The Wall of Perception, also known in physics as the Cafe Wall, gives the illusion that the rows of tiles become taller at the ends . The tiles are actually placed on the wall in a straight pattern and the illusion of the changing size is created by the way our eyes perceive the interface of the gray grout and the spacing of the tiles. This phenomenon was first notice by the physicist, Dr. Richard Gregory, who as a child was curious about a cafe in Bristol, England that had this same pattern. The artists used this concept and worked with the Yes Council youth art group to create text that related to ideas of perception/self perception. The youth also participated in the transfer of this text onto the tile in artist led workshops.