Persons with dexterity disabilities may have little or no motor control in their hands to perform daily tasks. Many of them (including yours truly) still can operate the computer using one hand, one foot, eyes, a headpointer or a mouth stick. Adaptive keyboards and switches can facilitate persons with dexterity impairments to use computers. Accessibility features in an operating system can further enable users who cannot use their hands to type on keyboards easily.
When MS Windows was an infant, it didn’t have adaptive key options. Consequently, persons who couldn’t hold down modifier keys simultaneously either had to wait for someone else to do it or had to ask a rehab engineer to make a latch to hold/release them. Persons who couldn’t maneuver the mouse had to rely on tabbing alone or, again, on another person to move the mouse. Windows certainly has evolved towards enabling persons with dexterity impairments to use the keyboard without obstacles.
Today, Microsoft Windows offers four such features and can be enabled or disabled in the Easy Access section of Control Panel.
Sticky Keys allows keyboard shortcuts to be executed one key at a time. When a modifier key is pressed, Sticky Keys can enable it to make a sound to alert users of the fact. If the user presses two modifiers simultaneously, Sticky Keys is disabled. To enable it, Shift has to be pressed five times.
Like Sticky Keys, Toggle Keys alerts users when a command key (e.g. CapsLock) is pressed by making a sound. However, the alert sounds can be sporadic in Windows 7 and 8. Some solutions may be the sound driver should be updated or a corrupted file should be fixed.
Filter Keys is an accessibility feature to make keyboard usage easier. It regulates keystroke rates. For example, if the user presses too hard on keys, Filter Keys can prevent repetitive keystrokes by adjusting the number of seconds a key is pressed. It also can prevent users from inadvertently pressing unwanted keys if the user’s hand trembles or slides across the keyboard. Filter Keys can be enabled by pressing the right Shift for five seconds.
Users with motor control impairments can manipulate the mouse cursor by pressing keys of the numeric pad located on the right of the keyboard. Below is a list of numeric pad keys and their mimic mouse moves:
- “/” – Mimics pressing the right mouse button
- “*” – Mimics pressing both buttons
- “-“ – Mimics pressing the left mouse button
- “7” – Moves the mouse cursor diagonally upward to the left
- “8” – Moves the mouse cursor straight up
- “9” – Moves the mouse cursor diagonally upward to the right
- *+” – Mimics a double click
- “4” – Moves the mouse cursor to the left
- “5” – Mimics a click
- “6” – Moves the mouse cursor to the right
- “1” – Moves the mouse cursor diagonally downward to the left
- “2” – Moves the mouse cursor straight down
- “3” – Moves the mouse cursor diagonally downward to the right
- “0” – Mimics holding down the mouse button
- “.” – Mimics releasing the mouse button
Windows provides settings to adjust the pointer speed and acceleration when a numeric pad key is pressed. These settings can make all the difference to a user. For example, some users have these settings set to high so they can move the mouse cursor easily without applying too much pressure while holding down the numeric pad keys with a headpointer, for instance. Otherwise, using the MouseKeys would be slow and tedious. Conversely, slower pointer speed and lower acceleration can benefit users who inadvertently apply too much pressure on the keys.
Tips for Developers
Developers can help implement Windows accessibility features on websites in certain ways.
- Provide instructions and lists of keyboard shortcut keys so Sticky Keys users can know the keyboard combinations.
- Create links and other active areas on a website with large enough space between them so Mouse Keys users can move the cursor to them easily.
- Most importantly, do not implement any scripting that would override any Windows accessibility feature.