Browsing by Author "Casali, Sherry P."

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    A Comparison of Three Cursor Control Devices on a Cursor Control Benchmark Task
    Chase, Joseph D.; Casali, Sherry P. (Department of Computer Science, Virginia Polytechnic Institute & State University, 1991)
    A number of past studies have compared performance of cursor control devices. Conclusions regarding the "best" device for a particular application are difficult to draw because the tasks used in previous comparisons have differed from one another and have not included all of the factors affecting performance with the devices. The present study used a target acquisition task whose components were derived from analyzing the cursor control device movements of users while performing actual tasks. The components of the task were target size, target distance, direction, and mode (i.e., point-and-click vs. drag). Three cursor control devices, cursor keys, mouse, and trackball, were each used by 12 subjects to perform the task. Results indicate the mouse and trackball perform similarly in most cases. The cursor keys always performed more poorly than the other devices. Hence, the mouse and trackball are preferable to the cursor keys based on objective measure of user performance. In conditions where cursor keys are necessary, careful attention should be paid to aspects of the interface listed above in order to attain the highest level of performance possible.
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    The effect of lessons-learned sharing processes for organizational learning on decision-making performance
    Kotnour, Timothy G. (Virginia Tech, 1995-07-05)
    The aim of this research was to operationalize and validate a lessons-learned sharing process for supporting organizational learning. I validated the process by measuring and evaluating the effects of the process on decision-making (i.e., management) performance. The research results provide tangible evidence about the effects of a lessons-learned sharing process to support organizational learning. A lessons-learned sharing process does improve decision-making performance as measured by decision quality. A three phase research process was used. The first phase consisted of a task analysis at an industrial site. The results of the task analysis served as the basis for an experiment. The second phase was a laboratory experiment. Sixty students participated in the experiment. The experiment involved twenty groups of three subjects. One subject completed a task and constructed a lesson learned based on feedback from his or her decisions. The next two subjects used different parts of the lesson learned to solve the same problem. The factors studied in the experiment were the content (no lesson learned, a lesson learned containing only recommendations, and a lesson learned containing the original set of decisions, results, and recommendations) and structure (informal or formal). Both quantitative and qualitative data were collected. The quantitative results of the experiment show: 1) having a lesson learned was better than not having a lesson learned; 2) a formal or structured lesson learned had a greater effect on decision quality than an informal or unstructured lesson learned; and 3) the formal or structured lesson learned produced an higher-quality lesson learned. The qualitative results show: 1) subjects want explanations for the recommendations in the lesson learned; 2) the accuracy and consistency of a lesson-learned content needs to be ensured because people may use the lesson learned as an answer without further work; and 3) prompts for eliciting the information in a lesson learned need to be developed. Subjects used the lesson learned in six different ways when solving the problem. The problem consisted of making a set of decisions for a manufacturing shift. The third phase of the research involved a follow-up at the original industrial site. The purpose of this second field study was to gain an insight into how the experimental findings related to a field setting. Implications are discussed for the theory of organizational learning and users of lessons-learned sharing processes in organizations.
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    The effects of recognition accuracy and vocabulary size of a speech recognition system on task performance and user acceptance
    Casali, Sherry P. (Virginia Tech, 1988-05-13)
    Automatic speech recognition systems have at last advanced to the state that they are now a feasible alternative for human-machine communication in selected applications. As such, research efforts are now beginning to focus on characteristics of the human, the recognition device, and the interface which optimize the system performance, rather than the previous trend of determining factors affecting recognizer performance alone. This study investigated two characteristics of the recognition device, the accuracy level at which it recognizes speech, and the vocabulary size of the recognizer as a percent of task vocabulary size to determine their effects on system performance. In addition, the study considered one characteristic of the user, age. Briefly, subjects performed a data entry task under each of the treatment conditions. Task completion time and the number of errors remaining at the end of each session were recorded. After each session, subjects rated the recognition device used as to its acceptability for the task. The accuracy level at which the recognizer was performing significantly influenced the task completion time as well as the user's acceptability ratings, but had only a small effect on the number of errors left uncorrected. The available vocabulary size also significantly affected the task completion time; however, its effect on the final error rate and on the acceptability ratings was negligible. The age of the subject was also found to influence both objective and subjective measures. Older subjects in general required longer times to complete the tasks; however, they consistently rated the speech input systems more favorably than the younger subjects.
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    An empirically developed system for the selection of input devices for users with physical disabilities
    Casali, Sherry P. (Virginia Tech, 1991-07-03)
    The selection of an input method to allow computer access by persons with disabilities is currently done by trained personnel; however, the selection process is unsystematic, subjective, and plagued with problems. This research has attempted to develop a systematic method, based on objective measures of an individual's hand skills, for selecting a computer input device. Each input device being considered was evaluated to determine the probable basic elements of motor performance which contribute to successful operation of the device. Subjects in the study consisted of individuals with various degrees of functional limitations of their upper extremities. Subjects first underwent a specially-developed motor assessment test designed to measure each of the motor functions identified as contributing to the operation and control of the input devices. Each subject then performed a series of computer-based tasks with each input device. The task itself was a modified target acquisition task with the independent variables of target size, target distance, mode (button up vs. button down (i.e. point vs. drag moves)), and trial block. The participants’ scores on both the assessment test and each device were analyzed in order to form the relationships between the two sets of scores. Results show that : 1) By analyzing a prospective input device with respect to the physical actions necessary for operation, and comparing an individual's scores on the subtests of the motor function assessment which correspond to those necessary actions, the test administrator can immediately identify actions which may be necessary, but which are extremely difficult or unavailable. If no discrepancies between the available and required actions exist, then one can conclude that the device is operable by the client. 2) Where discrepancies do exist between what a client can do and what a device requires, the assessment test targets the specific actions which create the difficulty. As a result, one can then recommend modifications to the device which may lead to the client being able to operate the device. 3) Finally, the effects of task parameters such as target size, target distance, and the effects of practice were determined for persons with different levels of hand skill (as measured by the assessment test). In general, persons with limited hand skill require only slightly longer to become proficient with a device than persons without disabilities. The rank ordering of the five devices tested with respect to input rates achievable was the same for persons with and without disabilities. Persons with disabilities were, as expected, slower overall with each device. In general, the trackball, mouse, and tablet resulted in better performance than the keys or joystick, for persons with and without disabilities. Persons with limited hand skill were more affected by the task parameter of target size on all devices, particularly for button down moves. Regardless of disability level, persons generally preferred the trackball over the remaining devices, and rated the joystick as being less preferable than the other devices. This research not only developed guidelines concerning the five devices selected for use in this study, but also serves to demonstrate the feasibility and utility of an accommodative aid selection system based on a functional assessment of the client's residual abilities. In addition, this research provides important information to hardware and software manufacturers regarding accessibility issues.
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    A study to develop and evaluate a taxonomic model of behavioral techniques for representing user interface designs
    Chase, Joseph D. (Virginia Tech, 1994-04-06)
    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. The original goal of this research was to modify and extend the User Action Notation (UAN), a user- and task-centered behavioral representation technique. In order to facilitate and evaluate the improvement in the UAN, we developed and evaluated a taxonomic model of behavioral representation techniques. The development and evaluation of our model followed the epistemological cycle of observation, theorization, and evaluation. The model provides a framework for discussing, analyzing, extending, and comparing existing behavioral representation techniques, as well as being a springboard for developing and evaluating new techniques.
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    Virtual reality-based investigation of four cognitive theories for navigation
    Bussi, Carolyn Ann (Virginia Tech, 1995-11-14)
    Intelligent Transportation Systems (ITS) refer to an integrated group of technologies which can improve safety, reduce congestion, enhance mobility, minimize environmental impact, save energy, and promote economic productivity in our transportation system. A driver-centered design philosophy will promote these benefits. These advanced technologies will thereby enhance the safety and efficiency of automobile transportation. This research dealt with In-vehicle Routing and Navigational Systems (IRANS). IRANS provide drivers with information about how to get from one place to another, information on traffic conditions, and recurrent and non-recurrent urban traffic congestion. The problem studied in this research was whether performance on navigation tasks can be predicted by cognitive theories (Multiple Resource Theory, Stimulus-Central Processing-Response Compatibility Theory, Recoding Mechanism Theory, and Dual Coding Theory). A secondary problem was the determination of the relationship between navigation and spatial ability. Spatial ability has been linked to map reading performance. Issues addressed included display modalities and information processing codes. The effect of different display modalities on driver performance and workload was the first issue. The different display methods investigated were visual systems (current dashboard mounted display types) and auditory systems (computer generated voice communication systems). The second issue was the effect of different information processing codes on driver performance and workload. The information processing code determines the method used to present information to the driver using the display; in this research both verbal and spatial codes were considered. Verbally coded information consists of a series of sequential directions (for example, "go to the next street and turn right"), while spatially coded information is presented using a map display for visual systems. The results indicate that the best cognitive theory for predicting navigational behavior is the dual coding theory. Subjects not only performed better, but also preferred navigational aids where the navigational information was presented in more than one way. This indicates that designers and engineers should develop navigational aid displays to incorporate redundant navigational information. Some differences for navigational performance were shown for high versus low spatial ability subjects, but the subjective measures of workload and preference did not show any differences.