Use of Eye Gaze and Eye Tracking Control Technology in Rett Syndrome
Rett syndrome (RTT) is a unique, severe, neuro-developmental disorder that occurs predominantly in girls,and causes loss of expressive speech and language skills. Eye Gaze control offers an altenative means of communication, and can give the person with Rett Syndrome access to computers for fun activities. In this brief article I refer to the person with RTT as “she”, but the information could equally apply to males with RTT.
Rett Syndrome manifests as psychomotor regression in early childhood, with loss of hand function, hand-wringing behavior, seizures, breathing abnormalities, and autonomic instability, some of which abate, albeit leaving individuals with severe disability, and in need of care and support throughout their lives. Individuals affected by RTT may have a normal life expectancy. It is a progressive disorder, with an apparent four stage progression. A predominant feature of the disorder is dyspraxia, the inability to perform a purposive movement; which interferes with their ability to carry out actions, particularly when instructed.
People with RTT are known to have specific preference oriented towards people and have genuine interest in establishing communication, but predominantly they are unable to communicate verbally. However, their nonverbal communication is effective and purposeful, and is dependent on carer interpretation and response.
Developmentally, visual fixing (looking at an item or person), visual tracking (watching an item as it moves) and visual scanning (looking from one item to another) are skills that develop in early infancy, i.e. before stage I of Rett syndrome becomes evident. Tracking means that the infant fixes her visual attention on an object, and follows it with her eyes through various planes of movement. Scanning requires that the infant is able to shift her focus from one object to another. An early communication skill often includes “referential looking”, where the infant looks at an item, and then looks at the caregiver. With infants, we tend to take this eye pointing as a request for information, or as a request for the item. Although dyspraxia may affect eye movements too, most girls and women with Rett syndrome can use their eyes effectively for communication.
Individuals with RTT have used eye gaze for many years, to select an object or a picture, to make choices, and to indicate needs and wants. Such methods have been recommended to give control over simple life events to people with RTT. The reason that this method is successful is because eye gaze seems to bypass the difficulty nearly all people with RTT have with indicating their interests through hand use or pointing. Loss of purposive hand use is a diagnostic characteristic of RTT, as is “stereotypic hand movements such as hand wringing/squeezing, clapping/tapping, mouthing and washing or rubbing automatisms”. People who have Rett Syndrome are not usually able to utilize access to communication devices or computers through hand use or switches. I have written a separate document about the systems that can be developed using simple eye gaze.
Eye tracking control
Since at least 2005, eye tracking has been used in conjunction with technology for access to communication systems for disabled persons: allowing the user to speak, send e-mail, browse the Internet, and perform other such activities, using only their eyes. The most widely used current designs are video-based eye trackers. A camera focuses on one or both eyes and records their movement as the viewer looks at some kind of stimulus. Most modern eye-trackers use contrast to locate the center of the pupil and use infrared or near-infrared light to create a corneal reflection. The vector between these two features can be used to compute gaze intersection with a surface after a simple calibration for an individual – in other words, the computer can tell what the user is looking at.
The new Tobii PCEye is an easy to use, stand-alone eye control device that can be used with most personal computers. It is quick to set up, highly accurate and provides total control of the computer using only the person’s eyes. It was developed primarily for individuals with impaired motor skills as a consequence of acquired neurological problems such as Motor Neurone Disease and spinal cord injuries or those needing an alternative method like eye control for controlling a mouse.
Research is needed to find out if the Tobii systems can help people with Rett Syndrome. Trials are being offered to collect information on the use of eye control for computers and communication devices. The company states:
The Tobii PCEye eye control unit flawlessly converts eye movement to a mouse cursor on a computer, attaches to many retail monitors and takes only seconds to complete the one-time calibration. With one of the largest track boxes on the market and award winning eye tracking technology, the Tobii PCEye can be used by over 95% of users to eye control a computer, regardless of eye color, glasses, contact lenses, lighting conditions or head movements. The “Tobii PCEye” eye control unit brings eye tracking to the standard computer and opens up the potential for a huge amount of eye tracking enabled applications, for example, the Tobii PCEye is compatible with: Tobii Communicator, The Grid 2, and Wizkeys Plus (ready-made on-screen keyboard.”
The TobiiPCEye can also enable the person to access other applications and have fun with a computer.
For a person with RTT, eye control of a computer would allow her family, teachers and caregivers to understand and meet even her most basic of needs; it would allow her to engage with appropriate software, and from her actions, we could determine her interests as well as her likes and dislikes.
It is my professional opinion having cared for girls and women with Rett syndrome since 1985, and having seen many on recent videos, that they are fully capable of utilizing eye gaze control in a functional way and would benefit greatly from this. They have the eye gaze control and apparent cognitive abilities to use eye control technology, such as the Tobii device.
Timing of introduction is essential. It is well known that appropriate stimulation has different effects at different stages of life. These periods are known as the “window of opportunity” where appropriate engagement has a direct impact on the development of brain structures. In order to use eye control technology, the person with RTT needs to be able to point with her eye gaze (low tech) and show that her visual searching strategies are meaningful. She also needs to have the ability to be sufficiently focused in order to memorise presented stimuli. Opportunity to repeat these actions will have a lasting effect on her developing brain - activation of neuronal networks is an essential prerequisite for development and strengthening of synaptic connections. Lack of appropriate engagement can have detrimental effect on the development of brain functions.
Rationale for Eye tracking control in Rett Syndrome
The eyes are closely connected to the brain – eye movements and gaze patterns provide first-hand information about brain activity and cognition. Humans perceive the world visually through fixations. The more complicated, confusing or interesting specific features are the longer we fix on them visually, and this provides stimuli that the brain processes.
Preferential looking is a methodology that uses the general concept that we immediately and automatically look at a visual feature when it is detected. Eye tracking is an automatic and reliable tool in detecting fixations; this preferential looking can be used in assessments, diagnostics and rehabilitation.
A feature that stands out as different compared to the background or surroundings is more attractive to look at than repetitive patterns or objects that are similar. Eye tracking makes it possible to use parameters such as “first fixation” and “preferred feature over time” as the marker for a feature seen or not seen. The methodology is already used in assessments of vision in infants, children and nonverbal adults. The use of eye tracking in assessments, diagnostics and rehabilitation as a response method is growing. By objectively registering if a person has seen stimuli or not, you can draw a conclusion, even without the person having to press a button or provide a verbal response.
The main advantages of using eye tracking to study preferential looking and analyze reaction, is because assessments using remote eye trackers are perceived as very relaxing and natural.
The respondents or patients do not even have to know that they are being assessed. It is possible to assess very young children and non-verbal adults.
The Tobii Eye Tracker registers eye and head movements and is therefore a perfect tool to register preferential looking in an objective and automatic way. Research is currently underway in UK on the use of eye control for assessment of cognition, and has been used in a recently published study in New York, for people with RTT.
Our knowledge of communication, language and speech development in Rett syndrome is very limited. Published research to date has not included modified assessment procedures, and the interpretation of results has so far indicated that the girls perform at early levels of pre-intentional communication development (9 to18 months). Future research should include the study of the developmental sequences of language development in Rett syndrome, and examine cognitive and linguistic skills using alternative assessment procedures, which are not dependent on motor responses (especially with the hands). Through the use of technology, such as eye gaze control of computers, we may come to a better understanding of cognitive and linguistic development in Rett syndrome.
In the last three years, Tobii Technology has seen a significantly growing number of users world wide, with a diagnosis of Rett Syndrome. When eye control arrived on the scene, it seemed to be a method to access computers and communication aids reserved for those children and adults with the most severe physical disabilities. Conversely, if children could physically hit an input switch then eye control would not be considered. However, the message which we are hearing from the parents and teachers of students with Rett Syndrome is, “Switches don’t seem to be working for her” or “She can hit a Big Mac but we have not been able to move on to switch scanning.” The delay in co-ordinating the movement to hit an input switch seems to be the stumbling block, whereas eye control seems to be a much more immediately controllable action.
We know that dyspraxia is the overwhelming difficulty that all people with Rett Syndrome have – often the most frustrating part of the disorder. Can you imagine wanting to hit the switch, but you mind’s message just doesn’t get down to the hands? Maybe eye control is more effective because it is more natural, and the girls have been watching the world, and using their eyes even when their hands don’t respond?
We are also noticing that it takes those with Rett Syndrome a relatively long time to start using their devices as communication aids or VOCAs. We know that processing time is delayed, but this difficulty is more likely to do with lack of experience of being able to use language. Most children need to learn the “cause and effect” relationship between hitting a switch or selecting a button and the message that can be activated. Tobii has therefore developed a great new programme called Sono Primo. This set of pages on the computer, based around fun communication concepts, gives a series of games, books and exploratory scenes which can be enjoyed on their own. Once we discover the subject matter which a child enjoys on the Tobii systems, there are communication grids and scripted conversations to support this interest. From here, we can start developing this new found skill into active communication. It is really exciting, especially being able to tailor-make the vocabulary – it is motivating to talk about things that you want to talk about!
Tobii users can also enjoy a number of extra activities by using their eyes, such as Sensory experiences, Painting and stamping in art programs, and Gaming. Many children’s activity websites, such as www.helpkidzlearn.com and www.poissonrouge.com can be accessed with eye control. Music players, Cameras and photo albums, and home automation – controlling TVs, DVDs and MP3 players, and even helping with cooking – all these are possible with eye control.
The person with Rett Syndrome needs the chance to spend time alone enjoying themselves and steadily building up their skills in this way.
One important consideration is funding. There are a number of options that can be purchased, from clip on eye control units for mainstream PCs to all encompassing AAC devices such as the Tobii C15, to so the cost can vary from£5,000 to £12,000. Many schools are also now buying eye gaze systems as a school resource. It is often a financial risk to provide an eye gaze system for an individual student without them proving that they will actually use it. So, some schools are now buying it to use for a variety of reasons and with multiple students. Schools can fund AAC systems for students who have this written into their statement, but the absolute situation remains patchy. Funding for adults is not generally very good, but Tobii can help to direct families and carers to local service providers. There are also charities that can provide funding for systems.
In February 2012, I attended the Rett Clinic in Cardiff, Wales, UK arranged by Professor Angus Clarke. Hector Minto from Tobii, and Shona Mitchell from Inclusive Technology brought along equipment so that each person attending the clinic was offered the chance to trial the system that day. Eye tracking offers us an insight into someone’s cognitive abilities, for example, how well someone responds to auditory prompts, and someone’s search strategy when confronted with information. The computer can accurately replay what someone looked at in real time. Through further work with the Rett Clinics, we hope to raise awareness of Tobii’s products but also to learn new capabilities in a larger sample group.
Health professionals worldwide want proof that this technology offers proven value to people with Rett Syndrome. We really hope that the Cardiff clinic will start the process of finding out and demonstrating what people with Rett syndrome understand.
To try a Tobii solution in UK, you can arrange a free demonstration and loan/trial by contacting Hector directly. Please inform your teachers and speech therapists that you are doing so. The ongoing support of your health and education professionals will be vital to successful implementation. Tobii and various re-sellers are also running eye control assessment clinics in schools around the country. They are free of charge as they really want to raise the skills of the staff in schools.
Hector Minto, UK Manager AT, Tobii Technology AB
Hector has worked in the field of Assistive Technology for 15 years, successfully growing businesses and providing solutions to people living with physical, cognitive and behavioural disabilities.
Sally-Ann Garrett, Highly Specialised Speech and Language Therapist in Independent Practice
Sally-Ann is a Speech and Language Therapist with more than 40 years of experience working with people who have special needs, both in UK and Canada. She has a particular interest in Rett syndrome, and the general field of sensory and learning disabilities