Flying with dichoptic displays: the interplay between display characteristics and attention control

Interest in the study of attention control under dichoptic-conditions is instigated by the contemporary development of night-vision systems based on single-eye helmet-mounted displays. Two experiments were conducted to investigate the concurrent performance of a tracking task and letter classification under dichoptic display conditions. Subjects were required to fly a simulated helicopter path while classifying letter pairs presented intermittently. Experimental instructions in Experiment A specifically emphasized a two-dimensional interpretation of the visual field. Under these instructions, the presentation of a common visual axis to the two eyes provided by the flight-tunnel did not aid subjects, and their performance deteriorated in dichoptic conditions. In Experiment B, the instructions to subjects were changed to advocate a three-dimensional interpretation of the display. Under these instructions, dichoptic performance-levels were substantially improved when the tunnel was present. These results imply that the presence of a common visual axis is not automatically beneficial. In order to improve performance, attention should be intentionally directed to utilize information supporting a three-dimensional frame of mind. These findings have important implications for understanding the dynamics of performance with single-eye helmet-mounted displays, and the training of pilots in their use.