Abstract

Computers offer valuable assistance to people with physical disabilities. However designing human-computer interfaces for these users is complicated. The range of abilities is more diverse than for able-bodied users, which makes analytical modelling harder. Practical user trials are also difficult and time consuming. We are developing a simulator to help with the evaluation of assistive interfaces. It can predict the likely interaction patterns when undertaking a task using a variety of input devices, and estimate the time to complete the task in the presence of different disabilities and for different levels of skill.

The simulator is developed according to the concept of Model Human Processor. It consists of a Perception model, a Cognitive model and a Motor-Behaviour Model. The perception model simulates the phenomenon of visual perception (like focussing and shifting attention). It can reproduce the results of previous experiments on visual perception in the context of Human-Computer Interaction and can also simulate the effects of different visual impairments on interaction. The cognitive model uses CPM -GOMS model to simulate expert performance. It also has a novel and easy-to-use module to simulate performance of novices based on the concept of dual-space model. Finally the motor-behaviour model is developed by statistical analysis of cursor traces from motor-impaired users. We have already used this simulator to design and evaluate a new interaction technique (a single-switch scanning approach based on clustering screen objects) of assistive interfaces.