AN INVESTIGATION OF SPATIAL REFERENCE FRAMES AND THE CHARACTERISTICS OF BODY-BASED INFORMATION FOR SPATIAL UPDATING

Abstract

<p>Successful navigation requires an accurate mental spatial representation of the environment that can be updated during movement. Experiments with animals and humans have demonstrated the existence of two forms of spatial representation: egocentric (observer-centered) and allocentric (environment-centered). Unfortunately, specifically how humans use these two systems is not well understood. The current dissertation was focused on providing evidence differentiating human use of egocentric and allocentric spatial reference frames, specifically examining the characteristics and contributions from body-based sources. Two empirical chapters are presented that include experiments involving two common spatial tasks. In Chapter 2, updating of feature relations within a room-sized environment was examined by having observers provide directional judgments to learned features with respect to an imagined orientation that was either congruent or incongruent with their physical orientation. The information available for updating the physical orientation was manipulated across experiments. Performance differences between congruent and incongruent conditions demonstrated the reliance on egocentric representations for updating, and differentiated body- and knowledge-based components of the egocentric updating process. The specificity of the body-based component was examined in Chapter 3 by having observers detect changes made to a tabletop spatial scene following a viewpoint shift resulting from their movement, scene rotation or both. The relation between the extent of observer movement and the magnitude of the experienced viewpoint shift was manipulated. Change detection performance was best when the extent of observer movement most closely matched the viewpoint shift, and declined as the match declined. Thus, body-based cues contributed specific information for updating self-to-feature relations that facilitated scene recognition. Throughout the course of the research program it has become clear that humans rely on egocentric representations to complete these tasks, and sensory and motor modalities involved in self-motion are integrated for updating spatial relations of novel environments.</p>