@phdthesis{Jaeger2015,
  author    = {J{\"a}ger, Lena Ann},
  title     = {Working memory and prediction in human sentence parsing},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-82517},
  school      = {Universit{\"a}t Potsdam},
  pages     = {xi, 144},
  year      = {2015},
  abstract  = {This dissertation investigates the working memory mechanism subserving human sentence processing and its relative contribution to processing difficulty as compared to syntactic prediction. Within the last decades, evidence for a content-addressable memory system underlying human cognition in general has accumulated (e.g., Anderson et al., 2004). In sentence processing research, it has been proposed that this general content-addressable architecture is also used for language processing (e.g., McElree, 2000). Although there is a growing body of evidence from various kinds of linguistic dependencies that is consistent with a general content-addressable memory subserving sentence processing (e.g., McElree et al., 2003; VanDyke2006), the case of reflexive-antecedent dependencies has challenged this view. It has been proposed that in the processing of reflexive-antecedent dependencies, a syntactic-structure based memory access is used rather than cue-based retrieval within a content-addressable framework (e.g., Sturt, 2003). Two eye-tracking experiments on Chinese reflexives were designed to tease apart accounts assuming a syntactic-structure based memory access mechanism from cue-based retrieval (implemented in ACT-R as proposed by Lewis and Vasishth (2005). In both experiments, interference effects were observed from noun phrases which syntactically do not qualify as the reflexive's antecedent but match the animacy requirement the reflexive imposes on its antecedent. These results are interpreted as evidence against a purely syntactic-structure based memory access. However, the exact pattern of effects observed in the data is only partially compatible with the Lewis and Vasishth cue-based parsing model. Therefore, an extension of the Lewis and Vasishth model is proposed. Two principles are added to the original model, namely 'cue confusion' and 'distractor prominence'. Although interference effects are generally interpreted in favor of a content-addressable memory architecture, an alternative explanation for interference effects in reflexive processing has been proposed which, crucially, might reconcile interference effects with a structure-based account. It has been argued that interference effects do not necessarily reflect cue-based retrieval interference in a content-addressable memory but might equally well be accounted for by interference effects which have already occurred at the moment of encoding the antecedent in memory (Dillon, 2011). Three experiments (eye-tracking and self-paced reading) on German reflexives and Swedish possessives were designed to tease apart cue-based retrieval interference from encoding interference. The results of all three experiments suggest that there is no evidence that encoding interference affects the retrieval of a reflexive's antecedent. Taken together, these findings suggest that the processing of reflexives can be explained with the same cue-based retrieval mechanism that has been invoked to explain syntactic dependency resolution in a range of other structures. This supports the view that the language processing system is located within a general cognitive architecture, with a general-purpose content-addressable working memory system operating on linguistic expressions. Finally, two experiments (self-paced reading and eye-tracking) using Chinese relative clauses were conducted to determine the relative contribution to sentence processing difficulty of working-memory processes as compared to syntactic prediction during incremental parsing. Chinese has the cross-linguistically rare property of being a language with subject-verb-object word order and pre-nominal relative clauses. This property leads to opposing predictions of expectation-based accounts and memory-based accounts with respect to the relative processing difficulty of subject vs. object relatives. Previous studies showed contradictory results, which has been attributed to different kinds local ambiguities confounding the materials (Lin and Bever, 2011). The two experiments presented are the first to compare Chinese relatives clauses in syntactically unambiguous contexts. The results of both experiments were consistent with the predictions of the expectation-based account of sentence processing but not with the memory-based account. From these findings, I conclude that any theory of human sentence processing needs to take into account the power of predictive processes unfolding in the human mind.},
  language  = {en}
}
@phdthesis{LopezGambino2023,
  author    = {L{\´o}pez Gambino, Maria Soledad},
  title     = {Time Buying in Task-Oriented Spoken Dialogue Systems},
  doi       = {10.25932/publishup-59280},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-592806},
  school      = {Universit{\"a}t Potsdam},
  pages     = {148},
  year      = {2023},
  abstract  = {This dissertation focuses on the handling of time in dialogue. Specifically, it investigates how humans bridge time, or "buy time", when they are expected to convey information that is not yet available to them (e.g. a travel agent searching for a flight in a long list while the customer is on the line, waiting). It also explores the feasibility of modeling such time-bridging behavior in spoken dialogue systems, and it examines how endowing such systems with more human-like time-bridging capabilities may affect humans' perception of them. The relevance of time-bridging in human-human dialogue seems to stem largely from a need to avoid lengthy pauses, as these may cause both confusion and discomfort among the participants of a conversation (Levinson, 1983; Lundholm Fors, 2015). However, this avoidance of prolonged silence is at odds with the incremental nature of speech production in dialogue (Schlangen and Skantze, 2011): Speakers often start to verbalize their contribution before it is fully formulated, and sometimes even before they possess the information they need to provide, which may result in them running out of content mid-turn. In this work, we elicit conversational data from humans, to learn how they avoid being silent while they search for information to convey to their interlocutor. We identify commonalities in the types of resources employed by different speakers, and we propose a classification scheme. We explore ways of modeling human time-buying behavior computationally, and we evaluate the effect on human listeners of embedding this behavior in a spoken dialogue system. Our results suggest that a system using conversational speech to bridge time while searching for information to convey (as humans do) can provide a better experience in several respects than one which remains silent for a long period of time. However, not all speech serves this purpose equally: Our experiments also show that a system whose time-buying behavior is more varied (i.e. which exploits several categories from the classification scheme we developed and samples them based on information from human data) can prevent overestimation of waiting time when compared, for example, with a system that repeatedly asks the interlocutor to wait (even if these requests for waiting are phrased differently each time). Finally, this research shows that it is possible to model human time-buying behavior on a relatively small corpus, and that a system using such a model can be preferred by participants over one employing a simpler strategy, such as randomly choosing utterances to produce during the wait —even when the utterances used by both strategies are the same.},
  language  = {en}
}
@phdthesis{Elin2018,
  author    = {Elin, Kirill},
  title     = {Morphological processing in older adults},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-418605},
  school      = {Universit{\"a}t Potsdam},
  pages     = {217},
  year      = {2018},
  abstract  = {Over the last decades mechanisms of recognition of morphologically complex words have been extensively examined in order to determine whether all word forms are stored and retrieved from the mental lexicon as wholes or whether they are decomposed into their morphological constituents such as stems and affixes. Most of the research in this domain focusses on English. Several factors have been argued to affect morphological processing including, for instance, morphological structure of a word (e.g., existence of allomorphic stem alternations) and its linguistic nature (e.g., whether it is a derived word or an inflected word form). It is not clear, however, whether processing accounts based on experimental evidence from English would hold for other languages. Furthermore, there is evidence that processing mechanisms may differ across various populations including children, adult native speakers and language learners. Recent studies claim that processing mechanisms could also differ between older and younger adults (Clahsen \& Reifegerste, 2017; Reifegerste, Meyer, \& Zwitserlood, 2017). The present thesis examined how properties of the morphological structure, types of linguistic operations involved (i.e., the linguistic contrast between inflection and derivation) and characteristics of the particular population such as older adults (e.g., potential effects of ageing as a result of the cognitive decline or greater experience and exposure of older adults) affect initial, supposedly automatic stages of morphological processing in Russian and German. To this end, a series of masked priming experiments was conducted. In experiments on Russian, the processing of derived -ost' nouns (e.g., glupost' 'stupidity') and of inflected forms with and without allomorphic stem alternations in 1P.Sg.Pr. (e.g., igraju - igrat' 'to play' vs. košu - kosit' 'to mow') was examined. The first experiment on German examined and directly compared processing of derived -ung nouns (e.g., Gr{\"u}ndung 'foundation') and inflected -t past participles (e.g., gegr{\"u}ndet 'founded'), whereas the second one investigated the processing of regular and irregular plural forms (-s forms such as Autos 'cars' and -er forms such as Kinder 'children', respectively). The experiments on both languages have shown robust and comparable facilitation effects for derived words and regularly inflected forms without stem changes (-t participles in German, forms of -aj verbs in Russian). Observed morphological priming effects could be clearly distinguished from purely semantic or orthographic relatedness between words. At the same time, we found a contrast between forms with and without allomorphic stem alternations in Russian and regular and irregular forms in German, with significantly more priming for unmarked stems (relative to alternated ones) and significantly more priming for regular (compared) word forms. These findings indicate the relevance of morphological properties of a word for initial stages of processing, contrary to claims made in the literature holding that priming effects are determined by surface form and meaning overlap only. Instead, our findings are more consistent with approaches positing a contrast between combinatorial, rule-based and lexically-stored forms (Clahsen, Sonnenstuhl, \& Blevins, 2003). The doctoral dissertation also addressed the role of ageing and age-related cognitive changes on morphological processing. The results obtained on this research issue are twofold. On the one hand, the data demonstrate effects of ageing on general measures of language performance, i.e., overall longer reaction times and/or higher accuracy rates in older than younger individuals. These findings replicate results from previous studies, which have been linked to the general slowing of processing speed at older age and to the larger vocabularies of older adults. One the other hand, we found that more specific aspects of language processing appear to be largely intact in older adults as revealed by largely similar morphological priming effects for older and younger adults. These latter results indicate that initial stages of morphological processing investigated here by means of the masked priming paradigm persist in older age. One caveat should, however, be noted. Achieving the same performance as a younger individual in a behavioral task may not necessarily mean that the same neural processes are involved. Older people may have to recruit a wider brain network than younger individuals, for example. To address this and related possibilities, future studies should examine older people's neural representations and mechanisms involved in morphological processing.},
  language  = {en}
}
@phdthesis{Nicenboim2016,
  author    = {Nicenboim, Bruno},
  title     = {Dependency resolution as a retrieval process},
  school      = {Universit{\"a}t Potsdam},
  pages     = {xiv, 209},
  year      = {2016},
  abstract  = {My thesis focused on the predictions of the activation-based model of Lewis and Vasishth (2005) to investigate the evidence for the use of the memory system in the formation of non-local dependencies in sentence comprehension. The activation-based model, which follows the Adaptive Control of Thought-Rational framework (ACT-R; Anderson et al., 2004), has been used to explain locality effects and similarity-based interference by assuming that dependencies are resolved by a cue-based retrieval mechanism, and that the retrieval mechanism is affected by decay and interference. Both locality effects and (inhibitory) similarity-based interference cause increased difficulty (e.g., longer reading times) at the site of the dependency completion where a retrieval is assumed: (I) Locality effects are attributed to the increased difficulty in the retrieval of a dependent when the distance from its retrieval site is increased. (II) Similarity-based interference is attributed to the retrieval being affected by the presence of items which have similar features as the dependent that needs to be retrieved. In this dissertation, I investigated some findings problematic to the activation-based model, namely, facilitation where locality effects are expected (e.g., Levy, 2008), and the lack of similarity-based interference from the number feature in grammatical sentences (e.g., Wagers et al., 2009). In addition, I used individual differences in working memory capacity and reading fluency as a way to validate the theories investigated (Underwood, 1975), and computational modeling to achieve a more precise account of the phenomena. Regarding locality effects, by using self-paced reading and eye-tracking-while reading methods with Spanish and German data, this dissertation yielded two main findings: (I) Locality effects seem to be modulated by working memory capacity, with high-capacity participants showing expectation-driven facilitation. (II) Once expectations and other potential confounds are controlled using baselines, with increased distance, high-capacity readers can show a slow-down (i.e., locality effects) and low-capacity readers can show a speedup. While the locality effects are compatible with the activation-based model, simulations show that the speedup of low-capacity readers can only be accounted for by changing some of the assumptions of the activation-based model. Regarding similarity-based interference, two relatively high-powered self-paced reading experiments in German using grammatical sentences yielded a slowdown at the verb as predicted by the activation-based model. This provides evidence in favor of dependency creation via cue-based retrieval, and in contrast with the view that cue-based retrieval is a reanalysis mechanism (Wagers et al., 2009). Finally, the same experimental results that showed inhibitory interference from the number feature are used for a finer grain evaluation of the retrieval process. Besides Lewis and Vasishth's (2005) activation-based model, also McElree's (2000) direct-access model can account for inhibitory interference. These two models assume a cue-based retrieval mechanism to build dependencies, but they are based on different assumptions. I present a computational evaluation of the predictions of these two theories of retrieval. The models were compared by implementing them in a Bayesian hierarchical framework. The evaluation of the models reveals that some aspects of the data fit better under the direct access model than under the activation-based model. However, a simple extension of the activation-based model provides a comparable fit to the direct access model. This serves as a proof of concept showing potential ways to improve the original activation-based model. In conclusion, this thesis adds to the body of evidence that argues for the use of the general memory system in dependency resolution, and in particular for a cue-based retrieval mechanism. However, it also shows that some of the default assumptions inherited from ACT-R in the activation-based model need to be revised.},
  language  = {en}
}