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 equal, human vision prefers to use the shortest possible cuts to parse silhouettes. We motivate this rule, and the well-known Petters rule for modal completion, by the principle of transversality. We present five psychophysical experiments that test the short-cut rule, show that it successfully predicts part cuts which connect boundary points given by the minima rule, and show that it can also create new boundary points.
The short-cut rule REF is simple: if boundary points can be joined in more than one way to parse a silhouette, choose the parsing that uses the shortest cuts.
Parsing silhouettes: The short-cut rule
Perception & psychophysics
Perception & psychophysics
Psychology Medicine