It is well-known that the meaning of a word often changes depending on the context in which the word is used. Determining the appropriate interpretation for a word occurrence requires a knowledge of the range of possible meanings for that word, and consideration of those possibilities given available contextual evidence. However, there is still much to be learned about the nature of our lexical knowledge, as well as how we make use of that knowledge in the course of language comprehension. I report on a series of three experiments that explore these issues. I begin with the question of how precise our perceptions of word meaning in context really are. In Experiment 1, I present a Magnitude Estimation study in which I obtain judgments of meaning-in-context similarity over pairs of intransitive verb occur- rences, such as The kid runs / The cat runs, or The cat runs / The lane runs. I find that participants supply a large range of very specific similarity judgments, that judgments are quite consistent across participants, and that these judgments can be at least partially predicted even by simple measures of contextual properties, such as subject noun animacy and human similarity ratings over pairs of subject nouns. However, I also find that while some participants supply a great variety of ratings, many participants supply only a few unique values during the task. This suggests that some individuals are making more fine-grained judgments than others. These differences in response granularity could stem from a variety of sources. However, the offline nature of Experiment 1 does not enable direct examination of the comprehension process, but rather focuses on its end result. In Experiment 2, I present a Speed-Accuracy Tradeoff study that explores the earliest stages of meaning-in-context resolution to better understand the dynamics of the comprehension process itself. In particular, I focus on the timecourse of meaning resolution and the question of whether verbs carry context-independent default interpretations that are activated prior to semantic integration. I find, consistent with what has previously been shown for nouns, that verbs do in fact carry such a default meaning, as can be seen in early false alarms to stimuli such as The dawn broke -- Something shattered. These default meanings appear to reflect the most frequent interpretation of the verb. While these default meanings are likely an emergent effect of repeated exposure to frequent interpretations of a verb, I hypothesize that they additionally support a shallow semantic processing strategy. Recently, a growing body of work has begun to demonstrate that our language comprehension is often less than exhaustive and less than maximally accurate -- people often vary the depth of their processing. In Experiment 3, I explore changes in depth of semantic processing by making an explicit connection to research on human decision making, particularly as regards questions of strategy selection and effort- accuracy tradeoffs. I present a semantic judgment task similar to that used in Experiment 2, but incorporating design principles common in studies on decision making, such as response-contingent financial payoffs and trial-by-trial feedback on response accuracy. I show that participants' preferences for deep and shallow semantic processing strategies are predictably influenced by factors known to affect decision making in other non-linguistic domains. In lower-risk situations, participants are more likely to accept default meanings even when they are not contextually supported, such as responding "True" to stimuli such as The dawn broke -- Something shattered, even without the presence of time pressure. In Experiment 3, I additionally show that participants can adjust not only their processing strategies but also their stimulus acceptance thresholds. Stimuli were normed for truthfulness, i.e. how strongly implied (or entailed) a probe sentence was given its context sentence. Some stimuli in the task posessed an intermediate degree of truthfulness, akin to implicature, as in The log burned -- Something was dangerous (truthfulness 4.55/7). Across 3 conditions, the threshold separating "true" from "false" stimuli was moved such that stimuli such as the example just given would be evaluated differently in different conditions. Participants rapidly learned these threshold placements via feedback, indicating that their perceptions of meaning-in-context, as expressed via the range of possible conclusions that could be drawn from the verb, could vary dynamically in response to situational constraints. This learning was additionally found to occur both faster and more accurately under increased levels of risk. This thesis makes two primary contributions to the literature. First, I present evidence that our knowledge of verb meanings is at least two-layered -- we have access to a very information-rich base of event knowledge, but we also have a more schematic level of representation that is easier to access. Second, I show that these different sources of information enable different semantic processing strategies, and that moreover the choice between these strategies is dependent upon situational characteristics. I additionally argue for the more general relevance of the decision making literature to the study of language processing, and suggest future applications of this approach for work in experimental semantics and pragmatics. / text

This work analyzes the effects that different information structures on the demand side of the market have on consumption decisions and the way prices are determined. We develop three theoretical models to address this issue in a systematic way. First, we focus our attention on the consumers' awareness, or lack thereof, of substitute products in the market and the strategic interaction between firms competing in prices and costly advertising in such an environment. We find that prior information held by consumers can drastically change the advertising equilibrium predictions. In particular, we provide sufficient conditions for the existence of three types of equilibria, in addition to one previously found in the literature, and provide a necessary condition for a fourth type of equilibrium. Additionally, we show that the effect of the resulting advertising strategies on the expected transaction price is qualitatively significant, although ambiguous when compared to the case of a newly formed market. We can establish, however, that the transaction price is increasing in the size of the smaller firm's captive market. In the second chapter, we study the optimal timing to buy a durable good with an embedded option to resell it at some point in the future, as well as its reservation price, where the agent faces Knightian uncertainty about the process generating the market prices. The problem is modeled as a stopping problem with multiple priors in continuous time with infinite horizon. We find that the direction of the change in the buyer's reservation price depends on the particular parametrization of the model. Furthermore, the change in the buying threshold due to an increase in ambiguity is greater as the fraction of the market at which the agent can resell the good decreases, and the value of the embedded option is decreasing in the perceived level of ambiguity. Finally, we introduce Knightian uncertainty to a model of price search by letting the consumers be ambiguous regarding the industry's cost of production. We characterize the equilibria of this game for high and low levels of the search cost and show that firms extract abnormal profits for low realizations of the marginal cost. Furthermore, we show that, as the search cost goes to zero, the equilibrium of the game under the low cost regime does not converge to the Bertrand marginal-cost pricing. Instead firms follow a mixed-strategy that includes all prices between the high and low production costs. / text

This thesis is a broad survey of the uses of ambiguity in academic discourse. I note the uses of ambiguity in literary criticism, linking ambiguity with epistemic relativism. Then I pose the question, is the notion of "reframing" in psychotherapy analogous to the concept of "spin" in propaganda, advertising and public relations? In a consideration of theories that posit the social construction of reality, I examine articles by Judith Butler and Ian Hacking, noting the ambiguous reception of performativity and nominalism, respectively, within academia. In 1996 a physicist named Alan Sokal published an article which argued that reality is a social and linguistic construct. Sokal later revealed that his article was actually an elaborate spoof of postmodernist and social constructionist writing. According to Sokal, such relativistic discourse erodes the distinction between fact and fiction. I look at the implications of Sokal's hoax for the social sciences and humanities.

Drawing on field work at three different juvenile justice organizations, this dissertation explores the joint problems of interpretation and coordination in the face of problems marked by moral ambiguity and practical uncertainty. The author draws on array of research from a wide array of social and cognitive sciences to examine the relationship between knowledge and cognition, on the one hand, and coordination of action, on the other. Based on this work, the author proposes a more expansive, multidimensional model of cognition made up of four interconnected dimensions: conceptual, practical, emotional, and coordinating. This model allows us to better understand how people may coordinate their actions with others despite a lack of shared conceptual understanding of the problem at hand. The author then presents separate case studies of the three organizations, exploring these themes in further detail. In the case of the juvenile delinquent treatment center, Berkshire Farm Center and Services for Youth, the author examines how formal organizational processes and standards help coordinate the practices of the administration and clinical staff, on the one hand, and the teachers and child care workers, on the other, despite their fundamentally different understandings the boys’ problems and how to deal with them. In the second case, on the sentencing process at a State’s Department of Juvenile Justice, the author details how the formal, ritualized nature of the sentencing meetings allows for various professionals to express conflicting rationales for a given sentence simultaneously. In the third case, the author explores how the introduction of formalized practices, standards, and measures helps overcome the practical confusions, emotional conflicts, and differences in conceptual understanding between street workers and case managers that nearly derailed the efforts of the pilot gang intervention program, StreetSafe Boston. Taken together, these three case studies suggest that the strength of an organization’s formal bureaucratic features comes in part from the fact that they facilitate coordination without the need to resolve conflicts and contradictions in substantive interpretations, which may be a troubling but necessary accomplishment in the face of a problem rife with moral ambiguity and practical uncertainty. / Sociology

The objective of this dissertation is to evaluate decision making related to medical innovations.

The purpose of this essay is to explore how different means are used to create indeterminate meaning in Henry James’s novella The Turn of the Screw. It suggests that the indeterminacy creates gaps in the text which the reader is required to fill in during the reading process, and that this indeterminacy is achieved chiefly through the use of an unreliable narrator and of ambiguity in the way the narrator relates the events that take place. The reliability of the narrator is called into question by her personal qualities as well as by narrative factors. Personal qualities that undermine the narrator’s reliability are youth, inexperience, nervousness, excitability and vanity. Narrative factors that damage the narrator’s reliability concern the story as manuscript, the narrator’s role in the story she narrates, and her line of argumentation. The ambiguity in the way events are reported is produced by ambiguous words, dismissed propositions and omissions. The essay demonstrates how the unreliable narrator and the ambiguity combine to make the reader question the narrator’s account and supply his or her own interpretation of key elements in the story, that is, how they invite the reader to “co-author” the text.

This thesis provides some evidence of variability in cognitive style, and refutes the notion of it being a stable, generalisable personality trait. The study is statistical in nature and uses the cognitive style construct tolerance/intolerance of ambiguity as the main dependent variable. The main independent variables are context, content, ideological conservatism and ideological commitment. The theoretical context for this thesis is the long.,.standing debate about the nature of cognitive style within the field of social psychological research. The four major theories constituting this context are the theory of authoritarianism, the theory of extremism, context theory and value pluralism theory. However, these appear to be inadequate to explain the contextual variability of value conflict. Hence an attempt has been made to develop a new theory, tentatively named the contextual value conflict theory. The founding hypothesis of contextual value conflict theory is that the different characteristics of the manipulated contexts would present subjects with different levels of contextual value conflict, thus resulting in the expression of different levels of tolerance of ambiguity. The assumption was that higher conflict leads to higher attitudinal ambiguity tolerance and lower conflict to lower attitudinal ambiguity tolerance. The quantitative part of the research is constituted by two studies in which the Attitudinal Ambiguity Tolerance (AAT) Scale (Durrheim, 1995) was used to measure cross-context and crosscontent variations in tolerancelintolerance of ambiguity. This was done by first administering the scale across two different contexts with a fixed university student sample. This procedure was repeated in a follow-up study in two different contexts with a fixed church sample. The AAT scale was used in conjunction with 3 scales measuring ideological conservatism/ideological belief, and two scales measuring ideological commitment. These were the Subtle Racism scale (Duckitt, 1991), the Conservatism scale (Durrheim & Foster, 1997) and the Right-Wing Authoritarian Scale (Duckitt, 1990). Scales measuring ideological commitment included the Religiosity Scale (Rohrbaugh & Jessor, 1975) and the Political Interest scale (an adaptation of the one used by Sidanius, 1988b). Results have indicated that it is important to distinguish between the various dimensions of ideological conservatism as the shape and direction of the relationship with attitudinal ambiguity tolerance depend on these dimensions. Although contextual value conflict has managed to better account for the vast variability in patterns of associations than any of the four other theories mentioned above, it too has its limitations. It was found that conflict caused by context is difficult to control and pre-define, and future studies need to address this shortfall by finding ways of determining more efficiently the level of contextual value conflict inherent in different situations. A recommendation for further research is that an attempt be made to develop an instrument for quantifying the level of contextual value conflict present in a particular situation. These shortfalls resulted in the major limitation of this study, i.e. the post hoc nature of explanations offered for the results. Thus, although contextual value conflict theory was not confirmed without contradiction, this thesis did uncover a degree of support for it. Due to the small sample size in both studies, but in particular that of the church study it is important, however, to treat the findings with caution. In conclusion, although the support for contextual value conflict was not conclusive, some confIrmation was found. What was most strongly evidenced though, was that tolerance of ambiguity cannot be seen as a stable, generalisable personality trait, but should rather be seen as performance in context that is fluid in nature. / Thesis (M.A.) - University of Natal, Pietermaritzburg, 2000.

The prospects for enhanced Positron Emission Tomography imaging using liquid xenon (LXe) gamma ray detectors had been examined. Monte-Carlo simulations using GEANT4 were performed and the results were used to study the expected performance of a small animal PET scanner in comparison with a simulated conventional small animal scanner (LSO Focus 120). A NEMA-like cylinder phantom and an image contrast phantom were simulated with both scanners to compare performance characteristics. A Compton reconstruction algorithm was developed for the LXe scanner, and its performance and limitations studied.

The current research aimed to develop a deeper understanding of the antecedents of job insecurity, and specifically focused on the perceived job insecurity; importance and probability of events likely to affect one’s total job. The aim of the current study was to explore relationships between the perceptions of perceived organisational support (POS), perceived employability, role ambiguity and role overload, and job insecurity. A questionnaire made up of seven separate scales investigated the perceptions of 100 employees from several different organisations experiencing change (e.g. recently been through a change process, currently going through a change process, about to go through a change process in the near future). Results confirmed three of the main hypotheses of the current study, suggesting negative relationships between POS, perceived employability, role overload and the dependent variable job insecurity (probability). Further analyses indicate that POS is a significant predictor of job insecurity (probability), and role overload and employability are significant predictors of job insecurity (importance). Overall, this paper provides support for the relationship between the antecedents highlighted in this study and job insecurity. Practical implications and directions for further research are discussed.

Land vehicle navigation is primarily dependent upon the Global Positioning System (GPS) which provides accurate navigation in open sky. However, in urban and rural canyons GPS accuracy degrades considerably. To help GPS in such scenarios, it is often integrated with inexpensive inertial sensors. Such sensors have complex stochastic errors which are difficult to mitigate. In the presence of speed measurements from land vehicle, a reduced number of inertial sensors can be used which improve performance and termed as the Reduced Inertial Sensor System (RISS). Existing low-cost RISS/GPS integrated algorithms have limited accuracy due to use of approximations in error models and employment of a Linearized Kalman Filter (LKF). This research developed an enhanced error model for RISS which was integrated with GPS using an Extended Kalman Filter (EKF) for improved navigation of land vehicles. The proposed system was tested on several road experiments and the results confirmed the sustainable performance of the system during long GPS outages. To further increase the accuracy, Differential GPS (DGPS) is employed where carrier phase measurements are typically used. This requires resolution of Integer Ambiguity (IA) that comes at computational and time expense. This research uses pseudorange measurements for DGPS which mitigate large biases due to atmospheric errors and obviate the resolution of IA. These measurements are integrated with the enhanced RISS to filter increased noise and help GPS during signal blockages. The performance of the proposed system was compared with two other algorithms employing undifferenced GPS measurements where atmospheric effects are mitigated using either the Klobuchar model or dual frequency receivers. The proposed system performed better than both the algorithms in positional accuracy, multipath and GPS outages. This research further explored the reduction of Time-to-Fix Ambiguities (TTFA) for land vehicle navigation. To reduce the TTFA through inertial aiding, previous research used high-end Inertial Measurement Units (IMUs). This research uses MEMS grade IMU by integrating the enhanced RISS with carrier phase measurements using EKF. This algorithm was also tested on three road trajectories and it was shown that this integration helps reduce the TTFA as compared to the GPS-only case when fewer satellites are visible. / Thesis (Ph.D, Electrical & Computer Engineering) -- Queen's University, 2014-06-23 11:30:58.036