GENERAL DISCUSSION 147 obligatory in order to form a grammatical sentence. Locality-based assumptions

predict that the greater storage costs in acc-initial sentences result in increased processing complexity. This is assumed to finally manifest in a disadvantage in reading times compared to the less costly nom-initial sentences. Expectation-based assumptions predict the opposite: the parser is eager to process the missing, but obligatory entities. As a consequence, additional material results in a speed-up in reading times. Thus, the significant effect of Order in the region AdvV might indicate beneficial effects of the additional adverbial clause in acc-initial sentences, compared to nom-initial sentences.

Third, the main verb region (MV) reveals some interesting and significant ef-fects of the factor Length. The data show that ‘RC’- and ‘ADV’-sentences are read significantly faster than ‘Short’-sentences. ‘Short’-sentences are read signif-icantly faster than ‘Long’-sentences. This suggests that the MV region displays both, locality and anti-locality effects. It seems that processing the matrix verb in the conditions ‘RC’ and ‘ADV’ profits from the previously processed additional material. Both conditions show the fastest reading times in this region. In con-trast, ‘Short’-sentences are read significantly slower. This fits expectation-based assumptions that predict a facilitating effect of additional processing effort for predictable entities. However, ‘Long’-sentences reveal the highest reading times in the MV region. Here, the matrix verb is significantly read longer than in all other sentence conditions. This is a clear locality-effect, as predicted in the DLT.

The findings of the region MV suggest that there are probably found both, local-ity and anti-locallocal-ity effects in working memory performance. The data indicate that a certain amount of additional material promotes the parsing process as pre-dicted in expectation-based hypotheses. However, when the level of processing effort reaches a certain high level, facilitating effects seem to dissolve. At this point, processing is affected adversely by additional costly distance between re-lated items.

Another important finding in Experiment 5 compared to Experiment 4 is the absence of length effects in the early regions. In the initial two regions WH and N1, all sentence conditions are similar with regard to the number of words. Sta-tistical analyses for the two regions RelCl and RCverb were only computed for sentences including a relative clause. Therefore, those two regions are also simi-lar with regard to the number of words up to this point in the sentence. Thus, in the first four sentence regions no difference in length exists and, hence, no effects of Length are predicted. As discussed above, Experiment 4 reveals unexpected local-ity effects (cf. in the early regions N1 and RCverb). Those effects seem to result from the chosen experimental design and the usage of the respective experimen-tal procedure. The study tested sentences containing different numbers of words.

As discussed above, the experimental procedure covers all words in a sentence

and replaces them with individual underlines. Although the self-paced reading procedure masks the content of the sentence, non-linguistic information is given about the number and the individual length of upcoming (and of past) words. It seems that participants used this non-linguistic information to (consciously or un-consciously) develop processing strategies. Those findings give rise to criticism on the moving-window self-paced reading procedure: if, as the results indicate, the number of underlines affects participants’ processing strategies then one also has to challenge previous findings on sentence processing that were collected with this procedure. This is especially the case in studies that investigated the process-ing of longer sentences or differences in memory performance between short and long sentences as in Experiment 4.

The lack of unexpected length effects in Experiment 5 supports the hypothe-sis that unwillingly provided non-linguistic information is the underlying source of significant effects of Length in Experiment 4. Adding tags to match all sen-tence conditions with regard to the number of words turned out to be a successful strategy.

In Experiment 6, complex manipulations of the factor Length were replaced with a simple binary distinction between short and long sentences. Additionally, the study widened the specification of the factor Status and tested ambiguous sen-tences, too. It was supposed that reducing the amount of intervening costly mate-rial to a minimal number of 1 NDR might result in finer-grained findings. It was suggested that only a small amount of additional processing costs might manifest in higher error rates or higher judgment times in critical conditions (such as syn-tactic ambiguity resolution or the detection of case violations). The current results fit previous findings for those sentence conditions. As discussed, results of Exper-iment 6 replicate well-known findings on both ambiguity resolution preferences and processing performance in parsing ungrammatical sentences. The data reveal a clear garden-path effect for acc-initial ambiguous sentences (again, cf. Bader and Bayer, 2006:89 and literature cited therein). Ungrammatical nom-inital sen-tences (exhibiting a double-case violation: NOM-NOM) show higher error rates compared to ungrammatical acc-initial sentences (cf. Frisch and Schlesewsky, 2001; Schlesewsky et al., 2003). Furthermore, the results show a main effect of Length that revealed a clear disadvantage of long sentences. This supports locality-based assumptions as predicted in Gibson (2000). However, the results fail to yield a significant interaction of additional length with the critical sentence conditions described above. Both, disambiguation of non-preferred syntactic am-biguities and the detection of case violations, are significantly more sensitive to additional length than other sentences. However, the results show a tendency to-wards the expected findings. The data reveal that, numerically, both garden path sentences and ungrammatical sentences are affected more strongly by additional

7.5. GENERAL DISCUSSION 149 costly length. This pattern is partly supported by findings in reaction times. First, both acc-initial ambiguous sentences and ungrammatical sentences independent of Order are judged the slowest. This phenomenon probably reflects the addi-tional time it takes to accomplish reanalysis processes. Moreover, the results show that short acc-initial ambiguous sentences are judged faster than long acc-initial ambiguous sentences. This fits the pattern that those sentences are more sensi-tive to additional costly length which fails to manifest in significant judgments, but is shown in higher reaction times. However, the results also show that long ungrammatical sentences are judged faster than short ones. This suggests a facili-tating effect of length for detection of case violations and somehow contrasts with earlier findings of locality effects. The tendency in judgments suggests that tasks such as garden-path recovery and the detection of case violations are more likely to be affected by additional costly length. As predicted in locality-based hypothe-ses: reaccessing of features is hampered with additional length as predicted in the DLT. This is only partly supported by findings in reaction times: it seems that some cognitive tasks such as disambiguations towards non-preferred readings are hampered by more intervening material and, thus, takes longer. However, it seems that processing ungrammatical sentences does benefit from a longer distance.

In summary, Experiments 5 and 6 reveal strong support for locality-based hy-potheses. The findings show that working memory performance decreases when long distance intervene between related items. This manifests in longer reading times per word (or region), in higher error rates and increased reaction times.

Furthermore, this is especially the case in critical conditions. However, the data also show some significant support for anti-locality assumptions. It seems that sometimes the process of sentence parsing benefits from additional intervening length. The findings of a co-occurrence of both expectation-based facilitation and distance-based locality effects supports previous findings and hypotheses (cf. Va-sishth and Drenhaus, 2011 and literature cited therein). VaVa-sishth and Drenhaus (2011) suggest that expectation-based facilitation and locality interact in sentence processing. They argue that beneficial effects of expectation only manifest in simple or frequent constructions which only put little burden to the limited work-ing memory capacity (see also: Edward Gibson. “Locality and anti-locality ef-fects in sentence comprehension.” Workshop on processing head-final languages, 2007; cited in Vasishth and Drenhaus, 2011:21). Those reports fit the data pre-sented in this chapter. Results of Experiments 5 reveal beneficial effects for the medium-sized sentence conditions ‘RC’ and ‘ADV’ compared to short sentences.

However, when sentence length and complexity passed a certain threshold (con-dition: ‘Long’), locality effects occurred. The reports also fit to the results of the Experiments 6. The data show that complex conditions, such as ungrammatical sentences or garden-path sentences are more sensitive to additional length than other sentence conditions.