Developing a model of cognitive interaction for analytical inclusive design evaluation

Inclusive design is a user-centred approach that examines designed product features with particular attention to the functional demands they make on the perceptual, thinking and physical capabilities of diverse users, including those with impairments and ageing. An analytic approach to the evaluation of designs mitigates the need for observational trials with products by relating data about the prevalence of capability ranges in the population with an analysis of the demands made by product properties and features. This enables a quantification of the number of users who can use a specific design. To date, there has been some success in identifying data sets and appropriate impairment and capability models for perception and movement in this novel "inclusive" research context. However, previous attempts to do so for cognitive aspects of product feature interaction have encountered a lack of suitable data and models. We propose some necessary requirements for a complete model of inclusive cognitive interaction and establish four criteria for what would constitute a good framework for the purpose of developing a research approach that could be used to construct and test predictive tools for design. Taking into account the immediately relevant literature, we examine some candidate approaches that may satisfy these requirements with reference to some of our own research findings. The results of the analysis suggest that this combined approach to cognitive demand is, in principle, capable of satisfying the proposed criteria in conjunction. It has also been successful in driving a research effort to identify important predictive variables and relate these to an underlying model of interaction. The utility of such a framework will ultimately be judged by empirical tests of the accuracy of the developed model and tools in predicting specific exclusion and difficulty during cognitive interaction. This will allow further iterative improvement of the model and will also permit modification of the development framework. A further test will be whether designers can use the resulting tools to help create designs for ICT products that are more inclusive in that they are usable by people with a wider range of functional capabilities.