Development of Landmark Knowledge at Decision Points

Two experiments investigated how people develop different landmark knowledge at decision points. Participants learned a route in a virtual city once or five times. One distinctive landmark was placed at each intersection of the route. At test, participants were released at each intersection according to the learning order and were required to determine the turning direction. At each intersection, the landmark was removed (no landmark), correctly placed (one landmark), duplicated on the other side (two identical landmarks), or misplaced from another intersection (two different landmarks) to disrupt the landmark sequence. The results suggested that humans develop different landmark knowledge (landmark knowledge for guidance, landmark knowledge for place recognition and knowledge of landmark sequence) with different navigation experience.     

Learning Spatial Localization: From Rat Studies to Computational Models of the Hippocampus

In his landmark article, Richard Morris (1981) introduced a set of rat experiments intended “to demonstrate that rats can rapidly learn to locate an object that they can never see, hear, or smell provided it remains in a fixed spatial location relative to distal room cues” (p. 239). These experimental studies have greatly impacted our understanding of rat spatial cognition. In this article, we address a spatial cognition model primarily based on hippocampus place cell computation where we extend the prior Barrera–Weitzenfeld model (2008) intended to allow navigation in mazes containing corridors. The current work extends beyond the limitations of corridors to enable navigation in open arenas where a rat may move in any direction at any time. The extended work reproduces Morris's rat experiments through virtual rats that search for a hidden platform using visual cues in a circular open maze analogous to the Morris water maze experiments. We show results with virtual rats comparing them to Morris's original studies with rats.     

Is Memory for Routes Enhanced by an Environment's Richness in Visual Landmarks?

We tested the hypothesis that a route's memorability is dependent on the frequency with which people are exposed to visual landmarks. Undergraduates learned either a route through an urban area lacking visually salient features, or a route in a neighborhood with many shops and urban objects. They were then asked to recall the learned route in the form of route directions and sketch maps. The results showed higher recall performance for the richer environment. When presented with photographs depicting scenes along the route, participants exposed to the richer environment had higher recognition scores and shorter response times than the others. The data confirm the functional role of landmarks in route memory and wayfinding.     

Choice zones: architecturally relevant areas of interest

A new type of area of interest (AOI) termed “choice zones” is proposed, that is relevant for eye tracking research in the built environment. Choice zones are an ex ante measure; this is in contrast to many existing definitions of AOIs which are data-driven. Choice zones are defined algorithmically using space-geometric parameters. The validity of the concept is tested against fixation data from an urban navigation experiment in which participants chose between alternative paths. Findings show that choice zones account for 90% of the fixations clusters. The merit of the measure for applied studies in built environment research is discussed.     

The role of motor processes in mental rotation: selective shaping of cognitive processing via specific sensorimotor experience

The involvement of motor processes in mental rotation is experience-dependent: different levels of expertise in sensorimotor interactions lead to different strategies in mental rotation. In the present study, wrestlers, gymnasts, and nonathletes physically rotated objects that were either light (wooden) or heavy (lead) but otherwise having the same sizes and shapes. They then performed a mental rotation task using photographs of these objects in which the material and therefore the weight was visible. I hypothesized that wrestlers would rely more heavily on experience-based sensorimotor strategies in performing mental rotation because during their athletic practice they not only manipulate external “objects” (i.e., their opponent) but also have to plan future actions taking into account past experience of these “objects” (for example their weight). All participants reported that lead objects were harder to physically rotate than wooden ones. However, only wrestlers mentally rotated lead objects more slowly than wooden ones—as they would if they were physically rotating them—suggesting the involvement of motor processes. These findings show that the involvement of motor processes in mental rotation depends on specific rather than mere sensorimotor experience.     

Environmental reference systems for large-scale spaces

Human navigation in well-known environments is guided by stored memory representations of spatial information. In three experiments (N = 43) we investigated the role of different spatial reference systems when accessing information about familiar objects at different locations in the city in which the participants lived. Our results indicate that two independent reference systems underly the retrieval of spatial knowledge. Environmental characteristics, e.g., the streets at an intersection, determine which headings are easier to imagine at a given location and lead to differences in accessibility of spatial information (orientation-specific behavior). In addition, access to spatial information depends on the relative direction of a location with respect to the imagined heading, such that information about locations imagined in front of oneself is easier to access than about locations towards the back. This influence of an egocentric reference system was found for environmental knowledge as well as map-based knowledge. In light of these reference system effects, position-dependent models of spatial memory for large-scale environments are discussed. To account for the simultaneous effect of an environmental and an egocentric reference system, we present a 2-level model of spatial memory access.     

Communication constraints,indexical countermeasures,and crew configuration effects in simulated space-dwelling groups

Previous research with groups of individually isolated crews communicating and problem-solving in a distributed interactive simulation environment has shown that the functional interchangeability of available communication channels can serve as an effective countermeasure to communication constraints. The present report extends these findings by investigating crew performance effects and psychosocial adaptation following: (1) the loss of all communication channels, and (2) changes in crew configuration. Three-person crews participated in a simulated planetary exploration mission that required identification, collection, and analysis of geologic samples. Results showed that crews developed and employed discrete navigation system operations that served as functionally effective communication signals (i.e., “indexical” or “deictic” cues) in generating appropriate crewmember responses and maintaining performance effectiveness in the absence of normal communication channels. Additionally, changes in crew configuration impacted both performance effectiveness and psychosocial adaptation.     

Dysfunctions of Spatial Cognition in Schizophrenic Patients

ABSTRACT

Twenty outpatients who fulfilled the criteria for a diagnosis of schizophrenia and 28 control participants were invited to learn a route through a complex outdoor environment. They were then tested in tasks intended to explore various aspects of their memorized representation of the navigational episode. Compared to controls, the patients showed significant impairment in both the verbal production of route directions and the drawing of sketch maps. They referred to fewer landmarks and provided fewer directional instructions than the controls, while making a greater number of irrelevant comments. When invited to distinguish between photographs showing views of landmarks encountered along the route and distractors, they performed as well as the controls, and they had similar response times. However, when they were presented with pairs of actual photographs taken along the route, they displayed special difficulty in deciding which of the two landmarks was encountered first along the route. This difficulty in retrieving the sequential structure of the navigational episode suggests that the patients' memories were not accurately linked to one another in their mental representation of the route. These findings are interpreted in the context of current hypotheses about the hippocampal impairment that affects schizophrenic patients.     

Place learning in humans: The role of distance and direction information

Although the process of establishing a memoryof a location is necessary for navigation,relatively little is known about theinformation that humans use when forming placememories. We examined the relative importanceof distance and angular information aboutlandmarks in place learning. Participantsrepeatedly learned a target location inrelation to three distinct landmarks in animmersive computer-generated (virtual)environment. Later, during testing, theyattempted to return to that location. Theconfigurations of landmarks used during testingwere altered from those participants learned inorder to separate the effects of metricdistance information and information aboutinter-landmark angles. In general,participants showed greater reliance ondistance information than angular information. This reliance was affected by nonmetricrelationships present during learning, as wellas by the degree to which the learnedenvironment contained right or straightangles.     

Route Knowledge in Complex Environments: An Analysis of Pedestrian Recall Using Stereoscopic Panoramic Interactive Navigation

In this study, we investigate whether data collected on route knowledge is influenced by the method of data collection. The results of stereoscopic panoramic interactive navigation re-enactment sessions and conventional paper and pencil maps are compared against observational tracing data of pedestrian route choice behavior in the city center of Eindhoven, The Netherlands. The findings of the study suggest that the data collected through maps better describe empirical observations of pedestrian route choice behavior that the data collected through stereoscopic panoramic interactive navigation sessions.     

When gestures show us the way: Co-thought gestures selectively facilitate navigation and spatial memory

How does gesturing during route learning relate to subsequent spatial performance? We examined the relationship between gestures produced spontaneously while studying route directions and spatial representations of the navigated environment. Participants studied route directions, then navigated those routes from memory in a virtual environment, and finally had their memory of the environment assessed. We found that, for navigators with low spatial perspective-taking performance on the Spatial Orientation Test, more gesturing from a survey perspective predicted more accurate memory following navigation. Thus, co-thought gestures accompanying route learning relate to performance selectively, depending on the gesturers’ spatial ability and the perspective of their gestures. Survey gestures may help some individuals visualize an overall route that they can retain in memory.     

The effects of maps and textual information on navigation in a desktop virtual environment

This study presents an experimentthat investigates how individuals perform anavigation test in a desktop virtualenvironment. The participants were randomlyassigned to one of the five test conditions:(C1) a map as information material during theentire test, (C2) the map only visible beforethe test, (C3) textual information during theentire test, (C4) textual information onlybefore the test and (C5) no additionalnavigational cues. The results were thatadditional information during the entire testwas more effective than short periods ofstudying the map or textual information onlybefore the test. However, participants weremore accurate in finding their route when anykind of navigational cues were used than whenno navigational cues were used. The results ofan additional questionnaire indicate thatbetween the test groups there were nodifferences in estimating the travelleddistances. The performance to draw the coveredpath into a sketch map of the landscape did notdiffer significantly between the test groupswith additional navigational cues. Theseresults indicate that in certain environmentstextual information may provide an effectivealternative to navigation training with a map.     

Information theory,animal communication,and the search for extraterrestrial intelligence

We present ongoing research in the application of information theory to animal communication systems with the goal of developing additional detectors and estimators for possible extraterrestrial intelligent signals. Regardless of the species, for intelligence (i.e., complex knowledge) to be transmitted certain rules of information theory must still be obeyed. We demonstrate some preliminary results of applying information theory to socially complex marine mammal species (bottlenose dolphins and humpback whales) as well as arboreal squirrel monkeys, because they almost exclusively rely on vocal signals for their communications, producing signals which can be readily characterized by signal analysis. Metrics such as Zipf's Law and higher-order information-entropic structure are emerging as indicators of the communicative complexity characteristic of an “intelligent message” content within these animals’ signals, perhaps not surprising given these species’ social complexity. In addition to human languages, for comparison we also apply these metrics to pulsar signals—perhaps (arguably) the most “organized” of stellar systems—as an example of astrophysical systems that would have to be distinguished from an extraterrestrial intelligence message by such information theoretic filters. We also look at a message transmitted from Earth (Arecibo Observatory) that contains a lot of meaning but little information in the mathematical sense we define it here. We conclude that the study of non-human communication systems on our own planet can make a valuable contribution to the detection of extraterrestrial intelligence by providing quantitative general measures of communicative complexity. Studying the complex communication systems of other intelligent species on our own planet may also be one of the best ways to deprovincialize our thinking about extraterrestrial communication systems in general.     

Space,Language and Ontology: A Response to Davis

Abstract

Ernest Davis' article “Qualititative Spatial Reasoning in Interpreting Text and Narrative” discusses challenges that the interpretation of natural language appears to raise for the formalization of commonsense spatial reasoning. Davis finds these to be of “surprising logical complexity,” but also “erratic” in that they do not show a logical structuring of the problem space that could guide productive research. In this response I argue that much of the apparent lack of structure Davis laments is due to the very style of formal modeling he pursues. By augmenting logical considerations with substantial input from other disciplines and by adopting a heterogeneous and modular approach to formalization, I suggest that the problem space is by no means as ill-structured as Davis presents it.     

Wayfinding Through Orientation

Dominant approaches in computer-assisted wayfinding support adhere to the deeply problematic principles of turn-by-turn navigation. In this article, we suggest a new approach called “Wayfinding Through Orientation,” which supports the acquisition of spatial knowledge and cognitive mapping for advancing the user’s spatial orientation. Being oriented on one’s way is a prerequisite to enabling people to verify instructions and to incorporate new spatial information into their existing knowledge structure. In three studies described in this article we first present empirical evidence that people can be supported in survey knowledge acquisition through suitable wayfinding instructions. Consequently, we explore orientation information in human wayfinding instructions. Finally, we outline how orientation information can be communicated within a prototypically implemented navigation assistance system.     

Rhetorical shadows: The conceptual representation of incongruent shadows

ABSTRACT

This article addresses the topic of conceptual representation of shadows. We analyze several examples of contemporary imagery, taken from advertising and cartooning, to shed light on the way shadow depictions are used as rhetorical devices. Instead of being inserted as a natural phenomenon, rhetorical shadows invite the construction of meaning, and instead of being a mere natural companion of their casters, they reveal things about their casters. Three so-called “shadow incongruity types” are distinguished: (1) shadows revealing the “true nature” of their caster or the “hidden contents” of the caster’s mind; (2) shadows marking some transition their caster is involved in; and (3) shadows suggesting a certain quality attached to one of a shadow’s main ingredients (casting object, light source or surface). For each of these types of rhetorical shadows, we demonstrate that the way they convey meaning basically follows the principles of perceiving and understanding natural shadows.     

Health scorecard of spacecraft platforms: Track record of on-orbit anomalies and failures and preliminary comparative analysis

Choosing the “right” satellite platform for a given market and mission requirements is a major investment decision for a satellite operator. With a variety of platforms available on the market from different manufacturers, and multiple offerings from the same manufacturer, the down-selection process can be quite involved. In addition, because data for on-obit failures and anomalies per platform is unavailable, incomplete, or fragmented, it is difficult to compare options and make an informed choice with respect to the critical attribute of field reliability of different platforms. In this work, we first survey a large number of geosynchronous satellite platforms by the major satellite manufacturers, and we provide a brief overview of their technical characteristics, timeline of introduction, and number of units launched. We then analyze an extensive database of satellite failures and anomalies, and develop for each platform a “health scorecard” that includes all the minor and major anomalies, and complete failures—that is failure events of different severities—observed on-orbit for each platform. We identify the subsystems that drive these failure events and how much each subsystem contributes to these events for each platform. In addition, we provide the percentage of units in each platform which have experienced failure events, and, after calculating the total number of years logged on-orbit by each platform, we compute its corresponding average failure and anomaly rate. We conclude this work with a preliminary comparative analysis of the health scorecards of different platforms.The concept of a “health scorecard” here introduced provides a useful snapshot of the failure and anomaly track record of a spacecraft platform on orbit. As such, it constitutes a useful and transparent benchmark that can be used by satellite operators to inform their acquisition choices (“inform” not “base” as other considerations are factored in when comparing different spacecraft platforms), and by satellite manufacturers to guide their testing and reliability improvement programs. Finally, it is important to keep in mind that these health scorecards should be considered dynamic documents to be updated on a regular basis if they are to remain accurate and relevant for comparative analysis purposes, as new information will impact their content.