Five experiments examined the influence of configural variables on perceived pointing of ambiguous (equilateral) triangles. The amount of time required to see the triangles point in specified directions was measured for single triangles and linear configurations of multiple triangles. The results show that perceived pointing is biased toward directions that are coincident with or perpendicular to the configural line. Perceptual interference occurs when the configural line biases pointing away from the correct direction, and facilitation sometimes occurs when it biases pointing toward the correct direction. The magnitude of interference increases (a) when the required direction is perceptually less salient, (b) when the configural line contains more triangles, and (c) when the triangles are closer together. Further results suggest that the spacing effect depends on relative rather than absolute distance and that the number and spacing effects are additive. In addition, substantial differences were found among individuals in terms of their susceptibility to configural interference. These results are discussed in terms of a sequential sampling model of perceived pointing. The samples result from spontaneous alternations in a multistable system of three mutually inhibitory directional subsystems. It is proposed that configural effects arise from low resolution pattern information that influences the behavior of the multistable system. Possible mechanisms are suggested through which directional, attentional, and individual differences might also arise.

Five experiments examined the influence of textural stripes on perceived pointing of ambiguous (equilateral) triangles. Reaction times for discriminating specific directions of pointing were measured for plain triangles and for triangles containing stripes that were either coincident with or perpendicular to one of the three possible directions of pointing. Perceptual interference occurred when the stripes biased a direction other than one specified by the discrimination task. The magnitude of the interference decreased (a) as the environmental salience of the specified direction increased and (b) as the spatial frequency of the stripes increased. Further results indicated that this frequency effect is relative to the size of the triangle; it is not determined by absolute (retinal) frequency. Stripes in the ground region surrounding the triangle also produced interference. However, this interference decreased as the region around the triangle was cleared of stripes. The results are discussed in terms of factors that determine the qualitative and quantitative nature of the interference effect, particularly symmetry and spatial frequency.

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Simulation scientists continually pursue improved flight simulation technology with the goal of closely replicating the “real world” physical environment. The presentation/display of visual information for flight simulation is one such area enjoying recent technical improvements that are fundamental for conducting simulated operations close to the terrain. Detailed and appropriate visual information is especially critical for Nap-Of-the-Earth (NOE) helicopter flight simulation where the pilot maintains an “eyes-out” orientation to avoid obstructions and terrain. This paper elaborates on the visually-coupled Wide Field Of View Helmet Mounted Display (WFOVHMD) system technology as a viable visual display system for helicopter simulation. In addition the paper discusses research conducted on the NASA-Ames Vertical Motion Simulator that examined one critical research issue for helmet mounted displays.