The recognition that design flaws had to be identified early in the design process has lead to the idea of User Centered Design, with techniques like QOC supporting the design process, and the development of evaluation methods, such as Cognitive Walkthroughs and codifications of practical advice in the form of Guidelines. To help designers understand why usability problems might have arisen, cognitive psychology theories are being couched as Supportive Evaluation Methods. One such approach, ICS, is an example of a trend away from the dyadic, turn-taking relationship between a single user and a single computer, towards a more complex view of computers as part of our everyday environment. This trend is increasing the involvement of social and organizational theorists. From another perspective, computer scientists see systems as built up from 'interactors' and argue that the user's cognitive processes can be modeled as just another set of interactors.
Syndetic models examine the overall system of human and computer interactors.
In general, HCI is focussing less on the individual, has a great deal to gain from other social sciences, and has the potential to provide insight into human behavior in return. The application of the model beyond laboratory tasks has inevitably brought more and more of these 'complex' aspects of task performance into play. While the general conception of the CE as an attentional organiser or contention scheduler has allowed some of these aspects to be dealt with, there remains no detailed account of how the CE is organised, nor how it functions, and more importantly, how it might fail to function. With the rise of interest in 'dysexecutive syndrome' this has become a critical problem for the application of the WM model. In this chapter, I argue that the problem lies in the absence of a clear distinction in the WM model between processing and storage resources, and in the lack of detail about how the CE communicates with the slave subsystems.