Solitaire, decomposed by the power of sight
Nadezhda Markina, "Science and Life"Russian physiologists presented a computer control system using eye movement at an international conference on Cognitive Science.
The ability to control a computer without the help of hands excites the minds of neurophysiologists all over the world, and several interfaces have already been created that connect a computer with different organs of the human body and directly with the brain. Scientists from the Research Institute of Physiology named after A.A.Ukhtomsky St. Petersburg State University suggest using eye movement for this purpose. The first experiments confirmed that this method works.
When we look at an object, our eyes make a lot of movements: these are abrupt movements of the gaze – the so-called saccades, slow shifts of the gaze, involuntary blinking, tremor of the eyeballs. All these movements are reflected in the recording of the electrical activity of the eye muscles – an oculogram, which is recorded by electrodes placed around the eyes.
When the eyes move on the oculogram, there are bursts – jumps of electrical potential. The sign and amplitude of these jumps depend on the direction and angle of rotation of the eyes. Accordingly, the trajectory of eye movement can be described by the nature of the potential jump. This possibility is at the heart of the idea of controlling the cursor on a computer monitor by eye movement.
Researchers of the Research Institute of Physiology have developed a special installation and software. Four electrodes were used to register the signal: two for each eye. The electrodes placed under the eyes reacted to the vertical displacement of the eyeballs, and the electrodes in the corners of the eyes reacted to horizontal movements. The developers selected such installation parameters – frequency filters and bandwidth that the system ignored the slow shifts of the gaze when tracking an object or when turning the head, and reacted only to saccades and blinks. The system recorded and measured the amplitude of the resulting potential surges. Then, using the ratio of amplitudes on four electrodes, the program calculated the direction and angle of rotation of the eyeballs.
In the experiment, the subject is in a special shielded room in a comfortable chair. In front of him is one of the computer monitors, the other monitor is owned by the experimenter. First, the device is calibrated: the subject tracks the movement of points on the monitor, and the system registers the corresponding potential jumps on the oculogram. In the main part of the experiment, the program solves the inverse problem, and according to the values of potential jumps as a result of eye movements, the cursor is placed in the right place. Blinking, in turn, with the right and left eyes is used as an analogue of pressing the buttons of a computer mouse.
Before the experiment, the subject was trained to control the cursor with the eyes as long as he could do it freely enough. Some of them needed several days to do this. At the end of the training, they could, for example, lay out solitaire on the monitor with their eyes.
The authors believe that this method would be extremely useful for completely paralyzed people, as well as for improving human communication with computer technology.
Portal "Eternal youth" www.vechnayamolodost.ru25.06.2008