ABSTRACT
Driving is an example of human-machine interaction in which the human (i.e., the driver) interacts with a machine (i.e., the vehicle). As well as interacting with the primary driving functions, such as steering, accelerating, braking, and changing gear, the driver also performs secondary tasks within the vehicle, and this often involves interacting with an IVIS. To design and evaluate any interactive system, it is necessary to be able to predict how that system will perform, based on the individual components which make up the system. Card, Moran, and Newell (1983) proposed a formula to describe system performance:
Task + User + Computer → System Performance. (1983, p. 404)
The task, user, and computer (or, for the purposes of this work, IVIS) are factors that combine to produce an approximation of system performance. Card et al. (1983) went on to state that modelling the interaction between the task, user, and computer would enable designers to predict system performance:
Model (Task, User, Computer) → Performance Prediction. (1983, p. 405)
These formulae were developed specifically to describe desktop computing systems and are applicable to systems operating in isolation, that is, without reference to the wider context of use. This is a limitation of existing HCI models, such as Card et al.’s Goals, Operators, Methods, and Selection Rules (GOMS) technique, which is underpinned by these formulae for the human-computer system. A major goal of the work described in this book is to account for the context-of-use of a product of system in usability evaluation, and the factors defined by Card et al. must therefore be described in relation to this context, which in this case is interacting with an IVIS whilst driving. Card et al.’s (1983) three factors of a human-computer system are described and discussed in relation to the IVIS interaction/ driving context in the following sections of this chapter. An extended version of the human-computer system model is presented in Figure 3.1; this places the interaction between task, user, and
system in the IVIS/ driving context and shows the modal interactions between the separate components.
