PUMA PROGRAMMABLE USER MODELLING APPLICATIONS The principle of rationality and models of highly interactive systems

One approach to reasoning about interactive behaviour is to assume that users of computer systems are rational, and that the behaviour of an interactive system results from the rational behaviour of the users together with the implemented behaviour of the devices that make up the total system. These assumptions can be expressed as a coherent set of principles. This approach enables an analyst to identify likely sources of user error and well as predicting (errorfree) behaviour patterns. This, in turn, can be used as a basis for identifying requirements on device designs. We present principles, based on those originally proposed by Newell, that can be used as a basis for reasoning about interactive behaviour. In particular, we accommodate the role of devices as resources that support memory and reasoning, active devices, and multiagent systems in which one user may be interacting with multiple devices and other users.