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Roger Shepard, pioneer in research on mental imagery, dies at 93

Headshot of Roger Shepard in black and white

Roger Shepard, 1929-2022

(Image credit: L.A. Cicero)

Jun 28 2022

By John Sanford

Roger N. Shepard, the Ray Lyman Wilbur Professor, Emeritus, in Stanford’s School of Humanities and Sciences, known for his groundbreaking research on mental imagery, died May 30 at his home in Tucson, Arizona. He was 93.

Awarded the National Medal of Science in 1995, Shepard conducted pioneering research on how the mind creates internal representations of objects in the world. He introduced techniques for quantifying mental processes when cognitive science was still dominated by research based on behavioral observations. His research contributions extended to the fields of computer science, artificial intelligence, linguistics, robotics, and physics.

“I think of him as a gentle genius,” said Ewart Thomas, former dean of the School of Humanities and Sciences (1988-93) and professor emeritus of psychology, who was a friend and colleague of Shepard’s. “His scientific ideas revolutionized psychology.”

One of his most famous research projects was inspired by a vision that came to him as he awoke one fall morning in 1968, the year he joined the faculty at Stanford as a professor in the Department of Psychology. In his mind’s eye, he saw an image of three-dimensional shapes rotating in space. He proceeded to launch a series of studies that transformed how scientists understand mental imagery.

In the first study, Shepard and graduate student Jacqueline Metzler, who earned a doctorate at Stanford in 1973, showed pairs of drawings depicting 3D objects composed of cubes to participants. Some of the paired drawings were identical, some were different – but most were presented at different angles of orientation. The researchers discovered that the time it took for the participants to determine whether the shapes were the same or different was directly related to the degree of difference in their orientations. The finding suggested that the participants were rotating the objects in their minds, and that they were doing so at an average rate of about 60 degrees per second.

One of Shepard’s former undergraduate students, the neuroscientist and best-selling author Daniel Levitin (’92), considers the studies on mental rotation his mentor’s most significant work. “They demonstrated that our inner, mental processes of imagining things are constrained by the laws of physics,” Levitin said. “Uniting the subjective experience of imagination with physics is a very big deal.”