Looking at images and reasoning about their content : the case of shadow depiction

摘要

The depiction of cast shadows is an interesting laboratory for solutions to representational problems, and in this they provide interesting material for the study of visual cognition. For instance, shadows in paintings have been alleged as examples of perceptual double dissociations: some perceptually acceptable shadows are physically impossible, and conversely some physically correct shadows are perceptually impossible. Here I discuss a larger set of cases that involve more topical inferences: shadows of invisible objects, of objects that should not cast shadows, of objects whose presence is only implied and not shown in the painting, cast by lights that are not visible. Interestingly, some shadows can be used to ascertain the original properties of a painting. In all these cases the viewer is moving from some visible features of pictorial content to features that are not displayed in the picture.