On certain grammatical prerequisites for agrammatic behaviour in comprehension

Volume 4, Number 2, pp. 179-211, 1989. Printed in Great Britain

J. Neurolinguisfics,

0911~6044/89 53.00 + .OO Pergamon Press plc

On Certain Grammatical Prerequisites for Agrammatic Behaviour in Comprehension

Victor Rosenthal

Marie-Claire Goldblum

INSERM- TLNP H6pital de la SalpCtrike Paris

INSERM U-324 Centre Paul Broca Paris

ABSTRACT

The present article examines the logical consistency of the interpretation of agrammatic deficits in comprehension in terms of the loss of syntactic processes and/or closed-class morphology. Drawing on a variety of neurolinguistic evidence and considering the structure of language comprehension tasks, we develop the argument that this account is logically untenable. We show that agrammatic behaviourincomprehension presupposes, in fact, the ability to run the morpho-syntactic disambiguation (MSD) of words in sentences. MSD, which consists in determining the lexical identity and syntactic category of words, is defined as the preliminary operation in language comprehension. This operation can only be done on the basis of grammatical rules and has to take into account all the words of a sentence. The running of MSD is necessary because the lexical identity and syntactic category of words in utterances is u priori indeterminate. Several implications of the present position are discussed and a new approach to the study of agrammatism is outlined. In particular, we explore the possibility that MSD in French involves gender determination by the article and, accordingly, that French speaking agrammatics are sensitive to this information. This prediction is borne out by a study, in four experiments, of the linguistic behaviour in comprehension of an agrammatic patient.

INTRODUCTION

The study of agrammatic behaviour has become increasingly sophisticated in recent years. New, subtle questions have been raised with respect to a variety of linguistic structures and phenomena; cross-linguistic variations have become a WE1 4:2-A

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legitimate subject of scrutiny and there has been a sizable development in experimental techniques (see Kean (1985) for further details). As regards the evolution of theoretical accounts of agrammatic disturbances, the principal consequence of this sophistication has been the fractionation of the previously dominating unitary explanation. Thus, for instance, it has been shown that agrammatism in comprehension and in production do not necessarily co-occur (see, for example, Miceli et al. 1983; Kolk et al. 1985), that deficits in the comprehension of oral and written language may not be concomitant and it has been suggested that morphological (i.e. closed-class morphology) and syntactical impairments are dissociable (cf. Goodglass and Menn 1985; Caramazza and Berndt 1985). Quite interestingly, none of these dissociations has imposed a major modification of the basic conceptual framework for the interpretation of agrammatism and, indeed, since the mid-1970s, the standard theory of agrammatic disturbances has undergone only minor reformulations. Schematically, with respect to language comprehension, the standard theory posits that agrammatic deficits are due to a failure to “retrieve” the syntactic structure of sentences. This failure is attributed either to the inability to carry out syntactic analyses, or to the fess of closed-class vocabulary (including both free and bound morphemes) and possibly to a combination of both (cf. Berndt and Caramazza 1980; Bradley th al. 1980; Schwartz et al. 1980). While the proposition that it is impossible to determine the syntactic structure of sentences when syntactic processes and/ or closed-class information are not available is undoubtedly reasonable, it constitutes either a trivial explanation of agrammatic deficits in comprehension or no explanation at all. The thrust of this “explanation” of agrammatism is based on a certain conception of language understanding, in general, and of the purpose of syntactic analyses, in particular. All things considered, only a single purpose is envisioned: to provide a hierarchic (e.g. tree-like) representation of sentence structure. This means that a full grammatical analysis is criterially required in order to yield sentence representation interfacable with cognitive processes (see, for example, Fodor 1983). The point is that incomplete parsing does not permit the specification of terminal nodes of structural sentence representation and thus doesn’t provide a result that can be exploited. Or, to put it in other words, given a single purpose computational mechanism, either its goal is achieved and thus the mechanism yields a result compatible with the know-how of the processes that take over the job or it isn’t achieved and consequently the incomplete result obtained does not satisfy the requirement of input-output compatibility (see Rosenthal 1988). Hence, such a result is perfectly useless. In short, the standard interpretation of agrammatic disorders in comprehension draws on a theory of parsing which is characterized by an all-or-none principle. Recently, Linebarger ef al. (1983) created quite a stir by providing evidence that

Grammatical Prerequisites for Agrammatism agrammatic

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patients

whose independently tested comprehension showed severe impairment may nevertheless be able to perform remarkably well on a grammaticality judgment task. The test involved a considerable variety of well-formed and ill-formed sentences, including apparently very subtle grammatical violations, such as the following. (1) (2) (3) (4) (5)

*He came my house at six o’clock. *The woman ran the store to. *Was the girl enjoy the show? *The workmen were expected would finish by noon. *How many did you see birds in the park?

The patients were able to correctly identify these sentences as ungrammatical and identified correct sentences as grammatical. What appears to be most striking in this context is the observation that certain violations involved function word manipulation (omission, substitution or movement). This led the authors to conclude that, contrary to what is generally assumed, “agrammatic aphasics are (. . .) capable of exploiting the closed-class vocabulary for the syntactic analysis of the sentences that they hear” (Schwartz et al. 1985: 120). The remarkable accuracy with which the four agrammatic subjects of the study made grammaticality judgments while performing very poorly on a comprehension test, which criterially required the ability to exploit certain grammatical relations, constitutes a finding that is astonishing on several grounds. First, because it stands in apparent contradiction to the concept of agrammatism as the inability to carry out grammatical analyses. Second, because it seems to be self-contradicting: assuming (quite reasonably) that grammaticality judgments do require the ability to carry out grammatical analyses, how can one be capable of parsing sentences and of making correct use of these analyses and, at the same time, be unable to make use of grammatical information in sentence comprehension. More importantly, however, we submit that Linebarger et al’s finding raises the following questions. (a) What is the purpose of grammatical analyses (both syntactical and morphological)? Is there a single purpose, or are there different grammatical analyses guided by different underlying goals? (b) What (or, alternatively, how complete parsing) is needed in order to detect grammatical violations in the aforementioned examples? What extent of parsing is (or may be) reflected by grammaticality judgments? In raising these questions we assume, of course, that Linebarger et al’s results are robust; in fact, they have already been formally (see, for example, Wulfeck 1984) and informally (to our knowledge, in at least two laboratories) replicated, but we have independent theoretical reasons (that we shall expose below) for believing

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them robust. This means that even the most serious objection to the authors’ use of an auditory format, on the grounds that no one knows how to fake correct sounding intonation contour for ungrammatical sentences, does not really hold. For, if incorrect intonation were actually the right cue, why did the patients systematically fail to detect certain categories of grammatical violations (see Linebarger et al. 1983; Schwartz ef al. 1985, for further detail)? It would do no harm, nevertheless, were this study replicated using a written format. Other objections, based on the arguable existence of considerable differences in task demands between grammaticality judgment and comprehension tasks (say, matching sentences to pictures), or between off- and on-line tasks, do not seem to be particularly pertinent. For one thing, granted that grammaticality judgment is an off-line task, this is also the case for metacognitive tasks used since the early 1970s to obtain the data upon which the standard definition of agrammatism has been based. Assuming, on the other hand, that grammaticality judgment does indeed make different processing demands than so-called comprehension tasks, the paradox of being at the same time able and unable to make use of grammatical cues still remains to be explained. In other words, this finding raises a host of troublesome questions for the standard theory of agrammatism and the underlying theory of normal parsing. And although the authors (Schwartz et al. 1985) posed still other questions regarding the status of the Syntactic Deficit Theory of agrammatism, they simply came up with another dissociation, namely, that between the ability to parse sentences and the capacity to exploit the results of parsing in sentence comprehension. That is, they suggested that agrammatics do parse sentences correctly, but cannot make use of the information thereby obtained in sentence comprehension. Unfortunately, this proposition poses more problems than it can reasonably be expected to solve. In particular, two problems stand out. One is that this proposition rests on the assumption (unsupported by available evidence) that the patients included in the Linebarger et al. experiment are able to achieve “a full parse”. Or, at least, that successful performance on their comprehension test doesn’t make more parsing demands than does grammaticality judgment (see, Zurif and Grodzinsky 1983, for a similar argument). Second, it (implicitly) resorts to a concept of “abnormal mechanism” to explain why agrammatic patients should be unable to make use of the results of grammatical analyses (since they are supposed to achieve a full parse), why, for instance, they shouldn’t be able to use certain of the most important cues, an obvious strategy liable to considerably improve their comprehension. Of course, no one can rule out a priori the possibility that certain patterns of aphasic performance are due to abnormal mechanisms which emerge after the onset of brain damage. However, it may be better advised to first try out an account in terms of %ormaY, though impaired, mechanisms whose functioning lends itself to

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rational explanation (see Semenza et al. 1988, for a discussion of this issue). It will be helpful in the present context to inquire about what may be needed in order to detect grammatical violations in Linebarger et al.3 (1983) examples. Although a task theory (see Rosenthal 1988) of grammaticality judgments has yet to be formulated, given the particular rule involving character of these judgments, it may be asked just what kind of grammatical rules are necessary and sufficient for the verification of whether sentences of the kind Linebarger et al. used are or are not ill-formed (note that this does not merely involve the ruies that are violated). Needless to say, in raising such a question one admits the possibility that only a limited amount of parsing will suffice. This is so because grammatical rules are governed by a hierarchy. This hierarchy implies that if certain rules are violated the sentence as such turns out to be unparsable because other necessary rules cannot be applied. And the failure to pursue parsing further on is ipsofacto equivalent to the detection of grammatical violation. (This doesn’t mean that we cannot analyze and “understand” ill informed sentences; in fact, in everyday life we deal with a substantial proportion of ungrammatical sentences which, under normal conditions, we often “correct” whether or not we are aware of doing so.) The subtlety of grammatical violations would depend on the grammatical rules of a given language and on the teleological structure of parsing (i.e. what has to be done and in what order.) This point will help us later on to understand why certain categories of violation in the Linebarger et al’s study are detected while others are not.

WHAT GRAMMATICAL COMPREHENSION

ANALYSES DO FOR LANGUAGE

Let us now consider the question of the overall purpose(s) of grammatical analyses in language comprehension. Is it to provide the language processor with a representation of the syntactic structure of an input sentence, as the standard theory stipulates? This proposition seemed so obvious during the last two decades that most researchers failed to notice that the “standard theory” is merely a conjecture and offers no supporting argument as to why there should be just a single purpose to grammatical analyses and why there ought to be structural representation. We submit that this conjecture is unwarranted and that the definition of the role of grammatical analyses in language comprehension has yet to be provided. It may be sufficient for our present purpose, though, to address this issue by asking what parsing provides that cannot be obtained in any alternative way? Note that this question calls for an answer in the form of a list of things to be done - not a random list but one structured according to a hierarchy that requires that goals be achieved in a certain order (i.e. certain goals have to be attained prior to others).

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Consider the following examples of goals that have to be achieved by syntactic analyses somewhere in the time course of language processing, (a) Determination of the lexical identity of every word in an input sentence. This means the identification of a word as a particular item in the morphemic inventory of the language and thereby the determination of its syntactic category. (b) Identifi~tion of the SW sf~c~~re of the input sentence. This implies, for instance, the determination of the subject and the complement which are necessary for the identification of the thematic structure (e.g. agent, patient). (c) Identification of the role of dererminers(e.g. definite articles, pronouns. . .). Cd) Determination of ~n~~~oric rei~~i~~s~i~s (i.e. of grammatically possible anaphoric referents). These few examples provide an illustration of the hierarchic structure of grammatical analyses. For instance, it is obviously impossible to identify the SVO structure of a sentence prior to the determination of the syntactic category of every word (not only nouns and verbs) of this sentence. Unless the lexical identity (and thereby the syntactic category) of all the words of a sentence is recognized, the SVO structure cannot be determined. Likewise, the determination of grammatically possible anaphoric referents cannot be performed prior to the identification of the SVO structure and of the role of determiners. The idea of the hierarchic structure of grammatical analyses is by no means new.1 On the contrary, it is so widely acknowledged as to make somewhat astonishing the small concern shown by neurolinguistic and psycholinguistic theories with such teleologically motivated questions as: what really has to come first, what has to come next and so on? Notice that this sort of question is very basic in computational linguistics, if only because no natural language parser can work without respecting the intrinsic order of grammatical analyses. But, unfortunately, no theoretical distinction has been drawn between algorithms and the structure of grammatical analyses. It should be stressed, in effect, that the present discussion is not concerned with the implementation of grammatical analyses (i.e. how they are carried out) but with the theory of what has to be done (cf. Marr 1977, 1982; Chomsky in Baars 1986; Rosenthal 1988). And this theory implies that certain analyses have to come first because their result is necessary for the running of other analyses. The primary problem with which any natural language parser is confronted is the determination of the lexical identity of every word of an input sentence. That is, the system has to determine for any given word to which particular dictionary entry it corresponds and thereby to identify its syntactic category. It is only once these syntactic categories have been determined that the system can engage in analyses purported to “retrieve” the syntactic structure of a sentence. Now, the whole issue

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would be trivial if words (taken individually) were not very often ambiguous, corresponding at the same time to different dictionary entries. To be sure, it is not polysemy that poses a problem at this stage but the fact that the different entries, to which a given word may simultaneously correspond, quite frequently belong to different syntactic categories. To put it plainly, the syntactic category of a word in a sentence cannot be “retrieved” by looking into a dictionary, because dictionaries are most likely to offer a few alternatives. Examples of such ambiguities are legion. Consider the following. (6) (7) (8) (9)

They bear guns since they decided to kill the bear. Don’t till the soil till I tell you the till is full. They shoot down dozens of birds for a handful of down. Will you respect my will?

Even the most cursory glance at an English dictionary will reveal dozens of similarly ambiguous items, not to mention such frequent ones as: can, might, mine, etc . . . And the proportion of ambiguities will be still higher in spoken English which abounds in syntactically ambiguous homophones (e.g. I vs eye, see vs sea, write vs right). Note that what makes the picture even darker is that these ambiguities hold across the open-closed-class vocabulary boundary (e.g. till is a noun, a verb, a preposition and a conjunction). Still, morpho-syntactic ambiguities are not as frequent in English as they are in languages endowed with a rich inflectional and derivational morphology. One will thus find many more ambiguous items in French, as for instance, the following. (10) I1 livre le lit. (He delivers the bed.) 11lit le livre. (He reads the book.) (11) 11montre la rkgle. (He points out the rule.) I1 r2gle la montre. (He sets the watch.) (12) Mets les sous l’armoire. (Put them under the cabinet.) Mets les sous dans l’armoire. (Put the money in the cabinet.) And in Polish, which uses inflectional morphology as its principal grammatical device, still more will be in evidence. Consider the following example wherein all words are potentially ambiguous. (13) Nie dumy ci grabi. (We won’t give you the rake.) The first two items NIE (adverb used to negate) and DAMY (conjugated form of: dac - to give) will change their lexical identity and syntactic category when used in a different syntactic structure, as in (14). (14) Te &my czekajq na nie. (These ladies wait for them.)

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Likewise, CI (indirect object (dative) pronoun: you) and GRAB1 (genitive form of the noun: grabie - rake) will undergo a similar identity-category change in (15) and (16). (15) Ci panowie byli pierwsi. (These gentlemen were first.) (16) Robin Hood grubi bogatych. (Robin Hood robs the rich.) The occurrence of this phenomenon is primarily explicable on combinatorial grounds, as are the differences in the proportion of ambiguities across languages. The richer the inflectional and derivational morphology of a language the greater the probability of the occurrence of morpho-syntactic ambiguities (especially for short words). That is, the more the morphology of lexical items varies, the greater the chance of overlap whereby an inflected word corresponds to several dictionary entries belonging to different syntactic categories. Morpho-syntactic ambiguity cannot thus be considered a minor, rare eccentricity restricted to certain languages. On the contrary, it turns out to be an inherent property of the lexicon, a property which thus has to be taken into account by any theory of language processing. The foregoing arguments make it clear that lexical identity cannot be obtained by simply mapping words to dictionary entries. The determination of lexical identity implies morpho-syntactic disambiguation. This disambiguation is totally independent of one’s semantic or pragmatic knowledge. Syntax, as Chomsky (1957) showed, cannot reduce to semantics or pragmatics. While these latter sorts of knowledge may play a far more considerable role in language comprehension than syntax does, without grammatical analyses they simply cannot be applied. Moreover, it should be borne in mind that all the information necessary for morphosyntactic disambiguation is couched in the very structure of utterances. Since the morphological and syntactical characteristics of utterances are lawfully embodied in sentence structure, the syntactic category of words will be obtained by analyzing the structure of a given sentence according to certain grammatical rules. It should be emphasized that given the very preliminary role of morpho-syntactic disambiguation in sentence comprehension and recognizing that this process serves precisely to identify words as particular items in the morphemic inventory of a language, semantic and pragmatic knowledge are simply of no use here. One cannot apply the knowledge of what the input is about prior to “knowing” what the input is about (see Fodor 1983). It is only once the words of an input sentence are identified as particular items in the morphemic inventory of the language that anything like knowledge of what the input is about can come into play. Two points of clarification may be needed here. First, it goes without saying that the analyses of sentence structure involved in morpho-syntactic disambiguation cunnot be selective. For selective analyses would mean that certain items could be identified a priori whereas in fact it is only through these analyses that words are

Grammatical

Prerequisites for Agrammatism

1g7

identified. It follows that closed-class items have no special status with respect to these preliminary processes. They may become a special category only as a result of morpho-syntactic disambiguation (whereby their syntactic category is identified), not prior to it. Second, morpho-syntactic disambiguation may not be sufficient to remove all syntactic ambiguities. Sentences (17) and (18) are well known examples of structurally ambiguous sentences that will resist disambiguation. (17) Visiting relatives can be boring. (18) Flying planes can be dangerous. But structural ambiguity is not at issue here and it should be recalled that the determination of the syntactic structure of an input sentence takes additional processing based on the results of preliminary morpho-syntactic disambiguation. While structural ambiguity means, for instance, that a sentence can be represented by two or more different syntactic structures, within any given alternative, the syntactic category of all lexical items is perfectly unequivocal. For as long as the lexical identity of the words of an input sentence is not recognized, no process of language comprehension, however limited or partial, can take place. MORPHO-SYNTACTIC

DISAMBIGUATION

AND AGRAMMATISM

Returning to the issue of agrammatism, what follows from the foregoing discussion is that the agrammatic comprehension of a sentence criterially implies the morpho-syntactic disambiguation of this sentence. Without this disambiguation, no deficit in language comprehension characteristic of agrammatism will be observed, because there will be simply no comprehension at all. A patient may well be unable to carry out any other syntactic analysis. He may thus assign wrong thematic roles to nouns and apparently ignore function words. But the very S-O inversion in assigning thematic roles implies the correct identification of nouns and it is only because a word has been identified as a closed-class item that it can henceforth be “ignored”. All this brings us to the conclusion that agrammatic behaviour in comprehension presupposes morpho-syntactic disambiguation (MSD) which in turn presupposes the ability to apply the grammatical rules on which it is based. This is in essence the argument put forward by Andreewsky and Seron (1975). They studied the performance of a patient whose comprehension was severely agrammatic for both visually and aurally presented utterances. The patient’s performance in reading sentences aloud was characteristically agrammatic: he behaved as a sort of grammatical filter producing only verbs and nouns and systematically omitting function words. By using syntactically ambiguous words, the authors demonstrated that this “grammatical filtering” was based on the

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implicit processing of grammatical rules. For instance, they presented the patient with the following.

(19) Le cur ralentit cur le moteur chauffe. (The bus slows down because the engine overheats.) wherein the string CAR occurs once as a noun (bus) and once as a conjunction (because). The patient uttered: (19 ‘) car ralentit moteur chauffe. (bus slows down engine overheats.) Since the patient produced the first CAR, thereby demonstrating the ability to read out this lexical string, it is clear that he omitted the second CAR upon the identification of its syntactic category. Likewise, even when this second CAR was replaced in the sentence by an unambiguous noun MER (sea), that is, by a lexical category that the patient was normally able to produce: (20) *Le train ralentit mer le moteur chauffe. (*The train slows down sea the engine overheats.), he uttered: (20 9 train ralentit moteur chauffe. (train slows down engine overheats.) leaving out MER, thereby implicitly treating it as a function word - the lexical category that he normally “ignored”. But, obviously, in order to determine which words were to be read out and which words were to be”ignored”, the patient had to identify the syntactic category of all the words of the target sentence and that, as Andreewsky and Seron (1975) argued, required the processing of certain grammatical rules. But this original demonstration that agrammatic behaviour implies MSD passed generally unnoticed. Consider now, once more, the task of grammaticality judgment presented by Linebarger et al. (1983) to their agrammatic patients. The primary point that needs to be clarified here is what kinds of grammatical analyses are necessary and sufficient for the detection of grammatical violations in examples (1) - (5) as well as the following. (21) *Is the boy is having a good time? (22) *The gift my mother is very nice. (23) *This job was expected Frank to get. It will be easier, though, to consider first what grammatical analyses are unnecesary for judging the grammaticality of the present examples. For instance, it is

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strictly useless to be able to determine anaphoric reference. On the other hand, although the ability to assign correct thematic roles (or to determine the SVO structure) may, in principle, be useful in certain cases - for instance, one can hardly assign thematic roles in (22) and (23) - it is not critical for the detection of grammatical violations in examples (1) - (5) and (21) - (23). In fact, problems arise prior to the assignment of thematic roles, at the level of the grammatical analyses necessary for the identification of the syntactic categories of the words in these sentences. They arise because certain basic rules of English involved in the identification of syntactic categories are violated. For instance, in (1):

(1)

*He came my house at six o’clock.

CAME can be followed by a preposition or an adverb but not by a pronoun. In (2): (2)

*The woman ran the store to.

TO is not a particle but a preposition and cannot undergo the rule of particle shift. In other words, an individual or an artificial system that is only capable of running MSD will detect the existence of grammatical violations in the present sentences simply because these violations render the sentences unparsable (without correcting the sentences). The performance of agrammatic patients, who correctly judged these sentences as ungrammatical and well-formed sentences as grammatical, thus shows unambiguously their sensitivity to the grammatical rules involved in the morpho-syntactic disambiguation of English utterances. And since these rules are both necessary and sufficient for the detection of the grammatical violations in the aforementioned sentences, there is no reason to assume that the patients studied by Linebarger and co-workers were able to apply any other grammatical rules. The case of the tag questions used in the same experiment, such as: (24) *The little boy fell down didn’t it? (25) *John is very tall doesn’t he? is however different because here the running of MSD is possible. Hence, a system endowed with the capacity to carry out MSD but no other syntactic analyses will fail to detect ill-formedness in (24) and (25). To put it in other words, the syntactic category of each lexical item in these two sentences can be correctly identified on the basis of the grammatical rules involved in the morpho-syntactic disambiguation of English utterances. It is only further on, presumably upon the analysis of the referential structure of these sentences, that in (24) the pronoun IT cannot be coindexed with LITTLE BOY and, in (25), the auxilliary DOESN’T cannot refer to the verb phrase. Accordingly, an individual able to achieve MSD but unable to analyze the co-referential structure of sentences will behave as Linebarger et al.‘s (1983) patients did: treat (24) and (25) as well-formed sentences.2 The Linebarger et al. (1983) study thus provides additional support for the

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following thesis: that morpho-syntactic disambiguation subsumes a natural kind; that it corresponds to an unavoidable preliminary process in the course of language comprehension; and that there could be no comprehension, even agrammatic, without the capacity to run this process. But, in fact, it is not data that are critical to this thesis but logic. Since no sentence can be processed without the determination ofthe lexical

identity

of its words,

and since the morpho-syntactic

ambiguity

of the

lexicon is inherent in the structure of language, morpho-syntactic disambiguation is inherent in the structure of language comprehension. This disambiguation can only be based on grammatical rules because no pragmatic or semantic knowledge can be helpful at this stage (see also Fodor 1983). What rules are precisely involved in this task depends on the characteristics ofparticular languages. The present suggestion is that the ideal case of agrammatism in comprehension would be that of a patient capable of doing anything the cognitive system normally does with the exception that MSD would be the only grammatical analysis he could achieve. By ideal we do not mean that such a case will be found but rather that any assessment of agrammatic behaviour could be done with reference to this hypothetical case, especially as regards the definition of the minimal parsing capacities underlying agrammatic comprehension. Since such an “ideal patient” would be able to determine the lexical identity of the words of a target sentence and be unable to infer any other information from the characteristics of the sentence structure, he would have to treat words as independent entities. This, in turn, would render certain closed-class morphemes (function words, suffixes, etc.) practically useless. On the other hand, he would be able to use a lot of context, or a lot of knowledge of how things normally are to compensate for the paucity of hit and nunc information, and that will enable him to cope quite well with everyday situations, except when confronted with reversible, counterfactual, certain passive or otherwise grammatically complicated sentences devised by smart neuropsychologists. Needless to add, this picture looks strangely like the standard description of agrammatic performance in comprehension (cf. Parisi and Pizzamiglio 1970; Caramazza and Zurif 1976; Schwartz et al. 1980; Deloche and Seron 1981). Admittedly, such an ideal case may simply not exist and actual agrammatic pathology presumably offers a panorama of residual effects of certain other spared grammatical analyses and of impairments that are not specifically “grammatical” in nature. Furthermore, this picture may only partly capture the deficits of agrammatic aphasics in comprehension. No adequate metrics exist to assess how good the comprehension is of a patient who picks correct targets showing that he correctly assigns thematic roles in a certain category of sentences. Or, to put it in other words, the assignment of thematic roles is relatively easy to test but it is only a part, though an important one, of language understanding. The same holds for most current metacognitive

tasks which, when correctly

performed,

say next to nothing

about

Grammatical Prerequisites for Agrammntism how impoverished

or imprecise

the interpretation

matic patients may be. It is startling to note how little is currently

of linguistic

understood

stimuli

191

by agram-

of the role of grammatical

cues in language interpretation. Even the definition of what precisely falls into the category of the analyses involved in MSD in such extensively studied languages as French, German, Italian or English has yet to be provided. One can, of course, use an articulate linguistic theory, as for instance Chomsky’s (1981) Government and Binding Theory, in an attempt to specify these grammatical analyses (as well as the others that follow them in the information processing course). However, this will imply a re-statement of structural linguistic concepts in a way that renders them compatible with the computational concepts of task theories (see Rosenthal 1988). To take an example, neither the subcomponents of the rule system nor the subsystems of the principles of the Government and Binding Theory can be directly mapped onto computational concepts. Thus, although the theories included in the subsystems can presumably be helpful in the development of a task theory of language comprehension, they are not stated so as to determine what is inherent in the structure of language comprehension tasks and to allow the specification of what has to be done and in what order and even if they were they would still be insufficient. It follows that the tentative explanations of agrammatic behaviour in comprehension which draw directly upon the Government and Binding Theory are, at best, in a position to account only for phenomena that are analyzable in structural terms. They are inadequate for the analysis of many other observed phenomena. This is, namely, the case for the theory recently presented by Grodzinsky (1986) who attempts to explain agrammatic performance in comprehension basically in terms of the disruption of the unity of For instance, he argues that if the there will be difficulty in assigning the case of active sentences (in thematic

roles will be correctly

the trace/antecedent chain (see Chomsky 1981). trace is “invisible” to the chain formation process thematic roles for passive sentences. However, in which no traces are involved in the chain) the

assigned.

But this sort of theory cannot

account

for

a host of well documented observations, including those bearing on the assignment of thematic roles. For instance, it does not account for the poor performance on simple active but pragmatically reversible sentences, such as: (26) Francois kisses Mary. (27) The Toyota overtakes

the Honda.

and fails to explain why agrammatic counter-intuitive sentences, such as: (28) The patient

patients

presented

with simple

active

but

account

of

takes care of the doctor.

tend to pick the second

noun

as AGENT.

Briefly, a purely structural

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agrammatism turns out to be insufficient even to cope with cases which, a priori, appear to be most suitable for a structural approach. Still, it is not the failure of this or other accounts of agrammatism which we intend to highlight here. The present discussion aims to criticize the tendency to pick up a few general linguistic or psycholinguistic concepts and show that they apply to (or account for) language pathology or, alternatively, to use a certain sort of pathology merely as a means to confirm a given linguistic theory. Should we add that this way of proceeding leaves little room for a genuinely neurolinguistic contribution to our knowledge of the normal language mechanisms; we fear that it is more liable to sterilize the field. It is always possible to take up a particular aspect of asphasic behaviour and show that it is consistent with a given linguistic theory but one would be better advised to study aphasic behaviour as a means to inform such a theory. So far we have been concerned with the basic theoretical reasons motivating our interpretation of agrammatic behaviour in comprehension around the concept of MSD. In the following sections we shall turn to empirical questions opened up by the present approach. These questions concern the analyses involved in the morpho-syntactic disambiguation of particular languages. Specifically, we shall report a study, conducted with an agrammatic patient, which appears to shed new light on the determination of the lexical identity of words in French. But before we do, let us illustrate the possibility of obtaining direct evidence of the ability of agrammatic aphasics to run MSD. To this end, we shall now summarize a sample of data drawn from a study of three French agrammatics which bore on certain ambiguities that characteristically occur in French. These data illustrate, we believe, the ability of the three patients to carry out the morpho-syntactic disambiguation of sentences despite their typically agrammatic performance on a variety of comprehensive tasks. We shall not go into the details of this study (see Desi et al. 1986), since our point is to be illustrative rather than demonstrative, but briefly summarize the relevant information concerning its rationale, procedure and results. The experimental technique can be easily illustrated with the following examples in English: (29) I heard they live in Sydney. (30) I heard them live in Sydney. in which LIVE is a homograph whose pronunciation differs depending on its syntactic category (here: verb or adjective). It is clearly not the semantic context that allows one to disambiguate LIVE in (29) and (30) (and thereby to pronounce it correctly) but syntax. Hence, an individual correctly pronouncing each LIVE shows ipso facto that he has applied certain grammatical rules of English permitting the disambiguation of these sentences. While in English such examples are relatively rare, French abounds in syntactically ambiguous homographs that

Gnmm8tkal Prerequisites for Agrammatism

differ in pronounciation

193

and apply to different semantic domains. Consider:

(31) Tu joues un as. (You play an ace.) AS (ace) is pronounced /as/. (32) Tu as un jouet. (You have a toy.) AS (a conjugated form of avoir - to have) is pronounced / a/. (33) Je vis a Paris. (I live in Paris.) VIS (a conjugated form of vivre - to live) is pronounced /vi/. (34) 11prend une vis. (He takes a screw). VIS (screw) is pronounced jvis/ . We used I2 sentences of this type built around 6 common French homographs and

asked subjects to read them aloud. The sentences were printed on cards and presented to patients one by one. We fixed as the criterion of successful performance that the patient either pronounce correctly the target ambiguous word, any one of its grammatically consistent possible forms (e.g. if the correct choice is a verb, any one of its suffixed or unsuffixed forms) or its grammatically consistent synonym. Thus, for instance if (31) was read: (35) Tu joues un roi. (You play a king). instead of: (31) Tu joues un as we considered it as correct disambiguation of the target AS (though, of course associated with a semantic paralexia) and, similarly, if (33) was read: (36) Vivre a Paris. (To live in Paris) instead of: (33) Je vis a Paris it was, in spite of the error, clearly a demonstration of the correct disambiguation of the target VIS. Three agrammatic subjects, all native French speakers, participated in the experiment. Two of them manifested characteristically agrammatic comprehension of both spoken and written language while the third was only agrammatic in reading. All of them had previously participated in a series of metacognitive tasks and showed considerable difficulty in matching reversible and counter-intuitive sentences to pictures and they had seldom succeeded in completing sentences which criterially required the “understanding” of a preposition (cf. Rosenthal and Bisiacchi 1982). In reading aloud sentences, they either tended to omit or to substitute certain function words (especially the prepositions) and often para-

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phrased the target. Their performance on single words matched the standard description of deep dyslexic reading (infrequent reading of function words, semantic paralexias on content words, impossibility of reading aloud pronounceable nonwords). Two patients performed the task in a manner meeting the criteria of correct disambiguation (spelled out above) in all 12 sentences whereas the third subject, whose speech was more severely disrupted, read only 6 targets (for the 6 other sentences he either uttered nothing or omitted the target) but all of them correctly according to the present criteria. This performance shows that the agrammatic patients involved in the study were able to carry out correctly the morpho-syntactic disambiguation of sentences containing syntactically ambiguous homographs, in spite of their limited capacity to conduct any other syntactic analyses. THE ROLE

OF ARTICLES

IN LEXICAL

IDENTIFICATION

The reasoning developed in the preceding sections was two-fold. On the one hand, we argued that the determination of the lexical identity of words in utterances constitutes the preliminary operation in language comprehension. This identification, we went on, is achieved via morpho-syntactic disambiguation and implies the processing of all the words of a sentence (including the function words). On the other hand, we considered a sample of empirical findings and marshalled logical arguments to the effect that agrammatic behaviour in comprehension presupposes the lexical identification of all the words of a given sentence. This, in turn, implies that agrammatic patients are able to run MSD. Endorsing this dual proposition raises many additional questions, both theoretical and empirical. What are the analyses involved in MSD? How can these grammatical analyses be distinguished from those which follow them in the information processing course? What are the grammatical cues to which agramare matic patients ought to be sensitive ? These and other related questions examples of issues raised by the present approach. One thing that stands out when considering these issues is that they imply answers which, to a considerable extent, varyfrom language to language. What is perhaps less visible from the outset is that the first of these questions is also the most difficult. It is the most difficult because it cannot be answered without specifying the hierarchic structure of analyses involved in MSD and it takes a well-developed theory to specify this structure. Nevertheless, insofar as the latter questions admit to partial answers, we submit that a clarification of these issues is relevant to the specification of the analyses involved in MSD. To this end, we shall assume that an analysis which appears to be logically necessary for lexical identification is also likely to be a part of MSD. Hence, it

Grammatical Prerequisites for Agrammrtism

195

ought to be preserved in agrammatism. This simple heuristic principle allows us to inquire into the role of particular grammatical cues. Consider again so called closed-class words. We insisted that these items cannot have a special status with respect to MSD because they are as necessary for the determination of lexical identity as are content words. It followed that an agrammatic can, in comprehension, selectively rely on content words and apparently disregard function words only because he is able to identify them as such. And this identification implies the processing of all the words of a sentence. It may now be useful to elaborate a bit on this point. Although the very presence of a given function word in a particular position in a sentence structure determines the syntactic category of certain items, it may not suffice for the lexical identification of all words. For instance, consider the case of particles in English. If English speaking agrammatics were not sensitive to particle role in idiomatic expressions (as contrasted to the role of prepositions), they simply would not be able to understand everyday idiomatic English. “Pull up” would be treated as “pull”, “give up” as “give”, no electricity could be laid on and no plane could take off. In other words, it is necessary to treat “up” as a particle modifying “pull” in order to identify “pull up”, “on” as a particle modifying “lay” and so on. A similar problem arises with respect to determiners (especially articles) in French. To put it in a nutshell, the gender information carried by an article is often necessary for the lexical identification of nouns. This point will become clearer as we proceed, but let us consider first what this proposition implies for agrammatic comprehension in French. Following the aforementioned heuristic principle it implies that French agrammatics should be sensitive to the gender information carried by an article. Yet the neuropsychological literature offers no evidence to this effect, though, to be sure, very little data concerning the “comprehension” of articles in any language is currently available. It is generally assumed, without strong evidence, that articles are merely ignored. The only exception are two studies conducted with English speaking agrammatics: one by Grossman et al. (1986) showing that agrammatics may be sensitive to the presence or absence of an article, the other by Goodenough et al. (1977) suggesting that these patients are insensitive to definite/ indefinite contrasts. Nevertheless, the literature provides a wealth of information relative to the production of closed-class items in several languages, information which may shed light on the present issue. The production of closed-class morphemes by agrammatic aphasics is commonly characterized by the omission of function words (e.g. articles, pronouns, auxiliaries, prepositions.. .) and of inflections (e.g. verbendings, plural marks). Although this characterization appears to be broadly (though not entirely) in keeping with the evidence arising from the observation of English-speaking agrammatics (see Goodglass and Menn 1985, for further details), its universal validity has been WE1 4:2-B

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challenged by a number of studies conducted with non-English patients. For instance, Grodzinsky (1984) has shown that Hebrew-speaking agrammatics, given the very structure of their language, are driven to produce inflected forms (though not necessarily the contextually correct ones); leaving out inflections would make them utter non-words. For this reason, Hebrew-speaking agrammatics make substitution errors but not omissions. Bates et al. (1987) examined specifically the production of determiners (articles) by English, German and Italian speaking agrammatics. The rationale behind this cross-linguistic comparison was that the richness of article information in German and Italian as compared to its poverty in English should affect the probability of article production by agrammatic patients, Accordingly, such a comparison may inform the issue of the relationship between article information and its function. Bates et al. (1987) found that English-speaking agrammatics tended to omit articles (73% of the time), whereas the German and Italian patients provided the article more than 80% of the time (of which over 85% were correct in the context of the task being used) “despite or perhaps because of the fact that articles are more complex and informative in those languages” (1987: 571) than in English. Since the article systems are very similar in French and Italian it may be worthwhile to compare the rates of article production by French and Italian agrammatics. The data currently available suggest that, much like Italian patients, French agrammatics are more likety to provide articles than omit them. In a single case study, Nespoulous et al. (1988) found that, at worst, articles were deleted in obligato~ contexts 13% of the time. A group study reported by Tissot et al. (I 973) concerned the production of articles by 19 agrammatics. The critical test involved the construction of 20 sentences (on the basis of 10 syntactic frames) out of a set of content words supplied by the experimenter. A total of 23 articles for the 20 sentences was expected if the patient conformed to the models with which he was provided. Unfortunately, the patients did not always stick to these models and the authors give no information about the number of articles which the structures actually produced should take. Nevertheless, the results reported by Tissot et al. (1973) show an overwhelming tendency to produce articles. The agrammatics included in the study provided correctiy a mean of 26.8 articles and omitted a mean of 3.3. Thus, although the available figures do not allow the computation of rates of article use, the results presented by Tissot et al. (1973) with French agrammatics broadly approximate those obtained by Bates et at. (1987) with their Italian patients. It would therefore appear that the same cause (richness of information carried by the article) leads to the same effect (tendency to produce articles). Although Bates et al. (I 987) were not concerned with article comprehension they made several observations relative to the structure of English, German and Italian which are directly relevant to the issue of comprehension. They pointed out that

Grammatical Prerequisites for Agrammatism

197

“morphology is minimally and sometimes contradictorily marked in English and it carries relatively little critical information in most sentence contexts’* (1987: 552) while “the article bears essential information about sentence structure in German” and in Italian the article forms “provide a great deal of disambiguating information” (1987: 553). If articles provide in certain languages a great deal of disambiguating information, the question arises as to how critical this information is for sentence understanding. We argued earlier that, regardless of whether an agrammatic aphasic does or does not produce function words, he or she should be able to carry out MSD. This means that all words have to be processed including the articles which in certain contexts are the only clues for the identification of nouns. But this minimal function, based on presence or absence, may not suffice for the lexical identification of French nouns. As in the other Romance languages, the article system in French basically combines three dimensions: masculine/ feminine, singular/plural, definite/indefinite. However, not all combinations will be found (there is no gender differentiation in the plural forms) and certain distinctions are blurred by morpho-phonological rules (the definite singular form used in front of words beginning with a vowel are not gender sensitive). There are seven article forms in French: UN, UNE, LE, LA, L’, DES and LES. UN and UNE are indefinite singular forms, masculine and feminine respectively. LE and LA are definite singular forms which differ along the masculine-feminine dimension (respectively), whereas L’ is used only in front of words beginning with a vowel, regardless of gender. The plural forms: DES and LES (indefinite and definite, respectively) are not gender sensitive. Not all article uses are relevant to the determination of the lexical identity of French words. In fact, the only relevant uses involve four article forms (UN, UNE, LE, LA) governed by gender agreement. Since it is the noun which determines article choice (as far as gender is concerned), it follows that in order to apply an appropriate article form it is first necessary to identify the noun’s gender. For native speakers to “recognize” that “seau” and “cable” are masculine whereas “peau” and “table”are feminine implies no special procedure, becausegender is an inherent part of the lexical identity of the noun. So when they pick a noun they pick its gender. In other words, the recognition of a noun’s gender is basically a matter of knowledge, rather than a matter of inference. Actually, the present examples suggest that it may even be difficult to assign gender to a noun merely by virtue of its morphology. Apart from a few regular classes of nouns whose gender abides by morphological rules, there are practically no reliable morpho-phonological rules for gender determination in French. And although in written language there appears to be a tendency to regularity, the distinction is often blurred by similar pronounciation of noun endings (e.g. le col-la sole, le cru-la grue, le sou-la moue, le joug-la joue, le coq-la coque.)3

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This indeterminacy of the morphology of French nouns with respect to gender would have no consequences in the present context were it not highly relevant to comprehension, as indeed it is. In point of fact, as the latter examples let one foresee, French abounds in homonyms whose meaning varies depending on gender (e.g. une mode/ fashion/ vs un mode/ manner, mood/, une moule/ mussel/ vs un moule /mold/, une tour /tower/ vs un tour /tour/, une coque /shell/ vs un coq /rooster/, une true /spate/ vs un cru /vintage/, une mtire 1blackberry/ vs un mur /wall/, etc . . .). Note that we are referring to nouns that either are both homographic and homophonic or just homophonic, the latter category being still larger. As a consequence, in the absence of semantic and/ or pragmatic cues, it is onlydeterminers (articles and pronouns) which allow the disambiguation of such nouns. To put it plainly, in French the gender of articles is highly relevant to and often necessary for, the determination of the lexical identity of nouns. This observation means that MSD in French is likely to involve gender determination by articles and pronouns. And since we assume that agrammatic comprehension presupposes the ability to conduct the morpho-syntactic disambiguation of sentences, it should then follow that French agrammatics ought to be sensitive to the gender information carried by the article. The study that follows was designed to explore this issue empirically. It involved a series of experiments conducted with a patient who was agrammatic in both comprehension and production. The testing materials in the whole series included homonyms (like those described in the preceding section) presented in a particular context such that the only disambiguating information available was supplied by the gender of the articles used. All tasks consisted in matching the target materials to pictures on a multiple choice array (which included the picture of the object related to the other, gender inconsistent reading of the target homonym). In other words, since successful performance on these experiments depended critically on the ability to use the gender information

carried by the article, we were thus testing

the patient’s sensitivity to this information. Although we were interested mainly in this sensitivity, the data reported below are relevant to the production of articles as well. Case Summary

A. M., a right-handed male, formerly an electronics engineer, was 66 in November 1986 when he incurred an ischemic accident in a part of the territory of the left middle cerebral artery (CT scan performed on 2 December 1986). On admission to BicCtre Hospital near Paris, on 14 November, he presented a right hemiparesis involving the upper limb and face, right hypoesthesia and was severely aphasic. The visual field was normal. The patient rapidly recovered from motor deficiency and on subsequent examinations presented no signs of agnosia or apraxia. His

Grammatical Prerequisites for Agrammatism linguistic

capabilities

February

and July

Neurolinguistic

were extensively

examined

199

by one of us (M. C. G.) between

1987.

Description

On standard neurolinguistic examination, A. M. was classified as a Broca’s agrammatic. His speech was slow and effortful. Phrase length was reduced and many phonemic paraphasias were present. He showed a marked difficulty with certain parts of speech: he either tended to omit or to substitute pronouns, verbs (or verb endings), auxiliaries and prepositions. This pattern of performance was also observed on a variety of metalinguistic tasks, such as grammatical transformations of sentences or sentence generation out of a given set of words. His reading was mildly impaired. In reading aloud a text, A. M. made frequent substitution errors for function words, but seldom dropped them altogether. A few semantic paralexias were present. His performance in writing a free text mirrored the patterns observed in his speech. Writing to dictation was excellent for single words (whether orthographically regular or irregular) but relatively difficult for non-words. For sentences mostly composed of closed-class items (e.g. Je le lui ai envoy& sans qu’il le veuille), writing to dictation was virtually impossible. A. M.‘s performance for simple sentences was variable. In most cases his strategy,consisted first to write down the nouns with their articles and then to fill in the blank space between these nouns with the verb and the remaining words. Repetition was mildly impaired (66% correct for words and 5 1% for nonwords). His auditory verbal STM was reduced (digit span: 4). Naming (20 objects and 20 pictures) was good in spite of long response latencies and articulatory distortions; name. Aurally given instructions instructions disregarding

the correct

article

was generally

were carried out correctly

96% of the time. The errors prepositions.

consisted

provided

with the

78% of the time and written mostly

in misinterpreting

or

A. M.‘s comprehension of syntactic structures was explored with a series of metacognitive tests. He was asked to act out 48 simple actions on the basis of 24 active sentences (I 2 reversibles and 12 non-reversibles) and 24 passive sentences (12 reversibles and 12 non-reversibles). He was also asked to match 36 sentences to pictures (on a multiple choice array); there were 12 coordinate, 12 cleft subject relative and 12 cleft object relative sentences. Table 1 summarizes the patient’s performance on these tests. All errors made by the patient on active and passive sentences consisted of inversions of thematic roles. Reversible sentences proved to be the most difficult to

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Journal of Neurolinguistics, Volume 4, Number 2 (1989)

TABLE 1 Sentence Comprehension: Percentage of Correct Responses Sentence type Actives (24) Passives (24) Co-ordinates (12) Cleft subject relatives (12) Cleft object relatives (12)

(12) Non-reversible

(12) Reversible

100% 92% 92% 92% 75%

83% 25%

interpret, especially the passives which yielded an error rate of 75%. This difficulty for reversible sentences appears to be most characteristic of agrammatic performance in comprehension (see Caramazza and Zurif 1976). Materials For all experiments the materials were based on: (a) 20 nouns which are both homographic and homophonic and whose meaning differs depending on gender (e.g. masculine: le moule /mold/, feminine: la moule / mussel/ ) - this makes for 10 distinct morphological forms; (b) 20 nouns which are homophones but not homographs (e.g. le mur /wall/, la mtire /blackberry); (c) 40 control nouns (neither homophonic nor homographic); (d) 10 sentences constructed with IO homographs; (e) 10 sentences constructed with 10 homophones; and (f) 5 control sentences containing neither homophonic nor homographic nouns. Note that (d) and (e) use both items of an ambiguous pair. All target materials are presented in the Appendix. Methods In experiment I, A. M. was presented aurally with 80 nouns preceded by an article: 20 homographs (list (a)), 20 homophones (list(b)) and 40 control nouns (list (c)). The stimuli were distributed so as to make 4 lists of 20 items. Each list consisted of 5 homophones, 5 homographs and IO control nouns and was evenly balanced with respect to gender. No list contained both members of the same ambiguous pair. The items were read, one by one, to the patient who was asked to match each noun to a picture on a multiple choice array. For the target nouns, this array

Grammatical Prerequisites for Agrammatism

201

contained 6 items including the correct picture, the picture of the object corresponding to the other, gender inconsistent reading of the target homophone and 4 distracters (2 items semantically related to the target pair of homonyms, one for each, I phonological foil and 1 unconnected item). Thus, for instance, le moule /mold/ was presented with pictures of a mold, a mussel and 4 distracters. For the control nouns, besides the correct picture the array contained 5 distractor pictures (1 item semantically connected to the target, 1 phonological foil and 3 unconnected items). The spatial arrangement of pictures in arrays varied from item to item. Experiment 2 was based on the same technique and the same materials except that the items were printed on cards and presented visually, one by one, to the patient. Both experiments differed, however, with respect to the order in which the 4 lists were presented. The other two experiments were based on the same principles except that they consisted in matching pictures to sentences. There were 25 sentences: 10 included homographic targets (list (d)), 10 homophonic targets (list (e)) and 5 control sentences (list (f)). Most of the gender determiners used in this condition were articles but there was also one demonstrative pronoun and one indefinite adjective. In both experiments A. M. was requested to match sentences to pictures on a multiple choice array. For the target sentences containing either a homograph or a homophone, this array consisted of 4 items including the correct picture, the picture involving the object corresponding to the other, gender inconsistent reading of the target homonym and 2 pictures unconnected to the target sentence. For control sentences, the picture choice was between the correct item and 3 distracters. In experiment 3 the sentence material was presented aurally to the patient whereas in experiment 4 the sentences were displayed visually. Both experiments involved the same sentences although not in the same order. Quite independently of these experiments we also tested A. M.‘s ability to provide the right article in speech. The task consisted of naming 80 pictures of objects, 40 pictures relative to the homonyms used in experiments 1 and 2 and 40 pictures of the control items used in the same experiments. There was a few days’ interval between each experiment. During this interval the patient was presented with a variety of tasks which differed in nature from the present experiments. Results and Discussion

Table 2 summarizes the results of the four experiments. On the whole, A. M. was almost always able to pick the correct gender of the article, disambiguating the target homonyms over 90% of the time. A closer examination of this table shows that the patient performed perfectly in the visual modality: his performance was errorless in experiments 2 and 4. His only

38

(20) Control items

9

(10) Homographs

Control items (5)

5

9

Homophones

(10)

_

2

-

_

I

1

2

3

_

40

20

20

Correct

_

_

-

Gender

Experiment 2 -

Words to Pictures

-

-

-

5

10

10

Correct

-

_

_

Gender

Experiment 4 -

B - Matching of Homonym Sentences to Pictures

_

-

_

Phonological

Experiment 3 - Oral Presentation Correct Errors Gender Others

15

(20) Homographs

w)

20

Homophones

TABLE 2 Matching of Homonym

Experiment I - Oral Presentation Errors Correct Semantic Gender

A-

_

-

-

-

_

_

Written Presentation Errors Others

_

-

-

Written Presentation Errors Phonological Semantic

Grammatical

Prerequisites for Agrammrtism

203

errors occurred in aural presentation and he was still correct over 90% of the time. In experiment I he missed, in fact, the disambiguation of only 2 target homographs (5%), opting for wrong gender, while the remaining 3 errors consisted in picking phonological foils which accorded with the target’s gender. Thus, although in experiment 1 his global performance for the target homonyms was 87.5%, he was correct on gender discrimination 95% of the time. In experiment 3 he also erred twice, missing the disambiguation of one homograph and one homophone (90% correct gender discrimination). A. M.‘s performance on the control items was also almost perfect; he erred only twice in experiment 1 (95% correct) picking phonological foils and made no errors in the other experiments. In the naming task, the patient uttered all the names with their articles. For the pictures relative to the target homonyms, on 2 occasions he didn’t use the expected name, producing a semantic paraphasia, but he only erred once using the wrong gender (97.5% correct gender production). For the control items he misnamed 2 pictures but the article was always correct. Thus, in spite of a few errors in the auditory modality, the finding of over 90% correct performance may suffice to demonstrate A. M.‘s sensitivity to the gender information carried by the article. It will be recalled that this information was in fact the only cue permitting to disambiguate the target homonyms. For instance, it was only LE (masculine) in front of MOULE which permitted matching this item to the picture of a mold and LA (feminine), to the picture of a mussel. Obviously, however, showing that A. M. is sensitive to the gender information carried by the article does not demonstrate that ipsofacto all French agrammatics are sensitive to this information. What these data do demonstrate is that the article’s gender can be adequately processed independently of the ability to make use of certain other types of closedclass information. One can thus misinterpret or apparently ignore prepositions and still be sensitive to the gender information carried by the article. So called closedclass morphology would, in this light, be something of a Pandora’s box. Thus, although further evidence may still be necessary, the present results lend support to the idea that French agrammatics should be sensitive to the gender information supplied by the article. They should be, because the determination of the lexical identity of French nouns often depends on the article’s (or pronoun’s) gender, and because agrammatic behaviour in comprehension presupposes lexical identification. Of course, it remains to be demonstrated that the processing of gender information pertains to MSD. Yet, the present experiments were carried out under the assumption that an analysis which appears to be logically necessary for lexical identification is also likely to be a part of MSD. This assumption may turn out to be unfounded as we still do not know what precisely is involved in MSD in French. WEL 49-C

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It might be argued that the determination of a noun’s gender on the basis of article information is a matter of lexical processing. In the preceding sections, when we described MSD we underscored its morpho-syntactic character. One could thus come to the conclusion that MSD is not, strictly speaking, lexical. But, on the other hand, insofar as lexical and morpho-syntactic cues are deeply interwoven this distinction may really not be overwhelmingly self-evident, especially when considering operations which aim at lexical identification. We are thus tempted to believe that morpho-syntactic disambiguation involves all the analyses necessary for lexical identification in a given language. In this sense, there would be no more device for the determination of a noun’s gender in French than for a verb with particle idiomatic expressions in English. In either case, the operations are aimed at lexical identification and, like the other analyses involved in MSD, they are a part of the minimal cognitive equipment necessary for the slightest understanding of anything. Another point which deserves attention is the observation that A. M. was not only sensitive to the article’s gender in comprehension, he was also able to provide correct articles when naming 80 objects. It will be recalled that he erred only once in this task, using the wrong gender (overall, this makes for I .25% gender errors in article production). This pattern of performance is congruent with the data reported by Bates et al. (1987): their German and Italian agrammatics furnished the article before nouns more than 80% of the time and made only 8.8% and 5.85% gender errors, respectively. But this tendency to produce articles cannot be explained using the previous arguments concerning lexical disambiguation. These arguments are relevant to comprehension not to production. We used homonyms which cut across gender because this affords the best opportunity for testing the sensitivity to the gender information carried by the article. But the ambiguity of homonymous nouns does not appear to hold in production. There is no logical reason to suggest that lexical identification should run both ways. Of course, it is not impossible that this finding of a parallelism in comprehension and production is purely coincidental. Still, assuming that our point relative to comprehension is correct, there is presently too much evidence showing that French agrammatics tend to provide the article in speech (see Tissot et al. 1973; Nespoulous et al. 1988) to suppose that this observation of parallelism is coincidental. Bates et al. (1987) tend to explain the finding that German and Italian agrammatics produce the article most of the time by the richness of article information in their languages. They suggest that “patients struggle to provide the article, in keeping with a lifetime habit of furnishing this important piece of information” (1987:560-561). This habit may not resist a severe morphological deficit - this may be why one of the patients described by Miceli et al. (1983) seldom provided articles in his speech.

Grammatical

Prerequisites for Agrammatism

205

Nevertheless, agrammatic patients often fail to provide other important pieces of information. It is thus necessary to evoke the functional properties of the article system in order to explain the tendency to produce articles in richly-inflected languages. As a point of fact, article information in French, German and Italian is a mixed bag. It is a combination of gender and number information, definite/ indefinite contrast and even case marking (in German). All these cues serve different goals. But only gender information appears to be functionally related to the likelihood of producing articles. It may be so because, unlike the other cues, gender is inherent in the lexical identity of nouns. Producing a noun is also expressing its gender. Since, in addition, the morphology of French nouns is often opaque with respect to gender, producing the article is the only consistent way of expressing this intrinsic property of the noun. Thus, as long as a patient is able to retrieve the noun he or she ought to be able to provide the article. It is perhaps here that the difference lies between the performance of French and Italian agrammatics whose deficit is qualified as morphological. If noun endings in Italian are indeed much less opaque with respect to gender than in French, the article carries no information which is critical for the noun. In other words, in spite of the apparent similarity between French and Italian, the article does not play the same role in both languages. And because the article does not play the same functionally basic role in the production of Italian nouns, it seems more liable to be deleted by morphologically impaired agrammatics. Indeed, one of the patients described by Miceli et al. (1983) omitted articles most of the time. In their study conducted with French agrammatics, Tissot et al. (1973) distinguished two groups of severe agrammatics: one group presented morphological deficits, the other did not. Severe agrammatics with a morphological deficit produced a mean of 20 articles and omitted a mean of 5.3 whereas those who did not present a morphological deficit furnished 27.6 articles against 6 omissions. Although the authors did not provide as extensive a description of their patients as did Miceli et al., what stands out is that the difference in the production of articles by both groups is far from overwhelming. More importantly, however, even severe agrammatics presenting a morphological deficit were able to provide the article most of the time. GENERAL

CONCLUSION

We began the present paper with the observation that the mainstream interpretations of agrammatism are based on certain pretheoretical a priori concepts of language comprehension, in general, and of the role of grammar, in particular. We suggested that these interpretations are more concerned with the description of the observable characteristics of an aphasic’s performance than with the understanding of the unobservable structure of language comprehension. Once one adopts the

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stance we have advanced, it turns out that the prevailing interpretation of agrammatic deficits in comprehension in terms of the loss of syntactic processes and/ or closed-class morphology is logically untenable. It is so if only because the lexicon is “marred” with morpho-syntactic ambiguities and thus the lexical identity (and the syntactic category) of words in utterances is apriori indeterminate. The determination of lexical identity requires the morpho-syntactic disambiguation of sentences and can only be done on the basis of grammatical rules. Logically, this disambiguation is the preliminary operation in language comprehension and constitutes a condition sine qua non for the running of any other operation. It follows that agrammatic syntactic disambiguation.

behaviour in comprehension Without this disambiguation

presupposes morphothere could simply be no

comprehension whatsoever. Furthermore, whenever a patient “disregards” a function word, he implicitly demonstrates the ability to identify it as such and the very S-O inversion in assigning thematic roles implies the correct identification of nouns. Our present proposal constitutes, we believe, a primary step in the development of a task theory of language comprehension. The aim is to understand what is inherent in the structure of language comprehension tasks, to specify what has to be done and in what order (cf. Rosenthal 1988). This teleologically motivated approach led us to distinguish MSD from other grammatical analyses that follow it in the time course. We marshalled a series of logical arguments to the effect that morpho-syntactic disambiguation subsumes a natural kind. Moreover, it seems reasonable to assume that this disambiguation is mandatory in the sense that Fodor’s input systems are supposed to be (cf. Fodor 1983), because prior to it no decision can materially be taken as to whether the organism is or is not “interested” by a given input. We suggested that the careful exploration of agrammatic behaviour along with the examination of the intrinsic structure of a given language may be useful for the specification of the analyses involved in MSD in this language as well as for the clarification of the role of other grammatical analyses in language comprehension. In this vein, we explored the possibility that MSD in French involves gender determination by articles and pronouns. This possibility is based on the observation that gender information supplied by determiners (articles, pronouns) often constitutes the only clue permitting to determine the lexical identity of certain ambiguous French nouns. Given this line of reasoning, we predicted that French speaking aphasics, who are agrammatics in comprehension, ought to be sensitive to the gender information supplied by the article. This prediction has been borne out by the evidence gathered in a series of four experiments conducted with an agrammatic patient. Although this evidence may not be decisive, if only because we are almost totally ignorant of the structure of MSD, it further supports the present

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suggestions concerning the status of MSD in language comprehension. Finally, this study also illustrates the empirical perspectives opened up by the present approach.

ACKNOWLEDGEMENTS The authors wish to thank Dr Martine Desi, M.D. for permission to study her patient and Reb Wolf Eisenberg for helpful suggestions and comments.

NOTES Note that the idea of the hierarchic structure of grammatical analyses does not imply a hierarchic representation of sentence structure. As a matter of fact, it does not even imply a representation. The suggestion that sensitivity to ill-formedness in tag questions requires additional parsing capacities in comparison to what is needed for the other classes of rule violations (with the exception of reflexives) used in the Linebarger et al. (1983) experiment has also been made in the framework of the Government and Binding Theory (Chomsky 1981) by Zurif and Grodzinsky (1983) and Bayer and De Bleser (1984). Note that we are not talking here about exceptions, which, by the way, are numerous. The present discussion refers to the observation that, orthographically, French nouns may have the same ending when they are masculine or feminine. For instance, the final “e” may terminate masculine and feminine nouns (e.g. le sable - la table, le casque - la vasque). What makes the picture look even darker is that the final “e” also marks certain groups of feminine nouns. Still worse, this final “e” can only be perceived in the written language, for it is not pronounced in speech. It should be noted, finally, that what we are considering in the present paper is fixed gender not alternate gender (e.g. le client - la cliente) which may also be found in English (e.g. waiter - waitress). The latter has nothing to do with lexical identity.

REFERENCES Andreewsky, E. and X. Seron 1975 “Implicit Processing of Grammatical Rules in a Classical Case of Agrammatism,” Correx 9, 379-390. Baars, B. J. 1986 The Cognirive Revolution in Psychology, New York: Guilford.

Journal of Neurolinguistics,

208

Bates, E., A. Friederici 1987

Volume 4, Number 2 (1989)

and B. Wulfeck

“Grammatical

Morphology

in Aphasia:

guages,” Cortex 23, 545-574. Bayer, J. and R. De Bleser n.d. “On So-called Grammaticality Unpublished Manuscript.

Evidence

Judgments

from Three

of Agrammatic

Lan-

Speakers,”

Berndt, R.S. and A. Caramazza of Broca’s Aphasia: Implications for a Neuropsycho1980 “A Redefinition logical Model of Language,” Applied Psycholinguistics 1, 225-278. Bradley, D. C., M. F. Garrett and E. B. Zurif “Syntactic Deficits in Broca’s Aphasia,” I980 Caramazza, 1985 Caramazza, I976

Chomsky, 1957 1981 Deloche, 1981

in Biological Studies of Mental

Processes, D. Caplan (ed.), Cambridge, MA: M.I.T. Press. A. and R. S. Berndt “A Multicomponent Deficit View of Agrammatic Broca’s Aphasia,” Agrammatism, M. L. Kean (ed.), Orlando, FL: Academic Press. A. and E. B. Zurif “Dissociation of Algorithmic and Heuristic Comprehension: Evidence from Aphasia,” 572-582. N. Syntactic

Structures,

The Hague,

Lectures on Government Foris Publications. G. and X. Seron “Sentence Understanding from a Sentence-Picture

Processes in Language Brain and Language 3,

The Netherlands:

and Binding,

Dordrecht,

Mouton. The Netherlands:

and Knowledge of the World: Evidences Matching Task Performed by Aphasic

Patients,” Brain and Language 14, 57-69. Desi, M., V. Rosenthal and E. Andreewsky “An Exploration of Residual Parsing, Capabilities I986 paper presented at the 4th European psychology, Bressanone, Italy. Fodor,

in

Workshop

in Agrammatism,” on Cognitive

Neuro-

J. A.

MA: M.I.T. Press. 1983 The Modularity of Mind, Cambridge, Goodenough, C., E. B. Zurif and S. Weintraub 1977 “Aphasics’ Attention to Grammatical Morphemes,” Language and Speech 20, 1I-19. Goodglass, H. and L. Menn a Unitary Phenomenon?” in Agrammatism, M. L. 1985 “Is Agrammatism Kean (ed.) Orlando,

FL: Academic

Press.

CrammaticaI

Grodzinsky, Y. ] 984 “The 1986 Grossman, 1986

Syntactic

99-120. “Language

Deficits

of Agrammatism,”

and the Theory

of Syntax,”

27, 135-159. M., S. Carey, E. B. Zurif and L. Diller Form Class “Proper and Common Nouns: Aphasia,”

Brain and Language

Kean, M. L. (ed.) 1985 Agrammafism, Kolk,

Characterization

Prerequisites for Agrammatism

Orlando,

Cognition

209

16,

Brain and Language

Judgments

in Broca’s

28, 114- 125.

FL: Academic

Press.

H., M. van Grunsven and A. Keyser 1985 “On Parallelism Between Production and Comprehension in Agrammatism,” in Agrammatism, M. L. Kean (ed.), Orlando, FL: Academic

Linebarger, 1983 Mart-, D. 1977

Press. M.C.,

M.F.

Schwartz

and E.M.

Saffran

“Sensitivity Aphasics,”

to Grammatical Structure Cognition 13, 36 l-392.

“Artificial 9, 37-48.

Intelligence

-

A Personal

in

So-called

Agrammatic

View,” Artifi:cial Intelligence

1982 Vision, New York: W. H. Freeman. Miceli, G., A. Mazzucchi, L. Menn and H. Goodglass 1983 “Contrasting Cases of Italian Agrammatic Aphasia without Comprehension Disorder,” Brain and Language 19, 65-97. Nespoulous, J.L., M. Dordain, C. Perron, B. Ska, D. Bub, D. Caplan, J. Mehler and A. R. Lecours 1988 “Agrammatism in Sentence Production without Comprehension Deficits: Reduced Availability of Syntactic Structures and/or of Grammatical Morphemes? A Case Study,” Brain and Language 33,237-295. Parisi, D. and L. Pizzamiglio 1970 “Syntactic Comprehension in Aphasia,” Cortex 2, 204-215. Rosenthal, V. 1988 “Does it Rattle When You Shake it: Modularity of Mind and the Epistemology of Cognitive Research,” in Perspectives on Cognitive Neuropsychology, G. Denes, P. Bisiacchi and C. Semenza (eds.), London: Lawrence Erlbaum. Rosenthal, V. and P. Bisiacchi 1982 “Representing Sentence Content in Aphasia: Strategies and Limitations,” Psychologica Belgica 22, 143- 160.

210

Journal of Neurolinguistics,

Volume 4, Number 2 (1989)

Schwartz, M. F., M. C. Linebarger and E. M. Saffran 1985 “The Status of the Syntactic Deficit Theory of Agrammatism,” in Agrammatism, M. L. Kean (ed.), Orlando, FL: Academic Press. Schwartz, M. F., E. M. Saffran and 0. S. M. Marin 1980 “The Word Order Problem in Agrammatism: I. Comprehension,” Brain and Language 10,249-262. Semenza, C., P. Bisiacchi and V. Rosenthal 1988 “A Function for Cognitive Neuropsychology,” in Perspectives on Cognitive Neuropsychology, G. Denes, P. Bisiacchi and C. Semenza (eds.), London: Lawrence Erlbaum. Tissot, R. J., G. Mounin and F. Lhermitte 1973 L’ugrummatisme, Bruxelles: Dessart Wulfeck, B. B. 1984 “Grammaticality Judgement and Sentence Comprehension in Agrammatic Aphasis,” Paper Presented at BABBLE, Niagara Falls. Zurif, E. B. and Y. Grodzinsky 1983 “Grammatical Sensitivity in Agrammatism: A Reply to Lindebarger et al.,” Cognition

15, 207-213.

APPENDIX Target Materials for Experiments 1 - 4 List (a) le rose (pink) la rose (rose) le pique (spade-cards) la pique (pike) le vase (vase) la vase (mud) le po&le (stove) la poCle (frying pan) le livre (book) la livre (pound) le moule (mold) la moule (mussel) le manche (handle) la manche (sleeve) le pendule (pendulum) la pendule (clock) le page (page-attendant) la page (page-book) le mousse (cabin boy) la mousse (moss) le le le le

List (b) bal (ball-dance) la balle (ball) cap (heading-course) la cape (cloak) co1 (collar) la colle (glue) renne (reindeer) la reine (queen)

Grnmmatical

le poil (fur) le chene (oak) le se1 (salt) le pis (udder) le mur (wall) le sol (floor)

la poele (frying la chaine

Prerequisites for Agrrmmatism

pan)

(chain)

la selle (saddle) la pie (magpie) la more (blackberry) la sole (sole-fish)

List (d) Ce manche est trop large. (This handle is too large.) Le voile se d&hire. (The veil is tearing.) Elle a perdu une livre. (She lost a pound.) Elle nettoie la poele. (She cleans the frying pan.) Elle prtfere le rose. (She prefers pink.) Cette manche est trop large. (This sleeve is too large.) La voile se d&hire. (The sail is tearing.) Elle a perdu un livre. (She lost a book.) Elle nettoie le poele. (She cleans the stove.) Elle prefere la rose. (She prefers the rose.) List (e) Le maire sort de la maison. (The mayor leaves the house.) Tous les pots sont fragiles. (All the pots are fragile.) 11 ne voit pas le bout. (He doesn’t see the end.) Je n’aime pas la selle. (I don’t like the saddle.) Le renne a succombt. (The reindeer died.) La mere sort de la maison. (The mother leaves the house.) Toutes les peaux sont fragiles. (All the hides are fragile.) 11 ne voit pas la boue. (He doesn’t see the muck.) Je n’aime pas le sel. (I don’t like salt.) La reine a succombt. (The queen died.)

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