How the brain easily deciphers motion in Japanese line drawing

Using brain scans, scientists at Kyoto University, Japan, have found why line drawings to show "implicit motion", used by an 18th-century Japanese artist, work so well.

Naoyuki Osaka admired line drawings by Hokusai Katsushika, and found that instead of using blur to suggest movement, as much modern art has done since the advent of photography, Katsushika created motion by drawing bodies in highly unstable positions.

And the technique is thought to work because the brain "fills in" the effects of gravity pulling the bodies down.

In earlier research it was shown that blurred photographs stimulate the same regions of the visual cortex as real-life motion, including the extrastriate visual cortex.

To discover whether sketches of unstable bodies would also activate these regions, Osaka showed Japanese students Katsushika's drawings while scanning their brains with functional MRI.

The scans revealed that drawings depicting motion did indeed prompt activity in the extrastriate visual cortex, unlike those of people or objects in static positions. Osaka concludes that there is a "common neural pathway" for interpreting implicit motion in art that is similar to the pathway used for perceiving real-life motion.

Patrick Johnston, a cognitive neuroscientist at Swinburne University of Technology in Melbourne, Australia, said that these findings could help "unlock how the brain processes visual information," reports New Scientist.

However, Oron Catts of SymbioticA, a biological arts centre at the University of Western Australia in Perth, warned that the influence of culture must not be ignored.

He suggested that Japanese people may perceive the motion more vividly than people from other cultures because they are accustomed to this type of art.

"In Japanese culture, people are trained to read those cartoon images as the representation of movement," he added.