In everyday life, smooth pursuit eye movement is used to track moving targets, Lorenceau explains. While people do have the ability to move their eyes in exquisitely sophisticated ways—and in fact our eyes never cease to move—it is normally impossible to control those movements smoothly in any direction.
Lorenceau's team got a hint that smooth eye movements just might be possible in a completely accidental way. He was moving his own eyes in front of an unusual visual display in his lab and discovered that it produced some odd effects. For one thing, he could see his own eye movements. With a little practice, he gradually discovered that he could control those eye movements, too.
The technology relies on changes in contrast to trick the eyes into the perception of motion. When viewing that changing visual display, people can learn to control their eye movements smoothly and at will, the new study shows. It doesn't take very much practice either.
"One can also imagine that, on the long term, eye movements can routinely be used in man-machine interactions," Lorenceau says.
Lorenceau is now working on a better version of his eye writer, and tests with ALS patients should start next year.
A new technology described in the paper published online on July 26 in Current Biology, a Cell Press publication, might allow people who have almost completely lost the ability to move their arms or legs to communicate freely, by using their eyes to write in cursive. The eye-writing technology tricks the neuromuscular machinery into doing something that is usually impossible: to voluntarily produce smooth eye movements in arbitrary directions.
(Photo Credit: Lorenceau et al., Current Biology)
These are examples of digits, letters, words, signature or drawings generated at will by projecting ones visual imagery onto the temporally modulated display depicted in the text. Neither smoothing nor filtering was applied to the eye traces that were only segmented into chunks, when necessary.
(Photo Credit: Lorenceau et al., Current Biology)
Source: Cell Press