Access to High Tech

• Access to High Tech

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    This topic starts with a discussion about eye gaze technology as it is often mentioned in AAC articles.  However, high tech eye-gaze does not work in all settings so alternatives such as switches may be used by children with the most complex physical disabilities.   We will explore:
    

    • The advantages and disadvantages of eyegaze technology
    • Types of switches
    • How to use switches with many links to resources in the Further Reading section
    • Switch scanning

  • High-Tech Eyegaze

    High-tech eyegaze is one of the most modern access methods available for AAC users. It is often used by children who are not efficient with direct access or pointer control. The technology is a useful alternative to low-tech eye pointing as it does not require the communication partner to be trained and able to observe small eye movements, such as when using an E-Tran frame.   The following key points are adapted from Vicki Clarke's article on PraacticalAAC (2016)
    

    What is required for eye gaze access:

    • Sufficient movement control - head and oculomotor. 
    • Sufficient visual acuity with at least one eye
    • Mounting equipment which allows for the device/camera to be positioned where it does not cause repetitive strain for the child (all axis movement on a mount is best, i.e. the device can be positioned higher/lower/left/right/tilted etc. to capture the reflection from the child’s eyes).
    • Cognitive and visual processing skills that allow a degree of attention to targets on the screen.  This can mean there needs to be a minimum of a .3 second pause on an image to begin to work on eye gaze.  This is a brief glance but contunually sustaining these pauses can be a strain for some children. 
    • Patience to calibrate the device, although settings are saved they may differ in various settings
    • Symbol sizes and targets that are comfortable at the distance between the device and the child - the distance from the screen may be from 53 plus cms (21 plus inches)

  •  Activity - Eye Gaze elements

    Drag the labels to the correct areas on the image.
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    Eyegaze isn't Perfect

    Eyegaze does have some disadvantages. Until recently it was one of the most expensive options, with integrated eyegaze communication aids costing more than many people could afford. More recently cameras have become available that work with most Windows computers and tablets. 

    In addition, eyegaze systems are very dependent on the ambient light. While they work without issue indoors, they usually fail outdoors and in sunny indoor spaces, such as in bright classrooms. Children who use eyegaze for AAC need to be able to access a reasonable number of symbols displayed on the screen at any one time. This requires good voluntary eye movements, something which can be hard for children with physical disabilities such as cerebral palsy. 

    Another factor to consider when evaluating eyegaze is the position that it needs to be accessed in order to work. Typically this is directly in front of the child, at head height, mounted safely to the wheelchair. Any variance in this position can greatly affect accuracy. This position can be difficult to achieve, and even if it is possible, then the presence of the eyegaze affects view which in turn affects mobility and awareness, as well as the ability to maintain appropriate eye contact during conversation. 

    
    

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    Activity - Reviewing eyegaze use 

    
    

    Watch the eyegaze video.   How is Jason selecting the symbols he wishes to use?   What are the advantages and disadvantages of this approach? 

    Can you think of any other approaches?   Make a note of your thoughts in your reflective journal. 

    
    

  • Switches

    Switches are robust in the sense that they work in a wide variety of environments as they are not affected by light. Switches are also more accessible as they cost as little as £25 and it is possible to make them yourself.

    There are many types of switch available for children who use AAC. Most are mechanical and require a push from the hand or another part of the body to activate. Other types of switch include electromagnetic that can detect eye blinks, pneumatic switches for children using their breathing to make a selection, through to electrical switches that can pick up tiny signals from muscles and even the brain. 

    The type of switch chosen is decided by the type of movement that the child can consistently repeat in a timely manner. Usually this is arm or hand movement, but switches are often accessed by the knee, foot or through head movements. 
    

    In this video Elliot is using two switches with a game.  Transcript available
  • Switch Scanning

    Switch scanning is the term used to access symbols using switches. Each symbol on the screen is highlighted for a second or two, providing the user an opportunity to press their switch to select it. Switch scanning is typically far slower than eye gaze or any of the other methods described in this module. 

    Fortunately there are a number of ways to make switch scanning more efficient, such as through the use of alternative symbol layouts, scanning entire rows and columns, or using two (or more) switches instead of one.  Examples below taken from Wikipedia

    
    

    
    

    Scanning Example

    Imagine you have a grid of 60 symbols. A typical scan pattern would start at the top leftmost symbol and move right, one symbol at a time, with a dwell on each symbol of 2 seconds. Upon reaching the end of the line the highlight moves to the start of the next line, just like when reading text. If the symbol wanted is in the bottom right corner the user would need to wait for the computer to highlight 59 other symbols before they are able to select the one they want, taking two minutes. 

    
    

    To speed this up most users learn to scan in rows then columns, rather than each symbol individually. A grid of 60 symbols would typically have 6 rows and 10 columns.  Starting with the top row it would take 12 seconds to reach the bottom row. A selection (with the switch) is made to activate this row. Then each symbol is highlighted, from left to right, each taking 2 seconds. Since there are 9 symbols in the row before the one we want this will take 18 seconds. So using this method it would take 18+12=30 seconds to scan to the bottom right, four times faster than using the conventional approach. 
    

  • Summary 

    • Eyegaze can be as efficient as direct access (touch) if the child has good voluntary movement of the eye
    • Eyegaze doesn’t work in all environments, particularly bright sunlight
    • Switches are robust and reliable but can very slow compared to all other access methods

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    Further Reading 

    Eyegaze

    • Eye Gaze 101: What Speech-Language Pathologists Should Know About Selecting Eye Gaze Augmentative and Alternative Communication Systems 
    • Tobii Dynavox: How Eye Tracking Works
    • Face Tracking and Eye Gaze for the iPhone and iPad: Access and AAC(Kathryn Helland, 2019)

    Assessing for Switch Access
    

    • AbleNet Switch Selection Guide (download PDF)
    • Switch Access to Technology 

    Developing Switch Skills
    

    • Stepping Stones to Switch Access (download PDF)
    • Inclusive Technology Switch Progression Roadmap (download PDF)
    • TalkSense: People using Switches

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    Reflective Journal 

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    Journal

    Reflective Journal - High Tech Access devices
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    Presentation slides

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    URL

    Eyegaze & Switch Access URL