Two types of shapes were investigated in this rather empirical study: outline maps of seven countries (with no particular respect to scale), and tool shapes. To generate the data sets only one original representative of each shape was obtained, and then distorted by manipulation of their images. For the outline maps, smoothing of the boundaries and occlusion were used to obtain further representatives. Occlusion consisted of simply cutting off part of the shape by a straight cut. For the tool shapes, on the contrary, their originally smooth outlines were perturbed by random noise (introducing wiggles in the boundary). Some of the images were also obtained by occlusion. In all, there were only six representatives of each of seven countries and of six tool shapes.

It is not clear if the outlines were digitized and processed by computer: “...Because of some limitation in experimental environment, the introduction of distortion and the matching algorithm of the chord method were not performed on discrete binary images." This reviewer could not draw any useful conclusions from the reported work.