Ranking of Apparent Area for Different Shapes of Equal Area

Direct and pairwise area estimation of physical shapes through vision and touch

On a perceptual task in which a participant estimated areas of five physical rigid shapes, participants could view and touch the shapes, using one of two estimation methods, direct or pairwise. For the direct method, participants held one shape at a time and estimated the area based on a unit square (equal to 1/10 of the actual area). Mean error by participants was 14.4%. In the pairwise method, when participants were simultaneously handed two shapes, their error was 0.3%. Both direct and pairwise errors for vision plus touch of physical stimuli were considerably lower than previous errors made when viewing with an overhead projector screen.

Apparent relative size in the judgment of apparent distance

In experiment 1 judgments of the apparent distance of comparison figures (squares or triangles) were obtained under reduction conditions. These comparison figures were either shaped the same as or different from equidistant standard figures, and were half, equal to, or double the area of the standard figures. Apparent distance was found to be a linear function of the relative area of the comparison figure both in same-shape and different-shape stimulus pair conditions. In addition, apparent distance was found to be a function of perceived area, because in different-shape conditions triangles were generally seen to be closer than squares even when the real area of the standard and comparison was equal. The results of experiment 2 and 3 provide some evidence that the effect of different shapes of standard and comparison on apparent distance is due to the observers' perception of the height rather than the area of figures. The series of experiments shows that the traditional transactionalists' explanation of relative size as a cue for distance is inadequate.