Nowadays cognitive science often views sensorial presentations and mental presentations as mutually exclusive, and they are also given separate treatment by neurophysiologists and by cognitive scientists, and some phenomena (like anomalous surfaces or various types of imagery) are reduced to either the former or the latter. Since no adequate methods for its investigation have been developed, the level of perceptual experiences analysed by Gestaltists and magnificently illustrated by Metzger in his Laws of Seeing remains unexplored. Starting from Metzger's analyses the paper deals with the question of the theoretical value of experimental phenomenology to the theory of knowledge and ontology.