Human Factors of Integrating Speech and Manual Input Devices:udThe Case of Computer Aided Design

摘要

The thesis investigates integrating the use of speech input and manual input devices in human-computer systems. The domain of computer aided design (CAD) is used as a case study.udA methodology for empirical evaluation of CAD systems is presented. The methodology is based on a framework that describes the input/output processes presumed to underlieudperformance in design activities, using behaviour protocols and performance indices as data.udFor modelling system behaviour, a framework derived from the Blackboard architecture of design is described. The framework employs knowledge sources to represent differentudbehaviour types recruited during CAD performance. Variability in user behaviour throughout the investigation is explained with reference to the model.udThe problems that expert CAD users experience in using manual input devices are first documented in an observational study conducted at their workplace. This demonstrates that the unitary use of manual input resulted in non-optimal behaviour. Possible solutions to theseudproblems, using speech input for some command and data entry tasks, are explored in three experiments. In each experiment, a comparative analysis of alternative systems is made using data obtained from naive and novice users.udIn Experiment 1, the use of speech as a unitary solution to the problems of manual input was also found to result in non-optimal behaviour and performance. The solution explored in Experiment 2 was to allocate some commands and alphanumeric data to each input device, using the frequency of use principle. This approach, however, entailed the additional problem of remembering which device to use. Experiment 3 evaluated the separate allocation ofudcommands to speech input and numeric plus graphical data to manual input. Additionally, performance aids and feedback facilities were provided to users. This clear-cut assignment of device to task characteristics and the use of such aids led to an enhancement in speech performance, in addition to improving behaviour.udThe findings from this research are used to develop guidelines for an integrated CAD system involving speech and manual input. The guidelines, which are intended for use by end users, CAD implementors and system designers, were validated in the workplace by the latter.udLastly, the thesis contextualises the research within an ergonomics framework, mapping the research development from problem specification to application and synthesis. Problems with the investigation are also discussed, and suggestions made as to how these might be resolved.