Integrating pragmatic reasoning in an efficiency-based theory of utterance choice

This thesis explores new methods of accounting for discourse-level linguistic phenomena, using computational modeling. When communicating, efficient speakers frequently choose to either omit, or otherwise reduce the length of their utterances wherever possible. Frameworks such as Uniform Information Density (UID) have argued that speakers preferentially reduce or omit those elements that are more predictable in context, and easier to recover. However, these frameworks have nothing to say about the effects of a linguistic choice on how a message is interpreted. I run 3 experiments which show that while UID posits no specific consequences to being "overinformative" (including more information in an utterance than is necessary), in fact overinformativeness can trigger pragmatic inferences which alter comprehenders' background beliefs about the world. In this case, I show that the Rational Speech Act (RSA) model, which models back-and-forth pragmatic reasoning between speakers and comprehenders, predicts both efficiency-based utterance choices, as well as any consequent change in perceived meaning. I also provide evidence that it's critical to model communication as a lossy process (which UID assumes), which allows the RSA model to account for phenomena that it otherwise is not able to. I further show that while UID predicts increased use of pronouns when referring to more contextually predictable referents, existing research does not unequivocally support this. I run 2 experiments which fail to show evidence that speakers use reduced expressions for predictable elements. In contrast to UID and similar frameworks, the RSA model can straightforwardly predict the results that have been observed to date. In the end, I argue that the RSA model is a highly attractive alternative for modeling speaker utterance choice at the discourse level. When it reflects communication as a lossy process, it is able to predict the same predictability-driven utterance reduction that UID does. However, by additionally modeling back-and-forth pragmatic reasoning, it successfully models utterance choice phenomena that simpler frameworks cannot account for.Diese Arbeit erforscht neue Methoden, linguistische Phänomene auf Gesprächsebene per Computermodellierung zu erfassen. Effiziente Sprecher:innen entscheiden sich bei der Kommunikation häufig dazu, wenn immer es möglich ist, Äußerungen entweder ganz auszulassen oder aber ihre Länge zu reduzieren. Modelle wie Uniform Information Density (UID) argumentieren, dass Sprecher:innen vorzugsweise diejenigen Elemente auslassen, die im jeweiligen Kontext vorhersagbarer und einfacher wiederherzustellen sind. Allerdings sagen diese Modelle nichts über die Auswirkungen einer linguistischen Entscheidung bezüglich der Interpretation einer Nachricht aus. Ich führe drei Experimente durch, die zeigen, dass wenngleich UID keine spezifischen Auswirkungen von "Überinformation" (einer Äußerung mehr Information als nötig geben) postuliert, Überinformationen doch pragmatische Schlussfolgerungen, die das gedankliche Weltmodell der Versteher:innen ändern können, auslöst. Für diesen Fall zeige ich, dass das Rational-Speech-Act-Modell (RSA), welches pragmatische Hin-und-Her-Schlussfolgerungen zwischen Sprecher:innen und Versteher:innen modelliert, sowohl effizienzbasierte Äußerungsauswahl als auch jegliche resultierende Verständnisänderung vorhersagt. Ich liefere auch Anhaltspunkte dafür, dass es entscheidend ist, Kommunikation als verlustbehafteten Prozess zu modellieren (wovon UID ausgeht), was es dem RSA-Modell erlaubt, Phänomene einzubeziehen, wozu es sonst nicht in der Lage wäre. Weiterhin zeige ich, dass obschon UID beim Bezug auf kontextuell vorhersagbarere Bezugswörter eine erhöhte Nutzung von Pronomen vorhersagt, dies von existierender Forschung nicht einstimmig gestützt wird. Ich führe zwei Experimente durch, die keine Anhaltspunkte dafür, dass Sprecher:innen reduzierte Ausdrücke für vorhersagbare Elemente verwenden, finden. Im Gegensatz zu UID und ähnlichen Modellen kann dass RSA-Modell direkt die bislang beobachteten Resultate vorhersagen. Schließlich lege ich dar, warum das RSA-Modell eine höchst attraktive Alternative zur Modellierung von Sprachäußerungsentscheidungen auf Gesprächsebene ist. Wenn es Kommunikation als einen verlustbehafteten Prozess widerspiegelt, kann es dieselbe vorhersagebasierte Äußerungsreduktion vorhersagen wie auch UID. Modelliert man jedoch zusätzlich pragmatische Hin-und-Her-Schlussfolgerungen, modelliert RSA erfolgreich Phänomene bei Äußerungsentscheidungen, die einfachere Modelle nicht abbilden können.German Research Foundation (DFG) as part of SFB 1102 - Information Density and Linguistic Encoding (IDeaL

Informationally redundant utterances elicit pragmatic inferences

Most theories of pragmatics and language processing predict that speakers avoid excessive informational redundancy. Informationally redundant utterances are, however, quite common in natural dialogue. From a comprehension standpoint, it remains unclear how comprehenders interpret these utterances, and whether they make attempts to reconcile the ‘dips’ in informational utility with expectations of ‘appropriate’ or ‘rational’ speaker informativity. We show that informationally redundant (overinformative) utterances can trigger pragmatic inferences that increase utterance utility in line with comprehender expectations. In a series of three studies, we look at utterances which refer to stereotyped event sequences describing common activities (scripts). When comprehenders encounter utterances describing events that can be easily inferred from prior context, they interpret them as signifying that the event conveys new, unstated information (i.e. an event otherwise assumed to be habitual, such as paying the cashier when shopping, is reinterpreted as non-habitual). We call these inferences atypicality inferences. Further, we show that the degree to which these atypicality inferences are triggered depends on the framing of the utterance. In the absence of an exclamation mark or a discourse marker indicating the speaker's specific intent to communicate the given information, such inferences are far less likely to arise. Overall, the results demonstrate that excessive conceptual redundancy leads to comprehenders revising the conversational common ground, in an effort to accommodate unexpected dips in informational utility

Studies on the structure of industrial high methoxyl pectins

The chemical structure of three industrial high methoxyl pectins (one extracted from apple pomace and two from lemon peels) has been extensively investigated. The apple pectin differs from the lemon ones by having a higher apparent molecular size, a higher neutral-sugar content, present either as covalently-linked side chains or as free neutral polysaccharides, a higher acetyl content and a higher phenolic content but a lower protein content. The lemon pectins appear to be very similar to each other except for their calcium cation content. Preparative size exclusion chromatography and ion exchange chromatography show that pectin samples are not homogeneous and that within one pectin preparation, the composition of pectin molecules varies with their molecular size or ionic charge. The lemon pectin sample richer in calcium cations contains a higher proportion of molecules with low degree of esterification, probably explaining its higher tendancy to form aggregates in the presence of calcium. Enzymic degradation of the pectin samples and subsequent analysis of the resulting fragments showed that at least part of the non-esterified carboxylic acids are grouped in blocks. However, such blocks are more numerous in the lemon pectin that is richer in calcium cations than in the apple or the other lemon pectin. Their presence explains the higher calcium-sensitivity of certain pectins and thus strongly influences their physical behaviour on application

Characterization of human papillomavirus subtype 72b.

We report the characterization of human papillomavirus (HPV) subtype 72b of the genus Alphapapillomavirus isolated from an oral rinse sample of a healthy woman. The HPV72b L1 open reading frame (ORF) was 90.2% identical to that of HPV72, indicating a subtype close to the border of a novel HPV type

Effects of Suspension Dispersity and Concentration on Flocculation Efficiency in Static and Dynamic Flocculators

Flocculation presents one of the most effective methods for enhancing separation of both anthropogenic and natural suspensions by sedimentation, filtration and flotation techniques.The flocculation effectiveness much depends on the medium shear rate in a flocculator. The objective of this research comprises the study how the suspension dispersity and concentration effect the efficiency of its flocculation in a static tubular flocculator and in a dynamic Couette flocculator. The studies used aqueous suspensions of ultra-fine calcium carbonate (<7 μm) and fine silica (<90 μm) as objects. It was established that treatment of ultra-fine calcium carbonate suspension in a static flocculator produced in the range 400-450 s-1 a pronounced primary maximum in the dependence "flocculation efficiency/shear rate". The increase of the suspension concentration to 70 g/l and above resulted in a small secondary maximum of the flocculation efficiency in the region of around 950 s-1. This can be due to a higher dissolution rate of flocculant and a corresponding increase of particles adhesion forces in flocs, which counteract viscous forces destroying them. In silicon dioxide suspension treatment, the primary and secondary peaks occur at both small and high suspension concentrations, but in a latter case, they are by far more pronounced and comparable in magnitude

Subject Preference and Ergativity

This paper presents the first-ever processing experiment on relativization in Avar, an ergative language with prenominal relatives. The results show no processing difference between the ergative subject gap and the absolutive object gap. The absolutive subject gap, however, is processed much faster. We propose a principled explanation for this result. On the one hand, Avar has a subject preference (cf. the Accessibility Hierarchy, Keenan and Comrie, 1977), which would make the processing of the ergative and the absolutive subject gap easier than the processing of the absolutive object gap. On the other hand, the ergative DP in a relative clause serves as a strong cue that allows the parser to project the remainder of the clause, including the absolutive object DP (cf. Marantz, 1991, 2000); such morphological cueing favors the absolutive object gap. Thus, two processing preferences, the one for subject relatives and the other for morphologically cued clauses, cancel each other out in terms of processing difficulty. As a result, reading time results for the ergative subject and absolutive object relative clauses are very similar. The overall processing results are significantly different from what is found in accusative languages, where subject preference and morphological cueing reinforce each other, leading to a strong transitive subject advantage.Linguistic