16,921 research outputs found

    Challenges for identifying the neural mechanisms that support spatial navigation: the impact of spatial scale.

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    Spatial navigation is a fascinating behavior that is essential for our everyday lives. It involves nearly all sensory systems, it requires numerous parallel computations, and it engages multiple memory systems. One of the key problems in this field pertains to the question of reference frames: spatial information such as direction or distance can be coded egocentrically-relative to an observer-or allocentrically-in a reference frame independent of the observer. While many studies have associated striatal and parietal circuits with egocentric coding and entorhinal/hippocampal circuits with allocentric coding, this strict dissociation is not in line with a growing body of experimental data. In this review, we discuss some of the problems that can arise when studying the neural mechanisms that are presumed to support different spatial reference frames. We argue that the scale of space in which a navigation task takes place plays a crucial role in determining the processes that are being recruited. This has important implications, particularly for the inferences that can be made from animal studies in small scale space about the neural mechanisms supporting human spatial navigation in large (environmental) spaces. Furthermore, we argue that many of the commonly used tasks to study spatial navigation and the underlying neuronal mechanisms involve different types of reference frames, which can complicate the interpretation of neurophysiological data

    A computational model of the referential semantics of projective prepositions

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    In this paper we present a framework for interpreting locative expressions containing the prepositions in front of and behind. These prepositions have different semantics in the viewer-centred and intrinsic frames of reference (Vandeloise, 1991). We define a model of their semantics in each frame of reference. The basis of these models is a novel parameterized continuum function that creates a 3-D spatial template. In the intrinsic frame of reference the origin used by the continuum function is assumed to be known a priori and object occlusion does not impact on the applicability rating of a point in the spatial template. In the viewer-centred frame the location of the spatial template’s origin is dependent on the user’s perception of the landmark at the time of the utterance and object occlusion is integrated into the model. Where there is an ambiguity with respect to the intended frame of reference, we define an algorithm for merging the spatial templates from the competing frames of reference, based on psycholinguistic observations in (Carlson-Radvansky, 1997)

    Spatial Relations and Natural-Language Semantics for Indoor Scenes

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    Over the past 15 years, there have been increased efforts to represent and communicate spatial information about entities within indoor environments. Automated annotation of information about indoor environments is needed for natural-language processing tasks, such as spatially anchoring events, tracking objects in motion, scene descriptions, and interpretation of thematic places in relationship to confirmed locations. Descriptions of indoor scenes often require a fine granularity of spatial information about the meaning of natural-language spatial utterances to improve human-computer interactions and applications for the retrieval of spatial information. The development needs of these systems provide a rationale as to why—despite an extensive body of research in spatial cognition and spatial linguistics—it is still necessary to investigate basic understandings of how humans conceptualize and communicate about objects and structures in indoor space. This thesis investigates the alignment of conceptual spatial relations and naturallanguage (NL) semantics in the representation of indoor space. The foundation of this work is grounded in spatial information theory as well as spatial cognition and spatial linguistics. In order to better understand how to align computational models and NL expressions about indoor space, this dissertation used an existing dataset of indoor scene descriptions to investigate patterns in entity identification, spatial relations, and spatial preposition use within vista-scale indoor settings. Three human-subject experiments were designed and conducted within virtual indoor environments. These experiments investigate alignment of human-subject NL expressions for a sub-set of conceptual spatial relations (contact, disjoint, and partof) within a controlled virtual environment. Each scene was designed to focus participant attention on a single relation depicted in the scene and elicit a spatial preposition term(s) to describe the focal relationship. The major results of this study are the identification of object and structure categories, spatial relationships, and patterns of spatial preposition use in the indoor scene descriptions that were consistent across both open response, closed response and ranking type items. There appeared to be a strong preference for describing scene objects in relation to the structural objects that bound the room depicted in the indoor scenes. Furthermore, for each of the three relations (contact, disjoint, and partof), a small set of spatial prepositions emerged that were strongly preferred by participants at statistically significant levels based on the overall frequency of response, image sorting, and ranking judgments. The use of certain spatial prepositions to describe relations between room structures suggests there may be differences in how indoor vista-scale space is understood in relation to tabletop and geographic scales. Finally, an indoor scene description corpus was developed as a product of this work, which should provide researchers with new human-subject based datasets for training NL algorithms used to generate more accurate and intuitive NL descriptions of indoor scenes

    Age-related effects on spatial memory across viewpoint changes relative to different reference frames

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    Remembering object positions across different views is a fundamental competence for acting and moving appropriately in a large-scale space. Behavioural and neurological changes in elderly subjects suggest that the spatial representations of the environment might decline compared to young participants. However, no data are available on the use of different reference frames within topographical space in aging. Here we investigated the use of allocentric and egocentric frames in aging, by asking young and older participants to encode the location of a target in a virtual room relative either to stable features of the room (allocentric environment-based frame), or to an unstable objects set (allocentric objects-based frame), or to the viewer's viewpoint (egocentric frame). After a viewpoint change of 0,circ,^{circ} (absent), 45,circ,^{circ} (small) or 135,circ,^{circ} (large), participants judged whether the target was in the same spatial position as before relative to one of the three frames. Results revealed a different susceptibility to viewpoint changes in older than young participants. Importantly, we detected a worst performance, in terms of reaction times, for older than young participants in the allocentric frames. The deficit was more marked for the environment-based frame, for which a lower sensitivity was revealed as well as a worst performance even when no viewpoint change occurred. Our data provide new evidence of a greater vulnerability of the allocentric, in particular environment-based, spatial coding with aging, in line with the retrogenesis theory according to which cognitive changes in aging reverse the sequence of acquisition in mental development

    Computer detection of spatial visualization in a location-based task

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    An untapped area of productivity gains hinges on automatic detection of user cognitive characteristics. One such characteristic, spatial visualization ability, relates to users’ computer performance. In this dissertation, we describe a novel, behavior-based, spatial visualization detection technique. The technique does not depend on sensors or knowledge of the environment and can be adopted on generic computers. In a Census Bureau location-based address verification task, detection rates exceeded 80% and approached 90%

    Local Alignment of Frame of Reference Assignment in English and Swedish Dialogue

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    In this paper we examine how people assign, interpret, negotiate and repair the frame of reference (FoR) in online text-based dialogues discussing spatial scenes in English and Swedish. We describe our corpus and data collection which involves a coordination experiment in which dyadic dialogue participants have to identify differences in their picture of a visual scene. As their perspectives of the scene are different, they must coordinate their FoRs in order to complete the task. Results show that participants do not align on a global FoR, but tend to align locally, for sub-portions (or particular conversational games) in the dialogue. This has implications for how dialogue systems should approach problems of FoR assignment – and what strategies for clarification they should implement

    Intuitive Cities: Pre-Reflective, Aesthetic and Political Aspects of Urban Design

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    Evidence affirms that aesthetic engagement patterns our movements, often with us barely aware. This invites an examination of pre-reflective engagement within cities and also aesthetic experience as a form of the pre-reflective. The invitation is amplified because design has political implications. For instance, it can draw people in or exclude them by establishing implicitly recognized public-private boundaries. The Value Sensitive Design school, which holds that artifacts embody ethical and political values, stresses some of this. But while emphasizing that design embodies implicit values, research in this field lacks sustained attention to largely unconscious background biases or values, rooted in cultural attitudes and personal interests, that lead theorists and planners—often too narrowly—to promote design organized around specific values such as defensibility. In examining these points, I draw on J. J. Gibson, a central figure for some writing on aesthetics and cities, and whom pragmatists and phenomenologists in turn influenced. Taking a cue from pragmatists in particular, I argue Gibson’s perceptual theory of affordances entails a theory of values, meaning our perception and therewith movements are inherently value-based. I advocate design that accounts for relatively constantly held values such as safety, while also handling the vast pluralism that exists and not crushing the aesthetic vibrancy of city life
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