An Experimental Study of Features Search under Visual Interference in Radar Situation-Interface

Battlefield situation is the major resource for pilots to learn about the flight status data, task information as well as threat and security state information. Pilots must grasp distinct, real and complete information of combat situation, so that to have the initiative to the battlefield in hands. Thus, it is clear that the display of information about the battlefield situation is extremely significant. However, multi-level information contents may cause visual interference, which will result on pilots’ wrong perception about the information at digital display interface. For example, a pilot may not be able to precisely capture the target due to misunderstanding when guide probability of the acquisition missile capture in radar situation-interface and thus bungle the chance of winning a battle. European and North American National Aeronautics, and Space Administrations have conducted lots of experimental studies on improving the naturalness and effectiveness of man–machine interactions in the pilot cockpit (Mark [1]; Heather et al. [2]). These experiments are aimed to avoid nonconforming to human cognition designs or even wrong designs, to relieve the pilots’ burdens and reduce the hazard ratio of flight.

However, the experimental study of target search still needs to be carried in the further. The information display regarding to automatic combat identification system has been studied (Heather et al. [2]). First they applied the testing environment of military simulation and virtual modeling to investigate the hostile and friendly forces as well as the information display formats of visual targets, for example, uniforms and helmets. The investigation results were displayed respectively in pie chart and mesh chart, as well as in separated and integrated information. This paper discussed how these two groups of forms be presented to conduct the identification of combat information as well as the information analysis with combination of information reliability. After obtaining the reliable simulated data, there was found that the display formats of mesh chart and integrated data are more adaptive for combat information identification. Refs. [3‐6] have studied the identification performances of the colors, positions and shapes of different symbols and texts, and have obtained a series of valuable results that suit to national conditions. Tong et al. [7] studies controlling machining progress based on information fusion in monitoring computer numerical and has established the structure model from information source. The layout design of fighter radar situation-interface has been evaluated experimentally and has been analyzed through an objective evaluation technology of eye’s tracker (Wang et al. [8, 9]). They also have selected a special scheme of rational layout optimization through the evaluation by eye’s moving data indexes. Liu [10] simulated the general operation sequence of enemy attack task in avionics system to conduct interface design on infrared radar system, navigation system, weapon mounting system and flight control system, and evaluated the rationality of interface layout, navigation and graphic symbols by the eye’s tracker experiment. Li et al. [11, 12] studied the influence of complex digital interfaces on color and shape codes to explore the identification performances under different time pressures. Refs. [13‐26] performed physiological research on the information representation and interface design of human–machine interfaces of complex systems.

For all the mentioned above studies, the experimental data are adopted as the main evaluation method to judge the rationality of complex information interface design. Few scholars have set foot in the fields like interference environment and information matter.

Regarding to the experimental study of visual search, the opinion has been held that the occurrence of attention capture basically depends on the significance level of the feature one stimulus relative to other stimuli (Theeuwes et al. [27, 28]). Then higher the featured significance level of a stimulus that higher the possibility of its generating attention captures. Through experimental observation, Fleetwood [29, 30] found that the first factor is the quantity of icons, which influence to the user’s visual search, the second is the target boundary, and the last one is the quality and resolution of icons. Patrick [31] has applied the experimental paradigm of visual delay search task to comparatively study of the binding experiment of colors, positions as well as colors and positions. The results showed that the binding experiment had not obviously shortened the search time comparing with the others two groups of experiments. It has been studied that the role of word gap played in visual interference, have adopted the same-different matching task and visual search the time series presented by word gap and stimulus as the variables (Yu et al. [32], and Luo [33]). These two experiments validated that word gap is a necessary and sufficient condition for visual interference derived from context. The researchers have employed the brightness and flash as the way of highlighting to study the symbol’s shapes and colors, and testified to the influence of this on search time (Van Orden et al. [34]). The information identifications have been studied in different color codes and spatial positions under multiple information channels (Wickens et al. [35] and Michelle et al. [36]).

According to the experimental study above, review of visual search for information symbols color, shape, typeface, position as well as icon quantity and quality have possessed a large experimental study basis, and their interactive interference effects have been primarily demonstrated by experiments. Although all of these are basic psychology experiments, they have certain reference value for practical application of radar situation-interface based on which the preliminary presupposition of this experiment could be obtained.

This experiment was planned to simulate the interface of radar situation display of American Fighter F35, and to simplify relevant icon’s information of the fighter into experimental conceptual symbols as experimental materials. The interface background is colored in black, and the commonly-used colors of navigation station in green, red, yellow, blue and white. These colors were adopted for the color selection of the item features. The Figure 1 below provides the attack display and the defense display the radar situation for F35 fighter.

The information matters with different meanings in F35 radar defense-situation interface were extracted and drawn by simulation. 12 kinds of information matters were regarded as the featured items of experimental stimulus. Their size was filled with the black box of 6 mm × 7.5 mm, through of combining the shape’s features of different information matters, and selecting red and green as the major colors. The features are defined in three types: feature 1 covers the regular-shape (single-shaped, with a vertical line below) single-color presentation individuals; feature 2 covers the irregular-shape single-color presentation individuals; feature 3 covers the irregular-shape (mainly internal deformable based on circle objects) hybrid-color integrated from red and green presentation individuals. See details in Figure 2. The experiment basically discussed the mutual interference degrees with different feature items, i.e., the interference effect of other similar sub features on one sub feature, which was taken as the target.

All these data are all displayed within a circle of radius 78 mm in the fighter situation-interface. In the circle, there is an attack range limit of 39 mm, which presented both the morphology of the lead plane in the center and the various data of current situation around, which is causing constant interferences to subjects. All of these displays on fighter screen are constant. At the same time, randomly presented in the defensive vision: enemy planes, friendly aircrafts and unidentified objects, are variable. However, we use a simulated defense situation-interface as the fixed vision display instead of the actual situation-interface. This interface displays information what involved in experiment and cannot fix the central visual field.

Consequently, while the stimulus items are presented, space distances are required to be kept around 25 mm as far as possible. The stimuli object and targets object are randomly shown, but all concentrate in the visual range of 6°‒11°. We have design two experimental display panels, as examination objects both under low-interference and high-interference environments, as indicated in Figure 3.

Based on the analysis above, this experiment adopt the within-group design of 3 × 2 × 4 and apply three factors of stimulus features (1, 2, 3 types) respectively, interference degree (low-interference and high-interference environment), and stimulus item quantity (2, 4, 6, 8 kinds). According to the interference degree, the experiment is divided into two groups, and the interference degrees will appear in the experiment alternatively, each accounts for 50%. Each factor has two tries, each group has 3 × 4 × 2 tries, and 48 tries in total.