Experiment 3: New Discourse Referents II

Findings in Experiment 2 clearly support locality-based hypotheses. The results back assumptions of the DLT (Gibson, 2000). Those findings suggest that only new discourse referents adequately challenge working memory capacity in order to increase sentence complexity verifiably. Adverbials that do not introduce new discourse referents do not affect sentence processing.

However, it was pointed out that Experiment 2 contains different verbs in the embedded relative clauses, as shown in Table 6.4. Investigating the role of new discourse referents on sentence complexity resulted in the necessity of applying different verb types in the previous study. Conditions C and D always contained two new referents and therefore needed to apply ditransitive verbs (e.g. ausleiht).

Conditions A and B lacked this necessity and succeeded with intransitive verbs.

The number of possible verbs with both ditransitive and intransitive usage that qualify for the experiment is limited. This constraint conflicted with the scale of Experiment 2, which was supposed to contain 128 sentences. In order not to reuse the same limited stock of verbs too often, and in order to keep material homogeneous, Experiment 2 always applied two different verbs for the RCs.

The fact that different verbs were employed in the same stimulus set, unfortu-nately yields a possible confound: processing differences between the conditions or at least between pairs of conditions (conditions A+B versus conditions C+D) might not only have occurred due to the introduction of new discourse referents.

The effects might unintentionally also result from the usage of different verbs lo-cated in the critical region between the two related items. In order to rule out this possibility, the current study was run as a follow-up to Experiment 2.

In order to capture the criticism discussed above, Experiment 3 applied the experimental material of Experiment 2. The original structure was kept as far as possible. Changes to the material were only accomplished in order to respond to the point of criticism. Just as the previous study, Experiment 3 consisted of 128 sentences with embedded relative clauses. It also employed case checking as the test case. Case checking had to be accomplished between a definite,

an-Table 6.4: Example of Relative Clauses of Experiment 2

A . . . die sehr gut erklärt (-NDR; -Adv)

B . . . die immer wieder sehr gut erklärt (-NDR; +Adv) C . . . die dem Studenten das Skript ausleiht . . . (+NDR; -Adv) D . . . die dem Studenten doch noch das Skript ausleiht . . . (+NDR; +Adv)

6.3. EXPERIMENT 3:NEW DISCOURSE REFERENTS II 105 imate clause-initial NP and a clause-final verb cluster (cf. examples (8) and (9) below. They display nom-initial grammatical sentences). Just as in Experiment 2, case of NP1 diejenige/derjenigen Professorin (‘the-one professor_{NOM, DAT}’) and grammaticality of the sentence were decoupled by alternating the auxiliaries hat (‘has’) and wurde (‘was’). While the cluster ‘verb + hat’ demands the NP to bear the nominative case, the cluster ‘verb + wurde’ asks for the dative case.

The design of Experiment 3 was modified with respect to the location of the relative clauses. In Experiment 2 all RCs were center-embedded between the two related items. In the current experiment, relative clauses are either intraposed and adjacent to the clause-initial NP or they are extraposed at the very end of the sentence. In the intraposed condition in (8), the embedded relative clause intervenes between the two related items (i) the initial NP diejenige Professorin (‘the-one professor’) and (ii) the verb cluster ausgeschrieben hat (‘offered has’).

Thus, the intraposed condition in the current experiment picks up the original sentence structure of Experiment 2.

‘(I guess,) that the professor [RC] has announced a vacant position.’

In the extraposed condition in (9), the related items are not separated by interven-ing material. Here, the relative clause is located directly after the clause-final verb at the very end of the matrix sentence.

(9) Eine

‘A vacant position has been announced by the professor, [RC].’

Just as in the previous study, manipulations in length were conducted to the rel-ative clauses only. The main alteration compared to the design of Experiment 2 is the relative clause position. As a consequence, the RC position was added as a new factor to Experiment 3. In order to keep the design manageable, the number of relative clause conditions was confined to two specifications. Thus, the con-ditions ‘-NDR/-Adv’ and ‘+NDR/ +Adv’ (concon-ditions A and D) of Experiment 2 were applied to the current study. In Experiment 3, the clauses were re-labeled

‘short’ (‘-NDR/-Adv’) and ‘long’ (‘+NDR/+Adv’), as shown in (10).

(10) Examples of Relative Clauses of Experiment 3:

a. ‘Short’ Condition:

die sehr gut erklärt who very good explains

‘. . . who explains very well’

b. ‘Long’ Condition:

die dem Studenten doch noch das Skript ausleiht who the student after all the script lends

‘. . . who after all lend the script to the student’

‘Short’ relative clauses always consist of four words and do not introduce addi-tional new discourse referents. ‘Long’ relative clauses always consist of eight words and introduce (i) two new discourse referents and (ii) two words for the adverbial, as shown in the example in (10).

6.3.1 Method

Participants. 32 students from the University of Konstanz participated for course credit or payment. All participants were native speakers of German and naive with respect to the purpose of the experiment.

Material. 128 sentences were created, each in 16 conditions according to the factors Order (nom-initial versus dat-initial), Status (grammatical versus ungram-matical), RC-position (intraposed versus extraposed) and RC-length (short versus long).

Table 6.5 shows a stimulus set of Experiment 3.

Procedure. Experiment 3 was presented using the same speeded grammaticality judgment paradigm as Experiment 2.

Predictions. Locality-based predictions that follow the core assumptions of the dependency locality theory (Gibson, 2000) are clear-cut: As discussed previously, the DLT assumes that only intervening new discourse referents consume com-putational resources. Therefore, intervening new discourse referents ensure that the usage of activation resources rises and that processing complexity increases.

Locality-based predictions for Experiment 3 are as follows:

(i) Intraposed: Sentences with intraposed RCs are supposed to reveal in-creased processing complexity for both ‘long’ and ‘short’ RCs compared to ex-traposed sentences. This results from the fact that the intervening regions host material that introduces NDRs: In the ‘short’ condition, the RC verb introduces one new referent. In the ‘long’ condition, the RC verb and the two argument-NPs altogether introduce three new discourse referents. Furthermore, in intraposed sentences, the temporal adverbial eine freie Stelle (‘a vacant position’) intervenes

6.3. EXPERIMENT 3:NEW DISCOURSE REFERENTS II 107