Effectiveness of expert semantic knowledge as a navigational aid within hypertext

Hypertext systems parse documents into content nodes connected by machine supported links or relationships. Many hypertext researchers claim that the node-link relationships of hypertext provide an information organization that models the structure of human knowledge and should therefore facilitate information access (Fiderio 1988). Yet, failures of information access occur when users lack an understanding of the overall scope and organization of a hypertext system (Gay and Mazur 1991). To support this understanding, the present research incorporated expert-based domain semantics in the design of prosthetic devices for hypertext navigation. The task domain was documentation for a word processing system. In the first experiment, the pathfinder algorithm (Schvaneveldt 1990) and cluster analysis were used to identify a set of expertbased semantic relationships between word-processing concepts. The results from these analyses contributed to the design of two prostheses to assist hypertext navigation: A hierarchical index and a local semantic browser. These aids were tested in a second experiment, crossing type of on-line documentation (semantically enhanced hypertext or an alphabetically indexed text) with level of subject expertise (novice or expert). Both performance and strategy measures suggest that the semantic prostheses improved the accessibility of information for novice users without hampering expert performance.     

Aesthetics of navigational performance in hypertext

A hypertext learner navigates with a instinctive feeling for a knowledge. The learner does not know her queries, although she has a feeling for them. A learners navigation appears as complete upon the emergence of an aesthetic pleasure, called rasa. The order of arrival or the associational logic and even the temporal order are not relevant to this emergence. The completeness of aesthetics is important. The learner does not look for the intention of the writer, neither does she look for significance. Lexia has a suggestive power and she is suggested in the arrival of aesthetics. Hypertext learning does not depend on communication. The learner in her pleasure transgresses the bounds of space-time to be in communion with several writers/learners. Hypertext learning does not appear to be fundamentally different from the analog learning; however, in performance, as in navigation, the learner assumes a mental state that helps her in her emergence into aesthetic bliss, of an arrival to the completed lexial navigation. This completeness is owing to aesthetics and is not owing to either the semantics or the query-fulfilling qualities.     

Using 3D sound as a navigational aid in virtual environments

As current virtual environments are less visually rich than real-world environments, careful consideration must be given to their design to ameliorate the lack of visual cues. One important design criterion in this respect is to make certain that adequate navigational cues are incorporated into complex virtual worlds. In this paper we show that adding 3D spatialized sound to a virtual environment can help people navigate through it. We conducted an experiment to determine if the incorporation of 3D sound (a) helps people find specific locations in the environment, and (b) influences the extent to which people acquire spatial knowledge about their environment. Our results show that the addition of 3D sound did reduce time taken to locate objects in a complex environment. However, the addition of sound did not increase the amount of spatial knowledge users were able to acquire. In fact, the addition of 3D auditory sound cues appears to suppress the development of overall spatial knowledge of the virtual environment.     

An evaluation of different navigational tools in using hypertext

Hypertext is a widely used form of information presentation which has gained wide popularity in the last few years due to the ease with which information can be portrayed and accessed. However, the very flexibility of hypertext creates problems of user disorientation and cognitive overhead. Designers in the past have tried to combat these problems by providing users with a myriad of navigational tools, with the most widely employed tools being a map and an index. The primary objective of this study was to evaluate the usefulness of the above mentioned navigational tools in alleviating the problems associated with using a hypertext system. For the purpose of this study, a hypertext package was developed using Hypercard on “Ancient Civilizations.” The experiment explored three variables: types of navigational tool available to the user (Map, Index and Combination of map and index); hypertext size (Small stack, Large stack) and trials (Before, After). The results of the study indicate significant differences in the use and effect of the navigational tools.     

Using 3D sound as a navigational aid in virtual environments

As current virtual environments are less visually rich than real-world environments, careful consideration must be given to their design to ameliorate the lack of visual cues. One important design criterion in this respect is to make certain that adequate navigational cues are incorporated into complex virtual worlds. In this paper we show that adding 3D spatialized sound to a virtual environment can help people navigate through it. We conducted an experiment to determine if the incorporation of 3D sound (a) helps people find specific locations in the environment, and (b) influences the extent to which people acquire spatial knowledge about their environment. Our results show that the addition of 3D sound did reduce time taken to locate objects in a complex environment. However, the addition of sound did not increase the amount of spatial knowledge users were able to acquire. In fact, the addition of 3D auditory sound cues appears to suppress the development of overall spatial knowledge of the virtual environment.     

领域知识语义距离及其在专家系统中的应用

面向专家系统中的可程序化知识间距离的测度,在构造领域知识本体及本体树的基础上,建立知识身份距离、知识概念距离、知识属性距离、知识描述距离四个测度,并在规范化后采用有序加权几何算子对其加以集结,形成一个更加全面且应用性强的领域知识语义距离模型,有效地解决了专家系统中领域知识的判别问题。实验表明：该模型可快速地判别专家系统中两领域知识的相似程度,并具有82%以上的评判正确率。     

Are expert users always better searchers? Interaction of expertise and semantic grouping in hypertext search tasks

The facilitative effect of expertise in hypertext information retrieval (IR) tasks has been widely reported in related literature. However, recent theories of human expertise question the robustness of this result, since previous works have not fully considered the interaction between user and system characteristics. In this study, the constraint attunement hypothesis (CAH) is considered in order to predict that the effect of expertise in IR would appear only when the user and system characteristics can be combined successfully. Results from an experiment revealed that expert users outperformed novice users in IR when the elements of a system interface are organized semantically, but not when organized randomly. Results are discussed in the framework of the CAH supporting the interactive nature of human behaviour in HCI.     

Effect of hypertext highlighting on browsing,reading, and navigational performance

Reading hypertext documents is more difficult than reading traditional linear text. Text highlighting plays the role of encoding for reading comprehension and may play the roles of contextual cues and landmarks for hypertext navigation. The purpose of this study was to examine the effect of text highlight and organizing highlighted text into a hierarchical structure on browsing, reading, and navigation performance in a network hypertext system. A randomized experiment was conducted. Ninety participants were randomly assigned to three conditions: a reading system with text highlighting, with text highlighting and organizing highlighted text, and without any aids. Dependent variables included browsing performance: time spent and the length of navigational path for reading; reading performance: recall and inference scores, navigational performance: scores of landmark and route knowledge and time spent and the length of navigational path for completing nine navigational tasks. The results showed that text highlight did not improve reading and navigational performance. By contrast, organizing highlighted text yielded significantly worst performance in reading and navigation. According to the results, we propose several suggestions for the design of reading instruction and digital highlighters.     

Incremental maintenance of semantic links in dynamically changing hypertext systems

One purported advantage of hypertext systems is the ability to move between semantically related parts of a document (or family of documents). If the document is undergoing frequent modification (for example while an author is writing a book or while a software design stored in the hypertext system is evolving) the question arises as to how to incrementally maintain semantic interconnections in the face of the modifications.

The paper presents an optimal technique for the incremental maintenance of such interconnections as a document evolves. The technique, based on theories of information retrieval based on lexical affinities and theories of incremental computation, updates semantic interconnections as nodes are checked into the hypertext system (either new or as a result of an edit). Because we use the semantic weight of lexical affinities to determine which affinities are meaningful in the global context of the document, introducing a new affinity or changing the weight of an existing affinity can potentially have an effect on any node in the system. The challenge met by our algorithm is to guarantee that despite this potentially arbitrary impact, we still update link information optimally.

Once established the semantic interconnections are used to allow the user to move from node to node based not on rigid connections but instead on dynamically determined semantic interrelationships among the nodes.     

The effect of questioning on concept learning within a hypertext system

Abstract Two studies report upon the effect of asking learners to answer questions when learning in a hypertext environment, even when no immediate feedback is given to learners about the appropriateness of their responses. Such questions may be useful as a means to induce responses that can be used to monitor learning, but here the hypothesis was investigated that their inclusion would also improve learning directly. In the first study, 80 student teachers answered embedded multiple-choice questions that encouraged analysis of examples. Concept learning achieved using this environment was significantly reduced when compared with an environment requiring no such responses. In the second study, a cohort of 68 students were asked to summarise the information illustrated by the examples. Here, learning was significantly improved as compared with the no-response condition.     

超文本教学系统中学生知识的自适应测评研究

知识空间理论提供了一种描述给定知识域结构的方法,它被看作是有效评估学生知识程度的一个基础,但它是一种基于问题的知识空间理论.利用超文本结构和知识空间结构相似的特性,将知识点超文本结构转换为超文本知识空间,使知识空间理论建立在知识点上,并在此超文本知识空间上利用自动机原理实现对学生知识结构的自适应测评过程.给出了基于自动机的自适应测评算法,并进一步分析了算法的有效性和复杂性.     

A semantic fuzzy expert system for a fuzzy balanced scorecard

Balanced scorecard is a widely recognized tool to support decision making in business management. Unfortunately, current balanced scorecard-based systems present two drawbacks: they do not allow to define explicitly the semantics of the underlying knowledge and they are not able to deal with imprecision and vagueness. To overcome these limitations, in this paper we propose a semantic fuzzy expert system which implements a generic framework for the balanced scorecard. In our approach, knowledge about balanced scorecard variables is represented using an OWL ontology, therefore allowing reuse and sharing of the model among different companies. The ontology acts as the basis for the fuzzy expert system, which uses highly interpretable fuzzy IF–THEN rules to infer new knowledge. Results are valuable pieces of information to help managers to improve the achievement of the strategic objectives of the company. A main contribution of this work it that the system is general and can be customized to adapt to different scenarios.     

The effects of graphical overviews on knowledge acquisition in hypertext

Abstract A central aspect of designing hypertext for learning concerns the structure of the information in the hypertext and the view the learner is offered of this structure. In this study, a hypertext environment was enhanced with a graphical overview that represented the basic, inherent, structure of the domain and the layout was designed in such a way that learners were unobtrusively encouraged to follow a sequence of exploration that followed the domain structure. This so-called 'visual' lay-out was compared with two lay-outs that presented randomly positioned nodes. One of these two lay-outs contained hints (using 'highlighting') to stimulate learners to follow a domain related exploration similar to the one incorporated in the visual lay-out. The other ('control') lay-out did not provide such hints. Results showed that participants from both the 'visual' and the 'hints' conditions demonstrated a more domain-related exploration pattern than participants from the 'control' condition. Participants in the 'visual' lay-out did not show a better recall of the content of the nodes as such, but showed a significantly better acquisition of knowledge of structure than participants from the other two conditions. These data indicate that a visual display conveys knowledge in its own right and that knowledge gained does not depend on the exploration route followed in the hypertext material.     

Interactive induction of expert knowledge

The process of extracting, structuring and organizing elicited knowledge (called knowledge acquisition) is a bottleneck in developing knowledge-based systems. A manual approach that elicits domain knowledge by interviewing human experts typically has problems, because the experts are often unable to articulate their reasoning rules. An automatic approach that induces knowledge from a set of training cases also suffers from the unavailability of sufficient training cases. We present an integrated approach that combines the strengths of both methods to compensate for their weaknesses. In this approach, human experts are responsible for solving problems, whereas an inductive learning algorithm is responsible for reasoning and consistency checking.     

Expert knowledge acquisition and the unwilling expert: a knowledge engineering perspective

Expert systems are an evolving technology with the potential to make human expertise widely and cheaply available. The literature describing the development of expert systems generally assumes that experts willingly give up their knowledge. This is unrealistic and may be a reason why most expert system projects fail. This paper explores the problem of unwilling experts from the perspective of a knowledge engineer building an expert system. The link between knowledge and organizational power is established and human motivation theories are discussed. Finally, a new motivational approach is introduced to help the knowledge engineer deal with unwilling experts.     

Analyzing the structure of expert knowledge

Knowledge is either explicit or tacit. The elicitation, codification, storage, and distribution of tacit knowledge are extremely challenging tasks that require innovative methods and techniques. This paper reports the results of a study in which the tacit knowledge of domain experts was elicited, represented, and analyzed for validity. The subjects were a group of instructors and students at a USPS training school whose memory structures were analyzed for evidence of two common characteristics of expertise: holistic perception and use of abstract concepts. No evidence of either characteristic was found in the more experienced instructor group but, when the subjects were regrouped based on observed performance, the cognitive models of the high performers contained structural evidence of both characteristics. This finding led to the conclusion that experience alone is not an indicator of expertise. Other factors, such as the cognitive ability to correctly structure those experiences, must also be present.     

纺织专家系统中知识与知识库的应用

专家系统是人工智能的一个分支，是一种模拟专家决策能力的计算机系统，知识库是系统的重要组成部分，是系统的核心。本文结合纺织工艺设计及管理专家系统介绍了基于知识的专家系统的概念和结构，对系统中知识的获取、存储方式予以说明．并对其知识的表示方法加以阐述。     

Using bat-modelled sonar as a navigational tool in virtual environments

Bats are able to use active sonar as a mechanism for locating object in three dimensions and for generating spatial maps of their environments. Humans use passive sound cues to detect features of the space they occupy, as well as react to the spatial location of objects which generate sound. The system described in this paper allows free-ranging humans to locate a virtual sound location using active sonar. An emitted pulse, centred on the users head, serves as an intensity and time marker. The return pulse is rendered at the virtual target location and emitted after a time delay corresponding to the two-way path from sender to target and back again. The sonar system is modelled on those of bats, using ultrasonic frequency-modulated signals reflected from simple targets. The model uses the reflectivity characteristics of ultrasound, but the frequency and temporal structure used are scaled, with the speed of sound being set to 8.5 ms⁻¹ to bring the frequency range and temporal resolution within the capabilities of the human auditory system. Orientation with respect to the ensonified target is achieved by time-of-flight time delays to give target range, and binaural location information derived from interaural timing differences, interaural intensity differences, and head-related transfer functions. Subjects performed significantly better at a localization task when given temporal data based on echo delays with an outgoing reference pulse than without a reference pulse. Frequency-modulated signals sweeping from 1.5 kHz–100 Hz over 500 ms provide the best localization cues, and users found them significantly easier to locate than continuous sounds.