Spatial updating relies on an egocentric representation of space: Effects of the number of objects

Models of spatial updating attempt to explain how representations of spatial relationships between the actor and objects in the environment change as the actor moves. In allocentric models, object locations are encoded in an external reference frame, and only the actor’s position and orientation in that reference frame need to be updated. Thus, spatial updating should be independent of the number of objects in the environment (set size). In egocentric updating models, object locations are encoded relative to the actor, so the location of each object relative to the actor must be updated as the actor moves. Thus, spatial updating efficiency should depend on set size. We examined which model better accounts for human spatial updating by having people reconstruct the locations of varying numbers of virtual objects either from the original study position or from a changed viewing position. In consistency with the egocentric updating model, object localization following a viewpoint change was affected by the number of objects in the environment.     

The CORTEX cognitive robotics architecture: Use cases

CORTEX is a cognitive robotics architecture inspired by three key ideas: modularity, internal modelling and graph representations. CORTEX is also a computational framework designed to support early forms of intelligence in real world, human interacting robots, by selecting an a priori functional decomposition of the capabilities of the robot. This set of abilities was then translated to computational modules or agents, each one built as a network of software interconnected components. The nature of these agents can range from pure reactive modules connected to sensors and/or actuators, to pure deliberative ones, but they can only communicate with each other through a graph structure called Deep State Representation (DSR). DSR is a short-term dynamic representation of the space surrounding the robot, the objects and the humans in it, and the robot itself. All these entities are perceived and transformed into different levels of abstraction, ranging from geometric data to high-level symbolic relations such as “the person is talking and gazing at me”. The combination of symbolic and geometric information endows the architecture with the potential to simulate and anticipate the outcome of the actions executed by the robot. In this paper we present recent advances in the CORTEX architecture and several real-world human-robot interaction scenarios in which they have been tested. We describe our interpretation of the ideas inspiring the architecture and the reasons why this specific computational framework is a promising architecture for the social robots of tomorrow.     

Map-based navigation in mobile robots:: II. A review of map-learning and path-planning strategies

This article reviews map-learning and path-planning strategies within the context of map-based navigation in mobile robots. Concerning map-learning, it distinguishes metric maps from topological maps and describes procedures that help maintain the coherency of these maps. Concerning path-planning, it distinguishes continuous from discretized spaces and describes procedures applicable when the execution of a plan fails. It insists on the need for an integrated conception of such procedures, which must be tightly tailored to the specific robot that is used, notably to the capacities and limitations of its sensory-motor equipment, and to the specific environment that is experienced. A hierarchy of navigation strategies is outlined in the discussion, together with the sort of adaptive capacities each affords to cope with unexpected obstacles or dangers encountered on an animat or robot’s way to its goal.     

Situating vision in the world

Recently, there has been a great deal of interest in what has been called 'situated cognition', which has included claims that certain forms of representation are inadequate for modeling active organisms or agents such as humans and robots. In this article, I suggest that a weakness in classical theories of visual representation is the way in which representations connect with the real world, which may account for many of the concerns expressed by the situated cognition community. Specifically, I claim that what current theories lack is any provision for a certain form of direct, preconceptual connection between objects in the visual world (visual objects or proto-objects) and their representations in the visual system. This type of connection is akin to what philosophers and semanticists have referred to as an 'indexical' or 'demonstrative' reference and what some cognitive scientists have referred to as 'deictic pointers'. I explain why such a mechanism is needed and suggest that many workers have, in fact, been studying precisely this under the term 'visual index'. The visual index hypothesis is illustrated with the results of some relevant experiments, including multiple object tracking, visual routines and subset-selected visual searches. Indexing theory provides a synthesis that has profound implications for explaining a wide range of psychophysical findings, certain results in infant cognitive development and also some ancient problems in the philosophy of mind.     

The shape of ears to come: dynamic coding of auditory space

In order to pinpoint the location of a sound source, we make use of a variety of spatial cues that arise from the direction-dependent manner in which sounds interact with the head, torso and external ears. Accurate sound localization relies on the neural discrimination of tiny differences in the values of these cues and requires that the brain circuits involved be calibrated to the cues experienced by each individual. There is growing evidence that the capacity for recalibrating auditory localization continues well into adult life. Many details of how the brain represents auditory space and of how those representations are shaped by learning and experience remain elusive. However, it is becoming increasingly clear that the task of processing auditory spatial information is distributed over different regions of the brain, some working hierarchically, others independently and in parallel, and each apparently using different strategies for encoding sound source location.     

空间再定向任务中心理表征的多样性——来自虚拟现实实验的证据

成人和儿童完成空间再定向的具体过程与内在机制一直是研究者们关注的问题,在空间中是否形成了关于环境的整体表征是其中的一个关键。研究者们的观点并不一致,研究结果也提供了不同的证据。使用传统的空间再定向任务在此问题上难以得到明确的结论。本研究采用虚拟现实技术,让被试在虚拟现实环境中观察所在空间,然后直接向被试呈现空间的俯视视角并要求完成位置再认。通过对正确率和反应时的模式分析,发现被试反应可以划分为三种类型：整体的、独立于视角的心理表征（各方向均为高正确率低反应时）;整体的、依赖于方向的心理表征（正确率和反应时在不同方向上差异显著）和视角匹配的心理表征（各方向上均为低正确率）。三种不同的表征形式在人群中同时存在,并且在同一个体身上表现出不稳定性。     

Attention-referenced visual representations: evidence from impaired visual localization

Spatial representations in the visual system were probed in 4 experiments involving A. H., a woman with a developmental deficit in localizing visual stimuli. Previous research (M. McCloskey et al., 1995) has shown that A. H.'s localization errors take the form of reflections across a central vertical or horizontal axis (e.g., a stimulus 30 degrees to her left localized to a position 30 degrees to her right). The present experiments demonstrate that A. H.'s errors vary systematically as a function of where her attention is focused, independent of how her eyes, head, or body are oriented, or what potential reference points are present in the visual field. These results suggest that the normal visual system constructs attention-referenced spatial representations, in which the focus of attention defines the origin of a spatial coordinate system. A more general implication is that some of the brain's spatial representations take the form of coordinate systems.     

A dynamic context model of interactive behavior

A dynamic context model of interactive behavior was developed to explain results from two experiments that tested the effects of interaction costs on encoding strategies, cognitive representations, and response selection processes in a decision-making and a judgment task. The model assumes that the dynamic context defined by the mixes of internal and external representations and processes are sensitive to the interaction cost imposed by the task environment. The model predicts that changes in the dynamic context may lead to systematic biases in cognitive representations and processes that eventually influence decision-making and judgment outcomes. Consistent with the predictions by the model, results from the experiments showed that as interaction costs increased, encoding strategies and cognitive representations shifted from perception-based to memory-based. Memory-based comparisons of the stimuli enhanced the similarity and dominance effects, and led to stronger systematic biases in response outcomes in a choice task. However, in a judgment task, memory-based representations enhanced only the dominance effects. Results suggested that systematic response biases in the dominance context were caused by biases in the cognitive representations of the stimuli, but response biases in the similarity context were caused by biases in the comparison process induced by the choice task. Results suggest that changes in interaction costs not only change whether information was assessed from the external world or from memory but also introduce systematic biases in the cognitive representation of the information, which act as biased inputs to the subsequent decision-making and judgment processes. Results are consistent with the idea of interactive cognition, which proposes that representations and processes are contingent on the dynamic context defined by the information flow between the external task environment and internal cognition.     

The Natural History of Desire

Sterelny (2003) develops an idealised natural history of folk-psychological kinds. He argues that belief-like states are natural elaborations of simpler control systems, called detection systems, which map directly from environmental cue to response. Belief-like states exhibit robust tracking (sensitivity to multiple environmental states), and response breadth (occasioning a wider range of behaviours). The development of robust tracking and response-breadth depend partly on properties of the informational environment. In a transparent environment the functional relevance of states of the world is directly detectable. Outside transparent environments, selection can favour decoupled representations.

Sterelny maintains that these arguments do not generalise to desire. Unlike the external environment, the internal processes of an organism, he argues, are selected for transparency. Parts of a single organism gain nothing from deceiving one another, but gain significantly from accurate signalling of their states and needs. Key conditions favouring the development of belief-like states are therefore absent in the case of desires. Here I argue that Sterelny's reasons for saying that his treatment of belief does not generalise to motivation (desires, or preferences) are insufficient. There are limits to the transparency that internal environments can achieve. Even if there were not, tracking the motivational salience of external states suggests possible gains for systematic tracking of outcome values in any system in which selection has driven the production of belief-like states.     

The silence of the library: environment,situational norm,and social behavior

On the basis of the idea that situational norms are mentally represented as associations between environments and normative behavior, it was proposed that an environment can automatically direct normative behavior. More specifically, when situational norms are well-established (e.g., when entering the library, one should be silent), an environment is capable of automatically activating mental representations of normative behavior and the behavior itself. In these experiments, participants were exposed to pictures of environments, and effects on accessibility of representations of normative behavior and on actual behavior were assessed. Results indicated that representations of behavior and actual behavior itself are activated automatically when (a) goals to visit the environment are active and (b) strong associations between environment and normative behavior are established.     

Why a Diagram is (Sometimes) Worth Ten Thousand Words

We distinguish diagrammatic from sentential paper-and-pencil representations of information by developing alternative models of information-processing systems that are informationally equivalent and that can be characterized as sentential or diagrammatic. Sentential representations are sequential, like the propositions in a text. Diagrammatic representations are indexed by location in a plane. Diagrammatic representations also typically display information that is only implicit in sentential representations and that therefore has to be computed, sometimes at great cost, to make it explicit for use. We then contrast the computational efficiency of these representations for solving several illustrative problems in mathematics and physics. When two representations are informationally equivalent, their computational efficiency depends on the information-processing operators that act on them. Two sets of operators may differ in their capabilities for recognizing patterns, in the inferences they can carry out directly, and in their control strategies (in particular, the control of search). Diagrammatic and sentential representations support operators that differ in all of these respects. Operators working on one representation may recognize features readily or make inferences directly that are difficult to realize in the other representation. Most important, however, are differences in the efficiency of search for information and in the explicitness of information. In the representations we call diagrammatic, information is organized by location, and often much of the information needed to make an inference is present and explicit at a single location. In addition, cues to the next logical step in the problem may be present at an adjacent location. Therefore problem solving can proceed through a smooth traversal of the diagram, and may require very little search or computation of elements that had been implicit.     

Object localisation and frames of reference

In this paper, we explore which spatial frames of reference, egocentric or allocentric, are used to locate objects either in relation to ourselves (i.e. subject-to-object localisation) or to other objects (i.e. object-to-object localisation). In particular, we wanted to know whether the same or different frames of reference are used in these two different kinds of localisation after learning the environment in an egocentric way. Egocentric frames of reference are determined by the position of the person in relation to the spatial layout, whereas allocentric frames of reference are centred on the environment or on objects, independent of a persons position. We hypothesised that subject-to-object localisation is based on egocentric spatial representations, whereas object-to-object localisation is based on allocentric spatial representations. Participants were asked to study eight common objects, placed in a circle. Next, half of the participants had to point to an object in relation to their imagined position (egocentric condition) and the other half to an object in relation to another object (allocentric condition). The overall results show no difference between subject-to-object and object-to-object localisation. In both cases, access to positions corresponding to the front/back body axis was facilitated, in terms of both latency and error. Moreover, participants were able to retrieve objects positions better from the perspective from which they had learned the spatial array than from new perspectives. These results support the conclusion that egocentric coordinates, which are selected on the basis of our body-centred experience of the environment, define spatial representations underlying both subject-to-object and object-to-object localisation.     

Adaptive user displays for intelligent tutoring software.

Intelligent tutoring software (ITS) holds great promise for K-12 instruction. Yet it is difficult to obtain rich information about users that can be used in realistic educational delivery settings--public school classrooms--in which eye tracking and other user sensing technologies are not suitable. We are pursuing three "cheap and cheerful" strategies to meet this challenge in the context of an ITS for high school math instruction. First, we use detailed representations of student cognitive skills, including tasks to assess individual users' proficiency with abstract reasoning, proficiency with simple math facts and computational skill, and spatial ability. Second, we are using data mining and machine learning algorithms to identify instructional sequences that have been effective with previous students, and to use these patterns to make decisions about current students. Third, we are integrating a simple focus-of-attention tracking system into the software, using inexpensive, web cameras. This coarse-grained information can be used to time the display of multimedia hints, explanations, and examples when the user is actually looking at the screen, and to diagnose causes of problem-solving errors. The ultimate goal is to create non-intrusive software that can adapt the display of instructional information in real time to the user's cognitive strengths, motivation, and attention.     

The physical symbol grounding problem

This paper presents an approach to solve the symbol grounding problem within the framework of embodied cognitive science. It will be argued that symbolic structures can be used within the paradigm of embodied cognitive science by adopting an alternative definition of a symbol. In this alternative definition, the symbol may be viewed as a structural coupling between an agent’s sensorimotor activations and its environment. A robotic experiment is presented in which mobile robots develop a symbolic structure from scratch by engaging in a series of language games. In this experiment it is shown that robots can develop a symbolic structure with which they can communicate the names of a few objects with a remarkable degree of success. It is further shown that, although the referents may be interpreted differently on different occasions, the objects are usually named with only one form.     

Comparing eye movements during position tracking and identity tracking: No evidence for separate systems

There is an ongoing debate as to whether people track multiple moving objects in a serial fashion or with a parallel mechanism. One recent study compared eye movements when observers tracked identical objects (Multiple Object Tracking—MOT task) versus when they tracked the identities of different objects (Multiple Identity Tracking—MIT task). Distinct eye-movement patterns were found and attributed to two separate tracking systems. However, the same results could be caused by differences in the stimuli viewed during tracking. In the present study, object identities in the MIT task were invisible during tracking, so observers performed MOT and MIT tasks with identical stimuli. Observer were able to track either position and identity depending on the task. There was no difference in eye movements between position tracking and identity tracking. This result suggests that, while observers can use different eye-movement strategies in MOT and MIT, it is not necessary.     

Self-regulation,health, and behavior: A perceptual-cognitive approach

Abstract

Self-regulation systems are designed to adapt to threats via coping procedures that make efficient use of resources based upon valid representations of the environment. We discuss two components of the common-sense model of health threats: illness representations (e.g., content and organization) and coping procedures (e.g., classes of procedure and their attributes - outcome expectancies, time-lines, dose-efficacy beliefs, etc.). Characteristics of each of these domains, and the connection between the two, are critical to understanding human adaptation to problems of physical health. Rather than posing a barrier to factors outside the person that control behavior, an emphasis on subjective construal involves a view of the person as an active problem-solver embedded in a bidirectional system of sensitivity and responsiveness vis á vis the social, physical, and institutional environments in which health threats occur and through which intervention efforts may be directed.