive complementizers -taka Ôafter, and thenÕ and -(u)myense Ôat the same time whenÕ are attached to the verb stem, not to the mood marker, and thus are grammatically obligatory.3 (7) (a) Minswu-nun wus-taka/*-£ wul-ess-ta. Minswu-T O P laugh-after/*-£ cry-P S T -D E C L ÔMinswu laughed and then cried.Õ (b) Minswu-ka wul-myense/*-£ o-n-ta. Minswu-N O M cry-at.the.same.time.when/*-£ come-N P S T -D E C L ÔMinswu is coming at the same time he is crying.Õ Korean complementizers have the typical properties of COMP discussed in Muysken and van Riemsdijk (1985). They indicate the boundary between matrix and embedded clauses by attaching to the embedded clause. Furthermore, the choice of a complementizer is sensitive to the matrix verb. For instance, the quotative complementizer -ko is usually licensed by a matrix verb such as malha-ta Ôsay,Õ ha-ta Ôdo,Õ mit-ta Ôbelieve,Õ pokoha-ta Ôreport,Õ cek-ta Ôwrite,Õ or myengleynghata Ôorder.Õ 2.3. Tense (T) Korean has only a past and non-past distinction for tense. The past tense is marked by the past tense morpheme -(a/e)ss, which marks not only simple past but also present perfect aspect, as seen in (8). This morpheme immediately follows the verb stem if there is no subject honorific suffix -si or passive suffix -hi. (8) (a) Simple past Mina-ka ecey Minswu-lul manna-ss-ta. Mina-N O M yesterday Minswu-A C C meet-P S T -D E C L ÔMina met Minswu yesterday.Õ

3

As mentioned earlier, since a verb stem is a bound morpheme in Korean, it should be followed by at least one inflectional marker.

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(b) Present perfect Pelsse pom-i o-ass-ta. already spring-N O M come-P S T -D E C L ÔSpring has already come.Õ The past tense morpheme is either allowed or suppressed in embedded clauses, depending on the complementizer. For example, the quotative -ko ÔthatÕ allows the past tense morpheme to occur freely, as seen in (9a). On the other hand, as in (9b), the conjunctive -taka Ôafter thenÕ or -(u)myense Ôat the same time whenÕ does not allow the past tense in the preceding verbal inflections (Sohn, 1994, p. 323).4 (9) (a) Minswu-nun [Mina-ka wus-ess-ta-ko] malhay-ss-ta Minswu-T O P Mina-N O M laugh-P S T -D E C L -C O M P say-P S T -D E C L ÔMinswu said that Mina laughed.Õ (b) Minswu-ka wus(*-ess)-taka wul-ess-ta. Minswu-N O M laugh-P S T -after.then cry-P S T -D E C L ÔMinswu cried after he laughed.Õ Non-past tenses of a verb such as present and future are represented by the tense suffix -(nu)n, as shown in (10).5 The -nun form is used after a verb stem ending in a consonant and -n after a stem ending in a vowel. The non-past tense of an adjectival verb, on the other hand, is realized as a zero morpheme, as in yeppu-£-ta Ôbe pretty.Õ (10) (a) Present Mina-ka chayk-ul ilk-nun-ta. Mina-N O M book-A C C read-N P S T -D E C L ÔMina reads a book.Õ (b) Future Mina-ka nayil isaha-n-ta. Mina-N O M tomorrow move-N P S T -D E C L ÔMina is going to move tomorrow.Õ Tense is the functional node responsible for Nominative Case in Korean (Ahn, 1991). Some evidence for this comes from the fact that the Exceptional Case Marking (ECM) construction in Korean is prohibited with the presence of Tense in the embedded clause, as seen in (11a). This is because in the embedded clause, there is no argument to which Tense can assign Nominative Case. On the other hand, (11b) with Nominative Case on Mina in the embedded clause is grammatical. (11) (a) ?*Minswu-nun Mina-lul chencay-i-ess-ta-ko mit-nun-ta. Minswu-T O P Mina-A C C genius-be-P S T -D E C L -C O M P believe-N P S T -D E C L ÔMinswu believes Mina to be a genius.Õ (b) Minswu-nun Mina-ka chencay-i-ess-ta-ko mit-nun-ta. Minswu-T O P Mina-N O M genius-be-P S T -D E C L -C O M P believe-N P S T -D E C L ÔMinswu believes that Mina was a genius.Õ

4 In fact, the past tense suffix can be used in the embedded clause preceding -taka and -(u)myense. In this case, however, the embedded past tense suffix denotes past perfect aspect (Sohn, 1999, p. 365). 5 The status of the suffix -(nu)n is controversial. Sohn (1994, 1999), for example, refers to it as an indicative suffix, which is used in a plain speech level declarative (e.g., ka-n-ta ÔgoÕ) and the familiar level interrogative (e.g., ka-nun-ka Ôare (you) going?Õ). On the other hand, Lukoff (1982) considers it as a present tense marker. In fact, Martin (1992) says that the suffix denotes the present tense although he classifies it as a processive aspect marker. I will consider the suffix -(nu)n the non-past tense marker in this paper.

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2.4. Clausal structure for Korean The linear order of these three categories of inflectional morphemes on verbs mirror the hierarchical order of the functional projections, as schematized in Fig. 2 which is adopted from Ahn (1991). Among the three, Tense is linearly closest to the verb stem and is located in the lowest position in the syntactic tree while COMP, furthest from the verb stem, is the highest node in the tree. The same hierarchical arrangement is found in English, of course, except that Korean is head-final while English is head-initial. A piece of evidence for this view comes from conjunction structures. Consider the following sentences. (12) (a) [ [Mina-nun naka-ss]-ko [Minswu-nun tuleo-ass] ]-ni? Mina-T O P go.out-P S T -and Minswu-T O P come.in-P S T -I N T R ÔDid Mina go out and Minswu come in?Õ (b) [ [pap-ul mek-ca] kuliko [swukcey-lul ha-ca] ]-ko malhay-ss-ta. rice-A C C eat-P R O P and homework-A C C do-P R O P -C O M P say-P S T -D E C L Ô(He) suggested having a meal and doing our homework.Õ In (12a), the first conjunct is interpreted as an interrogative although it does not end with the interrogative mood marker. This is because the interrogative mood marker -ni appearing at the sentence-final position has scope over the first conjunct as well as the second. This indicates that MP is higher than TP (Cho, 1994). This MP, in turn, is under the scope of CP. The sentence in (12b), for example, is interpreted as Ô(He) suggested having a meal and (he) suggested doing our homework,Õ but not as ÔLetÕs have a meal and (he) suggested doing our homework.Õ In other words, the quotative complementizer ko ÔthatÕ and the matrix verb malhay-ss-ta ÔsaidÕ have scope over both conjuncts. Given this hierarchical structure, the TPH makes a prediction about the fate of each functional category in agrammatism: in particular, M should be impaired when T is disrupted. In embedded clauses, in turn, C such as -ko ÔthatÕ should also be

Fig. 2. The structure for a Korean clause (irrelevant details aside).

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Table 1 Western Aphasia Battery scores Aphasia quotient Fluency Comprehension Repetition Naming Reading

67.8 5 8.4 7.0 7.9 8.6

impaired whenever M is impaired. A further prediction of the TPH is that all members of the same category should have the same fate: for example, if the mood markers are impaired in matrix sentences, they should also be compromised in embedded clauses.

3. Experiment I: Elicited production tasks 3.1. Subject YK, a native monolingual speaker of Korean, was a 56-year-old right-handed man with a college education. He had suffered a single ischemic CVA in the left middle cerebral artery 15 months before the current study. The diagnosis of aphasia was based on administration of the Korean version of the Western Aphasia Battery (WAB, Kertesz, 1982). The Aphasia quotient (AQ) derived from the WAB was 67.8 (see Table 1). The subjectÕs comprehension was much better than his verbal expressive ability. His speech evinced the clinical characteristics of agrammatism: that is, effortful, slow and non-fluent speech, usually accompanied by a marked reduction in phrase length and syntactic complexity. A normal control speaker, LS, also took part to provide a baseline of normal performance. He was a monolingual Korean speaker and was matched with YK in age, education, handedness and dialect. LSÕs performance was virtually 100% correct both on production and comprehension tasks. 3.2. Stimuli Test stimuli were chosen to investigate YKÕs use of three functional categories in Korean—C, M, and T. The elements tested for each category are shown in Table 2. The targeted complementizer was the quotative -ko Ôthat,Õ which is used at the end of an embedded clause. For the mood markers, the plain speech level propositive -ca and imperative -la were targeted both in matrix and embedded clauses.6 YKÕs use of the past and non-past tense was also tested. Since the non-past tense of adjectival verbs is marked with a zero-morpheme, only verbs that require -(nu)n for the nonpast tense were used. 3.3. Methods Elicited production tasks were designed to test the subjectÕs use of functional categories, which are rarely found in spontaneous speech by agrammatics. The 6 Mood markers are used in six different speech levels that reflect the speakerÕs relationship with the addressee: plain (PL), intimate (INT), familiar (FML), blunt (BLT), polite (PLT), and deferential (DEFR). See Sohn (1994, 1999) for more details.

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Table 2 Functional morphemes tested in the production tasks Functional category

Morpheme

Function

C

-ko

Quotative complementizer ÔthatÕ

M

-ca -la

Propositive mood marker in plain speech level Imperative mood marker in plain speech level

T

-(a/e)ss -(nu)n

Past tense Non-past tense

elicited production method allows the collection of a sufficiently large sample of the targeted structure in a carefully controlled contexts. However, in order for this method to work well, it is very important to provide felicitous contexts that obligatorily give rise to the targeted structure. In this experiment, a so-called lead-in statement was used by the experimenter to provide uniquely felicitous contexts to elicit the functional categories being investigated. The subject was to describe pictures or situations in response to these statements. The vocabulary and syntactic structures of the lead-in statements were controlled with respect to frequency and complexity. The frequency of vocabulary was determined based on the word frequency list given by Kim (1995), and relatively simple sentences were used. Up to three additional repetitions of a lead-in statement were given when the subject hesitated to respond or asked the experimenter to repeat it. The subject was given as much time as he needed to produce the target sentence. 3.3.1. Elicitation of complementizers (C) and mood markers (M) in embedded clauses The propositive and imperative mood markers -ca and -la were tested in embedded clauses along with the complementizer -ko. To elicit sentences containing these elements, the subject was instructed to tell his wife what he had heard from the experimenter, in response to his wifeÕs question. For example, when the experimenter said ÔLetÕs go home,Õ YKÕs wife asked him what the experimenter had said. Her question contained none of the target complementizer or mood markers. There were 40 target sentences containing a mood marker and the complementizer -ko. An example of a target sentence is given in (13). (13) Target sentence: Cip-ey ka-ca-ko hay-ss-ta. Home-to go-P R O P -C O M P do-P S T -D E C L Ô(She) suggested to go home.Õ 3.3.2. Elicitation of mood markers (M) in matrix clauses To elicit the propositive -ca and the imperative -la in matrix clauses, the subject was presented with a picture which depicted a situation involving a man/woman and a boy/girl. After being given a brief description of the situation, he was asked to produce a sentence, as exemplified in (14). Twenty pictures were used for the elicitation of each mood marker. (14) Elicitation of the imperative –la Lead-in statement (in Korean):

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ItÕs dinnertime and dinner is ready. You want your son to have dinner now. What would you say to him?7 Target sentence: Cenyek mek-ela.8 dinner eat-I M P R ÔHave dinner!Õ 3.3.3. Elicitation of tense (T) in matrix clauses A picture description task was used for the elicitation of tense markers. To elicit a past tense sentence, for example, Mina-ka swuyenghay-ss-ta ÔMina swam,Õ the subject was first provided with a picture in which a woman is swimming. Then, he was instructed to describe the picture after hearing a lead-in statement, as exemplified in (15). (15) Lead-in statement (in Korean): This is MinaÕs picture diary for yesterday. Please tell me about it. A total of 40 pictures were used to elicit production of sentences containing tense morphemes. 3.4. Procedure YK was tested in a series of four sessions of at most one hour each. Each session began with a brief practice that was designed to help the subject understand the experimental procedures in question. All of the production task sessions were taperecorded and YKÕs utterances were fully transcribed by the experimenter following the protocol introduced in Menn and Obler (1990). The transcriptions were later checked by another native speaker of Korean. 3.5. Scoring For scoring, YKÕs response was counted as ÔcorrectÕ only if the target functional morpheme was produced correctly in the right position. Substitution errors were counted. When an utterance was missing the obligatory target morpheme, it was also counted as an error. There were no occurrences of misplaced functional morphemes in the entire data set. Self-repetitions involving an attempt at saying the same word or morpheme in sequence were not taken into account.9 On the other hand, self-corrections which were attempts at a different target morpheme were counted as correct or wrong, depending on its form. 3.6. Results A chi-square test revealed a dissociation among functional categories (v2 ¼ 50:447, df ¼ 3, p < :01): that is, C, M, and T were not equally impaired in YKÕs production. Table 3 summarizes the percentage of correct responses made in the elicited production tasks.

7

This is a rough translation of the Korean lead-in statement. Between adults in a close relationship such as old friends or couples, the intimate speech level mood marker –a/e often replaces the plain speech level imperative marker –la (Sohn, 1999, p. 271). 9 There were no occurrences in the entire data set of repetitions which could be judged as merely reproducing the experimenterÕs lead-in statement. 8

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Table 3 Results on the elicited production tasks Clause type

Functional category

Morpheme

Percentage (number) correct

Embedded

C

-ko

95 (41/43)

M

-ca -la

35 (15/43)

M

-ca -la

88 (52/59)

T

-(e/a)ss -(nu)n

61 (30/49)

Matrix

As shown in Table 3, YK produced 43 embedded clauses in response to 40 pictures and made only two errors on the complementizer -ko while making 28 errors on mood markers (95% versus 35% correct; v2 ¼ 34:605, df ¼ 1, p < :01). The errors with embedded mood markers included both omission and substitution. Examples are provided in (16). (16) (a) Omission error with an embedded mood marker Kathi *mek-£-ko hay-ss-ta. [target: mek-ca-ko] together eat-£-C O M P do-P S T -D E C L eat-P R O P -C O M P Ô(She) suggested that we should eat together.Õ (b) Substitution error with an embedded mood marker Ppalli *swukceyha-ca-ko hay-ss-ta. [target: swukceyha-la-ko] quickly homework.do-P R O P -C O M P do-P S T -D E C L homework.do-I M P R -C O M P Ô(She) suggested that we should do our homework now.Õ In matrix sentences, he made seven substitution errors on the 59 mood markers that he produced in response to 40 pictures (88% correct). YK made more errors with tense morphemes. Here, he produced 49 tense morphemes in response to 40 pictures, 19 of which were errors (61% correct). The difference between these two categories is significant (v2 ¼ 10:402, df ¼ 1, p < :01). Most of the tense errors involved substitution of the non-past form (17/19) for the past. An example is given in (17). (17) Substitution of a non-past form for the past tense Ecey cha-lul *takk-nun-ta. [target: takk-ass-ta] Yesterday car-A C C wash-N P S T -D E C L wash-P S T -D E C L Ô(He) washes the car yesterday.Õ 3.7. Discussion The main finding of these elicited production tasks is that functional categories in Korean were not equally impaired, as shown in Fig. 3. This type of dissociation has been frequently observed in agrammatism across languages (e.g., Friedmann & Grodzinsky, 1997; Miceli et al., 1989; Nespoulous et al., 1988). However, the finding that higher nodes were intact even when lower nodes were impaired is the precise opposite of what the TPH predicts. That is, C—the uppermost node and the locus of complementizers—was almost perfectly intact in YKÕs production. The lower node T, on the other hand, was obviously impaired. The difference between C and T is significant (v2 ¼ 34:605, df ¼ 1, p < :01).

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Fig. 3. Percentage correct for each functional category in the elicited production tasks.

When we contrast YKÕs performance on matrix and embedded clauses as in Fig. 3, we further see that the lower node was more impaired than the upper node. In YKÕs matrix sentences, the lower node T was more impaired than the higher node M. In his embedded clauses, the M node was evidently impaired while the -koÕs in the higher C position were perfectly preserved. Contrary to the TPH and HagiwaraÕs hypothesis, then, YK could construct higher nodes in the tree even when a lower node was impaired. In other words, the impairment of functional morphemes was not hierarchical as proposed in previous work. Rather, it seems that the nearer the linear position of a functional element is to the end of the clause, the better it is preserved. The uppermost node C, which is the linearly outermost element in a clause was best preserved in YKÕs language. On the other hand, the hierarchically lower node T which is farther from the end of a clause was more severely impaired. Moreover, mood markers were intact when they occur at the end of a matrix clause. Meanwhile, they were severely impaired in embedded clauses where they are located at the inner position. This result is supported by the experimental findings from the production of functional morphemes in the speech of five other Korean agrammatics as reported in Lee (2000). Further support comes from work by Halliwell (2000). Drawing on spontaneous speech data from two Korean agrammatics, he reports a significantly higher incidence of correct uses of sentence final elements than tense markers—exactly as expected in light of the experimental findings reported here. In addition, it seems that the members of the same functional category are impaired or spared depending on their location in a clause. As shown in Table 3 and Fig. 3, mood markers were more susceptible to impairment in embedded clauses than in matrix sentences (v2 ¼ 31:293, df ¼ 1, p < :01). The only difference in the two cases lies in the linear position of the mood markers: they are located in the outermost position in a matrix sentence but are followed by a complementizer in an embedded clause. This result also runs counter to the TPH and HagiwaraÕs hypothesis, which imply that all the members of the same category should be disrupted to the same degree. In summary, as reported in other languages, the results from the elicited production tasks showed that functional morphemes are not equally impaired in Korean. However, the finding that the syntactic representation can be constructed higher than an impaired node undermines the TPH and HagiwaraÕs hypothesis. Also problematic is the finding that YK did not show the same disruption to all members

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of a particular functional category. Depending on their linear position in a clause, the members of the M node were either impaired or intact.

4. Experiment II: Comprehension tasks Studies on agrammatism have shown a modality dissociation between production and comprehension. Some agrammatic patients have problems with production but not with comprehension (Caramazza & Hillis, 1989; Friedmann & Grodzinsky, 1997; Kolk, Grunsven, & Keyser, 1985; Miceli, Mazzuchi, Menn, & Goodglass, 1983; Naeser, Haas, Auerbach, Helm-Estabrooks, & Levine, 1984; Nespoulous et al., 1984, 1988), and others have impaired comprehension and spared production (Bates, Friederici, & Wulfeck, 1987; Caplan, 1985; Caramazza, Basili, Koller, & Berndt, 1981; Smith & Bates, 1987). Even when agrammatics have problems both in production and in comprehension, the impaired structures are different (Bastiaanse, Jonkers, Quak, & Put, 1996). The observed dissociation could therefore be due to different structures, rather than language modality. In fact, there have been only a few studies that compare the same syntactic constructions in both production and comprehension (e.g., Friedmann & Grodzinsky, 1997). For this reason, it is hard to make conclusions about the modality dissociation in agrammatism. The purpose of this second experiment is to investigate agrammatic comprehension of functional categories and to compare it with agrammatic production of the same constructions, which were examined in the first experiment. This will provide a clue about the modality dissociation in agrammatism. 4.1. Stimuli The three functional categories that were tested in elicited production tasks (i.e., C, M, and T) were used in the second experiment. Because of the experimental design of the comprehension tasks, however, stimuli used to test the C category were different from those used in the production tasks. The elements tested for each category are listed in Table 4. 4.2. Methods To investigate the subjectÕs comprehension, a truth-value judgment task, a picture selection task, a verbal response task, and an act-out task were used, depending on the target functional categories.

Table 4 Functional morphemes tested in the comprehension tasks Functional category

Morpheme

Function

C

-(u)myense -taka

Conjunctive complementizer Ôat the same timeÕ Conjunctive complementizer ÔafterÕ

M

-ca -la

Propositive mood marker in plain speech level Imperative mood marker in plain speech level

T

-(a/e)ss -(nu)n

Past tense Non-past tense

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4.2.1. Comprehension of tense (T) A truth-value judgment task was used to test YKÕs comprehension of past and non-past tense suffixes (20 sentences for each morpheme). In this task, YK was first presented with a picture depicting an event along with a test sentence. The experimenter then presented a sentence that he had to evaluate as true or false by putting a circle around a smiling or frowning face ( ). An example is given in (18). (18) (a) Test sentence for tense: Mina-ka swuyenghay-ss-ta. Mina-N O M swim-P S T - D E C L ÔMina swam.Õ (b) Sentence for truth-value judgment task: Mina-ka pelsse swuyenghay-ss-ta. Mina-N O M already swim-P S T -D E C L ÔMina already swam.Õ Since the tense of the test sentence in (18a) describes a past event and the sentence for the truth-value judgment task in (18b) presents a true statement about that event, the smiling face should be chosen if the tense morpheme is understood correctly. The correct judgment depends crucially on the understanding of the past tense suffix in the test sentence in (18a); otherwise the sentence could also be interpreted as nonpast. 4.2.2. Comprehension of mood markers (M) in matrix sentences A picture selection task was used to investigate the subjectÕs understanding of mood markers -la and -ca in matrix sentences (20 stimuli for each). In this task, the subject listened to an experimental sentence and was asked to identify from a set of pictures the person who uttered the sentence. For instance, the experimenter first presented a test sentence such as Wuywu masi-ela ÔDrink milk,Õ along with a set of pictures shown in Fig. 4, and then asked who was saying the sentence. Since the test sentence ends with the imperative mood marker -la, the boy on the right in the lower picture should be chosen if the mood marker is understood correctly. When the propositive mood marker -ca was presented, as in Wuywu masi-ca

Fig. 4. A sample set of pictures used for the picture-selection task.

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ÔLetÕs drink milk,Õ the correct response involves selection of the picture of one of the boys in the upper picture. 4.2.3. Comprehension of mood markers (M) in embedded sentences A verbal response task was used to test the subjectÕs interpretation of mood markers in 40 embedded clauses. This task asked the subject to respond verbally to a command consisting of a biclausal sentence built around the matrix verb hata Ôdo.Õ The interpretation of ha-ta ÔdoÕ in these contexts is determined by the mood marker in the embedded sentence. Depending on the mood marker, the verb ha-ta can be interpreted as either ÔorderÕ or Ôsuggest.Õ For this reason, sentences where all but the embedded mood markers are identical have different meanings. For instance, when the experimenter used a command sentence such as (19a), which had the imperative marker -la in the embedded clause, YK was supposed to produce a direct command such as in (19b) to the doll called Mina sitting next to him. When he was given a command such as in (20a) that had the propositive marker -ca, he was to produce a propositive sentence as in (20b). (19) (a) Experimenter: Mina-eykey [cip-ey ka-la-ko] ha-sey-yo. Mina-to home-to go-I M P R -C O M P do-H O N -I M P R ÔPlease order Mina to go home.Õ (b) Target sentence: Mina-ya, (ne) Mina-voc (you) ÔMina, go home!Õ

cip-ey ka-la. home-to go-I M P R

(20) (a) Experimenter: Mina-eykey [cip-ey ka-ca-ko] ha-sey-yo. Mina-to home-to go-P R O P -C O M P do-H O N -I M P R ÔPlease suggest to Mina that we should go home.Õ (b) Target sentence: Mina-ya, cip-ey Mina-voc home-to ÔMina, letÕs go home.Õ

ka-ca. go-P R O P

4.2.4. Comprehension of complementizers (C) In order to see whether YK understood complementizers, he was asked to act out the meaning of 20 pairs of command sentences that were provided randomly by the experimenter. He was provided with a doll named Mina. Each pair consisted of the same embedded clause and matrix verb, with a contrast in the choice of the complementizer: one had -(u)myense Ôat the same time whenÕ and the other -taka Ôafter,Õ as shown in (21). These complementizers are preceded only by a verb stem, not by a mood marker or tense. The interpretation of each sentence thus depended on the subjectÕs understanding of the complementizer. (21) Experimenter: [wus-umyense] Mina-lul chyetapo-sey-yo. smile-C O M P :at.the.same.time.when Mina-A C C look-H O N -I M P R ÔPlease look at Mina while smiling.Õ [wus-taka] Mina-lul chyetapo-sey-yo. smile-C O M P :-after Mina-A C C look-H O N -I M P R ÔPlease look at Mina after smilingÕ

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4.3. Procedure Comprehension tasks were conducted in two sessions of at most one hour each two weeks after the elicited production tasks were conducted. Each task began with a brief practice session. YKÕs responses were marked as correct or wrong on the answer sheets by the experimenter. His verbal responses in the verbal response task were tape-recorded. 4.4. Results and discussion YKÕs correct responses were counted for each functional morpheme. The number and percentages of correct responses are presented in Table 5. YKÕs comprehension of functional morphemes showed the same pattern as his production: that is, functional morphemes were not equally impaired in YKÕs comprehension (v2 ¼ 23:4881, df ¼ 3, p < :01). Even those of the same category showed a discrepancy in the degree of impairment: YK performed poorly on embedded mood markers, whereas his comprehension of matrix mood markers was fairly good (63% versus 85% correct). It is, however, worth noting that this difference might have been due to the different experimental methods used to test YKÕs comprehension of mood markers. The method used for embedded mood markers involved a verbal response task that was a combination of comprehension and elicited production tasks. This double task could have been responsible for the subjectÕs poor performance on embedded mood markers. Also prominent was the finding that as in production, higher nodes were preserved even when lower nodes were impaired. For example, no errors were made on the complementizers -myense and -taka, compared to an error rate of 30% for tense. A chi-square test showed that this difference is significant (v2 ¼ 14:118, df ¼ 1, p < :01). This dissociation was also found in embedded clauses between perfectly intact complementizers and severely impaired mood markers (100% versus 63% correct, v2 ¼ 18:462, df ¼ 1, p < :01). In general, YK performed better on the comprehension tasks than on the production tasks. However, he showed very similar patterns of loss and retention in his production and comprehension, as seen in Fig. 5. Moreover, the modality dissociation between production and comprehension is not evident: the difference between the two modalities is not significant (v2 ¼ 5:902, df ¼ 3, p > :05). These findings seem to support the claim for a parallelism between comprehension and production. Since Caramazza and ZurifÕs (1976) seminal finding of comprehension deficits in BrocaÕs aphasia, the view of parallel impairments across all modalities has been advanced Table 5 Results on the comprehension tasks Clause type

Functional category

Morpheme

Percentage (number) correct

Embedded

C

-(u)myense -taka

100 (40/40)

M

-ca -la

63 (25/40)

M

-ca -la

85 (34/40)

T

-(e/a)ss -(nu)n

70 (28/40)

Matrix

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Fig. 5. Comparison of production and comprehension patterns.

(e.g., Zurif, 1978, 1980). This view assumes that the same mechanisms underlie both production and comprehension, located in the BrocaÕs area and the vicinity. Therefore, a lesion in the area should result in the same disruption to both modalities. If we consider YKÕs performance on embedded mood markers, however, a significant difference was found between the two modalities: YKÕs comprehension was much better than his production (63% versus 35% correct, v2 ¼ 6:33, df ¼ 1, p < :05). With these results, it does not seem that YKÕs deficits were entirely parallel or totally distinct in the two modalities. Rather, as Grodzinsky (2000) said, it is more likely that the mechanisms for production are partially distinct from those for comprehension although they are both affected by the same lesion, resulting in either parallel impairments in both modalities or different disruptions depending on modalities.

5. Conclusion This study presents experimental data from a Korean agrammatic subject who showed dissociations in production between M and T in matrix sentences and between C and M in embedded clauses, preserving the higher node while leaving the lower node impaired. This result is in accordance with the previous observations that not all functional morphemes are equally impaired in agrammatic production. Another dissociation is found between the members of the functional category M (i.e., mood markers in matrix sentences and embedded clauses). These findings conflict with the prediction of the TPH and HagiwaraÕs hypothesis, suggesting that the nearer to the end of the clause a functional element is located, the better it is preserved in Korean agrammatic speech production. Interestingly, parallel patterns of impairment were found in comprehension of the three functional morphemes, indicating that there was no evident modality dissociation between production and comprehension. To confirm the validity of this suggestion, of course, further crosslinguistic studies of a variety of functional morphemes are necessary.

Acknowledgments I thank William OÕGrady for his insightful comments on the earlier versions of this paper. I am also grateful to Cynthia K. Thompson and Steven Fix for their helpful suggestions on an earlier version of this paper. My special thanks go to my subjects YK and LS for their participation in this study.

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