Reasoning about order errors in interaction

Reliability of an interactive system depends on users as well as the device implementation. User errors can result in catastrophic system failure. However, work from the field of cognitive science shows that systems can be designed so as to completely eliminate whole classes of user errors. This means that user errors should also fall within the remit of verification methods. In this paper we demonstrate how the HOL theorem prover [7] can be used to detect and prove the absence of the family of errors known as order errors. This is done by taking account of the goals and knowledge of users. We provide an explicit generic user model which embodies theory from the cognitive sciences about the way people are known to act. The user model describes action based on user communication goals. These are goals that a user adopts based on their knowledge of the task they must perform to achieve their goals. We use a simple example of a vending machine to demonstrate the approach. We prove that a user does achieve their goal for a particular design of machine. In doing so we demonstrate that communication goal based errors cannot occur

The Design and evaluation of the specification framework for user interface design

This thesis presentsthe design and evaluation of an interface specification meta-language(ISML) that has been developed to explicitly support metaphor abstractions in a model-based, user interface design framework. The application of metaphor to user interface design is widely accepted within the HCI community, yet despite this, there exists relatively little formal support for user interface design practitioners. With the increasing range and power of user interface technologies made widely available comes the opportunity for the designof sophisticated, new forms of interactive environments. The inter-disciplinary nature of HCI offers many approaches to user interface design that include views on tasks, presentationand dialogue architectures and various domain models. Notations and tools that support these views vary equally, ranging from craft-based approachesthrough to computational or tool- based support and formal methods. Work in these areas depicts gradual cohesion of a number of these design views, but do not currently explicitly specify the application of metaphorical concepts in graphical user interface design. Towards addressing this omission, ISML was developed based on (and extending) some existing model- based user interface design concepts. Abstractions of metaphor and other interface design views are captured in the ISML framework using the extensible mark-up language(XML). A six-month case study, developing the `Urban Shout Cast' application is used to evaluate ISML. Two groups of four software engineers developed a networked, multi-user, virtual radio-broadcasting environment. A qualitative analysis examines both how each group developed metaphor designs within the ISML framework and also their perceptions of its utility and practicality. Subsequent analysis on the specification data from both groups reveals aspects of the project's design that ISML captured and those that were missed. Finally, the extent to which ISML can currently abstract the metaphors used in the case study is assessed through the development of a unified `meta-object' model. The results of the case study show that ISML is capable of expressing many of the features of each group's metaphor design, as well as highlighting important design considerations during development. Furthermore, it has been shown, in principle, how an underlying metaphor abstraction can be mapped to two different implementations. Evaluation of the case study also includes important design lessons: ISML metaphor models can be both very large and difficult to separate from other design views, some of which are either weakly expressed or unsupported. This suggests that the appropriate mappings between design abstractions cannot always be easily anticipated, and that understanding the use of model-based specifications in user interface design projects remains a challenge to the HCI community

The design and evaluation of the specification framework for user interface design

This thesis presentsthe design and evaluation of an interface specification meta-language(ISML) that has been developed to explicitly support metaphor abstractions in a model-based, user interface design framework. The application of metaphor to user interface design is widely accepted within the HCI community, yet despite this, there exists relatively little formal support for user interface design practitioners. With the increasing range and power of user interface technologies made widely available comes the opportunity for the designof sophisticated, new forms of interactive environments. The inter-disciplinary nature of HCI offers many approaches to user interface design that include views on tasks, presentationand dialogue architectures and various domain models. Notations and tools that support these views vary equally, ranging from craft-based approachesthrough to computational or tool- based support and formal methods. Work in these areas depicts gradual cohesion of a number of these design views, but do not currently explicitly specify the application of metaphorical concepts in graphical user interface design. Towards addressing this omission, ISML was developed based on (and extending) some existing model- based user interface design concepts. Abstractions of metaphor and other interface design views are captured in the ISML framework using the extensible mark-up language(XML). A six-month case study, developing the `Urban Shout Cast' application is used to evaluate ISML. Two groups of four software engineers developed a networked, multi-user, virtual radio-broadcasting environment. A qualitative analysis examines both how each group developed metaphor designs within the ISML framework and also their perceptions of its utility and practicality. Subsequent analysis on the specification data from both groups reveals aspects of the project's design that ISML captured and those that were missed. Finally, the extent to which ISML can currently abstract the metaphors used in the case study is assessed through the development of a unified `meta-object' model. The results of the case study show that ISML is capable of expressing many of the features of each group's metaphor design, as well as highlighting important design considerations during development. Furthermore, it has been shown, in principle, how an underlying metaphor abstraction can be mapped to two different implementations. Evaluation of the case study also includes important design lessons: ISML metaphor models can be both very large and difficult to separate from other design views, some of which are either weakly expressed or unsupported. This suggests that the appropriate mappings between design abstractions cannot always be easily anticipated, and that understanding the use of model-based specifications in user interface design projects remains a challenge to the HCI community.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Model-Based Usability Analysis of Safety-Critical Systems: A Formal Methods Framework

Complex, safety-critical systems are designed with a broad range of automated and configurable components, and usability problems often emerge for the end user during setup, operation, and troubleshooting procedures. Usability evaluations should consider the entire human-device interface including displays, controls, hardware configurations, and user documentation/procedures. To support the analyst, human factors researchers have developed a set of methods and measures for evaluating human-system interface usability, while formal methods researchers have developed a set of model-based technologies that enable mathematical verification of desired system behaviors. At the intersection of these disciplines, an evolving set of model-based frameworks enable highly automated verification of usability early in the design cycle. Models can be abstracted to enable broad coverage of possible problems, while measures can be formally verified to "prove" that the system is usable. Currently, frameworks cover a subset of the target system and user behaviors that must be modeled to ensure usability: procedures, visual displays, user controls, automation, and possible interactions among them. Similarly, verification methodologies focus on a subset of potential usability problems with respect to modeled interactions. This work provides an integrated formal methods framework enabling the holistic modeling and verification of safety-critical system usability. Building toward the framework, a set of five, novel approaches extend the capabilities of extant frameworks in different ways. Each approach is demonstrated in a medical device case study to show how the methods can be employed to identify potential usability problems in existing systems. A formal approach to documentation navigation models an end user navigating through a printed or electronic document and verifies page reachability. A formal approach to procedures in documentation models an end user executing steps as written and aids in identifying problems involving what device components are identified in task descriptions, what system configurations are addressed, and what temporal orderings of procedural steps could be improved. A formal approach to hardware configurability models end-user motor capabilities, relationships among the user and device components in the spatial environment, and opportunities for the user to physically manipulate components. An encoding tool facilitates the modeling process, while a verification methodology aids in ensuring that configurable hardware supports correct end- user actions and prevents incorrect ones. A formal approach to interface understandability models what information is provided to the end user through visual, audible, and haptic sensory channels, including explanations provided in accompanying documentation. An encoding tools facilitates the development of models and specifications, while the verification methodology aids in ensuring that what is displayed on the device is consistent; and, if needed, an explanation of what is displayed is provided in documentation. A formal approach to controlled actuators leverages an existing modeling technique and data collected from other engineering activities to model actuator dynamics mapping to referent data. An encoding tool facilitates model development, and a verification methodology aids in validating the model with respect to source data. Finally, new methodologies are combined within the integrated framework. A model architecture supports the analyst in representing a broad range of interactions among constituent framework models, and a set of ten specifications is developed to enable holistic usability verification. An implementation of the framework is demonstrated within a case study based on a medical device under development. This application shows how the framework could be utilized early in the design of a safety-critical system, without the need for a fully implemented device or a team of human evaluators.Ph.D., Biomedical Science -- Drexel University, 201