Three experiments were conducted to investigate how we recognize the space surrounding our bodies, especially the space behind us.
Undergraduates performed spatial perspective taking tasks after having learned the locations of five objects on a table while blindfolded. Results showed that (1) discrepancy between imagined orientation taken in the task and actual body orientation at that time had an effect on accuracy of subject's performance, (2) discrepancy between imagined orientation taken in the task and body orientation when they had learned the locations of objects had an effect on speed of subject's performance, (3) the complexity of object-array structure influenced whether the effect (2) emerged or not.
Based on Easton & Sholl (1995)'s model of spatial cognition with some supplementary assumptions, these results were interpreted in terms of the interference between a self-reference system at sensorimotor level and a self-reference system at representational level superposed on a representation of object-to-object relations, and the interference between a self-reference system involved in a “subject-to-object-object” representation and a self-reference system at representational level.

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Our movements to a destination tend to be done unconsciously, and shorter routes are usually selected. There are many studies on the relationship between physical distance and cognitive distance (e.g., Cadwallader, 1975, 1979; Sadalla, Staplin, & Burroughs, 1979; Sadalla & Magel, 1980; Sadalla & Staplin, 1980a, 1980b; Okamoto, 1983; Wakabayashi, 1989), but the results are still vague.
The current study examined the factors which affect cognitive distance (CD). The subjects (Ss) have used the building of the experiment for more than 2years, and they estimated each walk of 10 routes in there. Each of those routes (50 m-144 m) is longer than the standard route (34 m). Before the estimation of the distance, the pictures of both ends of each route were given on display through World Wide Web with questionnaires. Ratio method was used to obtain the data of CD. The CD data were converted to logarithm, and compared with real walks. Then, the CD data of approximate walk were paired, and a pair of them was compared.
As a result, six routes were estimated shorter than the real ones, and two routes were estimated longer. A pair of the CD data of approximate walk which are located right above or right below were estimated equally, but ones located on the same level and direction were estimated differently. It is suggested that the furniture (i.e., chair, garbage box), a varied structure (i.e., pillar) in building, and the lightness of route affect cognitive distance. Therefore, the CD in a building would depend on another factor that have not been suggested on studies in a large-scale environment, such as a city.

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Of much interests have been spatial cognition and wayfinding by the blind. The traditional approach to spatial cognition and locomotion have taken the central problem to be what kind of cognitive map the blind establish. The main reason for motivating such kind of studies is why holding a map in mind has been thought of as being crucial for blind travellers to reach to a destination. Review of previous studies leads to contradictory results; while visual experience and visual modality set influence on accuracy of cognitive map, some studies indicate the individual difference rather than these effects. The basic ideas of ecological approach offered by J. J. Gibson will be outlined. This approach to environment perception and locomotion concerns how organisms wayfind and reach a destination. The purpose of ecological studies is to determine information picked up in perceptual flows such as optical flow and to demonstrate some relationship between detected invariant structure of environment on the basis of information and performance of wayfinding. One challenging study which applied this approach to wayfinding by the blind will be shown. The results suggest as follows. First, by taking an ecological approach, it is possible to reveal how blind travellers negotiate through environment. Second, it is not so easy to evaluate accuracy of orientation defined by Gibson.

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“Cognitive map” has been one of the most frequently encountered concepts in the study of the spatial cognition of large-scale environment. But, recently, this concept becomes more and more sharply criticized by many psychologists. This study pointed out that the experimental paradigm based on the classical concept of “cognitive map” has a bias toward individualistic view of human behavior and thus shows lack of ecological validity. It takes into consideration only individuals moving alone neither with relation to others nor with materials available to them in the environment. In fact, when trying to find a way or to reach the destination in every-day situation, people try to use any available resources which others are possessing or even ask them to tell or show the way.
In an attempt to create a new type of research paradigm, we conducted an experiment designed to test the effects of moving in pair through the environment in the first trial on the performance of each of them when moving alone without partner in the next trial. Three types of pair were made in terms of the scores of the questionnaire about sense of direction (SDQ-S): high-high (H-H), high-low (H-L) and low-low (L-L) subjects' groups.
The results showed the following four points; (1) The decreasing order of the proportion of the correct navigation without partner in the second trial was as follows: H-H > HL[H] > HL[L] > L-L, that is, according to the types, moving in pair in the first trial seemed to have different effects on the performance of each of subjects when moving alone. (2) The analysis of verbal reports given by pair during navigation revealed that subjects L could minimize their dependent tendency to others when they were coupled with the subjects H without knowing the SDQ-S level of both of them. (3) Moving in pair gave a chance to the subjects L to get more effective informations from their partners H. (4) These latter two changes might lead to more active interaction of L with environments and thus to their better performance when moving alone.

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When people navigate through streets and cities, they use various kinds of information such as maps, landmarks, and guidance from other people. The purpose of this study is to examine when and why people make use of such external resources. In the experiment, subjects were asked to go to a local town where they had to visit six destinations using information obtained from either a route guidance service or from pedestrians. The routes they walked along were recorded by a Personal Handy phone System with location information (LI-PHS) and a video tape recorder. Their navigation processes and their verbal protocols were recorded and an analysis of when and why they relied on other people (route guidance and pedestrians) was made. The results indicate that people utilize various external resources, including human resources and situational cues which are both stable (e.g. finding a building) and unstable (e.g. finding a school girl when looking for a school), to choose their routes. The use of a route guidance service with mobile phones and location tracking devices (LI-PHS) to study human navigation processes is also discussed.

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Robotics has made remarkable progress. This paper overviews current robot research from a cognitive science perspective, and then discuss the possibility of using a mobile robot for a theory construction in spatial cognition. As a concrete case study, the paper presents our recent attempt to model infant's spatial development. In this modeling we address the following questions: (1) How does locomotion experience promote spatial development? (2) What is the relationship between body growth and spatial development? To explore these issues, we focus on the idea of mental tracking: the ability to update spatial relations between self and object without real (visual) tracking during the locomotion. We modeled the development of mental tracking as a learning task for a simulated robot, and conducted experiments simulating an infant's ability at locomotion.

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We introduce our researches about mobile robot navigation in real world. We have about 30 self-contained and autonomous mobile robots as experimental research platforms who are named “Yamabico”. The objective of our research is to realize a mobile robot, which can robustly navigate itself a long distance autonomously in a real environment. For navigation, a robot must recognize work space and have enough knowledge about environment. Since the information processing, sensors and actuators of the robot are very different from ones of human, the suitable representation of knowledge or the recognition of environment for the robot are also quite different. In this paper, we report some experiments on the navigation of autonomous robot being done in Intelligent Robot Laboratory of University of Tsukuba.

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This article reports two experiments on the use of right-left cues by pigeons. In Experiment 1, pigeons were trained to peck a left or a right key relative to a fixed red key. Then they were tested at the red key shifted in positions. The pigeons responded to both sides of the red key. This result showed that they used the red key as a landmark, and did not use right-left cue relative to this landmark. In Experiment 2, pigeons learned to peck a left key of three keys that were arranged horizontally on the front panel and illuminated in a same color. Then they were tested at a back-panel that had the same keys as the front-panel. Subjects mostly responded to the left-side key on the back-panel. These results showed that the pigeons could use right-left cue relative to their body, and did not use right-left cue relative to the landmark in the operant chamber.

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Incremental production has been a recent topic in language production studies. There are several levels in the sentence production process, such as the conceptual level, syntactic formulation level, phonetic formulation level, and so on. In incremental sentence production frameworks, a fragmental, incomplete segment can trigger a part of the sentence production process. For example, since an input to the syntactic formulator may be lacking case information on the noun to be produced, the syntactic formulator must complete the missing case information in order to produce an utterance incrementally. Furthermore, if the completed information causes inconsistency with the actual case information to be supplied later, the syntactic formulator must somehow dissolve this inconsistency. To examine how these processes are done in human sentence production, we conducted psycholinguistic experiments on incremental sentence production. Consequently, we found that the completion of missing case information is performed in a regular way, where a nominative case is assigned to the leftmost element in the sentence, and that the dissolving of inconsistency is done by means of passive voice construction or self-repair.

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Functional magnetic resonance imaging (fMRI) is a new tool to evaluate the brain activities by analyzing the time-series of the images obtained by magnetic resonance imaging (MRI) scanners. In the typical fMRI experiments, the dynamic response of the regional cerebral blood flow (rCBF) to the task performed by the subject is detected. The fluctuation of the regional blood oxygenation level induced by the rCBF changes raise the contrast of each pixel of the images between the two or more conditions in the time-series, and the difference is statistically evaluated to represent the brain activation. The role of fMRI is to test the hypothesis of the neurological or cognitive network models. In this paper, the fundamentals of fMRI, history of the technical development, the physiological backgrounds, the basic experiment designs, the methods of data acquisition, statistical data analysis, some recent topics and the limitations of fMRI are reviewed from the view points of medical physics.

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