Usability evaluation: models, methods, and applications

Usability is a recent, even sometimes debated, concept in the human and computer interaction field in which interdisciplinary issues of design engineering and philosophy, cognitive psychology and ergonomics converge. The approach we endorse in order to analyse this interdisciplinary concept is strictly related to the evolution of the evaluation models, methods and applications of usability. At first, we discuss the relation between usability and accessibility as dimensions of the intrasystemic relation between the user and technology, by proposing a definition and a model of evaluation. In the second section, we analyse the mental model’s role in system interaction and the distance between them as an outlook to understand usability problems. In the same section, the measures of usability are presented. In the third section, an application of the integrated model of evaluation is described as a step of an assistive technology assessment process in a centre for technical aid. Finally, in the last section, a brief history of human computer interaction evolution and the consequential development of usability and accessibility concepts and methods are presented, in order to understand that usability and accessibility are, at first, linked to technology changes and then strictly related to the spread of technologies.