Number of co-authors:3
Number of publications with 3 favourite co-authors:Joseph D. Chase:3Suvit Nopachai:1H. Rex Hartson:1
Sherry Perdue Casali's 3 most productive colleagues in number of publications:H. Rex Hartson:30Joseph D. Chase:3Suvit Nopachai:1
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Sherry Perdue Casali
Publications by Sherry Perdue Casali (bibliography)
Nopachai, Suvit and Casali, Sherry Perdue (1994): The Impact of Group Decision Support Systems on Group Consensus Processes and Outcomes. In: Proceedings of the Human Factors and Ergonomics Society 38th Annual Meeting 1994. pp. 215-219.
An experiment was conducted to examine how the use of a group decision support system (GDSS) influences the formation of group consensus. In a task requiring group members to jointly prioritize a list of items, 12 groups of eight members each were randomly assigned to one of three experimental conditions involving different levels of technological meeting support: (1) a group decision support system, (2) a manual counterpart to the structure imposed by the GDSS, and (3) no structured support. Measures of group consensus and perceived consensus, decision quality and perceived decision quality, and perceived opportunity to express views were made. The results revealed that the measures of consensus, decision quality and perceived decision quality, and perceived opportunity to express views were all similar across the three levels of technology investigated. Only perceived consensus was found to vary across conditions. The practical implications of these results are discussed.
© All rights reserved Nopachai and Casali and/or Human Factors Society
Casali, Sherry Perdue and Chase, Joseph D. (1993): The Effects of Physical Attributes of Computer Interface Design on Novice and Experienced Performance of Users with Physical Disabilities. In: Proceedings of the Human Factors and Ergonomics Society 37th Annual Meeting 1993. pp. 849-853.
It is well accepted that with even very simple tasks, a user's performance with a cursor control device improves substantially over some period of time before stabilizing. Although no systematic studies are available concerning how particular attributes of screen or device design affect the rate at which users learn to interact with a system, past studies with input devices have shown that the overall period of time required to learn to physically interact with a system is generally quite short. Hence the lack of attention paid to the "learning" phase with respect to physical interaction is probably justified. For users with mobility impairments, however, not only may the overall physical learning phase be significantly longer than for nondisabled users, but certain features of the interface design may require a longer learning period than others. Depending on how different "initial" performance is from "practiced" performance, systems meant for "walk up and use" or casual use may need to be designed differently to allow easy access for persons with mobility impairments. In addition, adaptive interfaces which change the physical design of features over time as a user becomes more proficient may facilitate access for individuals with impaired motor control. Twenty persons with impaired hand and arm function (as a result of spinal cord injury) performed a target acquisition task with five cursor control devices. The task required that the user select targets of different sizes and distances using both "point and click" and "drag" modes of interaction. Time and errors were recorded. The results indicate not only that some physical design attributes negatively effect performance, but that the magnitude of the effects differ for "initial" performance and "practiced" performance. In fact, in some cases attributes which had no effect once performance had asymptoted were shown to have a significant effect on novice performance. Also, some features required significantly longer periods of time for the users to become proficient at using than others. The implications for interface design are discussed.
© All rights reserved Casali and Chase and/or Human Factors Society
Chase, Joseph D. and Casali, Sherry Perdue (1993): The Effect of Direction on Object-Oriented Cursor Control Actions. In: Proceedings of the Fifth International Conference on Human-Computer Interaction 1993. pp. 231-236.
A number of past studies have compared user performance with a variety of cursor control devices. However, overall conclusions regarding the "best" cursor control device for a particular application are difficult to draw because the tasks used in previous comparisons have differed greedy from one another and have not necessarily included all of the factors affecting performance. One factor that has not received much attention is that of direction of cursor movement. The purpose of the portion of the present study reported herein was to determine if direction of cursor movement significantly effects target acquisition time with various input devices. A significant direction main effect as well as a number of interactions involving direction were found; with some conditions resulting in substantially degraded user performance. The results suggest that interface developers should consider the effects of direction of movement on user performance and design accordingly where rapid target acquisition is essential. These results also suggest that future empirical evaluations and comparisons of pointing devices should consider the inclusion of a direction component.
© All rights reserved Chase and Casali and/or Elsevier Science
Chase, Joseph D., Casali, Sherry Perdue and Hartson, H. Rex (1992): The Predictability of Cursor Control Device Performance Based on a Primitive Set of User Object-Oriented Cursor Actions. In: Proceedings of the Human Factors Society 36th Annual Meeting 1992. pp. 306-310.
The ability to predict performance with a cursor control device on a complex task by measuring performance on a simple task would be useful in evaluating alternative input devices in many types of novel situations. A user would simply have to perform simple cursor movements with each candidate device, and predictions could be made of his/her performance with the devices on any given software application. Such an approach would reduce tedious trial and error procedures, as well as eliminate the time necessary to first learn various software applications. The current study employed the User Action Notation (UAN), a task-oriented notation that describes the behavior of the user and the interface during their cooperative performance of a task, to decompose complex tasks into primitive components. A set of primitive cursor actions was developed which contains the elementary cursor actions found in complex tasks. A graphics software application was then evaluated, using the UAN, with respect to the frequency of occurrence of each of the primitive user-cursor actions. Individual's ability to perform each primitive user-cursor action with three different input devices was then be measured. These measures were used to form estimates of the individual's ability to perform the graphics task with each input device. Correlations between predicted performance and measured performance on the graphics task were found to exceed 0.9. Results demonstrate the success of the method described herein for predicting complex task performance based on simple task performance, as well as, the usefulness of the UAN for decomposing complex tasks into primitive components.
© All rights reserved Chase et al. and/or Human Factors Society
Casali, Sherry Perdue (1992): Cursor Control Device Use by Persons with Physical Disabilities: Implications for Hardware and Software Design. In: Proceedings of the Human Factors Society 36th Annual Meeting 1992. pp. 311-315.
Computer technology has the potential to offer individuals with physical limitations greater levels of independence and increased opportunities for meaningful employment, but this can only be realized when the individual can interact efficiently with the computer. Choosing a cursor control device is particularly important given the growing popularity of direct-manipulation style interfaces. Twenty persons with impaired hand and arm function (as a result of a spinal chord injury) and 10 nondisabled persons performed a target acquisition task with five cursor control devices: a mouse, trackball, cursor keys, joystick, and tablet. Even persons with profound impairment were able to compensate for their disability and operate each device by using minor device modifications and/or unique operating strategies. These modifications and compensation techniques are described. Regardless of the physical skill level of the user, the rank ordering of the five devices with respect to target acquisition time was the same. The mouse, trackball, and tablet provided better performance than the keys, which provided better performance than the joystick. Dragging was particularly problematic for persons with motor control limitations, as was acquiring small targets. The implications of the results for hardware and software design are discussed.
© All rights reserved Casali and/or Human Factors Society
Casali, Sherry Perdue (1991): An Empirically Developed System for the Selection of Computer Input Devices for Users with Physical Disabilities. In: Robertson, Scott P., Olson, Gary M. and Olson, Judith S. (eds.) Proceedings of the ACM CHI 91 Human Factors in Computing Systems Conference April 28 - June 5, 1991, New Orleans, Louisiana. p. 489.
Casali, Sherry Perdue (1991): An Empirically Developed System for the Selection of Computer Input Devices for Users with Physical Disabilities. In ACM SIGCHI Bulletin, 23 (4) p. 83.
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