Usability model of augmentative and alternative communication systems and pictographic systems in people with disabilities

Technological Augmentative and Alternative Communication Systems (AACS) based on pictograms are used concurrently today. They are expressed differently from oral language and compensate for communication difficulties with some verbal language limitations. Due to the specific requirements by people with special abilities, those systems must guarantee satisfaction, efficiency, and effectiveness during the users' communication. Also, the usability of those applications must demonstrate high usability characteristics. In this context, this paper presents an AACSS usability model, which can be used to evaluate pictographic systems oriented to people with disabilities. This contribution is based on a quality approach to assessing the quality of this kind of software product. The model is aligned with the ISO/IEC 25010 standard, which defines a set of main usability characteristics. Additionally, the ISO 14915-1 standard was considered, which addresses user interfaces for applications that incorporate text and interactive multimedia. Likewise, the ISO 9241-210 standard was used, which proposes characteristics, sub-characteristics, and metrics through design guides of Human-Computer Interfaces for interactive systems. The standards above allow the establishment of characteristics, sub-characteristics, attributes, and metrics of AACSs to quantify each attribute and identify any usability problems that may exist. Also, it is presented an evaluation method that uses the given usability model. Finally, an experiment that applies the proposed solution is carried out in which users have evaluated two pictographic AACSS mobile applications.