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Manual development of deep linguistic resources is time-consuming and costly and therefore often described as a bottleneck for traditional rule-based NLP. In my PhD thesis I present a treebank-based method for the automatic acquisition of LFG resources for German. The method automatically creates deep and rich linguistic presentations from labelled data (treebanks) and can be applied to large data sets. My research is based on and substantially extends previous work on automatically acquiring wide-coverage, deep, constraint-based grammatical resources from the English Penn-II treebank (Cahill et al.,2002; Burke et al., 2004; Cahill, 2004). Best results for English show a dependency f-score of 82.73% (Cahill et al., 2008) against the PARC 700 dependency bank, outperforming the best hand-crafted grammar of Kaplan et al. (2004). Preliminary work has been carried out to test the approach on languages other than English, providing proof of concept for the applicability of the method (Cahill et al., 2003; Cahill, 2004; Cahill et al., 2005). While first results have been promising, a number of important research questions have been raised. The original approach presented first in Cahill et al. (2002) is strongly tailored to English and the datastructures provided by the Penn-II treebank (Marcus et al., 1993). English is configurational and rather poor in inflectional forms. German, by contrast, features semi-free word order and a much richer morphology. Furthermore, treebanks for German differ considerably from the Penn-II treebank as regards data structures and encoding schemes underlying the grammar acquisition task. In my thesis I examine the impact of language-specific properties of German as well as linguistically motivated treebank design decisions on PCFG parsing and LFG grammar acquisition. I present experiments investigating the influence of treebank design on PCFG parsing and show which type of representations are useful for the PCFG and LFG grammar acquisition tasks. Furthermore, I present a novel approach to cross-treebank comparison, measuring the effect of controlled error insertion on treebank trees and parser output from different treebanks. I complement the cross-treebank comparison by providing a human evaluation using TePaCoC, a new testsuite for testing parser performance on complex grammatical constructions. Manual evaluation on TePaCoC data provides new insights on the impact of flat vs. hierarchical annotation schemes on data-driven parsing. I present treebank-based LFG acquisition methodologies for two German treebanks. An extensive evaluation along different dimensions complements the investigation and provides valuable insights for the future development of treebanks.
This dissertation investigates discourse-pragmatic differences between variably linked arguments appearing in alternating argument structure constructions in the sense of Goldberg (1995) and Kay (manuscript). The properties that are studied include givenness, pragmatic relation (topic/focus), salience of referents, animacy, and others. They derive from the literature on sentence-type constructions such as topicalization and from research on the referential properties of NP form types.
The research carried out here has multiple uses. At the most basic level, it serves as an empirical check on existing characterizations of the pragmatic properties of the relevant arguments that are the result of syntactic and semantic analysis based on introspection alone. For instance, for the epistemic raising alternation involving verbs like seem, the predicted topicality difference between the subjects of the raised and unraised constructions (Langacker 1995) could not be confirmed.
This dissertation also addresses the question what kinds of pragmatic factors, if any, are relevant to argument structure constructions. Based on the evidence of the dative alternation, it does not seem to be the case that the kind of pragmatic influences on argument structure constructions are different or limited compared to the ones found to be relevant to sentence-type constructions.
The kind of research undertaken here can also inform the syntactic and semantic analysis of constructions. In the case of the dative alternation, the discourse-pragmatic characteristics of the variably linked arguments provide evidence that Basilico’s (1998) analysis of the difference between the alternates in terms of VP-shells and a difference between thetic and categorical ‘inner’ predication, on the one hand does not account for all the data and on the other can be re-stated in pragmatic terms other than the thetic-categorical distinction.
In addition to studies of valence alternations, this dissertation also discusses various null instantiation phenomena, which provide further evidence for the need to specify discourse-pragmatic properties as part of argument structure constructions and lexical entries.
Finally, it is suggested that the use of randomly sampled corpus data and statistical modelling throughout this dissertation improves both empirical and analytical coverage.
A central question in psycholinguistics is how the human brain processes language in real time. To answer this question, the differences between auditory and visual processing have to be considered. The present dissertation examines the extent to which event-related potentials (ERPs) in the human electroencephalogram (EEG) interact with different modes of presentation during sentence comprehension. Besides the two classical modalities, auditory and rapid serial visual presentation (RSVP), the monitoring of readers’ eye movements was chosen as a new mode of presentation. Here, the temporal paradox between neuronal ERP effects and behavioral effects in the eye movement record were of particular interest. Specifically, by concurrently measuring ERPs and eye movements in natural reading, the dissertation aimed to shed light on the counterintuitive fact that difficulties in sentence comprehension arise earlier in eye movement measures than in the corresponding neuronal ERP effects. In contrast to RSVP and the auditory modality, reading offers a parafoveal preview of upcoming words (Rayner 1998), which enables the brain to process information of words before these are fixated for the first time (in foveal vision). When the word Gegenteil in example (1) below is fixated and processed, the brain concurrently processes some information of the upcoming parafoveal words von and weiß. (1) Schwarz ist das Gegenteil von weiß. (2) Schwarz […] blau. (3) Schwarz […] nett. The parafoveal preview mostly provides orthographic (word form) information, while semantic information is not conveyed (Inhoff & Starr 2004; White 2008). Whereas word form and lexical meaning are processed simultaneously with RSVP and auditory presentation, the parafoveal preview in natural reading allows for a temporal decoupling such that word forms are processed before meaning. This is one reason for the faster information uptake in reading. The present dissertation is the first to systematically investigate the influence of the parafoveal preview in sentence processing. Participants read sentences such as in (1)-(3), in which two adjectives were either antonyms (1), semantically related non-antonyms (2), or semantically unrelated non-antonyms (3). ERPs were computed for the last fixation before the target word (the sentence-final word in 1-3), which was assumed to capture parafoveal processing, and for the first fixation on the target, that should reflect foveal processing. The results were compared to two experiments using identical stimuli with auditory and RSVP presentation, and the parafoveal preview clearly led to different ERP results. While the RSVP and auditory presentations replicated the finding of a P300 to the second antonym in (1) (Kutas & Iragui 1998; Roehm et al. 2007), there was no P300 in response to antonyms at any fixation position in natural reading. However, the dissociation of parafoveal and foveal processing in reading also made it possible to disentangle different processes underlying the N400. There was a reduced parafoveal N400 for (1,2) compared with (3), which could be attributed to the preactivation of the word forms of the expected antonyms and of semantically related non-antonyms. In foveal vision, all non-antonyms (2,3) showed an enhanced N400 compared with (1) because they were unexpected and implausible in the sentence context. This dissociation between the preactivation of a word-form and the contextual fit of a word’s meaning is impossible with the other two modes of presentation, because orthographic and semantic information become available almost at the same time and are thus processed simultaneously. Furthermore, the parafoveal N400 effect was not accompanied by changes in the duration of the corresponding fixation, whereas the foveal N400 was. Similarly, with the concurrent measurement of ERPs and eye movements, the temporal paradox described above remained, as effects in the eye movement record preceded the neuronal ERP effects. Further support for these central findings came from two additional experiments that investigated different stimuli with concurrent ERP-eye tracking measures. Altogether, the experiments revealed that the previous findings on the language-related N400 can be replicated with natural reading, but they can also be differentiated qualitatively by virtue of the characteristics of natural reading. Although the behavioral and neuronal effects mirrored one another, not every neuronal effect necessarily translates into a behavioral output. Finally, even concurrent ERP-eye tracking measures cannot resolve the temporal paradox.
This thesis investigates temporal and aspectual reference in the typologically unrelated African languages Hausa (Chadic, Afro–Asiatic) and Medumba (Grassfields Bantu). It argues that Hausa is a genuinely tenseless language and compares the interpretation of temporally unmarked sentences in Hausa to that of morphologically tenseless sentences in Medumba, where tense marking is optional and graded. The empirical behavior of the optional temporal morphemes in Medumba motivates an analysis as existential quantifiers over times and thus provides new evidence suggesting that languages vary in whether their (past) tense is pronominal or quantificational (see also Sharvit 2014). The thesis proposes for both Hausa and Medumba that the alleged future tense marker is a modal element that obligatorily combines with a prospective future shifter (which is covert in Medumba). Cross-linguistic variation in whether or not a future marker is compatible with non-future interpretation is proposed to be predictable from the aspectual architecture of the given language.
This thesis investigates temporal and aspectual reference in the typologically unrelated African languages Hausa (Chadic, Afro–Asiatic) and Medumba (Grassfields Bantu).
It argues that Hausa is a genuinely tenseless language and compares the interpretation of temporally unmarked sentences in Hausa to that of morphologically tenseless sentences in Medumba, where tense marking is optional and graded.
The empirical behavior of the optional temporal morphemes in Medumba motivates an analysis as existential quantifiers over times and thus provides new evidence suggesting that languages vary in whether their (past) tense is pronominal or quantificational (see also Sharvit 2014).
The thesis proposes for both Hausa and Medumba that the alleged future tense marker is a modal element that obligatorily combines with a prospective future shifter (which is covert in Medumba). Cross-linguistic variation in whether or not a future marker is compatible with non-future interpretation is proposed to be predictable from the aspectual architecture of the given language.
When humans have a conversation with one-another, they generally take turns speaking one after the other without overlapping each others talk or leaving silence between turns for long stretches of time. Previous research has shown that conversation is a structured practice following rules that help interlocutors to manage the flow of conversation interactively. While at the beginning of a conversation it remains open who will speak when about what and for how long, interlocutors regulate the flow of conversation as it unfolds. One basic set of rules that interlocutors operate with governs the allocation of speaking turns, with the central rule stating that whoever starts speaking first at a point in time when speaker change becomes relevant has the rights and obligations to produce the next turn. The organization of turn allocation, therefore, is one reason for conversational turn taking to be so remarkably fast, with the beginnings of turns most often being quite accurately aligned with the ends of the previous turns. Observations of this outstanding speed of turn taking gave rise to a number of questions concerning language processing in conversational situations. The studies presented in this thesis investigate some of these questions from the perspective of the current listener preparing to be the next speaker who will respond to the current turn.
The study presented in Chapter 2 investigates when next speakers begin to plan their own turn with respect to two points in time, (i) the moment when the incoming turn’s message becomes clear enough to make response planning possible and (ii) the moment when the incoming turn terminates. Results of previous studies were inconclusive about the timing of language planning in conversation, with evidence in favour of both late and early response planning. Furthermore, previous studies presented both evidence as well as counter evidence indicating that response planning depends or does not depend on an accurate prediction of the timing of the incoming turn’s end. The study presented here makes use of a novel experimental paradigm which includes a dialogic task that participants need to fulfil in response to critical utterances by a confederate. These critical utterances were structured, on the one hand, so that their message became clear either only at the end of the turn or before the end of the turn, and, on the other hand, so that it was either predictable or not predictable when exactly the turn would end. Participant’s eye-movements as well as their response latencies indicated that they always planned their next turn as early as possible, irrespective of the predictability of the incoming turn’s end. The presented results provide evidence in favour of models of turn taking that predict speech planning to happen in overlap with the incoming turn.
Having established that next speakers begin to plan their turn in overlap, the study presented in Chapter 3 goes more into detail investigating to which depth language planning progresses while the incoming turn is still unfolding. To this end, a number of psycholinguistic paradigms were combined. In the study’s main experiment, participants had to fulfil a switch-task in which they switched from picture naming in response to an auditorily presented question to making a lexical decision. By manipulating the relatedness of the word for lexical decision with the picture that was prepared to be named before the task-switch it was possible to draw inferences on which processing stages were entered during the speech production process in overlap with the incoming turn. Participants’ behavioural responses in the lexical decision task revealed that they entered the stage of phonological encoding while the incoming turn was still unfolding, showing that planning in overlap is not limited to conceptual preparation but includes all sub-processes of formulation.
Given that speech production regularly enters the stages of formulation in overlap with the incoming turn, as shown in Chapters 2 and 3, the question arises whether planning the next turn in overlap is cognitively more demanding than during the gap between turns. This question is approached in the study presented in Chapter 4 by measuring pupillometric responses of participants in a dialogic task. An increase in pupil diameter during a cognitive task is indicative of increased processing load, and pupillometric responses to planning in overlap with the incoming turn were found to be greater than responses to planning in the gap between turns. These results show that planning in overlap is more demanding than planning during the gap, even though it is highly practiced by speakers.
After Chapters 2 to 4 investigated the timing and mechanisms of speech planning in conversation, Chapter 5 turns towards the timing of articulation of a planned turn, asking the question what sources of information next speakers use to time the articulation of a planned utterance to start closely after the incoming turn comes to an end. In this Chapter’s study, participants taking turns with a confederate responded to utterances containing or not containing different cues to the location of the incoming turn’s end. Participants made use of lexical and turn-final intonational cues, but not of turn-initial intonational cues, responding faster when the relevant cues were present than when they were not present. These results show that the timing of turn initiation in next speakers depends on the recognition of the incoming turn’s point of completion and not merely on the progress in planning the next turn.
All evidence presented in Chapters 2 to 5 is summed up and bundled together in a cognitive model of turn taking, which is being presented in Chapter 6. This model assumes, centrally, that the planning of a turn and the timing of its articulation are separate cognitive processes that run in parallel in any next speaker during conversation. Planning generally starts as early as possible, often in overlap with the incoming turn, while the timing of articulation depends on the next speaker’s level of certainty that speaker change has become relevant at a particular moment, with a number of cues to the end of the incoming turn leading to an increase of certainty. Next turns are assumed to often be planned down to fully formulated utterance plans including their phonological form as early as possible on the basis of anticipations of the incoming turn’s message, which are created with the help of the general and situational knowledge about the world, the current speaker and her intentions, as well as the input that has been received so far. The level of certainty that speaker change becomes relevant rises or decreases as lexico-syntactic, prosodic, and pragmatic projections about the development of the current turn are fulfilled or not fulfilled. As the incoming turn progresses towards its end as was projected by the current listener, he becomes certain that speaker change becomes relevant and will initiate articulation of the prepared next turn. Viewing these two processes, planning a next turn and timing of its articulation, as separate makes it possible to explain the observable fast timing of turn taking while still modelling the allocation of turns as interactionally managed by interlocutors — a considerable advantage of the presented model compared to more traditional perspectives on turn taking and conversation.
This is a study of how aspects of information structure can be captured within a formal grammar of Spanish, couched in the framework of Head-Driven Phrase Structure Grammar (HPSG, Pollard
and Sag 1994). While a large number of morphological, syntactic and semantic aspects in a variety of languages have been successfully analysed in this theory, information structure has not been paid the same attention in the HPSG literature. However, as a theory of signs, HPSG should include all
levels of description without which the structural descriptions offered by the grammar would ultimately remain incomplete. Languages often explicitly mark the information-structural partitioning of utterances. Depending on the particular language, linguistic resources used for this purpose include
prosody (stress/intonation), syntax (e. g. constituent order, special syntactic constructions) and morphology (e. g. special affixes). In HPSG, phonological, syntactic, semantic and pragmatic information is represented in parallel, which would seem to be a well-suited architecture for modelling
the sort of interfaces called for.
This thesis deals with expressions consisting of two noun phrases connected by a comitative preposition, referred to as comitative constructions (CCs). It focuses on CCs in Polish, with some comparisons to other languages, and provides an analysis at the morphosyntax-semantics-pragmatics interface in the paradigm of Head-Driven Phrase Structure Grammar with the integrated model-theoretic semantic framework of Lexicalized Flexible Ty2. After postulating three different readings of Polish CCs: accompanitive, conjunctive and (open and closed) inclusive, a number of semantic phenomena are discussed which provide evidence for this classification. Further examination of the data shows that all CC types behave uniformly with regard to their syntactic properties but exhibit differences regarding agreement and person, number and gender resolution. These differences have previously been explained by syntactic stipulations. This thesis argues that a syntactic approach to CCs lacks real empirical motivation and it demonstrates that some of the existing analyses are problematic for a number of empirical and / or theoretical reasons. It further offers an alternative analysis based on the assumption that all CC types have a uniform, adjunctionbased syntactic structure, and that the crucial differences between them are semantic in nature, being triggered by the meaning of the comitative preposition. The core of the proposed semantic analysis are three different logical representations of the comitative preposition, whose truth conditions allow us to make the right predictions about the different behavior of the three CC types. All other lexical components of CCs, including plural pronouns, bear in each type of CC their customary forms and meanings. Implementing this idea in a constraint-based framework whose description language incorporates a formal semantic representation language, and modeling the morphosyntactic, semantic, pragmatic and referential properties of CCs within a single grammatical paradigm, we arrive at an analysis that accounts for these expressions in a very natural way.
Understanding the design of talk-in-interaction is important in many domains, including speech technology. Although phonetic, linguistic and gestural correlates have been identified for some of the social actions that conversational participants accomplish, it is only recently that researchers have begun to take account of the immediately prior interactional context as an important factor influencing the design of a speaker’s turn. The present study explores the influence of context by focussing on characteristics of short turns produced by one speaker between turns from another speaker. The hypothesis is that the speaker designs her inserted turn as a match to the prior turn when wishing to align with the previous speaker’s agenda. By contrast, non-matching would display that the speaker is non-aligning, preferring instead to initiate a new action for example. Data are taken from the AMI corpus, focussing on the spontaneous talk of first-language English participants. Using sequential analysis, such short turns are classified as either aligning or non-aligning in accordance with definitions in the Conversation Analysis literature. The degree of prosodic similarity between the inserted turn and the prior speaker’s turn is measured using novel acoustic techniques. The results show that aligning turns are significantly more similar to the immediately preceding turn, in terms of pitch contour, than non-aligning turns. In contrast to the prosodic-acoustic analysis, the results of the gestural analysis indicate that aligning and non-aligning are differentiated by the use of distinct gestures, rather than by the matching (or non-matching) of gestures across the adjacent turns. These results support the view that choice of pitch contour is managed locally, rather than by reference to an intonational lexicon. However, this is not the case for speakers’ use of gesture. The implications of these findings for a model of talk-in-interaction are considered, along with potential applications.
This thesis describes work in three areas: grammar engineering, computer-assisted language learning and grammar learning. These three parts are connected by the concept of a grammar-based language learning application. Two types of grammars are of concern. The first we call resource grammars, extensive descriptions a natural languages. Part I focuses on this kind of grammars. The other are domain-specific or application-specific grammars. These grammars only describe a fragment of natural language that is determined by the domain of a certain application. Domain-specific grammars are relevant for Part II and Part III. Another important distinction is between humans learning a new natural language using computational grammars (Part II) and computers learning grammars from example sentences (Part III). Part I of this thesis focuses on grammar engineering and grammar testing. It describes the development and evaluation of a computational resource grammar for Latin. Latin is known for its rich morphology and free word order, both have to be handled in a computationally efficient way. A special focus is on methods how computational grammars can be evaluated using corpus data. Such an evaluation is presented for the Latin resource grammar. Part II, the central part, describes a computer-assisted language learning application based on domain-specific grammars. The language learning application demonstrates how computational grammars can be used to guide the user input and how language learning exercises can be modeled as grammars. This allows us to put computational grammars in the center of the design of language learning exercises used to help humans learn new languages. Part III, the final part, is dedicated to a method to learn domain- or application-specific grammars based on a wide-coverage grammar and small sets of example sentences. Here a computer is learning a grammar for a fragment of a natural language from example sentences, potentially without any additional human intervention. These learned grammars can be based e.g. on the Latin resource grammar described in Part II and used as domain-specific lesson grammars in the language learning application described Part II.