Some things are just too terrible for my mind to process. The story of Richard Marsh, who woke up in intensive care following a stroke with “full cognitive and physical awareness, but an almost complete paralysis of nearly all the voluntary muscles in my body” to hear doctors discussing whether to switch off his life support machine, was one of the most harrowing things I have ever read. A religious person would have read that story and prayed – but my instinctive reaction was to hope that science would find a way to make these terrible situations better. And as it happened, just two days after I read Marsh’s story in the Guardian, New Scientist carried a story of an amazing new technology that will allow locked-in survivors to communicate much more naturally and easily than they do now.
Amazingly, Marsh recovered and now has a healthy and active lifestyle. He has recovered 95% of his cognitive ability and has even taken up cycling. Other sufferers of locked-in syndrome are not so lucky but once it is recognised that their cognitive ability is intact, they may be able to communicate by blinking. French author Jean-Dominique Bauby dictated his entire memoir, The Diving Bell and the Butterfly, by blinking, and the Sun carried a remarkable story of an even more remarkable woman and her inspiring young family who are living and loving life even though she is paralysed from the neck down. Her husband reads the alphabet to her and she blinks at the relevant letters to spell out her thoughts.
This is inspiring and deeply moving, but one thing it cannot be is easy. Marsh described his lonliness in the long nights spent alone at the hospital, “the loneliess of knowing there’s no one there who really understands how to communicate with you.”
People have investigated using the eyes to write before now, but this is difficult as our eyes constantly make fast, jerky movements called saccade. When we look at something, we our eyes are constantly moving even if we think our gaze is fixed. Our eyes focus on something, then move, stop, move, stop again – much faster even than the blink of an eye. This enables us to see much more effriciently, but as we cannot consciously control the speed at which our eyes move in between stops, it has made it challenging for us to move our eyes smoothly enough to trace out letters that people around us can read.
But Jean Lorenceau, a researcher at the Pierre and Marie Curie University, Paris, has developed an ingenious optical illusionthat will trick our eyes into moving
smoothly – smoothly enough that we can draw with them. For all the locked-in patients in the world, this could change their lives. Unable to move, they must rely on others to meet every physical need, and the ability to communicate is absolutely essential. Marsh remembers some rough handling in hospital – this was probably not intentional, but when Marsh had no way to tell the nurses that he was uncomfortable, they could not have known to be more gentle. The ability to write will surely make it easier for locked-in patients to meet and communicate with new people – people who aren’t already familiar with the blinking system that a particular person has developed for their own use.
Phi motion is the technology used to convert still pictures into a moving film. Lorenceau has used a technology called “reverse phi motion.” By changing the colour of an object, that object can appear to be moving backwards. It’s a strange concept, and hard to believe until you’ve seen it:
Lorenceau was idly watching an illusion just like this one when he noticed that his eyes were doing something unexpected – they were following a field of flickering dots smoothly, without saccade. This type of eye movement, called smooth pursuit, is what we use to track moving objects, but it is difficult for us to start and maintain it. Partly this is because when we are tracking a moving object, the still background constantly slips away from the moving object, injucing saccades. But reverse phi motion is different in that the background appears to move with a moving object, making it possible for us to track something smoothly.
Lorenceau has since designed his own reverse phi display, featuring 200 disks that switch between black and white and are projected on a gray background. People follow a moving dot with their eyes, and the reverse phi motion keeps their movement smooth enough that a gaze-tracking camera can follow the right eye’s movements and use them to move a cursor on a screen which will spell out words and sentences.
This technique is not natural, and Lorenceau did note that some people could pick it up much more readily than others. However, 6 volunteers were trained to control their eye movements in just three 30 minute sessions. Lorenceau is currently perfecting his training so that the technique can be learned by anyone, including paralysed patients. He seems to think it is possible “It’s like surfing, you move your eyes to get on the wave and once you’re on you just slide with it.”