A combinatory approach to assessing user performance of digital interfaces

Digital devices are often restricted by the complexity of their user interface (UI) design. While accessibility guidelines exist that reduce the barriers to access information and communications technology (ICT), guidelines alone do not guarantee a fully inclusive design. In the past, iterative design processes using representative user groups to test prototypes were the standard methods for increasing the inclusivity of a given design, but cognitive modelling (the modelling of human behaviour, in this instance when interacting with a device) has recently become a feasible alternative to rigorous user testing (John and Suzuki 2009). Nonetheless, many models are limited to an output that communicates little more than the assumed time the modelled user would require to complete the task given a specific way of doing so (John 2011). This chapter introduces a novel approach that makes use of the overlay of user modelling output (timings) onto a graphical representation of an entire UI, thereby enabling the computation of new metrics that indicate the relative inclusiveness of individual screens of the UI