Fig. 1.

Illustration of a typical scene during each of four different tasks. Images were taken from the head-mounted camera of the ESC. The red square indicates the current gaze position of a participant. a Task I: fixating stationary targets with a fixed distance of 7° in a freely selectable and self-paced order as projected by a head-fixed laser pointer of the ESC (enhanced in this figure for visualization). b Task II: sitting in a clinic hallway with free gaze. c Task III: walking down the hallway with free gaze and d Task IV: visually tracking two stationary targets on the floor while walking straight-ahead