Eric Hodgson

Transient and enduring spatial representations under disorientation and self-rotation.

Current theories of environmental cognition typically differentiate between an online, transient, and dynamic system of spatial representation and an offline and enduring system of memory representation. Here the authors present additional evidence for such 2-system theories in the context of the disorientation paradigm introduced by R. F. Wang and E. S. Spelke (2000). Several experiments replicate the finding that disorientation results in a decrease in the precision of peoples estimates of relative directions. In contrast to the typical interpretation of this effect as indicating the primacy of a transient spatial system, the present results are generally more consistent with an interpretation of it as indicating a switch from a relatively precise online representation to a relatively coarse enduring one. Further experiments examine the relative precision of transient and enduring representations and show that switching between them does not require disorientation, but can also be produced by self-rotations as small as 135 degrees .

The HIVE: a huge immersive virtual environment for research in spatial cognition.

Research in human spatial cognition has benefited from the advent of virtual environment (VE) technology; however, few VE systems currently enable users to move realistically over large physical spaces. Here, we describe a huge immersive virtual environment (HIVE) that offers untethered tracking of users in a 570 m2 physical space. This large tracking area allows users to move through virtual worlds in the same manner in which they move in the real world and enables behavioral research in spatial cognition examining mental processes that require extensive movement through an environment. We provide a detailed description of this system, and report an experiment examining distance estimation in virtual environments that illustrates the utility of the HIVE.

Lack of Set Size Effects in Spatial Updating: Evidence for Offline Updating.

Four experiments required participants to keep track of the locations of (i.e., update) 1, 2, 3, 4, 6, 8, 10, or 15 target objects after rotating. Across all conditions, updating was unaffected by set size. Although some traditional set size effects (i.e., a linear increase of latency with memory load) were observed under some conditions, these effects were independent of the updating process. Patterns of data and participant strategies were inconsistent with the common view of spatial updating as an online process. Instead, the authors concluded that participants formed enduring, long-term memory representations of the layouts at learning that were used to reconstruct spatial information about the layouts as needed (i.e., offline updating). These results support M. Amorim, S. Glasauer, K. Corpinot, and A. Berthozs (1997) 2-system model of spatial updating that includes both online and offline updating.

Redirected walking to explore virtual environments: Assessing the potential for spatial interference

Redirected walking has gained popularity in recent years as a way of enhancing the safety of users immersed in a virtual reality simulation and of extending the amount of space that can be simulated in a virtual environment (VE). Limits imposed by the available physical space and functional tracking area are overcome by inducing immersed users to veer imperceptibly in a way that prevents them from leaving the confines of the tracking space. Redirected walking has been shown to be feasible at levels below noticeable thresholds and to function without increasing the incidence of simulator sickness. The present studies demonstrate that redirected walking can function without negatively impacting memory for spatial locations of landmarks in a VE, despite introducing discrepancies between various spatial senses and distorting the spatial mapping of movement onto the environment. Additionally, the present studies implement what, to our knowledge, is the first generalized redirected walking algorithm that is independent of any task or environment structure, and can adaptively steer users in real time as they engage in spontaneous, unconstrained navigation. The studies also demonstrate that such an algorithm can be implemented successfully in a gymnasium-sized space.

Comparing Four Approaches to Generalized Redirected Walking: Simulation and Live User Data

Redirected walking algorithms imperceptibly rotate a virtual scene and scale movements to guide users of immersive virtual environment systems away from tracking area boundaries. These distortions ideally permit users to explore large and potentially unbounded virtual worlds while walking naturally through a physically limited space. Estimates of the physical space required to perform effective redirected walking have been based largely on the ability of humans to perceive the distortions introduced by redirected walking and have not examined the impact the overall steering strategy used. This work compares four generalized redirected walking algorithms, including Steer-to-Center, Steer-to-Orbit, Steer-to-Multiple-Targets and Steer-to-Multiple+Center. Two experiments are presented based on simulated navigation as well as live-user navigation carried out in a large immersive virtual environment facility. Simulations were conducted with both synthetic paths and previously-logged user data. Primary comparison metrics include mean and maximum distances from the tracking area center for each algorithm, number of wall contacts, and mean rates of redirection. Results indicated that Steer-to-Center out-performed all other algorithms relative to these metrics. Steer-to-Orbit also performed well in some circumstances.

Virtual reality in the wild: A self-contained and wearable simulation system

We implement and describe a computer simulation system that takes virtual reality technology beyond specialized laboratories and research sites, and makes them available in any space, such as a high-school gymnasium or a public park. Our hardware and software systems enable HMD-based immersive virtual reality simulations to be conducted in any arbitrary location with no external infrastructure and little-to-no setup required. We demonstrate the ability of this system to provide realistically motion-tracked navigation for users and to generate usable behavioral data by having participants navigate through a full-scale virtual grocery store while physically situated in a grassy field. Applications for behavioral research and use cases for other fields are discussed.

Optimizing Constrained-Environment Redirected Walking Instructions Using Search Techniques

A goal of redirected walking (RDW) is to allow large virtual worlds to be explored within small tracking areas. Generalized steering algorithms, such as steer-to-center, simply move the user toward locations that are considered to be collision free in most cases. The algorithm developed here, FORCE, identifies collision-free paths by using a map of the tracking areas shape and obstacles, in addition to a multistep, probabilistic prediction of the users virtual path through a known virtual environment. In the present implementation, the path predictions describe a users possible movements through a virtual store with aisles. Based on both the users physical and virtual location / orientation, a search-based optimization technique identifies the optimal steering instruction given the possible user paths. Path prediction uses the map of the virtual world; consequently, the search may propose steering instructions that put the user close to walls if the users future actions eventually lead away from the wall. Results from both simulated and real users are presented. FORCE identifies collision-free paths in 55.0 percent of the starting conditions compared to 46.1 percent for generalized methods. When considering only the conditions that result in different outcomes, redirection based on FORCE produces collision-free path 94.5 percent of the time.

Virtual reality disaster training: Translation to practice

Disaster training is crucial to the mitigation of both mortality and morbidity associated with disasters. Just as clinical practice needs to be grounded in evidence, effective disaster education is dependent upon the development and use of andragogic and pedagogic evidence. Educational research findings must be transformed into useable education strategies. Virtual reality simulation is a teaching methodology that has the potential to be a powerful educational tool. The purpose of this article is to translate research findings related to the use of virtual reality simulation in disaster training into education practice. The Ace Star Model serves as a valuable framework to translate the VRS teaching methodology and improve disaster training of healthcare professionals. Using the Ace Star Model as a framework to put evidence into practice, strategies for implementing a virtual reality simulation are addressed. Practice guidelines, implementation recommendations, integration to practice and evaluation are discussed. It is imperative that health educators provide more exemplars of how research evidence can be moved through the various stages of the model to advance practice and sustain learning outcomes.

Up north and down south: Implicit associations between topography and cardinal direction

Route planners show a reliable tendency to select south- relative to north-going routes between two horizontally (east/west) aligned landmarks, suggesting the application of a north-is-up heuristic (Brunyé, Mahoney, Gardony, & Taylor, 2010). The source of this north-is-up bias remains unknown, and there is no strong evidence to suggest that it is due to explicit strategy use. In four experiments, we attempt to further elucidate the source of this effect by testing whether it can be attributed to implicit associations between cardinal direction (north/south) and topography (mountainous/level terrain). Experiments 1 and 2 used an adapted Implicit Association Test and demonstrate automatically activated judgements that associate north with mountainous and south with relatively level terrain. Experiment 3 rules out the possibility that this effect is due to the local topography of New England by replicating in participants from the topographically dissimilar Midwestern United States. Finally, Experiment 4 tests the relative contribution of implicit versus explicit associations between cardinal direction and topography in predicting route-planning asymmetries; we show that implicit associations are a stronger predictor of southern route biases than explicit processes. Overall, results demonstrate that the conceptualization of space can be driven by physically unfounded implicit associations between cardinal directions and topographical features, and these associations are at least partially responsible for southern route preferences.

Learning scenes from multiple views: novel views can be recognized more efficiently than learned views.

In two experiments, participants were trained to recognize a playground scene from four vantage points and were subsequently asked to recognize the playground from a novel perspective between the four learned viewing perspectives, as well as from the trained perspectives. In both experiments, people recognized the novel view more efficiently than those that they had recently used in order to learn the scene. Additionally, in Experiment 2, participants who viewed a novel stimulus on their very first test trial correctly recognized it more quickly (and also tended to recognize it more accurately) than did participants whose first test trial was a familiar view of the scene. These findings call into question the idea that scenes are recognized by comparing them with single previous experiences, and support a growing body of literature on the existence of psychological mechanisms that combine spatial information from multiple views of a scene.