He advanced the study of a millenniums-old mystery: why the moon appears larger on the horizon than it does high in the night sky.
Lloyd Kaufman, a leading figure in the study of a phenomenon called the moon illusion, an optical trick puzzled over for millenniums by the likes of Aristotle and Kepler, died on Aug. 20 at his home in the Floral Park neighborhood of Queens. He was 97.
His death was confirmed by his daughter Robin Sellier.
Professor Kaufman, a cognitive psychologist with appointments at New York University and Long Island University, spent nearly half a century studying the mental mechanics that help produce human vision, becoming an eminent figure in that academic field.
In the popular press, he was known for his attempts to solve an age-old paradox: Why does the moon look so much bigger rising over the horizon than it does high in the sky late at night, even though in each position the moon is the same size and roughly the same distance from Earth?
“The moon illusion might be the world’s most widely known optical illusion,” Vox wrote in 2015.
Some say the earliest record of humanity’s awareness of the moon illusion is a Mesopotamian clay tablet from about the 7th century B.C. bearing cuneiform script that describes the changing sizes of the moon.
The earliest known scientific inquirer into the phenomenon was Aristotle, who ascribed the effect to qualities of the atmosphere, according to “The Mystery of the Moon Illusion: Exploring Size Perception” (2002), a survey of the subject written by the psychologists Helen Elizabeth Ross and Cornelius Plug.
In later centuries, the problem drew the attention of the Egyptian astronomer Ptolemy, the medieval Arab physicist Ibn al-Haytham and figures like Leonardo da Vinci, Johannes Kepler and René Descartes.