Abstract

This research studied the representation and perception of light in monochromatic engravings in two experiments. The first experiment was dedicated to the perception of Illumination, the second one to the perception of luminosity. The stimuli of the first experiment were monochromatic engravings by classic artists; the observers had to arrange the stimuli according to the phenomenal evidence of emerging light. In the second experiment, using a similar procedure, another group of observers had to rate the luminosity of halos. The results of experiment 1 show that in some of the engravings physical changes in reflectance correspond to percepts of brightness which are seen as emerging light. The results of experiment 1 have been discussed in accordance with Gilchrist & Jacobsen's hypothesis on the importance of contours present in a scene for the perception of illumination and color. Such contours are at least of two kind: those which define objects and those which define cast shadows. The presence of two separated systems of contours in a same scene leads to a higher order of regularities which have yet to be rendered explicit, but which seem to be effectual in the perception of emerging light. Also the results of experiment 2 seem to depend on the role played by contours, physically present or anomalous.