A two-dimensional pursuit tracking task was paired with three variants of a letter typing task to test predictions about the effects of task difficulty and task emphasis derived from a model of multiple resources, which states that tasks can overlap to various degrees in their demand for resources. Under dual-task conditions, when difficulty and priorities of tasks are jointly manipulated, difficulty parameters that tap processing
When pilots fly an aircraft with sensor imagery rather than direct vision, their instantaneous field of view (FOV) is restricted severely. This limitation has been identified as a major human factors problem in aviation and has fostered efforts to develop displays with much wider FOVs than are currently available. Two experiments are reported investigating FOV effects in simulated flights with sensor imagery appearing on a Head-Down Display (HDD) and a Head-Up Display (HUD). The outside world was viewed via a simulated sensor image with a 25, 40, or 55 deg FOV, while the surrounding world was dark and provided no additional information. The subjects task was to fly a slalom course without hitting the pylons or missing the intervals between pylons. The results indicate significant effects of FOV on both hits and misses for both the HDD and the HUD. In addition, performance was significantly affected by the speed of flying and the level of training. With the narrow FOV, subjects flew closer to the pylons than with the wide FOV and hit the pylons more often. These results are interpreted as an indication that subjects perceived the sensor display as the entire world rather than as a window into the world. This effect was somewhat smaller with the HUD than with the HDD, possibly because the HUD better represented a window into the world. The differences between the HUD and the HDD, however, did not reach statistical significance.
Thermal imaging (TI) systems, transform the distribution of relative temperatures in a scene into a visible TV image. TIs differ significantly from regular TV images. Most TI systems allow their operators to select preferred polarity which determines the way in which gray shades represent different temperatures. Polarity may be set to either black hot (BH) or white hot (WH). The present experiments were designed to investigate the effects of polarity on object recognition performance in TI and to compare object recognition performance of experts and novices. In the first experiment, twenty flight candidates were asked to recognize target objects in 60 dynamic TI recordings taken from two different TI systems. The targets included a variety of human placed and natural objects. Each subject viewed half the targets in BH and the other half in WH polarity in a balanced experimental design. For 24 out of the 60 targets one direction of polarity produced better performance than the other. Although the direction of superior polarity (BH or WH better) was not consistent, the preferred representation of the target object was very consistent. For example, vegetation was more readily recognized when presented as dark objects on a brighter background. The results are discussed in terms of importance of surface determinants versus edge determinants in the recognition of TI objects. In the second experiment, the performance of 10 expert TI users was found to be significantly more accurate but not much faster than the performance of 20 novice subjects.
This study explores the operational utility of fusing synthetic aperture radar (SAR) imagery and digital terrain map (DTM) data. Specifically, the two-dimensional (2D) display of SAR imagery was compared against a two and a half dimension (21/2D) display of SAR overlaid on corresponding DTM data. Eight imagery analysts (IAs), assigned to the Israeli Ground Corps Command Imagery Analysis Unit and to the Israeli Air Force, and two weapon system officers served as subject matter experts. The measures employed in this comparison included both an assessment of operator situational awareness (SA) and of performance in an information extraction task. Based on the SAR imagery which was used in the experiment, performance measures (accuracy and speed in feature location) and SA measures did not yield significant performance differences between the 2D and the 2 _D displays. The average time required to complete each task was significantly longer for the 2 _D displays. Based on experience, the SMEÕs opinion was that the 2 _D imagery display may be potentially helpful in the performance of various imagery analysis tasks and in enhancing SA.
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