Human Systems Integration Division @ NASA Ames

Pilots rely upon visual information conveyed by computer-generated perspective displays in cockpits, and also by out-the-window (OTW) scenes rendered in simulators, to perform control tasks. Because even the most advanced graphics system cannot recreate the full complexity of a natural perspective scene (due to limitations in spatial and temporal resolution, dynamic range, field-of-view, and scene detail), it is necessary to understand which characteristics of the perspective scene are used by the pilot to accomplish vehicular control. In the current study we investigated the effects of simulated OTW visual scene content on an operator's ability to control pitch attitude of a simulated vehicle in the presence of both pitch disturbances and longitudinal position disturbances. Two types of vehicle dynamics were simulated, first-order and second-order; two types of ground textures were assessed, and the task was performed with and without a visible horizon. Data from 12 participants were analyzed to determine task performance, and to estimate describing functions of the human operator characteristics. Task performance with both types of vehicle dynamics was significantly better with a visible horizon. The type of ground texture did not affect performance. Parameterized models were fit to the describing function measurements. The resulting models exhibited excellent correlation with the describing functions. Identified parameters related to the visual cue usage showed excellent correlation with the available scene features.