Browsing by Author "Hix, Deborah S."

Now showing 1 - 20 of 32
  • Thumbnail Image
    Application and Evaluation of Unified Medical Language System Resources to Facilitate Patient Information Acquisition through Enhanced Vocabulary Coverage
    Mills, Eric M. III (Virginia Tech, 1998-04-13)
    Two broad themes of this research are, 1) to develop a generalized framework for studying the process of patient information acquisition and 2) to develop and evaluate automated techniques for identifying domain-specific vocabulary terms contained in, or missing from, a standardized controlled medical vocabulary with emphasis on those terms necessary for representing the canine physical examination. A generalized framework for studying the process of patient information acquisition is addressed by the Patient Information Acquisition Model (PIAM). PIAM illustrates the decision-to-perception chain which links a clinician's decision to collect information, either personally or through another, with the perception of the resulting information. PIAM serves as a framework for a systematic approach to identifying causes of missing or inaccurate information. The vocabulary studies in this research were conducted using free-text with two objectives in mind, 1) develop and evaluate automated techniques for identifying canine physical examination terms contained in the Systematized Nomenclature of Medicine and Veterinary Medicine (SNOMED), version 3.3 and 2) develop and evaluate automated techniques for identifying canine physical examination terms not documented in the 1997 release of the Unified Medical Language System (UMLS). Two lexical matching techniques for identifying SNOMED concepts contained in free-text were evaluated, 1) lexical matching using SNOMED version 3.3 terms alone and 2) Metathesaurus-enhanced lexical matching. Metathesaurus-enhanced lexical matching utilized non-SNOMED terms from the source vocabularies of the Metathesaurus of the Unified Medical Language System to identify SNOMED concepts in free-text using links among synonymous terms contained in the Metathesaurus. Explicit synonym disagreement between the Metathesaurus and its source vocabularies was identified during the Metathesaurus-enhanced lexical matching studies. Explicit synonym disagreement occurs, 1) when terms within a single concept group in a source vocabulary are mapped to multiple Metathesaurus concepts, and 2) when terms from multiple concept groups in a source vocabulary are mapped to a single Metathesaurus concept. Five causes of explicit synonym disagreement between a source vocabulary and the Metathesaurus were identified in this research, 1) errors within a source vocabulary, 2) errors within the Metathesaurus, 3) errors in mapping between the Metathesaurus and a source vocabulary, 4) systematic differences in vocabulary management between the Metathesaurus and a source vocabulary, and 5) differences regarding synonymy among domain experts, based on perspective or context. Three approaches to reconciling differences among domain experts are proposed. First, document which terms are involved. Second, provide a mechanism for selecting either vocabulary-based or Metathesaurus-based synonymy. Third, assign a "basis of synonymy" attribute to each set of synonymous terms in order to identify the perspective or context of synonymy explicitly. The second objective, identifying canine physical examination terms not documented in the 1997 release of the UMLS was accomplished using lexical matching, domain-specific free-text, the Metathesaurus and the SPECIALIST Lexicon. Terms contained in the Metathesaurus and SPECIALIST Lexicon were removed from free-text and the remaining character strings were presented to domain experts along with the original sections of text for manual review.
  • Thumbnail Image
    Application of Augmented Reality to Dimensional and Geometric Inspection
    Chung, Kyung Ho (Virginia Tech, 2002-02-11)
    Ensuring inspection performance is not a trivial design problem, because inspection is a complex and difficult task that tends to be error-prone, whether performed by human or by automated machines. Due to economical or technological reasons, human inspectors are responsible for inspection functions in many cases. Humans, however, are rarely perfect. A system of manual inspection was found to be approximately 80-90% effective, thus allowing non-confirming parts to be processed (Harris & Chaney, 1969; Drury, 1975). As the attributes of interest or the variety of products increases, the complexity of an inspection task increases. The inspection system becomes less effective because of the sensory and cognitive limitations of human inspectors. Any means that can support or aid the human inspectors is necessary to compensate for inspection difficulty. Augmented reality offers a new approach in designing an inspection system as a means to augment the cognitive capability of inspectors. To realize the potential benefits of AR, however the design of AR-aided inspection requires a through understanding of the inspection process as well as AR technology. The cognitive demands of inspection and the capabilities of AR to aid inspectors need to be evaluated to decide when and how to use AR for a dimensional inspection. The objectives of this study are to improve the performance of a dimensional inspection task by using AR and to develop guidelines in designing an AR-aided inspection system. The performance of four inspection methods (i.e., manual, 2D-aided, 3D-aided, and AR-aided inspections) was compared in terms of inspection time and measurement accuracy. The results suggest that AR might be an effective tool that reduces inspection time. However, the measuring accuracy was basically the same across all inspection methods. The questionnaire results showed that the AR and 3D-aided inspection conditions are preferred over the manual and 2D-aided inspection. Based on the results, four design guidelines were formed in using AR technology for a dimensional inspection.
  • Thumbnail Image
    A Common Software Development Framework For Coordinating Usability Engineering and Software Engineering Activities
    Pawar, Sourabh A. (Virginia Tech, 2004-05-10)
    Currently, the Usability Engineering (UE) and Software Engineering (SE) processes are practiced as being independent of each other. However, several dependencies and constraints exist between the interface specifications and the functional core, which make coordination between the UE and the SE teams crucial. Failure of coordination between the UE and SE teams leads to software that often lacks necessary functionality and impedes user performance. At the same time, the UE and SE processes cannot be integrated because of the differences in focus, techniques, and terminology. We therefore propose a development framework that incorporates SE and UE efforts to guide current software development. The framework characterizes the information exchange that must exist between the UE and SE teams during software development to form the basis of the coordinated development framework. The UE Scenario-Based Design (SBD) process provides the basis for identifying UE activities. Similarly, the Requirements Generation Model (RGM), and Structured Analysis and Design are used to identify SE activities. We identify UE and SE activities that can influence each other, and identify the high-level exchange of information that must exist among these activities. We further examine these interactions to gain a more in-depth understanding as to the precise exchange of information that must exist among them. The identification of interacting activities forms the basis of a coordinated development framework that incorporates and synchronizes the UE and SE processes. An examination of the Incremental and Spiral models as they relate to the SBD is provided, and outlines how our integration framework can be composed. Using the results of and insights gained from our research, we also suggest additional avenues for future work.
  • Thumbnail Image
    Comparison of an object-oriented programming language to a procedural programming language for effectiveness in program maintenance
    Humphrey, 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.
  • Thumbnail Image
    Computer-based user interface evaluation by analysis of repeating usage patterns in transcripts of user sessions
    Siochi, Antonio C. (Virginia Polytechnic Institute and State University, 1989)
    It is generally acknowledged that the production of quality user interfaces requires a thorough understanding of the user and that this involves evaluating the system by observing the user using the system, or by performing human factors experiments. Such methods traditionally involve the use of videotape, protocol analysis, critical incident analysis, etc. These methods require time consuming analyses and may be invasive. In addition, the data obtained through such methods represent a relatively small portion of the use of a system. An alternative approach is to record all user input and system output onto a file, i.e., log the user session. Such transcripts can be collected automatically and over a long period of time. Unfortunately, this produces voluminous amounts of data. There is therefore a need for tools and techniques that allow an evaluator to extract from such data potential performance and usability problems. It is hypothesized that repetition of user actions is an important indicator of potential user interface problems. This research reports on the use of the repetition indicator as a means of studying user session transcripts in the evaluation of user interfaces. The dissertation discusses the algorithms involved, the interactive tool constructed, the results of an extensive application of the technique in the evaluation of a large image-processing system, and extensions and refinements to the technique. Evidence suggests that the hypothesis is justified and that such a technique is convincingly useful.
  • Thumbnail Image
    Connecting the usability and software engineering life cycles through a communication-fostering software development framework and cross-pollinated computer science courses
    Pyla, 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.
  • Thumbnail Image
    A controlled experiment to identify and test a representative primitive set of user object-oriented cursor actions
    Chase, 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.
  • Thumbnail Image
    Design and Evaluation of 3D Multiple Object Selection Techniques
    Lucas, John Finley (Virginia Tech, 2005-01-17)
    Few researchers have addressed the important issue of three-dimensional multiple object selection (MOS) in immersive Virtual Environments (VEs). We have developed a taxonomy of the MOS task as a framework for exploring the design space of these techniques. In this thesis, we describe four techniques for selecting multiple objects in immersive VEs. Of the four techniques, two are serial (where only one object can be indicated per operation), and two are parallel (where one or more objects may be indicated per operation). Within each of the two categories we also investigated two metaphors of interaction: a 3D spatial metaphor and the pen and tablet metaphor. Two usability studies were used to evaluate the four techniques, iterate their designs, and gain a deeper understanding of the design space of MOS techniques. The results from our studies show that parallel MOS techniques can select objects faster than serial techniques as the number of target objects increase. We also show that effective techniques for MOS in immersive VEs can be created using both pen and tablet and 3D metaphors.
  • Thumbnail Image
    Developing and Evaluating the (LUCID/Star)*Usability Engineering Process Model
    Helms, 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.
  • Thumbnail Image
    The effects of map type and availability on performance with hypermedia
    Harris, Jean Elisabeth (Virginia Tech, 1992-05-05)
    Much of the hypermedia literature instructs developers to "Use a map to prevent users from becoming lost." However, there is very little empirical evidence that maps are effective. In addition, no one has examined how to design the maps to make them most helpful to the users. This research evaluates both issues for information retrieval tasks with a fairly small hypermedia application (about 175 nodes). This study evaluates the overall effectiveness of maps by comparing the subjects' performance using hypermedia without a map to performance with one of four maps. Then, it reveals the relative effectiveness of the different types of maps by comparing the results of the subjects' performance with four variations of a map. In addition, this research evaluates (1) the effects of the experimental conditions on the subjects' mental models of the application and (2) the effects of the subjects' spatial abilities on their performance with hypermedia. The results reveal that there is generally no difference between the subjects' performance with a map and performance without a map. In addition, users who had to navigate using the links within the application rather than selecting nodes from the map (using a "passive" map) viewed more extra nodes, but spent less time on each node and completed the tasks in less time than those who could select nodes directly from the map (using an "active" map). However, many of the subjects using the passive map would have preferred to use an active map. Also, subjects who always had a map available to them (using a "present" map) performed as well as subjects who had to call up a map to use it (a "called" map). In addition, there is no difference in the accuracy of the subjects' mental models. All the subjects understood the application fairly well. A few of the spatial abilities test results are correlated with performance, and all of significant correlations indicate that higher spatial abilities leads to improved performance with hypermedia. It is believed that the lack of differences among the conditions is due to a number of factors, including the simplicity of the application the subjects used and the tasks they performed.
  • Thumbnail Image
    Effects of Visual Displays on 3D Iteraction in Virtual Environments
    Manek, Dhruv B. (Virginia Tech, 2004-06-08)
    In this thesis, we explore some of the effects of virtual environment displays, specifically the head-mounted display (HMD) and the Cave Automatic Virtual Environment (CAVE), on 3D interaction tasks involving selection and manipulation. The motivation for this thesis comes from the lack of previous work that has studied the effects of differences between the HMD and the CAVE on 3D interaction tasks. We conducted three user studies to determine how the differences between these two displays affect selection and manipulation in a 3D environment. Our first study demonstrates that 3D selection and manipulation tasks can be affected by the display type. Our second user study shows that task performance can suffer when a selection and manipulation technique is migrated to a display for which it is not intended. The third user study we conducted suggests that we can modify a selection and manipulation technique and improve its usability in the display to which it is migrated. We conclude with a set of guidelines to ease the migration of selection and manipulation techniques from the HMD to the CAVE while trying to maintain usability.
  • Thumbnail Image
    An Empirical Study of the Effects of Context-Switch, Object Distance, and Focus Depth on Human Performance in Augmented Reality
    Gupta, Divya (Virginia Tech, 2004-06-09)
    Augmented reality provides its user with additional information not available through the natural real-world environment. This additional information displayed to the user potentially poses a risk of perceptual and cognitive load and vision-based difficulties. The presence of real-world objects together with virtual augmenting information requires the user to repeatedly switch eye focus between the two in order to extract information from both environments. Switching eye focus may result in additional time on user tasks and lower task accuracy. Thus, one of the goals of this research was to understand the impact of switching eye focus between real-world and virtual information on user task performance. Secondly, focus depth, which is an important parameter and a depth cue, may affect the user's view of the augmented world. If focus depth is not adjusted properly, it may result in vision-based difficulties and reduce speed, accuracy, and comfort while using an augmented reality display. Thus, the second goal of this thesis was to study the effect of focus depth on task performance in augmented reality systems. In augmented reality environments, real-world and virtual information are found at different distances from the user. To focus at different depths, the user's eye needs to accommodate and converge, which may strain the eye and degrade performance on tasks. However, no research in augmented reality has explored this issue. Hence, the third goal of this thesis was to determine if distance of virtual information from the user impacts task performance. To accomplish these goals, a 3x3x3 within subjects design was used. The experimental task for the study required the user to repeatedly switch eye focus between the virtual text and real-world text. A monocular see-through head- mounted display was used for this research. Results of this study revealed that switching between real-world and virtual information in augmented reality is extremely difficult when information is displayed at optical infinity. Virtual information displayed at optical infinity may be unsuitable for tasks of the nature used in this research. There was no impact of focus depth on user task performance and hence it is preliminarily recommended that manufacturers of head-mounted displays may only need to make fixed focus depth displays; this clearly merits additional intensive research. Further, user task performance was better when focus depth, virtual information, and real-world information were all at the same distance from the user as compared to conditions when they were mismatched. Based on this result we recommend presenting virtual information at the same distance as real-world information of interest.
  • Thumbnail Image
    A foundation for translating user interaction designs into OSF/Motif-based software
    Hinson, Kenneth Paul (Virginia Tech, 1994-04-05)
    The user interface development process occurs in a behavioral domain and in a constructional domain. The development process in the behavioral domain focuses on the "look and feel" of the user interface and its behavior in response to user actions. The development process in the constructional domain focuses on developing software to implement the user interface. Although one may attempt to design a user interface from a constructional view, it is important to concentrate design efforts in the behavioral domain to improve software usability. User Action Notation (UAN) is a useful technique for representing user interaction designs in the behavioral domain. Primary abstractions in UAN-expressed designs are user tasks. Information about interface objects is encapsulated in user task descriptions and scenarios. Primary abstractions in a GUI such as Motif™ are interface objects. Motif implements objects' behavior and appearance using system functions that are encapsulated within pre-defined object classes. Therefore, user interaction developers and software developers must communicate well to translate UAN-expressed interaction designs into Motif-based software designs. Translation is not trivial since it is a translation between two significantly different domains. This thesis contributes to understanding of the user interface development process by developing a foundation to assist translation of user interaction designs into Motif-based software designs. This thesis develops the foundation as follows: 1. Adapt UAN for use with Motif. 2. Summarize Motif concepts about objects and object relationships. 3. Develop new approaches for discussing objects and object relationships. 4. Develop a partial translation guide containing VAN descriptions of selected Motif abstractions.
  • Thumbnail Image
    Graphical Encoding for Information Visualization: Using Icon Color, Shape, and Size to Convey Nominal and Quantitative Data
    Nowell, Lucille Terry (Virginia Tech, 1997-11-07)
    In producing a user interface design to visualize search results for a digital library called Envision [Nowell, France, Hix, Heath, & Fox, 1996] [Fox, Hix, Nowell, et al., 1993] [Nowell & Hix, 1993], we found that choosing graphical devices and document attributes to be encoded with each graphical device is a surprisingly difficult task. By graphical devices we mean those visual display elements (e.g., color, shape, size, position, etc.) used to convey encoded, semantic information. Research in the areas of psychophysics of visual search and identification tasks, graphical perception, and graphical language development provides scientific guidance for design and evaluation of graphical encodings which might otherwise be reduced to opinion and personal taste. However, literature offers inconclusive and often conflicting viewpoints, suggesting a need for further research. The goal of this research was to determine empirically the effectiveness of graphical devices for encoding nominal and quantitative information in complex visualization displays. Using the Envision Graphic View, we conducted a within-subjects empirical investigation of the effectiveness of three graphical devices - icon color, icon shape, and icon size - in communicating nominal (document type) and quantitative (document relevance) data. Our study provides empirical evidence regarding the relative effectiveness of icon color, shape, and size for conveying both nominal and quantitative data. While our studies consistently rank color as most effective, the rankings differ for shape and size. For nominal data, icon shape ranks ahead of icon size by all measures except time for task completion, which places shape behind size. For quantitative data, we found, by all measures, that encodings with icon shape are more effective than with icon size. We conclude that the nature of tasks performed and the relative importance of measures of effectiveness are more significant than the type of data represented for designers choosing among rankings.
  • Thumbnail Image
    IDEAL: a tool to enable usability specification and evaluation
    Ashlund, Stacey Lynn (Virginia Tech, 1992-02-03)
    While interactive design tools, rapid prototyping tools, and user interface management systems (UIMSs) are advancing as cost-effective ways of producing interfaces, attention to usability is rarely incorporated into such tools. The advancement of producing interfaces more rapidly without addressing their quality is of limited worth. This thesis reports on the design and prototype implementation of a software tool, IDEAL (Interface Design Environment and Analysis Lattice), that encourages and enables user-centered design as an integral part of the user interface development process. IDEAL integrates usability engineering techniques and behavioral task representations with a graphical hierarchy of associated user tasks to support formative evaluation of an evolving user interface. IDEAL supplements the functionality of current interface construction tools by focusing on usability through user-centered design. IDEAL was designed and developed using the techniques it supports: formative evaluation and iterative refinement. Representative users participated in two phases of qualitative formative evaluations from which critical incidents, verbal protocol, and qualitative data were collected. Feedback from each phase contributed to the revised design of IDEAL. This empirical evaluation showed IDEAL to be useful as an automated tool for managing the interrelated tasks of interface development, including design, usability specification definition, and formative evaluation, that are currently performed manually (e.g., using pencil and paper.)
  • Thumbnail Image
    Implementing an intelligent information retrieval system: the CODER system, version 1.0
    Weaver, Marybeth Therese (Virginia Tech, 1988-02-05)
    For individuals requiring interactive access to online text, information storage and retrieval systems provide a way to retrieve desired documents and/or text passages. The CODER (COmposite Document Expert/effective/extended Retrieval) system is a testbed for determining how useful various artificial intelligence techniques are for increasing the effectiveness of information storage and retrieval systems. The system, designed previously, has three components: an analysis subsystem for analyzing and storing document contents, a central spine for manipulation and storage of world and domain knowledge, and a retrieval subsystem for matching user queries to relevant documents. This thesis discusses the implementation of the retrieval subsystem and portions of the spine and analysis subsystem. It illustrates that logic programming, specifically with the Prolog language, is suitable for development of an intelligent information retrieval system. Furthermore, it shows that system modularity provides a flexible research testbed, allowing many individuals to work on different parts of the system which may later be quickly integrated. The retrieval subsystem has been implemented in a modular fashion so that new approaches to information retrieval can be easily compared to more traditional ones. A powerful knowledge representation language, a comprehensive lexicon and individually tailored experts using standardized blackboard modules for communication and control allowed rapid prototyping, incremental development and ready adaptability to change. The system executes on a DEC VAX ll/785 running ULTRIX™, a variant of 4.2 BSD UNIX. It has been implemented as a set of MU-Prolog and C modules communicating through TCP/IP sockets.
  • Thumbnail Image
    Integral Perception in Augmented Reality
    McGee, Michael K. (Virginia Tech, 1999-09-24)
    Augmented reality, the superimposing of graphics or text onto an actual visual scene, is intended to enhance a user's understanding of the real world. This research examines the perceptual, cognitive, and human factors implications of combining integrally designed computer-generated imagery with real world scenes. Three experiments were conducted to test the theoretical and practical consequences of integral perception in augmented reality. The first experiment was a psychophysical study that had participants subjectively assess the integrality of 32 scenes comprising four different augmented reality object environments (computer, brain, text, and liquid dynamic model), projected at two transparency levels (opaque, and semi-transparent), and presented with four different graphic textures (color, grayscale, white, and wireframe). The second experiment expanded the psychophysical integrality assessment of augmented scenes to 32 different images composed of four new environments (housing development, computer lab, planetary photo, and trees in countryside), with multiple computer-generated graphics (two, four, six, and eight), at two levels of integrality as defined by experiment one (high, low). The third experiment was an applied study that had two phases: 1) learning tasks using three augmented environments; and, 2) assembly tasks using eight augmented video instructions. The computer-generated graphics for each phase of experiment three were presented at two levels of integrality (high, low) as defined by experiment one. The primary results of the three experiments show that augmented reality scenes with computer-generated imagery presented transparently and in color were perceived most integrally; increasing the number of graphics from two to eight decreased integral perception; and, high integral graphics aided performance in learning and real assembly tasks. From the statistical results and experimenter observation of the three experiments, guidelines for designing integrally perceived graphics in augmented environments were compiled based on principles of human factors, perception, and graphic design. The key themes of the design guidelines were: 1) maintaining true shape information in the computer-generated graphics 2) using highly realistic graphics for naturalistic augmented settings; 3) considering the hardware limitations of the augmented system, particularly the display; and, 4) designing appropriately for the task (simple, complex, hands-on, cognitive, dynamic, static, etc.).
  • Thumbnail Image
    Problem-based learning: a case study in integrating teachers, students, methods, and hypermedia data bases
    Myers, Robert J. (Virginia Tech, 1993)
    This study describes two efforts: (1) the development of a learning environment that includes a hypermedia data base about Mesoamerica, and (2) an observational study of middle school students using the system within a framework of problem-based learning for mastering content and thinking skills. The goal was to create a learning environment influenced by metacognitive strategies, hypermedia interface design, and problem-solving scenarios preceded by discrepant events. Participants consisted of 25 seventh-grade social studies students. They were divided into four groups, each having access to a microcomputer with the hypermedia data base. They also had additional resources such as books and magazines dealing with Mesoamerican civilizations. Data collection included direct observations from four facilitator/evaluators, audiotape, videotape, student products, software routines, and questionnaires. Findings suggest: · the hypermedia data base navigation was usable and easy to learn for these students · a discrepant event inquiry model was among the factors contributing to sustained student activity · embedded problem-solving strategies facilitated higher-order thinking only when coupled with teacher support. The key in the environment appeared to be teacher-student interactions which allowed the teacher to dynamically assess students' abilities, then provide necessary support for independent action. The computer's role was that of a tool which mediated between the teacher and students.
  • Thumbnail Image
    Product usability and process improvement based on usability problem classification
    Keenan, Susan Lynn (Virginia Tech, 1996-08-05)
    Although research and practice have shown that the success of a usability engineering program depends on the identification and correction of usability problems, these problems remain an underutilized source of information. Insufficient guidance regarding the capture of usability problem data results in the loss of information during the problem reporting phase as problem reports are often vague, imprecise, and incomplete. In addition, the absence of a framework for understanding, comparing, categorizing, and analyzing those problems, and their relationship to development context, not only constrains product improvement, but hampers efforts to improve the user interface development process. A new taxonomic model (the Usability Problem Taxonomy) is presented which contributes to both product and process improvement. The Usability Problem Taxonomy (UPT) is used to classify and organize usability problems detected on interactive software development projects. Individual UPT categories are associated with two aspects of development context: developer roles and skills, and development activities, methods, and techniques. Two studies were conducted during the course of this research. The first study showed that the UPT can be used to classify usability problems reliably. Findings indicated that level of agreement among classifiers (beyond chance agreement) was statistically significant. Findings in the second study led to the identification of roles and activities that address individual UPT categories as well as those that do not. Procedures for using the UPT in both product and process improvement are outlined. Examples are presented that illustrate how the UPT can be used to generate higher quality problem descriptions and to group those problem descriptions prior to prioritization and correction. In addition, steps that guide developers in diagnosing weaknesses in the current user interface development process are enumerated. Possible improvement strategies are presented that focus on the selection of specific development activities and team members appropriate for a given project.
  • Thumbnail Image
    QUANTUM: Quick User Action Notation Tool for User interface Management
    Castillo, Arcel Macaraeg (Virginia Tech, 1993-09-09)
    The UAN (User Action Notation) is a task- and user-oriented behavioral representation technique for specifying interface designs that is used to communicate interface designs, support task analysis, and facilitate usability evaluation. A UAN interface description is made up of several linked sheets of paper containing task descriptions, notes, and sketches. UAN users have reported that writing and reading these designs is difficult. It is our hypothesis that these problems in usability are not inherent in the notation itself, but rather that effective use of UAN is hampered by the manual manipulation necessitated by pencil and paper. QUANTUM (Quick User Action Notation Tool for User interface Management), a software tool to facilitate writing and reading of UAN for user interface design, was developed through an iterative process based on formative evaluation by expert UAN users. QUANTUM supports development of a graph-based representation of a task abstraction hierarchy for a user interface design, with each node representing a user task. Task description windows for each task node allow entry of UAN in a tabular, spreadsheet-like format. Task libraries enable designers to build archives of task descriptions, enabling their reuse in other interface design projects. Note addenda containing explanatory text, screen sketches, design questions, and/or audio/video can be placed anywhere within a design description. These features, not afforded by pencil and paper, give QUANTUM a functional advantage over such media. Expert evaluators used in qualitative formative evaluation of the QUANTUM prototype indicated a strong preference over pencil and paper for using QUANTUM to produce UAN task descriptions. As a result of this work, we claim that QUANTUM improves usability of the UAN.