Parsing silhouettes: The short-cut rule

Many researchers have proposed that, for the purpose of recognition, human vision parses shapes into component parts. Precisely how is not yet known. The minima rule for silhouettes (Hoffman & Richards, 1984) defines boundary points at which to parse but does not tell how to use these points to cut silhouettes and, therefore, does not tell what the parts are. In this paper , we propose the short-cut rule, which states that, other things being equa l, human vision prefers to use the shortest possible cuts to parse silhouet tes. We motivate this rule, and the well-known Fetter's rule for modal comp letion, by the principle of transversality. We present five psychophysical experiments that test the short-cut rule, show that it successfully predict s part cuts that connect boundary points given by the minima rule, and show that it can also create new boundary points.