Datensatz

Zusammenfassung

We investigated the usability of vestibular translatory motion cues in self stabilization. Six blindfolded observers were asked to control the pitch or roll axis of a Stewart motion platform which followed the movements of a virtual inverse pendulum. Specifically, we varied the turning point of the pendulum with respect to the observer's head. Shifting the turning point along the body axis leaves the vestibular rotational cues identical while changing only the translatory component of the motion. We started with three hypotheses: I) If the translatory components do not affect stabilization, performance should be equal for all conditions. II) If translation does affect stabilization, then increasing the distance between head and turning point should systematically alter performance. III) In posture control, humans always rotate (tilt) around points below the head and therefore those conditions should result in better performance. Subjects controlled the pendulum with a virtual force proportional to the deflection of a joystick (acceleration based control). Five different turning point heights with respect to the head (h=0.0m, ±0.6m, and ±1.2m) were tested in trials that lasted 120 seconds each. To exclude learning artifacts, observers were trained in random order at all heights four times. Observers typically reached a stable performance after three of the four blocks (i.e., after about 30 minutes of training). Surprisingly, the final performance (absolute error and variability) was best for the condition where the turning point was 0.6m above the head. Performance decreased with increasing distance from this optimum. Therefore, none of our hypotheses seem to be true. These results might have important implications for training in helicopter simulators.