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Computer Human Interface Devices for People with Upper Body and Cognitive Impairments

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Much thought and work has gone into making the two most ubiquitous computer-human interface devices easier to use for large groups of people. Different manufacturers boast different ways of making their product "ergonomic" and "easy to use". What is lost, however, is whether these additions actually help the populations they try to provide for. This article will cover both the keyboard and mouse for two populations, those with upper body and cognitive impairments; In doing this, we will cover the issues caused by the input device, what assistive technologies have been provided to aid in the use of everyday versions, and what special assistive devices have been developed.

Contents

How Impairments Affect Using Computer Human Interface Devices

Upper Body Impairments

The inability to reach and lift the arms and hands makes for difficult continued use of the keyboard and mouse. Continued use of the keyboard and mouse have been known to cause repetitive stress injuries to those with normal use of their limbs. The normal layout of a keyboard requires precision movement of both hands over and over to type words and phrases. Many of the keys on the keyboard are not accessible from the normal position of the hands. This continual movement would cause quick fatigue in those with an inability to teach and lift their hands and arms. Most mice, both trackball and laser, require the user to slide the mouse around the mouse pad, making precision movement to guide the cursor to the correct place on the screen. To complicate things, many mice have a scroll wheel or other smaller buttons used for specialized tasks. These smaller buttons would be harder to press for those with the lack of fine motor control. When looking for a everyday product for those with upper body impairments, look for large keys, large buttons, and little resistance for presses. The keyboard should have space to rest the wrists and the mouse should be on a pad that would allow for somewhat frictionless gliding.

Cognitive Impairments

Those with cognitive impairments would have the most problem with mapping how their input into the keyboard and mouse translates to the computer's activity. The keyboard translates a linguistic task (speaking) into a spatial task (finding and selecting keys). This translation causes confusion in those with certain cognitive impairments. The mouse also translates information, this time as motion in one dimension to motion in another. This translation is difficult for many not used to computers, even those with no cognitive impairments. Those with cognitive impairments have it worse. Everyday technologies for those with cognitive impairments should have easily perceptible information and be as simple to operate as possible.

Assistive Technologies that Aid in the Use of Everyday Technologies

The Keyboard

Upper Body Impairments
A Keyboard Wrist Support
A Keyboard Wrist Support

Most of the assistive technology made to aid in the use of the everyday keyboard is available and marketed to the general public as "ergonomic" wrist rests. These foam or gel rests elevate the wrists to a level at which the keyboard can be comfortably used without having to suspend the wrists over the keyboard for lengthy amounts of time. This helps with the fatigue of reaching and lifting the wrists. It does not aid with movement of the hands or the fine motor control required.

Cognitive Impairments

Very few assistive solutions have been developed to help with the use of a keyboard. The best solutions come in the programming of the computer itself to vocally repeat everything that has been typed as a sort of feedback to the impaired user. These types of programs are generally called "text to speech" applications. Microsoft Windows provides this function as an accessibility option.

The Mouse

Upper Body Impairments
A Mouse Wrist Support
A Mouse Wrist Support

Similar to the keyboard, "ergonomic" wrist supports are sold to place the wrist at a correct height. This removes the problem of fatigue but not the problem of precision motion or small buttons and scroll wheels.

Cognitive Impairments

There are no widespread solutions to help in the use of everyday mice for those with cognitive impairments. Most solutions take the place of the mouse, not aid in using an everyday one.

Assistive Technologies that Take the Place of Everyday Technologies

The Keyboard

Upper Body Impairments
The Kinesis Advantage
The Kinesis Advantage

The recent proliferation of "ergonomic" keyboards is both a blessing a curse. The most common of these keyboards splits the keyboard in half, tilting each half closer to the hand that keys in those letters. This helps by placing both the hands in a more natural position, removing the need to rotate the wrists inward. More expensive and harder-to-find keyboards such as the Kinesis Advantage Contoured Keyboard[1] curve the keys so that no movement of the wrists is required to press all the keys; all keys are within reach of a finger at all times with no wrist movement. Some level of precision is still required, but the last of hand movement makes developing muscle memory easier.

Cognitive Impairments

In relation to cognitive impairments, it is easier to remove the keyboard from the interaction entirely, instead relying on more direct input of linguistic stimuli. Speech recognition programs are becoming easier and easier to find and better and better at recognizing speech. Microsoft Windows already has this feature integrated into many programs. All that is required is some type of microphone to allow the computer to pick up the speech.

The Mouse

Upper Body Impairments
The Logitech TrackMan Wheel
The Logitech TrackMan Wheel

The most well-known mouse replacement available to those with upper body impairments is the "trackball mouse". The one shown is the Logitech TrackMan Wheel mouse[2]. Instead of moving the mouse to move the cursor, the ball is rolled in its socket. This removes the need to move the mouse. Many of the trackballs on the market have mouse buttons larger and less resistant than those on normal mice and are shaped to fit the hand. These changes allow those with a lack of fine motor strength and control be able to make the necessary movements to use the mouse without reaching or lifting. The ball is also somewhat large, allowing for precision movement onscreen with less precise hand movements.

Cognitive Impairments
The Wacom Cintiq
The Wacom Cintiq

Two possible solutions are available to those with cognitive impairments. To alleviate the translation errors, input devices with a better one to one mapping to the screen itself have the best success. The first solution is a touchscreen. Touchscreens remove the mapping problem; they allow for direct interaction and selection on the screen itself. Touchscreens are expensive, though, and often have a hard time with precision selection. The second most common solution is a writing tablet, either on the screen itself or attached like a mouse. The Wacom Cintiq Tablet is shown[3]. Good writing tablets are currently used by artists to crate digitally, so they have no problem with precision work. They do require more abstraction than a touchscreen, though, as they require the use of a pen or stylus.

References and Authorship

  1. Kinesis Corporation, The manufacturers of the Kinesis Advantage Keyboard.
  2. The Logitech TrackMan Wheel Mouse, An example of a trackball mouse.
  3. Wacom International, The manufacturers of the Wacom Cintiq.


Author: Ralph Cullen
Affiliation: Georgia Tech