Measuring website usability for visually impaired people-a modified GOMS analysis
Web designers regularly wonder which version of a design would suit best their target groups' needs. This becomes even more complicated if the design is to comply with accessibility rules. This paper describes an interaction model of blind users' interaction strategies. This model is based on GOMS (Goals, Operators, Methods, Selection rules) and can be used to measure aspects of website usability for blind users. The model evolved from findings of user observations and field studies. It can be applied to specific layouts in order to find the 'best' alternative. 'Classic' GOMS models lack functions which are necessary for the presented GOMS model. Thus, new structures to extend the classic GOMS notation are proposed. Finally, an example GOMS analysis is run on a modified version of the ASSETS '06 web page.