A Practical Inclusive Design Approach

Abstract

Designers instinctively design for able-bodied users and are either unaware of
\nthe needs of users with different capabilities, or do not know how to accommodate
\ntheir needs into the design cycle. Hence, there is an urgent need for design methods,
\nbased on a better understanding of age and ability related factors, which will lead
\nto a minimising of the impact of impairments and thereby extend quality life.
\nThe aim of this paper is to present a methodological design approach for
\nimplementing inclusive design. A summary of the principal methods for designing
\nfor users with different capabilities is given along with a description of a model,
\n the Inclusive Design Cube, that displays how the different approaches are
\ncomplementary and can provide complete population coverage. Building on the
\nconcept of the user pyramid design approach (Benktzon, 1993), the authors have
\ndeveloped a model that relates capability level, population profile and suitable
\ndesign approach in a simple graphical format. The resultant model is the inclusive
\ndesign cube (IDC) (Keates and Clarkson, 1999). Each axis on the cube represents
\nuser capability and the enclosed volumes reflect population coverage. The IDC is a
\nvery potent visualisation tool and communicates the needs of different sections of
\nthe population. However, for practical implementation of inclusive design practices,
\nit is necessary to have an accompanying rigorous methodology.
\nDeveloping a usable product interface for wider user capabilities involves
\nunderstanding the fundamental nature of the interaction. Typical interaction with
\nan interface consists of the user perceiving the output from the product (perception),
\ndeciding a course of action (cognition) and the implementing the response (motor
\nfunction) (Card et al., 1983). These steps relate directly to the user’s sensory,
\ncognitive and motor capabilities respectively. Building on this and Nielsen’s usability
\nheuristics (Nielsen and Mack, 1993), a design approach has been developed, where
\neach level is accompanied by user trial evaluations before progression to the next
\nlevel. 
\nThe 7-level approach has been successfully applied to the design of a software
\ninterface for the control of an interactive, assistive technology robot (Clarkson et al,
\n1999) and the evaluation of an information point for use in post offices. The latter
\nshall be presented as a case study to demonstrate how application of the 7-level
\napproach would have affected its overall usability. Using the 7-level approach
\nand the Inclusive Design Cube, serious usability and accessibility shortfalls were
\nidentified that are being addressed in the information point re-design.