Implicit Processing of Grammatical Rules in a Classical Case of Agrammatism

IMPLICIT PROCESSING OF GRAMMATICAL RULES IN A CLASSICAL CASE OF AGRAMMATISM l E. Andreewsky' and X. Seron' (Unite de Recherche en Neuropsychologie, La Salpetriere Hospital, Paris)

The psychological reality of linguistic structures has been amply demonstrated by various works, notably in the domain of language acquisition in children (Berko, 1958; Epstein, 1962). Thus, the regularization of the inflection of an irregular verb by a child who says "J'ai prendu" (I taked) for "J'ai pris" (I took) is not the repetition of a previously heard linguistic form. This erroneous inflection represents the application of an algorithmic rule, developed out of the child's linguistic experience and systematically generalized. Observation of this type of linguistic error permits us, through an elementary logical analysis, to infer the implicit application of a grammatical rule. The object of the present work is to analyze, in somewhat analogous fashion, the evidence of implicit rules in the production of particular aphasic responses, this analysis being carried out through the use of a mathematical formalism appropriate to the demonstration of the rules involved. The demonstration of a particular linguistic deviation in an aphasic is the basis for inferring a neurolinguistic mechanism whose absence or dysfunction brings about the observed deviation. Support for any such inference depends on the consistency of the pathological response, which eliminates the possibility of randomly varying behavior. If, in addition, other patients are observed to present similar deviant performances, we may make a further inference about the universality 6f the neurolinguistic processes governed by the particular mechanism being studied. It is with this point of view that we have carried out a psycholinguistic study concerning the implicit processing of grammatical rules in a patient who presents, in a dramatically clear and stable fashion, the linguistic symptoms of agrammatism.

I Translated by H. Goodglass. '·Chargee de recherche, INSERM U.84, Unite de Recherche en Neuropsychologie, Pro F. Lhermitte, La Salpetriere, Paris . , Aspirant de Recherche, FNRS, University of Liege.

Cortex (1975) 11, 379-390.

380

E. Andreewsky and X. Seron CASE REPORT

M.D., a 65 year old bookkeeping clerk, sustained a cerebral vascular accident in February 1964, with the sudden onset of a right hemiplegia, predominantly brachiofacial, and a very severe aphasia. Upon performance of a left parietal bone flap in March 1964, softening was observed in the parieto-temporo-rolandic area. The post-operative course was routine: persistance of the aphasia, with a prolonged period of speechlessness (about four years). The right hemiplegia improved, but remained severe; no language retraining was considered for seven years. This patient was referred to the Language Retraining Center of the Neuropsychological Service of the Salpetriere in September, 1971. The Neuropsychological examination carried out at that time showed a severe agrammatism, good naming to visual confrontation, with occasional verbal paraphasias, good comprehension of oral and written material and a clear cut buccofacial apraxia. At present, the patient is well oriented for time and place; he has neither ideational nor ideomotor apraxia. There is a mild constructional apraxia, but finger gnosis and visual recognition are intact. The patient's verbal behavior has been described previously by one of us (Andreewsky, 1974). With respect to his reading - the only modality of verbal behavior which we are examining here - it appears essentially as follows: ( 1) Comprehension of written messages is such that the patient understands every word which he verbalizes. On the other hand, the words (or morphemes) which are not produced are not taken into account in the decoding process. (2) M.D.'s oral reading duplicates the characteristics of his agrammatic conversational language, namely, the omission of "grammatical words" and of verbal inflections. M .D. as a grammatical (lIter

The characteristics of M.D.'s production in the course of oral reading (which, it is recalled, are the same as those of his conversation) make it appear as though he were processing the various words presented for him to read through a grammatical filter. Indeed, if we list the details governing the production of words presented in isolation, we obtain the following picture: - Substantives are produced without notable difficulty. However, the patient occasionally produces a synonym of a presented substantive. - Conjugated verbs are produced without inflection. There are occasional substantivizations of verbs. - Auxiliary verbs are rarely produced. - Adjectives are produced with some difficulties: omissions, substantivizations, prolonged latency. - Conjunctions, prepositions, adverbs, pronouns are not produced. - Letters, syllables, and nonsense words are not produced. In the following discussion, we will deal exclusively with the special property of syntactic filtration , which this patient's production presents. We have dealt elsewhere (Andreewsky, 1974) with the problems presented by the production of synonyms, the suppression of inflections, the use of semantic inferences, and the comprehension of sentences in terms of their "key words."

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381

Formalization of the concepts of 'grammatical class' and 'syntactic analysis'

In order to deal in precise fashion with the observations of M.D.'s oral reading of simple sentences, we will use a mathematical formalism which is economical and sufficient for the description of the sentences. This formalism is that of 'categorial grammars,' described by Bar Hillel (Bar Hillel, 1964; Chomsky, 1963). A categorial grammar assigns to each word one or more morpho syntactic categories. It is a 'recognition grammar' which makes it possible to determine, by means of specific rules, whether or not a sequence is an acceptable sentence of the language. The quasi-arithmetic notation which belongs to this grammar assigns every word of the language to a category which is represented by means of two basic categories: 'n' and's' ('n' for the substantive and's' for the sentence). All terms, other than 'n' and's' are expressed in fractional notation, the direction of the slant line restricting their operation to the term either on their right or their left, so that any grammatical sentence can be reduced to's' with a rule similar to the principle of cancellation of fractions. Thus, n"""s n """s/ n n """n n/n s """s/ s etc.

intransitive verb transitive verb post nominal adjective article conjunction

For example, the sentence: "The patient sleeps" would be transcribed: n/n

n

n"""s

In this expression, the intransitive verb "sleeps" is considered as an operator n"""s, which can act on a substantive to the left of it; the article "the," n/n, as an operator acting on the term to its right. Thus, we obtain (2) after a first step of reduction. (1) n/n

n

n"""s

I--n--[

n"""s

I

(2)

I

I

Then, with a second step of reduction, (2) (3)

n

n"""s

l-s_1

All acceptable sentences of the language can be reduced to's' in this way. Note, however, that if we had carried out the first step of reduction with the two last words of the sentence, we would not have been able to end up with a reduction to's.' In this way, the process of reduction reveals the immediate constituents of the sentence, through the constraints on the terms which may be chosen to carry out the successive steps for reduction to's.' It should be noted that ambiguous sentences, having p alternative interpretations, can be reduced to 's' in p different ways.

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We therefore have at our disposal a formalism which offers the following advantages with respect to the present study: - Simplicity: Grammatical ambiguities are resolved with a single quasiarithmetical rule. Furthermore, application of the method permits the demonstration of the immediate constituents of the sentence. - There is a certain correlation between the complexity of the notations for the various grammatical classes and M.D.'s difficulty in verbalizing members of these classes; indeed, words transcribed as 'n' are produced without trouble; those written as n and n/ n are produced with some difficulty: those written as s""'s/s are never produced.

""'S

Psycholinguistic study of M.D. as a grammatical filter

As indicated above, we may consider ourselves as dealing with a filter. This is the interpretation we have placed on the behavior of M.D. with regard to his oral reading of isolated words belonging to particular grammatical classes. This filter allows the emission only of those items belonging to the grammatical classes of substantive, verbs, and adjectives. Its operation implies a process which attaches a grammatical tag to every word presented in writing to M.D., and which may then lead to the emission of the word, depending on the nature of the tag. The processing of any word M is therefore a function of the grammatical class to which it belongs. What does this function become when the word M is grammatically ambiguous -that is when (out of context) it can belong to two or more different grammatical classes? In this study we propose to answer this question by observing and analyzing the behavior of our filter, M.D., when the grammatical class of grapheme M meets one of the following conditions: (1) Indeterminate: The word presented in isolation can equally well belong to either of two grammatical classes. (2) Context determined: The grammatical class is a function of the position of word M in the sentence. Production of grammatically ambiguous words Class (S,C) - substantive or conjunction

It should be noted that for M.D. one of the possible interpretations of the members of the class (S,C) - car, or, mais,4 belongs to a category which he normally produces - i.e., substantives, while the other belongs to his never-uttered category of conjunctions. To determine the behavior of M.D. in regard to members of the class (S,C) the patient was repeatedly presented, over a number of sessions, three lists of seven words each consisting of seven conjunctions (et, ou, ni, mais, car, or, done), among them the three test words, seven substantives, including the same three words, or a mixed list including substantives, conjunctions and the above members 4 For example, in French the grapheme "or" (English translations: either "gold" or "now") belongs simultaneously to the classes S (substantive) and C (conjunction). There are available in French two homographs in addition to "or" which involves ambiguities of this type. They are "car" (English: "bus" or "because") and mais (English: "corn" or, when the dieresis is absent, "but"). There are a considerably greater number of words which can be either S or V (conjugated verbs): for example marche (English: "walks" or "stair"); lit (English: "reads" or "bed"); ferme (English: "closes" or "farm"); porte (English: "carries" or "door"); couvent (English: "lay eggs" or "convent"); est (English: "is" of "east") ...

Grammatical rules in agrammatism

383

of the class (S,C). In every presentation, and in all types of list, the words belonging to the class (S,C) are produced as follows: graphic form car or mais

oral response "car" "or" (occasionally paraphasically read as 'diamant') "mats" (or omittedl

The production of members of the class (S,C) is thus preserved even when they appear in a list of conjunctions, in which case they are the only words in the list which are emitted. We therefore note that our filter M.D. treats members of the class (S,C), presented in isolation, as he treats substantives. Class (sy) substantive or conjugated verb

While many French words belong to this class, the number of homographs which are not also homonyms is more restricted. It should be noted that only in the case of non-homonymonic homographs does the patient's production permit us to determine the grammatical category which he implicitly chose. Non-homonymous homograph (SY)

We used the words "est" and "couvent" (see footnote 4) which are pronounced respectively lestl and Ikuval as substantives and If I and Ikuvl as verbs. As in the preceding case, those words were placed in different lists constituted either of conjugated verbs, of substantives, or of combinations of both classes. Several repetitions of these lists revealed that in every case "est" in produced as Iestl (or "nord") "couvent" is produced as Ikuva/. We note that in this case, too, our filter, M.D., treats members of the class (S,V), in isolation, as substantives. Presentation of homonymous homographs of the class (SY)

Given only the production by M.D. of words such as "lit," "ferme," "porte," "marche," it is not possible to infer with certainty, as it was in the preceding case, the grammatical category implicitly assigned to these words. We ~ucceeded in determining unequivocally which grammatical category was implicitly intended in the following manner: M.D.'s behavior was observed in a multiple choice sentence completion task under two conditions, in the plural and in the singular. In the singular, the word which meets the semantic requirements is a member of the class (S,V), as opposed to the situation in the plural where there is no grammatical ambiguity and were the correct response is a V. Thus, a number of different sequences, with multiple choice completions were composed as follows: Ll Les voyageurs Ie journal. (The travellers the paper). 5 Translator's note: The fact that M.D. always reads "mals as though it were "mais" /mais/ indicates substantivisation, since the conjunction is pronounced /me/.

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384

The multiple choices for completion of this sentence are: (Md hesitent ('hesitate' - 3rd pers. plur.) lisent ('read' - 3rd pers. plur.) existent ('exist' - 3rd pers. plur.) The elements of this list are unambiguous members of the class V. Lz

Le voyageur - Ie journal. (The traveller - the paper).

For sentence L2 , the multiple choice list is. (M z) hesite ('hesitates') lit ('reads' or 'bed') existe (exists). Applying the syntactic notation which we have adopted, sequences (Ld and (L z) are both written: nfn'n

I-n-I

x

1

nfn

n

I-n-I

I_--l--_I

In order to turn these sequences into grammatical sentences it is necessary that the word chosen as a completion permit them to be reduced to's'. The element x, which is needed is a n ,,",s/ n, that is, a transitive verb. In the plural, all three elements of list Ml (above) meet this condition. In completing sequence (L l ), M.D. immediately chooses the verb 'lisent,' the only one which is semantically appropriate. In the singular, however, the word" lit," which fits semantically, is ambiguous: 'lit' is either a n ,,",s/ n or an n . .In this situation, which is identical to the preceding one, save for the ambiguity of the word 'lit,' M.D. categorically rejects the word 'lit' and proposes in succession, but without confidence, the two other words, 'existe' and 'hesite.' This behavior can be explained only by the assignment of 'lit' in list Mz to the category of substantive (bed), which leads to its rejection because it fits neither at the syntactic nor the semantic level. The verbs 'hesite' and 'existe' are, indeed, suggested by M.D., but their semantic inappropriateness explains the patient's difficulties. Here, again, M.D. as a filter, interprets members of (S,V) as substantives. It can thus be shown, by various approaches, that the category 'substantive' is applied to all members of the categories (S,C) and (S,V), presented out of context in word lists. Reading of a sentence with grammatically ambiguous words As a very first approximation, the oral production of any written sentence by M.D. may be approached as the concatenation of the production of the several words which constitute the sentence, considered as a list (with suppression of all words other than substantives, verbs, and adjectives, and certain distortions in the elements which are uttered). The foregoing observations lead to the question as to the behavior of M.D.

385

Grammatical rules in agrammatism

when confronted with sentences including grammatically ambiguous words, more specifically, words of the class (S,C). These, it will be recalled are always produced as substantives when presented out of context. M.D. is presented with sentences of type PI:

PI

Le car ralentit car le moteur chauffe. (The bus slows down because the motor overheats).

Using the notation we have adopted, PI corresponds to the sequence FI, which can be reduced to s as follows: F I : n/n

n

n~s

I

I

I-n-I

I

s

I

I

I

s~s/s

I I I

n

n/n

n~s

I-n-I

s~s/s

I

I

s

s

I

This sequence is obtained on resolution of the grammatical ambiguities inherent in: car, which can be either a substantive - n (bus) or a conjunction s~s/s (because). ralentit (slows down) and chauffe (overheats), which can be either transitive verbs - n~s/n or intransitive n~s. -

Upon presentation of sentence PI, M.D. produced (Ed. EI = /kar rala:ti motrer f ofe/ (bus slowed down motor overheated)

Thus, the second occurrence of the word "car," which occupies the posltlOn of conjunction in sentence PI (labelled as s ~s/ s in Fd is not uttered, while the word is produced without hesitation in the position of the substantive (labelled n). This observation indicates clearly that the patient is processing and analyzing the parameters of the syntactic function of all the words, whether or not they are uttered, in particular the parameter of word-position in the sentence. The functioning of the grammatical filter, M.D. thus appears to depend on the execution of a contextual syntactic analysis. The consistency with which this implicit analysis is carried out was verified by means of a large number of sentences including the words of the class (S,C) - i.e., 'car' ('bus' or 'because') and 'or' ('gold' or 'now'). They are always produced in the noun position, never in the position of conjunction. Reading of sequences with syntactic incompatibility

Observation of M.D.'s response EI to sentence PI has led us to postulate that there is some level of analysis of the syntactic functions of a word in a sentence. What, then would be the product of this analysis if we introduced an incompatibility between the syntactic function of a word in a sentence and the grammatical part of speech of the word? In other words, how does the filter

E. Andreewsky and X. Seron

M.D. behave in the face of sequences which are not grammatical sentences, in which a grammatically unambiguous word is placed in a position incompatible (in the sense of the possibility of 'reduction to s') with its grammatical category? In order to answer this question we examined the family of sequences of form: P(X,Y) = Le X ralentit Y Ie moteur chauffe. (The X slowdown Y the motor overheats.) Introduction of a substantive in position Y

A first experiment consists of introducing into pOSItIOn Y that is in the conjunction slot (s"'-s/s) - a word which is an unambiguous substantive. In this way we produce incompatibility between the label "n" of the word and its syntactic function, which is necessarily s"'-s/ s in position Y, if the sequence P(X,Y) is a sentence belonging to the language. Thus, if "y" is the category of word Y (X being a substantive) we have: F(X,Y) =

n/n

n

n "'-s

I-n-I I__- s - _ - ,

y

y

n/n

n

I-n-I I---s---,

The first two steps of solution of the sequence determine the immediate constituents on each side of word Y. (F(X,Y) is rewritten s y s. This new sequence reduces to s if, and only if y = s"'-s/s. Two hypotheses are possible for predicting the function of the filter, M.D. (1) If the syntactic function "y" (corresponding to position Y) is induced by the context, this will correspond to s"'-s/s and the substantive introduced in Y will not be produced; it will, in fact, be treated as a conjunction - a class of words which M.D. does not utter. (2) If, on the contrary, the syntactic organization of the sentence is subordinate to the form-class label, the substantive introduced into slot Y will be produced. (We recall that substantives presented either out of context or in grammatically correct written sentences are produced without too much trouble.) We present the sentence : P 2 (train, mer) (train, ocean) = Le train ralentit mer (The train slows down ocean

Ie moteur chauffe. the engine overheats.)

M.D. produces for this sequence and for sequences of the same type, which Y is a short substantive, a response sequence of type E 2•

Ez =

I trt

(Train

raliiti motcer slowed-down motor

10

f ofel overheated.)

The production of sequence E2 shows that in this case, the first of the proposed hypotheses was supported. Thus, under some conditions, the syntactic class determined by word position overrides the part of speech membership which would apply out-of-context. This implies: (a) the existence of a context-determined syntactic analysis, and (b) the predominance of this analysis.

387

Grammatical rules in agrammatism

Introduction of a conjunction in position X

Using X = 'done' (therefore) and Y = 'car' ('bus' or 'because') the sequence P3 was devised as follows:

P3

= P (done,

car)

= Le

done

ralentit

The therefore slows down

l

car Ie moteur chauffe. because the motor overheats). bus

It will be noted that the modification introduced in P3 is not analogous to the preceding one (P2 ). The word "done" disrupts the first segment of P3 and prevents its reduction. This effect was not produced when, in P2 , the word "mer" appeared in position Y and we had shown that two subsequences were preserved, each reducible to s, on each side of "mer." In the case of P3, one attempt at solution leads to the following segmentation:

P'3 = Le done ralentit car. (The therefore slows the bus down). n/n

x

n/n

x

I

I

Only one step of reduction is possible with this sequence, while P'3 'Ie moteur chauffe' is resolved as in the earlier sentence (P2 ). It will be seen, that for P'3 it is necessary to label "ralentit" as a transitive verb (n,,",s/n) and 'car' as a substantive in order to carry out one step of reduction. This is the interpretation which comes closest to making P 3 a possible sentence of the language. Upon presentation of P 3, M.D. produced the following, after a very long delay. /mm rala:ti kar; (mm slow-down bus;

motcer f ofe/ motor overheated).

We see then that the filter M.D. now considered the 'car' in posltion Y to be a substantive. This observation seems consistent with the formal analysis, which as we have seen, shows that the only possible first step of resolution is the assignment of the label 'n' to 'car,' and the operation upon this substantive by the preceding transitive verb "ralentit" (n,,",s/n). The proposed solution P'3 + P"3 thus appears to correspond well with the subject's behavior. We further observe, in the indeterminate sound "mm" an effort to process the sequence "Ie done" ("the therefore"). This attempt can be interpreted within the framework of the formal analysis, by noting that assigning the value (( n" to x / (the word "done"), permits one further step in the resolution of sequence F 3.

F'3

= n/n

assuming x = n, we have: and finally:

x

I 1-- n _ _ I

I

n,,",s/n

I

n

I

1-- n ,,",s -_I

I -s-_I

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E. Andreewsky and X. Seron

The patient behaves as though he is trying to discover a sentence of the language in the test sequences which are presented to him, and as though the implicit syntactic analysis which he carries out have as their end point, the partition of the sequence into resolvable constituents. These constituents thus appear to be the pertinent features for the recognition (in the grammatical sense) of the sentence. We now present the subject with a sequence P (X,Y) in which even the first step of resolution for the first subsequence is impossible, for example P4 =P (done, parce que): P 4 = Le done (The therefore

aeeelere

paree que le moteur

speeds up because

motor

ehau/Je.

overheats ).

We now obtain (after a very prolonged latency) only the production of the substantive 'acceleration' for the first part of P4 ; the second part is treated just as before; Only after many fruitless effort, reflected in his prolonged latency, does M.D. seem to have become resigned to deal only with the word "aeeelere" (accelerate), in the first part of P4, emitting the substantivized form (as he frequently does with verbs presented out of context).

DISCUSSION

We have analyzed some aspects of the processing of written linguistic messages by an agrammatic patient. This patient's errors and omissions during oral reading are parallel to those in his free conversation. In general, the patient's linguistic behavior corresponds to the defining features of agrammatism with major morphological problems (Tissot, Mounin and Lhermitte, 1974). The oral reading of isolated words had led us to postulate a neurolinguistic mechanism which filters through only those elements belonging to the classes substantive, verb, and adjective (producing in the process certain errors, such as the omission of inflections and emission of synonyms). Oral reading of a sentence by this patient is not merely the result of the concatenation of each word taken in isolation. In fact, when a grammatically ambiguous word appears in a sentence, its emission is a function of the syntactic parameters of sentence position. When a contradiction is experimentally created between the grammatical class out of context and the class induced by the syntactic function of the sentence position, the parameters associated with the syntactic function prevent the production of a word which is correctly produced in out-ofcontext presentation. These observations establish that the agrammatic patient M.D. carries out a syntactic analysis of sentences presented to him. This analysis appears to go even as far as to restructure in more correct form sequences which are not grammatical sentences. This is indeed the 6 Correct in the sense of 'reduction to s', which is the definition of a sentence in the syntactic formalism which we have u8t'd.

Grammatical rules in agrammatism

389

only consistent explanation we have been able to find for the omission of a substantive inserted in the conjunction slot - given that the same word is correctly produced in all other presentations, whether out of context or in a grammatical sentence. While we are convinced that an implicit syntactic analysis takes place, the exact nature of this analysis is more difficult to define - i.e., what parameters does the patient use to determine the structure of the sentence. This question can obviously be given only a partial answer. However, we have shown that the linguistic processing leading to the production of the words of a sentence is not unlike the recognition of the immediate constituents of that sentence. Further, when the words of a written sentence are uncovered in sequence one after another, the patient almost always holds off his utterance of a word until all of the constituent has been uncovered. A complementary study, using eye movements in reading, might perhaps find some support to this interpretation, by demonstrating specifically to what degree the production of a word depends on the perception of the word's linguistic environment. To proceed further with an effort at the functional analysis of the observed disorder, it would be interesting to see if one can find, in other languages, phenomena analogous to those described here. In English and Russian, for example, there are no homographs of the class (S,C). We can report that the experimental procedure described above, administered to four other agrammatics, gave results of the same type as those obtained with M.D. Although less consistent, the omissions, hesitations, and repeated self-corrections recorded during the oral reading of these patients, occur specifically under the same conditions in which M.D. produces them with high consistency. We therefore seem to be dealing with a difference in the severity but not in the nature of the disorder. Thus, perhaps paradoxically, the preservation of contextual syntactic analysis is the easier to demonstrate, the more severe the agrammatism. The agreement between the behavior of the other agrammatics with that of M.D. permits us to generalize the interpretation suggested for M.D. The objective evidence of a syntactic analysis implicitly executed seems to point to the preservation of a psycholinguistic process in normal speakers, which our patient's pathology has put in relief. We have found that this process is dependent on the detection of the immediate constituents of the sentence. This latter observation seems to us to contribute to the study of sentence recognition by normal speakers.

390

E. Andreewsky and X. Seron SUMMARY

The speech production of an agrammatic patient is viewed as the output of a syntactic filter which allows only nouns, verbs, and adjectives to pass. In this paper, we study the behavior of this filter in the processing of grammatically ambiguous words. Our results indicate that these words are either uttered or not as a function of their syntactic role in the sentence. Thus, the patient's oral reading of a sentence is not a concatenation of isolated words, but depends on an implicit, contextsensitive analysis. These observations bring to light a new aspect of the agrammatic's syntactic competence and may contribute to the study of psycholinguistic processes in normals.

Acknowledgements. We wish to thank Prof. F. Lhermitte for comments and helpful criticism, and Prof. H. Goodglass for advice on both the form and content of this paper and for its English translation and adaptation. REFERENCES ANDREEWSKY, E. (1974) Un modele semantique; application a la pathologie du langage, "T.A. Informations," 2, 3-27. BAR-HILLEL, Y. (1964) Language and Information, Addison-Wesley, Reading, Mass. BERKO, J. (1958) The child's learnnig of English morphology, "Word," 14, 150-177. CHOMSKY, N. (1963) Formal properties of grammars, in "Handbook of Mathematical Psychology," John Wiley, New York, 328-412. EpSTEIN, W. (1961) The influence of syntactical structure on learning, "Amer. J. Psycho!.," 74, 80-85. GOODGLASS, H., GLEASON, J. B., BERNOLTZ, N. A., and HYDE, M. R. (1972) Some linguistic structures in the speech of Broca's aphasic, "Cortex," 8, 191-292. TISSOT, R., MOUNIN, G., LHERMITTE, F. (1974) L'Agrammatisme, Etude Neuropsycholinguistique, Charles Dessart, Brussels. SCHLESINGER,!. M. (1968) Sentences Structures and the Reading Process, Mouton, The Hague. ZURIF, E. B., CARAMAZZA, A., and MYERSON, R. (1972) Grammatical judgement of agrammatic aphasics, "Neuropsychologia," 10, 405-417.

Madame E. Andreewsky, Hopital de la Salpetriere, Service de Neuropsychologie (F. Lhermitte), 47 Boulevard de l'Hopital, 75013, Paris, France.