Cognitive design in action: developing assistive technology for situational awareness for persons who are blind.

Cognitive design constitutes a cognitively-informed engineering method for developing assistive technologies. The approach is challenging in that it involves matching key cognitive principles for a given problem domain to engineering principles, and that an independent validation procedure is required for the cognitive component. In addition, we argue for a broad set of evaluation criteria and adapt a participatory design framework, one that involves the client population throughout the design process. After laying out the main precepts of the approach, we illustrate these via a particular design process, seeking to provide situational awareness and navigational assistance to persons who are blind. The problem domain is described in some detail. A solution is then presented that involves matching the need for configural knowledge about the person's surroundings with a hierarchical organisation in the spatial database so that information may be presented to the user at different levels of detail. The process involved to implement this solution is then outlined, and appropriate validation experiments described. It is noted that the cognitive design process as presented here is in use now in a number of initiatives, and that it involves a high degree of collaboration between experts from different disciplines.