Teaching People with Profound Disabilities to Control the Computer with Eye Movements: The EagleEyes Project.
The EagleEyes technology senses a person's electro-oculographic potential (EOG) through five electrodes placed on the head. Two channels are sensed: vertical and horizontal. The primary source of the signals is the potential difference between the cornea and the retina. The signals change by about 20 microvolts for each degree of eye movement. The electrodes are connected to two Grass Instruments electrophysiological amplifiers. The signals from the amplifiers are read by a National Instruments data acquisition board in a Windows or Macintosh computer. Specially developed driver software takes the signals from the board every 10 milliseconds and converts them into mouse pointer coordinates
Thus as a person changes the angle of the eyes in the head the mouse pointer moves accordingly on the screen. The operator uses a switch (or the NumLock key) to change between mouse control and EagleEyes control.
EagleEyes works as a mouse replacement with both commercial and custom software. The picture below shows Alexa using EagleEyes to "eye paint", to paint a picture on the screen with her eyes. In addition to the eye painting software, we have developed a variety of customized software for use with EagleEyes, including simple video games, spell and speak communication software, and educational software. We also use popular commercial software, such as the Living Books series, Disney software, Speaking Dynamically, and Clicker with EagleEyes.
The EagleEyes driver allows for a mouse click to be generated based on dwell time. That is, if the pointer is held within a certain radius on the screen (usually 30 pixels) for a certain period of time (usually ½ second) the driver can generate a mouse click for the application program.
A major challenge of the project is to teach people how to move the pointer reliably by controlling the signals sensed by the electrodes. Undergraduates without disabilities learn how to control the signals well enough in 30 minutes to spell out messages using an on-screen keyboard at the rate of one character every 2.5 seconds. The young people with whom we work have more difficulty. People who were born with no voluntary movement may lack even the notion that they can cause changes in the world. They always have been spectators. First they need to realize that they can actually move the pointer on the screen by moving their eyes. Some of the people have involuntary tremors or spasms. Some lack normal eye control. Some have nystagmus. Some of the people with whom we work are profoundly depressed and need to decide that they want to become actively involved with the world. Some are teenagers and do the opposite of what you request out of the sheer joy of being able to rebel for the first time.
The signals we sense are primarily the EOG. The horizontal EOG is much more reliable than the vertical EOG, which can be affected, for example, by involuntary eyelid movements. Our philosophy is that whatever works for the children is fine with us. One young man moves the pointer by moving his tongue as well as his eyes. The software provides immediate feedback. Controlling the pointer through EagleEyes becomes an acquired subconscious skill like riding a bicycle or skiing.
We currently have several dozen young people using EagleEyes, some with good success. Any success is a gift, a gift that can have a profound effect on the person, on the person's sense of self and self-esteem, and on the family.
The EagleEyes Project is a non-profit humanitarian effort by Boston College. We have a facility at the Campus School, a school for children with profound disabilities that is located on the Boston College campus. We have two satellite facilities at collaborative schools in towns near Boston. There is an EagleEyes system at an early intervention center in Connecticut and one at the Holly Bank School in West Yorkshire, England. An EagleEyes system should be in operation at the Assistive Technology Center in Birmingham, England soon. Half a dozen children have EagleEyes systems in their homes. All dissemination and licensing of EagleEyes systems is done through the Campus School. We are interested in making the EagleEyes technology available to anyone who can use it.
We have tried the technology with some adults with cerebral palsy, muscular dystrophy, disabling strokes, and ALS. One gentleman with advanced ALS used EagleEyes to spell out the message "There is no way to the end of the journey but to travel the road that leads to it".
For more information see http://www.bc.edu/eagleeyes or the forthcoming monograph
P. DiMattia, F.X. Curran, and J. Gips, EagleEyes: Emancipating the Intellect of Learners with Severe Disabilities, Edwin Mellen Press, in press.