The primary intent of this study was to gain insight into children's ability to use visual information in planning reaching movements. More specifically, the work presented here examined, from a developmental perspective, the use of visual information to use a) egocentric cues, b) allocentric cues, and c) the combination, in the form of visual background around a target. Children representing the age groups 5-, 7-, 9-, 11 years and adults participated in three experiments. All experiments were conducted using an immediate (visually-guided) and response-delay (memory-guided) paradigm. Experiment 1 examined the ability of participants to use an egocentric frame of reference to estimate reach via motor imagery. Results indicated that introducing a >̲ 2s delay affected responses in all age groups, especially the younger age groups (5- and 7-year-olds). As delay increased, children as a group tended to overestimate, while adults underestimated. Experiment 2 investigated how participants used allocentric cues to estimate the location of objects in a perceptual estimate paradigm. Results revealed that introducing a delay affected the estimation of distance among all age groups, with greater effect on the younger age groups. Experiment 3 examined how a visual background surrounding a target would affect estimation of reach. Results revealed that there were no differences when targets were surrounded with or without a background. Results also showed that the 5- and 7-year-olds were most affected on their perception of reach and estimates by longer delays. Considered together, these results hint that: (1) there is a significant temporal constraint on the representation of movement through the visoumotor stream, especially with children 7 years and younger, and (2) children as a whole tend to operate and rely more on an egocentric frame of reference; therefore, responses of reachability and distance estimates were susceptible to greater error when performed after a 2s delay.

The behavior of animals is often complex and requires them to interact with their surroundings. Within the brain, there are specialized neural systems in place to create and store representations of space. In order to effectively utilize these spatial mappings, there must be coordination between sub-cortical systems, which are responsible for allocentric spatial processing, and cortical regions, which handle sensory processing in egocentric coordinates. The retrosplenial cortex is a candidate for the role in facilitating the transformation between different coordinates, as it is anatomically located between the hippocampus and sensory cortical areas and exhibits both egocentric and allocentric spatial responses. The first experiment explored the firing properties of neurons in the retrosplenial cortex in response to boundaries defined in egocentric coordinates. Based on previous research conducted in our lab, which showed that cells in the striatum respond to such boundaries, rats were implanted with electrodes to record the activity of neurons in the retrosplenial cortex while they roamed freely in an open field. The response properties of these neurons were analyzed as the arena was expanded, its shape altered, and boundaries were added and removed. A subgroup of neurons, referred to as Egocentric Boundary Cells, showed increased or decreased firing when the rat was at a specific distance and direction from any of the arena's boundaries. These cells showed no preference for any particular boundary, and their firing was not biased by the animal's angular velocity or turning behavior, suggesting that they respond to boundaries in a general manner, regardless of the features of the boundary or the animal's behavior. Building on experiment one, the second experiment examined the behavior of retrosplenial neurons in rats during open field exploration when alterations were made to the environment. In three separate sessions, a subset of neurons recorded showed either an increase or decrease in their mean firing rate throughout the entire session in which the environment was altered, then returned to prior levels when the environment was returned to a familiar configuration. These alterations included the introduction of an object, rotation of boundaries, expansion of boundaries, changes in the arena's geometry, and removal of boundaries. Similar proportions of neurons exhibited increases or decreases in firing rate for all experimental manipulations. Furthermore, the majority of retrosplenial neurons showed strong speed sensitivity. Some neurons showed an increase in firing rate as speed increased, others showed a decrease in firing rate as speed increased, and some had a specific speed at which their firing rate was the highest. These results support the idea that the RSC is involved in contextual and memory processing, scene processing, as well as transmitting information about self-movement to downstream regions. The third experiment analyzed the different poses of rats as they moved through open field arenas, using simultaneous high-resolution thermal, depth, and RGB cameras. This was organized into a new open-source dataset called Rodent3D. The three-dimensional posture of the animal was reconstructed from the two-dimensional videos using a model called OptiPose. We investigated aspects of the environment where the animals spent the most time looking, such as boundaries and objects, and the frequency and duration of behaviors such as rearing and changes in heading. Finally, we discuss the significance of our model and the potential uses of our unique dataset for the fields of neuroscience and computer vision, as well as future research plans. These experiments demonstrated that the retrosplenial cortex is a vital region for spatial processing, particularly emphasizing egocentric responses. We show that aspects of the environment, such as boundaries, the presence of objects, and changes to the local features induce multiple changes in spatial firing properties of neurons. We also provide a novel open-source model and dataset that provides an innovative tool for more rigorous behavioral analysis that can be used in many disciplines. Altogether, these results suggest that the retrosplenial cortex plays a crucial role as a hub for egocentric spatial processing and coordinating of spatial reference frames to support spatial memory and navigation.

No description available.

In the study of navigation, frequently it is assumed that navigation is accomplished using either an allocentric strategy based on a cognitive map, or an egocentric strategy based on stimulus response associations. Further, it is frequently assumed that individual navigators, or even entire genders, are only capable of navigating by one strategy or the other. The present study investigated whether individuals or genders were limited to a particular navigational strategy and whether both strategies might be learned or used at the same time. In the present study, undergraduate students were tested in a virtual Morris water maze that was modified to allow successful and efficient navigation using either an allocentric or an egocentric strategy. Learning trials on which the participants had to learn the location of the platform were alternated with probe trials on which participants would show which strategy they were using. At the end of testing, participants were given a series of tests to determine what knowledge they had acquired and which strategies they were capable of using. Results indicated that: a) most people preferred to navigate egocentrically in this maze, but some preferred to navigate allocentrically, b) people tended to use an egocentrically strategy first, but it was not a necessary step to learning to navigate allocentrically, c) people were better at their preferred strategy, d) people learned information about their non-preferred strategy, and e) those who preferred to navigate egocentrically could nevertheless learn to navigate allocentrically. Surprisingly, all of these results were true for both men and women, although women tended to prefer egocentric navigation at a higher rate than men, and men outperformed women when forced to navigate allocentrically. These results suggest it may be too simple to think of navigators as being capable of only a single navigational strategy or of learning only one strategy at a time. / Graduate

This dissertation presents the theory and practice of Decritique, a critical pedagogy for the first-year college English classroom that offers an alternative to contemporary applications of critical theory. Underscored by a philosophy of language drawn from Husserl's pure phenomenology and Derrida's deconstruction, a key characteristic of the pedagogy is delineation between re-cognition and recognition: the former actively seeking ways to re-position one's own thinking in relation to perceptions of the world; the latter endorsing existing perception. Concepts of "respect" and "tolerance" are questioned in Decritique, positing that they can operate as agents of oppression; instead, students engage in critical interaction and animated introspection that, in turn, opens the possibility of change. Concerned with the theory and practice of a reconceptualized critical pedagogy, the question at the core of Decritique is ways for students to reach a point of cognitive struggle leading to genuine discovery without the pain that can accompany criticism and critical self-reflection acting as a barrier to learning. Chapters One through Three examine what constitutes "the critical"; namely, critical thinking, critical pedagogy, critical literacy, and critical care, Chapter Four discusses a reconceptualization of these criticalities, Chapter Five examines the theory of Decritique, Chapter Six presents a three-semester pilot study comparing Decritique with a pedagogy of "caring" in both face-to-face and online learning environments, and Chapter Seven provides the study’s conclusions. Results indicate that students taught with Decritique consistently produced more writing than those taught with a "caring" approach, demonstrated greater evidence of "critical" reflection on essay revisions, engaged more animatedly in verbal and written discourse, exhibited a strong sense of critical camaraderie, particularly in the face-to-face classroom, and that essays averaged nearly five percent, or half a letter grade, higher. Retention and pass rates were higher in the Decritique classes and students were more likely to be satisfied with their learning experience. Implementation of the pedagogy on a wider, cross-institutional level is recommended in order to investigate the potential of Decritique as an alternative critical pedagogy for the first-year college English classroom, one that promotes reflective critical analysis of discourse with a commitment to the possibilities of praxis.

The objective of this thesis is to examine random effect models applied to binary data. I will use classical and Bayesian inference to fit generalized linear mixed models to a specific data set. The data analyzed in this thesis comes from a study examining the injection practices of needle exchange clientele in Victoria, B.C. focusing on their risk networks. First, I will examine the application of social network analysis to the study of injection drug use, focusing on issues of gender, norms, and the problem of hidden populations. Next the focus will be on random effect models, where I will provide some background and a few examples pertaining to generalized linear mixed models (GLMMs). After GLMMs, I will discuss the nature of the injection drug use study and the data which will then be analyzed using a GLMM. Lastly, I will provide a discussion about my results of the GLMM analysis along with a summary of the injection practices of the needle exchange clientele. / Graduate / 0463

国立情報学研究所で電子化したコンテンツを使用している。

A critical function of the human visual system is to parse objects from the larger context of the environment, allowing for the identification of, and potential interaction with, those objects. The use of contextual information allows us to rapidly locate, identify, and interact with objects that appear in the environment. Contextual information can help specify an object's location within the environment (allocentric encoding) or with respect to the observer (egocentric encoding). Understanding how contextual information influences perceptual organization, and the neural systems that process a complex scene, is critical in understanding how contextual information assists in parsing local information from background. In the real world, relying on context is typically beneficial, as most objects occur in circumscribed environments. However, there are circumstances in which context can harm performance. In the case of visual illusions, relying on the context can bias observers' perceptions and cause significant motor errors. Studying the illusory conditions under which perceptual/motor functions are "fooled", or breakdown, can provide valuable information about how the brain computes allocentric and egocentric frames of reference. The following studies examine how attentional (Chapters II & III) manipulations of visuospatial context affect components of observers' egocentric reference frames (e.g., perceived vertical or subjective midline) and how neural manipulations (Chapter IV) can modulate observers' reliance on contextual information. In Chapter II, the role of attentional control settings on contextual processing is examined. Chapter III addresses the question of how visuospatial shifts of attention interact with an egocentric frame of reference. Finally, Chapter IV examines the functional role of superior parietal cortex in the processing of egocentric contextual information.

Doctor of Philosophy / Department of Electrical and Computer Engineering / Pietro Poggi-Corradini / Caterina M. Scoglio / The modulus of a family of walks quanti es the richness of the family by favoring having many short walks over a few longer ones. In this dissertation, we investigate various families of walks to study new measures for quantifying network properties using modulus. The proposed new measures are compared to other known quantities. Our proposed method is based on walks on a network, and therefore will work in great generality. For instance, the networks we consider can be directed, multi-edged, weighted, and even contain disconnected parts. We study the popular centrality measure known in some circles as information centrality, also known as e ective conductance centrality. After reinterpreting this measure in terms of modulus of families of walks, we introduce a modi cation called shell modulus centrality, that relies on the egocentric structure of the graph. Ego networks are networks formed around egos with a speci c order of neighborhoods. We then propose e cient analytical and approximate methods for computing these measures on both directed and undirected networks. Finally, we describe a simple method inspired by shell modulus centrality, called general degree, which improves simple degree centrality and could prove to be a useful tool for practitioners in the applied sciences. General degree is useful for detecting the best set of nodes for immunization. We also study the structure of loops in networks using the notion of modulus of loop families. We introduce a new measure of network clustering by quantifying the richness of families of (simple) loops. Modulus tries to minimize the expected overlap among loops by spreading the expected link-usage optimally. We propose weighting networks using these expected link-usages to improve classical community detection algorithms. We show that the proposed method enhances the performance of certain algorithms, such as spectral partitioning and modularity maximization heuristics, on standard benchmarks. Computing loop modulus bene ts from e cient algorithms for nding shortest loops, thus we propose a deterministic combinatorial algorithm that nds a shortest cycle in graphs. The proposed algorithm reduces the worst case time complexity of the existing combinatorial algorithms to O(nm) or O(hkin2 log n) while visiting at most m - n + 1 cycles (size of cycle basis). For most empirical networks with average degree in O(n1􀀀 ) our algorithm is subcubic.

<div>For either entertainment or documenting purposes, people are starting to record their life using egocentric cameras, mounted on either a person or a vehicle. Our target is to improve the utility of these egocentric videos. </div><div><br></div><div>For egocentric videos with an entertainment purpose, we aim to enhance the viewing experience to improve overall enjoyment. We focus on First-Person Videos (FPVs), which are recorded by wearable cameras. People record FPVs in order to share their First-Person Experience (FPE). However, raw FPVs are usually too shaky to watch, which ruins the experience. We explore the mechanism of human perception and propose a biometric-based measurement called the Viewing Experience (VE) score, which measures both the stability and the First-person Motion Information (FPMI) of a FPV. This enables us to further develop a system to stabilize FPVs while preserving their FPMI. Experimental results show that our system is robust and efficient in measuring and improving the VE of FPVs.</div><div><br></div><div>For egocentric videos whose goal is documentation, we aim to build a system that can centrally collect, compress and manage the videos. We focus on Dash Camera Videos (DCVs), which are used by people to document the route they drive each day. We proposed a system that can classify videos according to the route they drove using GPS information and visual information. When new DCVs are recorded, their bit-rate can be reduced by jointly compressing them with videos recorded on the similar route. Experimental results show that our system outperforms other similar solutions and the standard HEVC particularly in varying illumination.</div><div><br></div><div>The First-Person Video viewing experience topic and the Dashcam Video compression topic are two representations of applications rely on Visual Odometers (VOs): visual augmentation and robotic perception. Different applications have different requirement for VOs. And the performance of VOs are also influenced by many different factors. To help our system and other users that also work on similar applications, we further propose a system that can investigate the performance of different VOs under various factors. The proposed system is shown to be able to provide suggestion on selecting VOs based on the application.</div>