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This paper concerns the role of the language of the scale which observers employ in estimating the position of a mark on a polar coordinate display. Previous determinations have shown the accuracy of distance judgments to be a function of the relative position of the stimulus. The question at stake about such functions is whether they reflect a common perceptual tendency in distance estimations, or whether instead they are artifacts of the number scales in which the judgments were expressed. The problem was undertaken as a part of a broad program of research dealing with visual communication on radar display devices. A common type of radar display, the polar coordinate plot, is a circular map with concentric circles marked off on the map to denote distances from the center. The task of the radar operator is to estimate the position of small marks on the display. This paper concerns judgments of that type, but presumably the findings can be generalized to apply to estimations of distance on other kinds of displays. The specific question attacked is whether three scales, with an identical number of subdivision units but with different names or tags for those units, will afford the same relative accuracy. Accuracy was analyzed in terms of two different indices: one is the mean constant error in the estimates for different positions, the other the standard deviation of those estimates about their mean. (Author)