Large Button Keyboards

Earlier, a blog post was done on mini keyboards.  It is also important to know about large button keyboards.  


Typically, mini keyboards are indicated for one handed users or individuals that good fine motor control but impaired gross motor control.  Conversely, large button keyboards are indicated for individuals with impaired fine motor, poor gross motor skills.  Users with poor fine motor require larger buttons since they need larger targets for increased accuracy.  

With both mini keyboards and large button keyboards alternative layouts can be obtained; either the standard QWERTY layout that is most commonly used or an ABC layout.  Depending on the keyboard, additional features can be obtained such as alternative colors or number of keys.

Something as simple as changing the size of the keyboard can facilitate independence for an person with impairments.  Individuals that would benefit from this type of change can vary but are not limited to individuals with Parkinson's disease, stroke survivors, Multiple Sclerosis, or Cerebral Palsy.  It is important to always evaluate all forms of technology, including various large button keyboards to make sure to find the best fit for the user for an adaptABLE world.

Direct vs. Indirection Selection?

Selection Options for Device Use:

When evaluating an assistive technology device,  the selection method is one of the most important aspects of the evaluation.  The if the appropriate type of selection method is not being utilized then the user cannot be as efficient and might become frustrated with the device use. These selection methods can be used with computer access, communication devices (AAC or SGD), and environmental control units.

Direct Selection:  Direct selection simply is just what it sounds like; you press a switch and your "selection" is made.  An everyday example of direct selection is a light switch; you "flip" the switch and the light turns on or off.  Other examples of direct selection is the left or right buttons on the mouse, dwell click software, or touch screen use/access for computer skills.  Direct selection can be a very quick form of access for the appropriate individual.  If it is not appropriate, then the individual might spend an extended amount of time to fix errors or be unable to effectively access the device at all.  Direct Selection does not need to be performed with a hand but any body part or technical device in order to make a selection.

Indirect Selection or Scanning:  Indirect selection is also known as scanning which is an indirect way of accessing a device.    

The user will access a switch which will begin intermdiate steps or scanning in order to make a choice.  There are several different types of scanning.  Either one or two switches can be used with scanning; these switches are mounted or positioned at the body part with the best strength or that will not create fatigue with use over time.  

The most common form of scanning or indirect selection is linear scanning.  With linear scanning, the user accesses their switch which begins the scan.  This scanning moves row by row.  When the scan gets to the line with the letter or choice that the user wants, they access the switch again; this begins a column scan.  Once the scan gets to the desired choice, the user accesses their switch again and the desired action happens.  This could be a pre-saved phrase for communication or a letter for typing with an on screen keyboard.

Inverse Scanning is performed with the user holds their switch down to being the scan.  The user holds their switch down until the desired choice is highlighted and lets go to have their choice made.

Group Scanning:  With group scanning, the user accesses their switch and groups are highlighted.  As the group with the desired choice is highlighted, the user accesses their switch.  It then will narrow the choices with a linear scan.

Item by Item Scanning:  The user accesses their switch to move the highlight or cursor in order to make a choice.  This method requires multiple switch access "hits" in order to get to the desired choice.

Other, individuals are concerned that scanning is slower than direct selection.  Points to consider are if the individual is unable to perform direct selection without making a considerable amount of mistakes, indirect selection will be more efficient and less fatiguing.  

Indirect selection is appropriate for an individual with limited movement.  For example, if the user has only one area of movement such as one finger, scanning would be an appropriate access method for access of the computer or a communication device.

Positioning is very important for scanning use.  The switch must be mounted to the area with the best strength so that the user will not become fatigued over time.  Switches can be mounted to any surface such as a wheelchair, tabletop, or bedrail.

Considerations with scanning is that it requires a higher cognitive load.  The user must be able to anticipate the scan and understand the cause and effect of indirect selection.

There are many features that can be modified with scanning.  These include:

• The rate of the speed of the scan
• The type of scan
• The type of feedback
• Audio
• Click sounds
• Reading the scan choices out loud
• Visual
• Highlight color
• Magnification of the scan
• One or two switches

When evaluating an assistive technology device, the type of selection is one of the most important parts of the evaluation and consideration of particular devices.  It is important to remember that the most appropriate access method might not be established within the first session; it can take time to figure out the best method as well as the modifications required to make this method the most appropriate.

Switch Use

What is a switch?


Switches are used with all forms of assistive technology.  The easiest way to think about a switch is a device that can start or stop a device.  The most common type of switch is activate with some kind of touch, creating the contact of two surfaces or switches to work with an assistive technology device.

What kind of switches are there?


There are literally hundreds (if not thousands) of switches available for assistive technology access.  Switches are meant to be accessed by the available body part or motion that is strongest for the user.  This area of access needs to be consistent and not create fatigue with extended use.  The area of access can also vary dependent on the position of the individual.  For example, a person might use their finger for switch access when in their wheelchair and a sip and puff switch for when they are in their bed.


When evaluating what is the best switch site, it is recommended to evaluate distal to proximal.  This means, start with the hands or fingers.  If this is not an appropriate site, what can be done as we move up?  Are gross movements easier than fine movements?  If the individual cannot use their arms, what other areas are appropriate?  


Addition considerations for switch use is the amount of force required to press the switch (if it is a tactile switch).  When looking at the "specs" of the switch, you can find the amount of force in ounces or pounds for access.  This is very important for an individual with limited movement or a harder switch user that needs a more durable switch.

How can a switch be mounted for access?


There are many ways that a switch can be mounted.  Switches can be mounted to a wheelchair, tabletop, or any other surface for best access.  If appropriate, Velcro can be instrumental in attaching a switch for access.  


If additional mounting options are required, a simple tabletop mount might be appropriate.

Removable mounts can be used that would attach the switch to a wheelchair, tabletop, or any other surface.  These mounts can be purchased with varying arm lengths and plate sizes.

More permanent mounting can be done in wheelchair components such as in the headrest.  Conductive fabric and clothing can be used to create novel switches, making it a part of clothing.


What if the user cannot "hit" a switch?


There are switch options for an individual with limited or lack of movement that would be required in order to touch a switch.


Sip and puff:  A sip and puff switch is a great option for users with limited movement or issues with significant fatigue when attempting to touch a switch. Through the actions of sipping and puffing, the user can control their assistive 
technology device.

Proximity:  A proximity switch is activated when the user gets closer to the switch.  Dependent on the switch chosen, the range of how close the individual the user has to get to the switch to activate it can vary.  This switch can be mounted pointing at any area for the user.

EMG switch:  An EMG switch is also known as a muscle twitch switch.  A muscle twitch sensor is placed on a muscle that can be used consistently without pain or fatigue.  When the user contracts the muscle, it activates the assistive technology service. 


Sound switch:  This is a switch option that has been around for sometime.  The Clapper is an example of a sound switch.  When the individual makes a sound, it activates the device such as a communication device.  There are very sensitive sounds switches available allowing for changes in the sensitivity, how loud or soft the sounds needs for access.  


To conclude, the importance of switches and their positioning is very important. If the individual is not setup with the best switch for the strongest access site the user will not be efficient or conserve their energy.  Through a full evaluation, an appropriate recommendation can be made not only for the device but for the appropriate access method.