Modelling interaction with distributed information. So much information and so little time

The paper describes work investigating the modelling of temporal and real-time requirements within human computer interaction. One particular focus for this work is the highly interactive tools used to access widely distributed information sources on the Internet, such as “Mosaic”. We argue that the manner in which such tools accommodate inherent communication delays can significantly influence how users cope with the mass of information available. By developing a model of temporal and real-time interaction we are able to express general usability requirements which are applicable in a variety of contexts, and can improve the design of interactive tools for accessing information. We propose that the extent to which delays within interface behaviour hinder effective use can be assessed in terms of: (i) the generality of behaviours particular inputs can generate (termed behavioural resolution), and (ii) the degree to which inputs generate similar feedback (termed behavioural discrimination). These notions can be defined in terms of properties of an abstract model of interaction. In particular we adopt an architectural model of interaction consisting of inter-connected processing elements, termed interactors. Within this framework interactive behaviour can be specified in terms of an event algebra and system delays can be associated with the cost of communication between interactors. We employ the notions of behavioural resolution and discrimination in the analysis of usability problems within existing tools and consider the impact of usability issues for the access of distributed information in general