UNLABELLED: The concept of product usability has been discussed in several areas of product research and development. Usability, within the realm of assistive technology (AT) devices, determines how effectively and efficiently AT users with disabilities can function in different contexts and environments. OBJECTIVE: This article conceptualizes and proposes the significance of AT usability and its measurement in entirety from a human factors perspective. Conceptual models that characterize the interaction of the AT user, the AT device, the context and the involved activity is considered to be the hallmark of measurement of AT usability. On that basis, the article highlights the methodology and the initial progress of the development of an AT outcome tool, the Usability Scale for Assistive Technology (USAT), to measure self reported degree of AT usability. METHODOLOGY: In order to identify usability indicators for measurement, a qualitative study was conducted by exploring the experiences of AT users. Ten participants who used either wheeled mobility or computer based AT devices were interviewed with questions based on the theme of a usability framework. RESULTS: The coded interview data generated more than 800 usability indicators specific to the two categories of AT devices. These indicators were mapped to a generic usability criteria list for construction of the USAT-Wheeled Mobility and the USAT-Computer Access. IMPLICATIONS: The USAT, when developed, is projected to be valid and useful for AT outcomes research as well as clinical practice. The use of the USAT will enable researchers and clinicians to comprehensively identify factors that underlie effectiveness and efficiency in AT device use and establish intervention protocols to optimize user-AT interaction.
