Browsing by Author "Hartson, H. Rex"
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- 5SGraph: A Modeling Tool for Digital LibrariesZhu, Qinwei (Virginia Tech, 2002-11-18)The high demand for building digital libraries by non-experts requires a simplified modeling process and rapid generation of digital libraries. To enable rapid generation, digital libraries should be modeled with descriptive languages. A visual modeling tool would be helpful to non-experts so they may model a digital library without knowing the theoretical foundations and the syntactical details of the descriptive language. In this thesis, we describe the design and implementation of a domain-specific visual modeling tool, 5SGraph, aimed at modeling digital libraries. 5SGraph is based on a metamodel that describes digital libraries using the 5S theory. The output from 5SGraph is a digital library model that is an instance of the metamodel, expressed in the 5S description language (5SL). 5SGraph presents the metamodel in a structured toolbox, and provides a top-down visual building environment for designers. The visual proximity of the metamodel and instance model facilitates requirements gathering and simplifies the modeling process. Furthermore, 5SGraph maintains semantic constraints specified by the 5S metamodel and enforces these constraints over the instance model to ensure semantic consistency and correctness. 5SGraph enables component reuse to reduce the time and efforts of designers. The results from a pilot usability test confirm the usefulness of 5SGraph.
- An Agenda for Human-Computer Interaction Research: User Interface Development Processes and MethodologiesHartson, H. Rex (Department of Computer Science, Virginia Polytechnic Institute & State University, 1991)This paper is the result of one working group in a workshop entitled "An Agenda for Human-Computer Interaction Research: Science and Engineering Serving Human Needs." The workshop, sponsored by the National Science Foundation, brought together "20-25 of the most prominent HCI researchers from the disciplines of computer science, engineering, information science, psychology, and human factors along with several NSF staff members." The workshop results, to appear in the HCI literature, identify critical research issues and potential avenues for assaulting them, along with necessary infrastructure recommendations related to educational, professional, and facility problems. The overall topical area was divided into five areas, each with an individual researcher in charge of directing discussion and reporting on the area. The areas included theory and taxonomy of HCI models, the interface development process, I/O devices and interaction styles, software tools, and computer supported collaborative work.
- Building Bridges and Interfaces: Toward the Next Generation of UIMSHartson, H. Rex; Hix, Deborah (Department of Computer Science, Virginia Polytechnic Institute & State University, 1987)User interface management systems (UIMS) have established themselves in both research and commercial arenas. We present several generations in UIMS evolution and discuss some problems of the early generations. In particular, we discuss the problems of a gap between methods used by behavioral scientists and computer scientists during the process of building interfaces. We present an empirical approach to begin bridging this gap and results of our preliminary observations: a human-computer interface development life cycle and recording techniques for interface development, as well as UIMS needed to support them. We conclude with future directions for the evolution of UIMS.
- Charting Presence in Virtual Environments and its Effects on PerformanceSnow, Michael P. (Virginia Tech, 1998-08-21)Virtual reality (VR) involves an attempt to create an illusion that the user of the VR system is actually present in a synthetic (usually computer-generated) environment. Little is known about how various system parameters affect the illusion of presence in a virtual environment (VE). In particular, there seem to be very little quantitative data on which to base VR system design decisions. Also, while presence (or immersion) in VEs is a primary goal of VR, not much is known about how this variable affects task performance. The goal of this research was to provide a ratio-scale measure of perceived presence in a VE, to explore the effects of a number of environmental parameters on this measure and construct empirical models of these effects, and to relate perceived presence to user performance. This was done by manipulating eleven independent variables in a series of three experiments. The independent variables manipulated were scene update rate, visual display resolution, field of view, sound, textures, head-tracking, stereopsis, virtual personal risk, number of possible interactions, presence of a second user, and environmental detail. Participants performed a set of five tasks in the VE and rated perceived presence at the end of each set using the technique of free-modulus magnitude estimation. The amount of time spent in the VE was also recorded. The results indicate that the VR system parameters manipulated and analyzed in this research did affect participants' subjective feeling of presence in the VE. Field of view, sound, and head-tracking showed the largest effects. Other significant effects found were those of visual display resolution, texture-mapping, stereopsis, and the presence of a second user. Free-modulus magnitude estimation worked well as a measure of perceived presence. A positive relationship was found between perceived presence and task performance, but this relationship was relatively weak. Second-order empirical models were constructed that predicted perceived presence with moderate success and, with less success, task performance.
- Comparison of an object-oriented programming language to a procedural programming language for effectiveness in program maintenanceHumphrey, Matthew Cameron (Virginia Tech, 1988-05-05)New software tools and methodologies make claims that managers often believe intuitively without evidence. Many unsupported claims have been made about object-oriented programming. However, without rigorous scientific evidence, it is impossible to accept these claims as valid. Although experimentation has been done in the past, most of the research is very recent and the most relevant research has serious drawbacks. This study attempts to empirically verify the claim that object-oriented languages produce programs that are more easily maintained than those programmed with procedural languages. Measurements of subjects performing maintenance tasks onto two identical programs, one object-oriented and the other procedure-oriented show the object-oriented version to be more maintainable.
- Complexity measurement of a graphical programming language and comparison of a graphical and a textual design languageGoff, Roger Allen (Virginia Tech, 1987-06-15)For many years the software engineering community has been attacking the software reliability problem on two fronts. First via design methodologies, languages and tools as a precheck on quality and second by measuring the quality of produced software as a postcheck. This research attempts to unify the approach to creating reliable software by providing the ability to measure the quality of a design prior to its implementation. Also presented is a comparison of a graphical and a textual design language in an effort to support cognitive science research findings that the human brain works more effectively in images than in text.
- Connecting the usability and software engineering life cycles through a communication-fostering software development framework and cross-pollinated computer science coursesPyla, Pardha S. (Virginia Tech, 2007-09-10)Interactive software systems have both functional and user interface components. User interface design and development requires specialized usability engineering (UE) knowledge, training, and experience in topics such as psychology, cognition, specialized design guidelines, and task analysis. The design and development of a functional core requires specialized software engineering (SE) knowledge, training, and experience in topics such as algorithms, data structures, software architectures, calling structures, and database management. Given that the user interface and the functional core are two closely coupled components of an interactive software system, with each constraining the design of the other, there is a need for the SE and UE life cycles to be connected to support communication among roles between the two development life cycles. Additionally, there is a corresponding need for appropriate computer science curricula to train the SE and UE roles about the connections between the two processes. In this dissertation, we connected the SE and UE life cycles by creating the Ripple project development environment which fosters communication between the SE and UE roles and by creating a graduate-level cross-pollinated SE-UE joint course offering, with student teams spanning the two classes, to educate students about the intricacies of interactive-software development. Using this joint course we simulated different conditions of interactive-software development (i.e. with different types of project constraints and role playing) and assigned different teams to these conditions. As part of semester-long class projects these teams developed prototype systems for a real client using their assigned development condition. Two of the total of eight teams in this study used the Ripple framework. As part of this experimental course offering, various instruments were employed throughout the semester to assess the effectiveness of a framework like Ripple and to investigate candidate factors that impact the quality of product and process of interactive-software systems. The study highlighted the importance of communication among the SE and UE roles and exemplified the need for the two roles to respect each other and to have the willingness to work with one another. Also, there appears to exist an inherent conflict of interest when the same people play both UE and SE roles as they seem to choose user interface features that are easy to implement and not necessarily easy to use by system's target users. Regarding pedagogy, students in this study indicated that this joint SE-UE course was more useful in learning about interactive-software development and that it provided a better learning experience than traditional SE-only or UE-only courses.
- Consistency and tool abstraction: issues in the taskmaster environmentJackels, Brenda J. (Virginia Tech, 1990-04-12)This thesis presents Taskmaster.2, a graphical environment for interactive task specification, execution and monitoring. Problem solving in the Taskmaster environment can be accomplished with top-down programming, bottom-up programming, or a mixture of the two. The use of top-down programming permits the user to start with a high level task and refine this task into successively lower level subtasks until, at the lowest level, each subtasks represents a software tool. Bottom-up programming is accomplished by beginning with the lowest level subtasks, software tools, and then combining these tools into successively higher level subtasks until, at the highest level, the high level subtask represents the original problem task. These programming methods provide the user with abstraction capabilities. Another abstraction capability within the Taskmaster.2 environment is the network tools. The user creates network tools by selecting several software tools that, combined, provide a certain functionality. These network tools can then be reused in solving other problem tasks. In fact, these tools appear no different to the user than the low level software tools: they are both single indivisible units. Providing complete abstraction capabilities, i.e., mixing programming styles (top-down and bottom-up) and network tools, maintains the consistency of the Taskmaster.2 environment. This makes the environment an easy one to learn, as well as remember.
- A controlled experiment to identify and test a representative primitive set of user object-oriented cursor actionsChase, Joseph D. (Virginia Tech, 1990-07-06)A method for decomposing the user cursor action component of human-computer interfaces into individual components based on the four categories: target size, target distance, target direction, and selection mode, was investigated. A primitive task set consisting of the Cartesian product of specific elements of the four categories listed above was proposed based on observation of user tasks and a cursor action benchmark task set was developed to measure a user's performance for each element of the set of primitive elements with a given cursor control device. An experiment was conducted to test the proposed primitive task set and associated benchmark task set as a predictor of performance for a set of representative graphics tasks. The predicted times and actual times were shown to have very strong correlations and the data were also shown to conform to Fitts' Law. A description of the experiment, the data collected, and the analysis of these data are included.
- Design and evaluation of a web-based training tool for the User Action Framework ExplorerBalasubramanian, Venkatramanan (Virginia Tech, 2002-05-10)explosion in the use of computing and interactive systems of all kinds. This growth has brought with it an awareness among developers of interactive systems about the importance of user centered design and usability. In the Virginia Tech Usability tools lab, efforts are underway to develop tools and processes that assist in usability evaluation. This has led to the development of the User Action Framework (UAF) (Andre et al., 1999), a framework that forms the basis of several usability inspection tools like the Explorer, UPI (Usability Problem Inspector), UPC (Usability Problem Classifier) and the usability problem database. The UAF explorer is the tool in the toolkit, which allows users to explore and learn the structure of the UAF. The framework, in its final stages of development, is based on an interaction cycle derived from Norman's action model (1986). For its acceptance, the user action framework, which is based on human factors and cognitive concepts, needed a training program to make it accessible and understandable to the usability practioners in industry and academia. This thesis addressed the following research activities: (1) Developing a web-based training tool for the User Action Framework explorer and (2) Evaluating a web- based training tool using various formative evaluation techniques and a final summative evaluation to measure effectiveness of the training, transfer of training, knowledge/skill acquisition and reaction to the training. The summative evaluation used a pretest-posttest between subjects experimental design to determine the effectiveness of the training tool with the use of lecture-based training as a control group. The data collection included objective measures of performance and subjective measures through questionnaires and rating scales. The summative evaluation found no significant differences between gain scores on lecture-based training and web-based training under controlled conditions. Opportunities for future research were identified and the training tool is expected to contribute to the efforts of the VT usability tools lab towards educating usability professionals and researchers alike on the usefulness of the User Action Framework and its associated tools. This work also seeks to proliferate the use of web based training methods as a valuable way to train remote learners on such developing frameworks and toolkits.
- Design Metrics Which Predict Source Code QualityHartson, H. Rex; Smith, Eric C.; Henry, Sallie M.; Selig, Calvin (Department of Computer Science, Virginia Polytechnic Institute & State University, 1987)Since the inception of software engineering, the major goal has been to control the development and maintenance of reliable software. To this end, many different design methodologies have been presented as a means to improve software quality through semantic clarity and syntactic accuracy during the specification and design phases of the software life cycle. On the other end of the life cycle, software quality metrics have been proposed to supply quantitative measures of the resultant software. This study is an attempt to unify the concepts of design methodologies and software quantity metrics by providing a means to determine the quality of a design before its implementation. By knowing (quantitatively) the quality of the design, a considerable amount of time and money can be saved by realizing design problems and being able to correct these problems at design time. All of this can be accomplished before any effort has been expended on the implementation of the software. This paper provides a means of allowing a software designer to predict the quality of the source code at design time. Actual equations for predicting source code quality from design metric values are given.
- Determining the Effectiveness of the Usability Problem Inspector: A Theory-Based Model and Tool for Finding Usability ProblemsAndre, Terence Scott (Virginia Tech, 2000-04-03)The need for cost-effective usability evaluation has led to the development of methodologies to support the usability practitioner in finding usability problems during formative evaluation. Even though various methods exist for performing usability evaluation, practitioners seldom have the information needed to decide which method is appropriate for their specific purpose. In addition, most methods do not have an integrated relationship with a theoretical foundation for applying the method in a reliable and efficient manner. Practitioners often have to apply their own judgment and techniques, leading to inconsistencies in how the method is applied in the field. Usability practitioners need validated information to determine if a given usability evaluation method is effective and why it should be used instead of some other method. Such a desire motivates the need for formal, empirical comparison studies to evaluate and compare usability evaluation methods. In reality, the current data for comparing usability evaluation methods suffers from a lack of consistent measures, standards, and criteria for identifying effective methods. The work described here addresses three important research activities. First, the User Action Framework was developed to help organize usability concepts and issues into a knowledge base that supports usability methods and tools. From the User Action Framework, a mapping was made to the Usability Problem Inspector; a tool to help practitioners conduct a highly focused inspection of an interface design. Second, the reliability of the User Action Framework was evaluated to determine if usability practitioners could use the framework in a consistent manner when classifying a set of usability problems. Third, a comprehensive comparison study was conducted to determine if the Usability Problem Inspector, based on the User Action Framework, could produce results just as effective as two other inspection methods (i.e., the heuristic evaluation and the cognitive walkthrough). The comparison study used a new comparison approach with standards, measures, and criteria to prove the effectiveness of methods. Results from the User Action Framework reliability study showed higher agreement scores at all classification levels than was found in previous work with a similar classification tool. In addition, agreement using the User Action Framework was stronger than the results obtained from the same experts using the heuristic evaluation. From the inspection method comparison study, results showed the Usability Problem Inspector to be more effective than the heuristic evaluation and consistent with effectiveness scores from the cognitive walkthrough.
- Developing and Evaluating the (LUCID/Star)*Usability Engineering Process ModelHelms, James W. (Virginia Tech, 2001-05-03)In recent years, interactive systems developers have increasingly included usability engineering and interaction design as an integral part of software development. With recognition of the importance of usability come attempts to structure this new aspect of system design, leading to a variety of processes and methodologies. Unfortunately, these processes have often lacked flexibility, completeness and breadth of coverage, customizability, and tool support. This thesis shows the development of a process model, that we call LUCID/Star*, which addresses and overcomes the characteristics lacking in existing methodologies and an evaluation of its application in a real-world development environment. To demonstrate the goal of this thesis, we have used a combination of empirical and analytical evidence. The (LUCID/Star)* process model for usability engineering grew out of the examination, adaptation, and extension of several existing usability and software methodologies. The methods that most greatly impacted the creation of (LUCID/Star)*were the LUCID Framework of interaction design, the Star Life Cycle of usability engineering, and the Waterfall and Spiral models of Software engineering. Unlike most of these, we have found that a sequence of cycles (each of which produces a product evolution) is a more effective analogy for the interaction development process. A sequence of cycles is more modular and makes it easier to focus on each cycle separately. Working with Optim Systems, Inc. in Falls Church, VA we instantiated the process model and introduced it as a process to develop a web-based device management system. (LUCID/Star)* performed remarkably in the Optim case, overcoming the tight constraints of budget and schedule cuts to produce an excellent prototype of the system.
- Developing Human-Computer Interface Models and Representation Techniques(Dialogue Management as an Integral Part of Software Engineering)Hartson, H. Rex; Hix, Deborah; Kraly, Thomas M. (Department of Computer Science, Virginia Polytechnic Institute & State University, 1987)The Dialogue Management Project at Virginia Tech is studying the poorly understood problem of human-computer dialogue development. This problem often leads to low usability in human-computer dialogues. The Dialogue Management Project approaches solutions to low usability in interfaces by addressing human-computer dialogue development as an integral and equal part of the total system development process. This project consists of two rather distinct, but dependent, parts. One is development of concepts for dialogue management, and the other is implementation of a dialogue management system (DMS) to evaluate these concepts. The goal of this paper is to describe our approach to the development of two of these conceptual aspects and how we oriented those toward the needs of practical implementation. The two conceptual aspects are (a) a structural, descriptive model of human-computer interaction, and (b) Techniques for representing both the behavioral (end-user's) view and the constructional (developer's) view of dialogue. The approach to their development was a technology transfer process that was part of a two-year university/industry research liaison between the Dialogue Management Project and IBM Federal Systems Division (FSD), now called Systems Integration Division. Part of this liaison was aimed at moving our research ideas and results into a real-world dialogue development environment. Following presentation of the technical problems and solutions, the paper concludes with a discussion of results of our liaison and by raising and addressing some questions of mutual interest that arose during our cooperative interaction.
- Development and Evaluation of a Model of Behavioral Representation TechniquesChase, Joseph D.; Schulman, Robert S.; Hartson, H. Rex; Hix, Deborah (Department of Computer Science, Virginia Polytechnic Institute & State University, 1993)A user-centered approach to interactive system development requires a way to represent the behavior of a user interacting with an interface. While a number of behavioral representation techniques exist, not all provide the capabilities necessary to support the interaction development process. Based on observations of existing representation techniques and comments from users of the User Action Notation (UAN), a user- and task-centered behavioral representation technique, we have developed a model of behavioral representation techniques. Our model is an epistemological framework for discussing, analyzing, extending, and comparing existing behavioral representation techniques, as well as being a springboard for developing and evaluating new techniques. We present the model and results of our evaluation demonstrating the model's reusability and utility within the context of behavioral representation techniques.
- The effects of a computer-based design aid in the selection of guidelines within the USI design processFox, Jeffrey A. (Virginia Tech, 1991-12-15)Designing a User-System Interface (USn is a complex task and has been approached in many ways. One approach has been to use USI design guidelines to help improve the quality and consistency of USIs. To use guidelines effectively, a general set of guidelines must be tailored to a specific application. One popular set of guidelines is the Smith and Mosier Guidelines for Designing User Interface Software (1986). This thesis investigated the effects of using a computer-based hypertext design aid (DRUID, Dynamic Rules for User Interface Design) for the selection of USI guidelines for both experienced and novice Guidelines users. Also, the relative usability of the software and hardcopy document was examined to improve the interface for the next iteration of DRUID. Both performance and variability in guideline selection strategies were studied within the context of the experimental tasks. Results indicate that subjects effectively used both the book and hypertext presentation media. However, subjects selected more relevant guidelines with the book. The media influenced the subjects' selection strategies, and the subjects read less when using DRUID. Subjectively, the software was preferred because it provided assistance in the selection process. The presentation of the guidelines could be improved for both media, and many of the factors which led subjects to select fewer relevant guidelines with DRUID could be overcome with improved USI design and implementation. Also, to overcome the limitations of presenting large texts on-line, "value added" features should be incorporated into on-line tools to help users better perform their tasks.
- Efficient Computation of Voronoi DiagramsHartson, H. Rex (Department of Computer Science, Virginia Polytechnic Institute & State University, 1988)It is generally agreed that some kind of separation is needed between the human-computer dialogue and the computational component of an interactive software system. This paper addresses two major issues:
- An empirical study of software reuse: the impact of the object-oriented paradigm and human factorsLewis, John A. (Virginia Tech, 1991-04-05)Little or no empirical validation exists for many of software engineering's basic assumptions. While some of these assumptions are intuitive, the need for scientific experimentation remains clear. Several assumptions are made about the factors affecting software reuse. In particular, the object-oriented paradigm and various human factors are hypothesized to affect the successful reuse of software components. This dissertation describes a controlled experiment designed to evaluate the impact of the object-oriented paradigm and human factors on software reuse. The human factors under investigation include managerial influence and cognitive abilities. This experiment concludes (a) the object-oriented paradigm makes significant contributions to productivity, (b) language differences are far more important when programmers reuse than when they do not, and (c) the object-oriented paradigm holds a particular affinity to the reuse process, (d) reuse results in higher productivity than no reuse independent of language paradigm, (e) the level of management encouragement does affect the reuse process, and (f) the cognitive ability of visualization does relate to effective reuse.
- An Exploration of End-User Critical Incident ClassificationCapra, Miranda Galadriel (Virginia Tech, 2001-10-18)Laboratory usability tests can be a rich source of usability information for software design, but are expensive to run and involve time-consuming data analysis. Expert review of software is cheaper, but highly dependent on the experience of the expert. Techniques are needed that maintain user involvement while reducing both the cost of user involvement and the time required to analyze data. The User Action Framework (UAF) is a classification scheme for usability problems that facilitates data analysis and reusability of information learned from one project to another, but is also reliant on expert interpretation of usability data, and classification can be difficult when user-supplied problem descriptions are incomplete. This study explored end-user classification of self-reported critical incidents (usability issues) using the UAF, a technique that was hoped to reduce expert interpretation of usability problems. It also explored end-user critical incident reporting from a usability session recording, rather than reporting incidents as soon as they occur, a technique that could be used in future studies to compare effectiveness of usability methods. Results indicate that users are not good at diagnosing their own critical incidents due to the level of detail required for proper classification, although observations suggest that users were able to provide usability information that would not have been captured by an expert observer. The recording technique was successful, and is recommended for future studies to further explore differences in the kind of information that can be gathered from end-users and from experts during usability studies.
- Formative Evaluation: Ensuring Usability in User InterfacesHix, Deborah; Hartson, H. Rex (Department of Computer Science, Virginia Polytechnic Institute & State University, 1992)Ensuring usability has become a key goal of interactive system development, as developers have begun to realize that it matters little how effectively an interactive system can compute, if human users cannot communicate effectively with the system. In this paper we discuss what we have found to be two main types of formative user interface evaluation: analytic and empirical. Both these types occur as part of the development process. We do not attempt to survey all approaches to either of these types of formative evaluation, but rather to offer a sampling of some approaches that have been found (by us and by others) to be useful in ensuring usability. We give only an overview of analytic methods, and then focus on empirical methods. We conclude with some observations on future trends in user interface evaluation.