Individuals with aphasia vary in the speed and accuracy they perform sentence comprehension tasks. Previous results indicate that the performance patterns of individuals with aphasia vary between tasks (e.g., Caplan, DeDe, & Michaud, 2006; Caplan, Michaud, & Hufford, 2013a). Similarly, it has been found that the comprehension performance of individuals with aphasia varies between homogeneous test sentences within and between sessions (e.g., McNeil, Hageman, & Matthews, 2005). These studies ascribed the variability in the performance of individuals with aphasia to random noise. This conclusion would be in line with an influential theory on sentence comprehension in aphasia, the resource reduction hypothesis (Caplan, 2012). However, previous studies did not directly compare variability in language-impaired and language-unimpaired adults. Thus, it is still unclear how the variability in sentence comprehension differs between individuals with and without aphasia. Furthermore, the previous studies were exclusively carried out in English. Therefore, the findings on variability in sentence processing in English still need to be replicated in a different language. This dissertation aims to give a systematic overview of the patterns of variability in sentence comprehension performance in aphasia in German and, based on this overview, to put the resource reduction hypothesis to the test. In order to reach the first aim, variability was considered on three different dimensions (persons, measures, and occasions) following the classification by Hultsch, Strauss, Hunter, and MacDonald (2011). At the dimension of persons, the thesis compared the performance of individuals with aphasia and language-unimpaired adults. At the dimension of measures, this work explored the performance across different sentence comprehension tasks (object manipulation, sentence-picture matching). Finally, at the dimension of occasions, this work compared the performance in each task between two test sessions. Several methods were combined to study variability to gain a large and diverse database. In addition to the offline comprehension tasks, the self-paced-listening paradigm and the visual world eye-tracking paradigm were used in this work. The findings are in line with the previous results. As in the previous studies, variability in sentence comprehension in individuals with aphasia emerged between test sessions and between tasks. Additionally, it was possible to characterize the variability further using hierarchical Bayesian models. For individuals with aphasia, it was shown that both between-task and between-session variability are unsystematic. In contrast to that, language-unimpaired individuals exhibited systematic differences between measures and between sessions. However, these systematic differences occurred only in the offline tasks. Hence, variability in sentence comprehension differed between language-impaired and language-unimpaired adults, and this difference could be narrowed down to the offline measures. Based on this overview of the patterns of variability, the resource reduction hypothesis was evaluated. According to the hypothesis, the variability in the performance of individuals with aphasia can be ascribed to random fluctuations in the resources available for sentence processing. Given that the performance of the individuals with aphasia varied unsystematically, the results support the resource reduction hypothesis. Furthermore, the thesis proposes that the differences in variability between language-impaired and language-unimpaired adults can also be explained by the resource reduction hypothesis. More specifically, it is suggested that the systematic changes in the performance of language-unimpaired adults are due to decreasing fluctuations in available processing resources. In parallel, the unsystematic variability in the performance of individuals with aphasia could be due to constant fluctuations in available processing resources. In conclusion, the systematic investigation of variability contributes to a better understanding of language processing in aphasia and thus enriches aphasia research.

What is the processing cost of being garden-pathed by a temporary syntactic ambiguity? We argue that comparing average reading times in garden-path versus non-garden-path sentences is not enough to answer this question. Trial-level contaminants such as inattention, the fact that garden pathing may occur non-deterministically in the ambiguous condition, and "triage" (rejecting the sentence without reanalysis; Fodor & Inoue, 2000) lead to systematic underestimates of the true cost of garden pathing. Furthermore, the "pure" garden-path effect due to encountering an unexpected word needs to be separated from the additional cost of syntactic reanalysis. To get more realistic estimates for the individual processing costs of garden pathing and syntactic reanalysis, we implement a novel computational model that includes trial-level contaminants as probabilistically occurring latent cognitive processes. The model shows a good predictive fit to existing reading time and judgment data. Furthermore, the latent-process approach captures differences between noun phrase/zero complement (NP/Z) garden-path sentences and semantically biased reduced relative clause (RRC) garden-path sentences: The NP/Z garden path occurs nearly deterministically but can be mostly eliminated by adding a comma. By contrast, the RRC garden path occurs with a lower probability, but disambiguation via semantic plausibility is not always effective.

This thesis is concerned with the phenomenon of quantifier scope ambiguities. This phenomenon has been researched extensively, both from a theoretical and from an empirical point of view. Nevertheless, there are still a number of under-researched topics in the field of quantifier scope, which will be the main focus of this thesis. I will take a closer look at three languages, English, German, and the Asante Twi dialect of Akan (Kwa, Niger-Kongo). The goal is a better understanding of the phenomenon of quantifier scope both within each language, as well as from a cross-linguistic perspective. First, this thesis will provide a series of experiments that allow a direct cross-linguistic comparison between English and German – two languages about which specific claims have been made in the literature. I will also provide exploratory research in the case of Asante Twi, where so far, no work has been dedicated specifically to the study of quantifier scope. The work on Asante Twi will go beyond quantifier scope and also target the quantifier and determiner system in general. The question is not only if particular scope readings are possible or not, but also which factors contribute to an increase or decrease of scope availability, and if there are factors that block certain scope readings altogether. While some of the results confirm and thereby strengthen previous claims, other results contradict general assumptions in the literature. This is particularly the case for inverse readings in German and inverse readings across clause-boundaries.

Der neurodegenerativen Erkrankung Morbus Parkinson (MP) liegt der Zerfall von Neuronen in den Basalganglien (BG) zugrunde, der mitunter zu kognitiv-sprachlichen Einschränkungen führt. Dies betrifft beispielsweise die Lautstärkeproduktion und -wahrnehmung. Betroffene sprechen signifikant leiser und weisen eine verringerte Wahrnehmungsspanne für Lautstärke auf. Dieses Wahrnehmungsdefizit und die Tatsache, dass die BG die betroffene neurologische Struktur bei MP sind, lässt eine Beteiligung dieser bei der Lautstärkeverarbeitung von Gesunden vermuten. Um die Rolle der BG bei der Lautstärkeverarbeitung zu untersuchen, wurde eine generalisierte lineare Modellanalyse durchgeführt. Anhand von fMRT-Daten von gesunden Proband*innen, erhoben von Erb et al. (2020), wurde nach linearen Regressionen zwischen den präsentierten Lautstärkewerten und dem BOLD-Signal in acht BG-Regionen gesucht. Hierfür wurden Daten von 63 Proband*innen im Alter zwischen 18 und 78 Jahren (Durchschnitt: 43,4 Jahre) genutzt. Im linken und rechten Putamen angrenzend zum Globus pallidus pars externa war eine positive lineare Regression beobachtbar. Eine negative lineare Regression zeigte sich im Kopf des Nucleus caudatus beider Hemisphären. Teile der BG scheinen somit möglicherweise eine Rolle bei der Verarbeitung von Lautstärke zu spielen. In Bezug auf MP besteht die Möglichkeit, dass ihre neuronale Degeneration mitursächlich für die Wahrnehmungseinschränkungen ist. Dies sowie der Einfluss dieses rezeptiven Lautstärkedefizits auf die produktiven sprachlichen Einschränkungen sollten Gegenstand zukünftiger Untersuchungen sein. Es ist gut möglich, dass die Ursache der produktiven Lautstärkedefizite nicht motorischer, sondern rezeptiver Natur ist. Dies hätte einen großen Einfluss auf künftige sprachtherapeutische Konzepte bei der Behandlung produktiver Sprachstörungen bei MP.

In diesem Beitrag werden das Konzept der „Virtuellen Runden Tische“ (ViRuTi) sowie Ergebnisse ihrer Pilotierung und Perspektiven für die Implementierung vorgestellt. Dabei geht es um die ressourcenfreundliche, digitale Umsetzung und niederschwellige Durchführung der ViRuTi. Inklusive Bestrebungen sind fest mit der Notwendigkeit interdisziplinärer Fallbesprechungen verknüpft. Akteure aus Kita, Schule und Gesundheitswesen können mit Bezugspersonen des betreffenden Kindes gemeinsam am runden Tisch Perspektiven austauschen und Entscheidungen treffen, bspw. zur Einleitung und Evaluierung von Sprachförder- oder -therapiemaßnahmen. Eine durch ein Konzept vorgegebene Struktur erleichtert den Austausch und die Fokussierung der Beteiligten auf die Ressourcen und Bedürfnisse des Kindes. Außerdem ist dieser interprofessionelle bzw. transdisziplinäre Austausch auch digital möglich.