Assistive Technology for Computer System Input - Alternative Keyboards

If changing the way someone accesses a standard keyboard by using typing aids is not effective, the next step is to look into alternative keyboards. Alternative keyboards provide different layouts, shapes, and sizes to benefit people with various disabilities ranging from repetitive stress injuries to severe visual impairments and amputations. This section discusses several types of alternative keyboards.

• Ergonomic Keyboards - There are many different designs of keyboards that are considered ergonomic keyboards. The common thread among all of them is that they are designed to hold the user's hands and wrists in a neutral position when typing to help prevent RSIs. An easy way to determine if the hands are in a neutral position is to look at the user's wrists while they are typing. If there are no wrinkles present on the skin due to wrist bending, the user's hands are in an ideal typing position. Preventing RSIs has resulted in many versions of ergonomic keyboards all which have some variation of a curved and raised-in-the-center keyboard design along with some type of palm padding, both of which prevent unnatural bending of the wrists. Occasionally,  the design results in a split keyboard that the user can customize by bending and positioning it to a comfortable/neutral position. Although the design of ergonomic keyboards is different to help prevent RSIs, the key layout has no effect on RSIs, so the layout remains the same as that of a standard keyboard.



• Large Key Keyboards - These keyboards are designed similar to standard keyboards, but with physically larger keys. The larger size provides both a larger target area and a larger display representation for each key. A typical user would be either someone with a fine motor disability who needs a slightly larger target area to type accurately or someone with a visual impairment. The larger key size provides a correcting factor, not present on a standard keyboard, for slightly inaccurate targeting resulting in a more accurate typing for people with slight fine motor disabilities.



• Small Key Keyboards - These keyboards are designed with smaller keys and smaller gaps between keys than a standard keyboard. Often, the layout is also changed so that the most frequently used keys are located near the center of the keyboard. These keyboards are typically used by people who type with one hand, who fatigue easily when typing, or who have good fine motor control but lack consistent arm movement due to a disability. The smaller keys, shorter distances to move, and frequency layout allow easier, quicker access for one-handed typing while also limiting necessary movements to prevent fatigue. The limited distance to move also maximizes the use of fine motor control while reducing the need for gross motor movement when typing.



• One-handed Keyboards -  These keyboards are typically designed as half the size of a standard keyboard. Each key represents both a primary key as well as a secondary key ( a key in the mirrored position on the other half of the keyboard).   For example, the "Q" key would also be the "P" key. To utilize the secondary letter (on a left-handed keyboard "Q" is primary and "P" is secondary), the user must hold down the spacebar key while pressing the primary key. These keyboards are available as either the right or left half of a standard keyboard. Typical users of this type of keyboard are people who can only type with one hand due to an amputation or a stroke. Blind people who want to limit the number of keys the need to navigate are also common users. There is an acknowledged steep learning curve associated with this type of keyboard, especially for people who were not two-handed touch typists prior to their disability. However, when it has been mastered, typing speed can be close to that of a two-hand typist on a standard keyboard.



• Onscreen Keyboards -  These keyboards are virtual keyboards, displayed directly on a computer screen. They can be customized in terms of size, key spacing, and color and are accessed using a mouse, mouse emulating device, or a touch screen. These keyboards are used by people with disabilities who's primary access to a computer is through the use of a mouse emulating device. The downside to an onscreen keyboard is that is must sit over the program one is typing in, limiting functional space on the screen.



• Braille Keyboards -  Braille keyboards are simply standard keyboards with stickers over each key that provide Braille representation of that particular key. These keyboards provide access to people who are blind and who are not touch typists.



• Chorded Keyboards - While most of the other keyboards discussed look similar to a standard keyboard, chorded keyboards are dramatically different. Chorded keyboards consist of a limited number of keys (usually 5 - 12). Each letter or command is produced through a series of key combinations. This results in a high cognitive load because the user must remember a key combination for each letter. These keyboards are often categorized as one-handed keyboards because due to the small number of keys, the typical user is someone who lacks function in one hand due to an amputation, stroke or other disability resulting in an inability to use one hand.

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Alternative Keyboard Examples