An Ames room is a distorted room that creates an optical illusion. Likely influenced by the writings of Hermann Helmholtz, it was invented by American scientist Adelbert Ames Jr. in 1946, and constructed in the following year. Usage and effect An Ames room is viewed with one eye through a peephole. Through the peephole, the room appears to be an ordinary rectangular cuboid, with a back wall that is vertical and at right angles to the observer's line of sight, two vertical side walls parallel to each other, and a horizontal floor and ceiling. The observer will see that an adult standing in one corner of the room along the back wall appears to be a giant, while another adult standing in the other corner along the back wall appears to be a dwarf. And if an adult moves from one corner of the room to the other, they will appear to dramatically change in size. Explanation The true shape of the room is that of an irregular hexahedron: depending on the design of the room, all surfaces can be regular or irregular quadrilaterals, so that one corner of the room is farther from an observer than the other. The illusion of an ordinary room is because most information about the true shape of the room does not reach the observer's eye. The geometry of the room is carefully designed, using perspective, so that, from the peephole, the image projected onto the retina of the observer's eye is the same as that of an ordinary room. Once the observer is prevented from perceiving the real locations of the parts of the room, the illusion that it is an ordinary room occurs. One key aspect of preventing the observer from perceiving the true shape of the room is the peephole. It has at least three consequences: It forces the observer to be at the location where the image projected into their eye is of an ordinary room. From any other location, the observer would see the room's true shape. It forces the observer to use one eye to look into the room, preventing them from getting any information about the real shape of the room from stereopsis, which requires two eyes. It prevents the observer from moving their eye to a different location, preventing them from getting any information about the real shape of the room from motion parallax. Other sources