Processing of Case Marked Arguments

In spontaneous speech production, children start to produce articles at about 2 years of age. Nominative case markings are acquired before accusative and dative case markings. Overgeneralizations may occur, such that nominative is produced in contexts requiring accusative, and accusative is produced in contexts requiring dative. Case marking errors persist at least up to the age of 5 (Clahsen, 1984; Mills, 1985; Clahsen, Eisenbeiss, & Vainikka, 1994; Szagun, 2004). In addition, variable word ordering with the object preceding the subject is closely related to the ability to case mark the arguments (Clahsen, 1984; Meisel, 1986).

But how does morphological case information contribute to children's sen- tence processing? At what age does object case marking prevent children from analyzing the first argument as the subject of the sentence? Within the past three decades, several studies examined the role of case information in children's sen- tence interpretation. They investigated the processing of object-initial sentences and the degree to which morphological case marking of the object and/or the subject contributes to the correct understanding of the sentences.

One of the first experiments in this field was again conducted by Mills (1977). She presented subject- and object-initial sentences. In each sentence, either the first (cf. (4.4)) or the second NP (cf. (4.5)) was unambiguously case marked. The remaining NP was always case ambiguous. In a sentence-picture matching task children were asked to point to the picture corresponding to the sentence. In ad- dition to the matching picture, a distractor picture was presented showing the re- versed action.

(4.4) Den Hund sieht die Katze. [the dog]ACCsees [the cat]AMB

'The dog sees the cat' (4.5) Das Mädchen ruft der Mann. [the girl]AMB calls [the man]NOM

'The man calls the girl'

Fifteen children aged 5;11 to 8;11 took part in the experiment. The results showed that children were much more error-prone when object-initial sentences were disambiguated on the final NP (cf. (4.5)). In these sentences, they pointed to the correct picture in 32 % of all cases, which is even below chance level. In contrast, if the accusative marked NP was at the beginning of the sentence (cf. (4.4)), 63 % of all reactions were correct. Thus, the probability of detecting the object-initial word order was higher, the earlier the unambiguous case marking appeared. However, even then performance was by no means perfect. Rather, it seems to be slightly above a chance level decision between the correct and the distractor picture. If the relevant information was presented at the end of the sentence, a general subject-first preference seemed to override case information.

Similar to Mills' study, Schaner-Wolles (1989) conducted a comprehension experiment with object-initial sentences. Either both arguments were unambigu- ously case marked (cf. (4.6)), or one of them was ambiguous (cf. (4.7), (4.8)). The task consisted in sentence-picture matching. Besides the correct picture, two distractors were presented. One showed the reversed action, and one showed only a single person performing the action.

(4.6) Den Vater fotografiert der Bub.

[the father]ACCtakes a picture of [the boy]NOM 'The boy takes a picture of the father' (4.7) Den Vater frisiert das Mädchen.

[the father]ACCdoes the hair of [the girl]AMB 'The girl does the hair of the father'

(4.8) Das Mädchen zwickt der Bub. [the girl]AMB pinches [the boy]NOM

'The boy pinches the girl'

Three age groups participated, comprising 9 children each at the ages of 3, 4, and 5, respectively. The results suggested that the accusative case markings could be used by the 5-year-old children, if the first argument was case marked. The 4- year-olds succeeded if the first and the second NP were case marked (cf. (4.6)). For the 3-year-olds, all conditions led to 50 % incorrect responses. Presumably, this reflected a chance level decision between the correct picture and the one with the reversed action. The most difficult sentences were those in which only the second NP was unambiguously case marked, as in (4.8). In this case, children of all ages performed on chance level. Nevertheless, the presence of an accusative marked argument in a sentence seemed to inhibit the exclusive use of a subject- first strategy. Otherwise higher error rates would have been expected.

In a further experiment, Lindner (2003) investigated the comprehension of subject- and object-initial sentences (cf. (4.9) and (4.10)). The arguments of a sentence were unambiguously case marked. In addition, the arguments were either animate or inanimate, and they did or did not agree with the verb.

(4.9) Der Frosch schubst den Storch. [the frog]NOMpushes [the stork]ACC

'The frog pushes the stork' (4.10) Den Frosch schubst der Storch. [the frog]ACCpushes [the stork]NOM

'The frog pushes the stork'

Eighty-four children between 2;8 and 9;6 years were asked to act out the sentences. The dependent variable was the choice of the agent. The youngest children chose the agent of a sentence on the basis of animacy information, with animate entities being interpreted as actors. From the age of 4 years on, case information slowly became more and more important, with nominative marked arguments being chosen as actors. Finally, from the age of 6 on, case information in combination with subject- verb agreement information primarily determined sentence interpretation.

As mentioned above, there are further languages, which allow subject- and object-initial sentences and have morphological case markings. The use of mor- phological case markers in object-initial sentences was, for instance, investigated in Turkish, Serbo-Croatian, Polish, and Hungarian by means of the acting out paradigm. Turkish seems to be the language in which object-initial sentences are correctly understood at the youngest age, namely from 2;0 on (Slobin & Bever, 1982). Crucially, in Turkish sentence initial objects are always unambiguously case marked, as ambiguous NPs can never be moved (Kornfilt, 2003). In lan- guages where also ambiguous arguments can be fronted, correct understanding of object-initial sentences is mastered at a later age. In Polish, children correctly understood object-initial sentences from the age of 2;6 onwards (Weist, 1983), in Hungarian from the age of 3;1 onwards (MacWhinney et al., 1985), and in Serbo-Croatian from 4;2 on (Slobin & Bever, 1982)2.

To summarize, the ability of German children to use case information in sen- tence interpretation changes with age. From the age of about 5 or 6 years onwards case information becomes more and more important for determining the agent of an action, although there are still problems. This is concordant with data from Serbo-Croatian children. By contrast, in other languages like Turkish, Polish, or Hungarian, morphological case information is already reliably used at an earlier age.

However, several critical points have to be mentioned with regard to the pre- sented studies on children's sentence comprehension. First, some of them com- prised only a small number of participants, and/or a very small number of ex- perimental items per condition (e.g. Mills, 1977; Schaner-Wolles, 1989), which diminishes the generalizability of the results. Second, in the experiments using a sentence-picture matching paradigm it has to be kept in mind that the procedure always offers a certain chance to pick out the right picture. Third, the large age range of some studies does not allow specific conclusions about developmental stages (e.g. Mills, 1977).

2

Nevertheless, the result of Slobin & Bever (1982) has to be treated with attention. It comprises the understanding of sentences with unambiguously and ambiguously case marked arguments. Presumably, the bad performance of the Serbo-Croatian children was mainly due to object- initial sentences starting with an ambiguous argument, a condition which seems to be mastered only relatively late (Schaner-Wolles, 1989).

Moreover, it has to be pointed out that all the presented studies relied on be- havioral paradigms, in which much time elapsed between the presentation of a sentence until the children chose a picture or acted it out with toys. In most cases, the experimental sentences were read out twice or even more times (e.g. Mills, 1977; Schaner-Wolles, 1989; Lindner, 2003). Thus, many cognitive processes comprising initial sentence comprehension, syntactic reanalysis processes, general cognitive and strategic decision processes had time to proceed before the children reacted. Consequently, these off-line measures do not allow a direct deduction of the initial mechanisms uniquely specialized for sentence processing, for they were obscured by a variety of later processes. Moreover, such later processes like conscious decision strategies might even be enhanced in the proc- essing of ungrammatical sentences, like many of those presented by Lindner (2003) (e.g. *'Den Frosch der Klotz schubst' ([the frog]ACC [the block]NOM pushes) or *'Der Storch schubsen die Frösche' ([the stork]NOM,SG pushPL [the frogs]AMB,PL)).

In addition, the previously used off-line measures could not directly address questions regarding the nature of incremental sentence processing. Thus, nothing can be said about the specific structure which is built up and extended during the course of a sentence. More specifically, one does not know whether the children processed the arguments of a sentence independently of the verb, or whether the lexical information of the verb mainly determined structure building. Moreover, the specific type of abstract structure representation cannot be distinguished, namely whether the initial structure is thematic or syntactic in nature, or whether thematic and syntactic hierarchies are established in parallel.

Finally, in the German experiments, only accusative verbs were used. As laid out in the preceding chapters, sentences where the accusative precedes the nomi- native marked argument have a marked syntactic structure. At the same time, accusative case indicates that the respective argument has to be ranked low in a thematic hierarchy. Hence, it cannot be decided whether the interpretation of the presented object-initial sentences depended more on the establishment of syntac- tic or thematic dependencies.