Abstract
The hollow-face illusion, the compelling impression of a convex face for a mask, has been believed as the only perception of three-dimensional shape of a face from shading under the single-light source rule, although there are other possible physical interpretations to the mask. This gives rise to questions what extent this rule can be applied and how powerful this rule can constrain the perceived shape. To answer these questions, we investigated shape perceived of a circle (test) located around the hollow face stimulus (inducer) as functions of a distance between the test and the inducer and of a position of the test to the inducer. Results of all of eight observers (undergraduates) showed the hollow-face illusion were produced when the inducer was presented alone. We found there were two types of the results. One group of the observers followed the single-light source rule, and another group responded perception so that the observers interpreted that each of the object in the stimulus field was casted by different light sources. Despite of these different trends of the results, for all observers there was no effect of the inducer to the test in terms of relative location to the inducer and distance from the inducer. These results indicate that across the wide-range of the spatial configuration of the stimulus the single-light source rule is not of robust for a mechanism of the perceptual shape from shading.
Meeting abstract presented at VSS 2015