Influences of task complexity and individual differences on the performance of gaze-assisted human-machine interfaces

Human-machine interfaces can be enhanced by incorporating knowledge of the user's current point of regard. For example, Zhai and colleagues (1999) showed that faster task completion times could be achieved on a simple pointing task if the display pointer was translocated according to the user's gaze. This manipulation removes the need to manually move the pointer and hence, promises time-savings that grows in proportion to display size. Here, we report the findings of applying the same technique on a wall-sized display (2.2 m × 1.8 m), across more complex pointing task. Two main components comprised the four tasks that participants were required to perform, with and without gaze-assisted pointing: Namely, conjunctive search of colored shapes and click-and-drag of items to a circumscribed region. Contrary to previous findings, we found that gaze-assisted pointer placement significantly increased task completion times, relative to manual pointer placement. Detailed analyses revealed that task complexity and individual differences in gaze behaviour and eye-hand coordination had an adverse effect on task performance, which emphasizes the importance of considering these factors in future implementations of gaze-assisted interfaces