The validity of using non-representative users in gaze communication research.

Gaze-based interaction techniques have been investigated for the last two decades, and in many cases the evaluation of these has been based on trials with able-bodied users and conventional usability criteria, mainly speed and accuracy. The target user group of many of the gaze-based techniques investigated is, however, people with different types of physical disabilities. We present the outcomes of two studies that compare the performance of two groups of participants with a type of physical disability (one being cerebral palsy and the other muscular dystrophy) with that of a control group of able-bodied participants doing a task using a particular gaze interaction technique. One study used a task based on dwell-time selection, and the other used a task based on gaze gestures. In both studies, the groups of participants with physical disabilities performed significantly worse than the able-bodied control participants. We question the ecological validity of research into gaze interaction intended for people with physical disabilities that only uses able-bodied participants in evaluation studies without any testing using members of the target user population.