In a polygon display, each system parameter is indicated by the radial distance of one vertex of a polygon from the centre. Earlier results showed that the detectability of faults is enhanced by increasing the number of polygon vertices from four to twenty but a practical display-control system also requires the absence of adverse effects with more parameters. Speed and accuracy of responses when peripherally viewing a polygon display with an inset dynamic task were investigated for two tasks: detecting the presence of an out-of-limits parameter and locating the most deviant parameter. The number of vertices in the display was varied, and the vertices were permitted either a wide or a narrow range of variation. Performance was best when the deviation of the extreme vertex was outwards. As the number of parameters increased from 4 to 20, speed and accuracy in detecting a fault remained constant or improved if system variability was low but locating the most extreme parameter became poorer, especially when the other vertices varied widely. (A)
Samenvatting