Indication of direction with electronic map – Effects of display size and availbable time

This report presents a study performed with the purpose of investigating the effects of display size and available performance time on the task of indicating the direction in the terrain to symbols that are shown on a digital map. In the future soldiers will most likely be equipped with some type of digital support, including a navigational aid where directions and positions of own units/soldiers and threats will be displayed. At present, the design of this type of equipment is not decided, and several solutions have been suggested with various sizes of displays and resolutions. The advantage with a larger display is that it provides a clear picture that is easy to grasp, but the drawback is that it is more difficult to handle and carry. The advantage with a smaller display is that it is easier to handle and carry, but the drawback is that the picture may be filled with symbols and thus perceived as messy and less easy to grasp, and therefore it may be necessary to zoom the picture. Previous experiments have shown relatively good precision of indication of direction with an electronic map on a small display when the indications are performed without time pressure. Therefore, in this experiment the time available to perform the indication task was varied, with the purpose of investigating the effects on precision when the available time was limited. In addition, it was investigated if the precision of the indication task could be further improved if a larger display was used. This study was performed with 16 participants who performed the task of indicating the direction in the terrain to targets presented on an electronic map. Two displays were used for the indication task, one small (3.5-inches) and one large display (9.7-inches). The time available for the indication task was limited to 5, 10, 15, and 20 seconds. In addition, the relation between spatial ability, as measured with tree different established spatial tests, and the precision on the indication task was investigated. The results showed that the precision with the large display was significantly better compared to the small screen. However, in practice the difference was relatively small (1.6 degrees) and most likely it does not outweigh the disadvantages of carrying and handling a large display. Time available for the indication task did not affect the precision on the task for any of the two displays. However, time pressure, task difficulty, and mental workload were rated higher when the time available for the indication task was shortened. The relation between the spatial test PTSOT and the precision on the indication task was relatively strong. In particular this was true when the indications were performed with the small display and with short time available for the indication task. This is also most likely a situation which puts high demands on spatial ability.