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Notes & Lines discusses the intersection of math, science, and technology with performing and visual arts. Topics include bizarre instruments, technically-minded musicians, and cross-pollination of science and art.

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The Interesting Career and Optical Illusions of Adelbert Ames, Jr.

Posted June 09, 2017 9:20 AM by Hannes

While his name is not a household one, the career of Adelbert Ames, Jr. sprawled across physics, ophthalmology, physiology, psychology and philosophy. He also developed and lent his name to two common optical illusions: the Ames room and Ames window.

The younger Ames was born in 1880. His father was a noted general in the American Civil War and was heavily involved at the Battle of Gettysburg, later becoming provisional governor of Mississippi and an inventor. Ames, Jr. earned a Harvard law degree, studying with William James and George Santayana in the process, but abandoned law to become a painter. Ames figured that he could become a better painter by scientifically studying vision, so he began reading about the optical components of the eye. The study of vision made such an impression on Ames that he abandoned painting and attended Clark University in 1914 to study physiological optics.

Ames began working at Dartmouth College following World War I, and eventually became research director of the short-lived Dartmouth Eye Institute. At the DEI he led research efforts concentrating on binocular vision, specifically cyclophoria—torsion that occurs when the eyes rotate in opposite directions—and aniseikonia, when each eye perceives an identical image to be a different size. Ames published 38 books and papers and held 21 patents. His work covered not only physiological optics but also the psychology of vision and perception. His son, Adelbert Ames III, is a professor emeritus of neuroscience at Harvard.

Ames’ interest in optical illusions may stem from his background in visual art and his interest in the psychology of perception. The Ames room, perhaps his best-known illusion, asks an observer to view a room through a pinhole in one of the walls. The viewer perceives the room to be square, but in reality it’s trapezoidal, so that a person walking from corner to corner appears to grow and shrink. Ames’ original design also included a groove that transported a ball across the room, giving an “anti-gravity” illusion in that the ball appears to roll uphill. TV and movie productions frequently use the Ames room technique to create the illusion that one character is much taller than the rest. The Lord of the Rings trilogy, for example, used several Ames room sets when filming hobbits next to the much-taller Gandalf.

The Ames window is a flat piece of cardboard illustrated with panes to appear as a window. To the observer it appears as a rectangular window oriented toward a focal point, but in reality the cardboard is trapezoidal. The illusion becomes more complex when the window is attached to a rotating shaft; if the viewer assumes that the window is rectangular, it appears to oscillate and rotate at less than 180 degrees. After Ames’ death, psychologists used the window experiment to test whether a viewer’s mental expectation of the rotation could affect their actual perception.

An unusual illusion is the Ames chair experiment. A viewer sees three images through different peepholes, and all three appear to be a line drawing of a chair with a solid white seat. But when shown the actual objects, viewers find that only one object is an actual chair, and it was only the viewing angle that caused the other two to appear that way. In fact, one of the objects, the bottom-middle one in this image, is a mess of wires in front of a backdrop with a white shape painted on it and appearing as the “chair’s” seat. Ames used the illusion to show the inherent ambiguity behind perception.

More details about Ames’ life and inventions are described in this research paper.


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