When a person's mobility impairment prevents the use of a standard keyboard or mouse, using a switch may be a possibility. Switches come in a nearly limitless array and can be controlled with nearly any body part. Switches can be activated with a kick, a swipe of the hand, sip and puff by mouth, head movement, an eyeblink, or touch. Even physical closeness can activate a proximity switch. These switches work in concert with a box or an emulator that sends commands for the keyboard and/or mouse to the computer. Although switch input may be slow, it allows for independent computer use for some people who could not otherwise access a computer.
A variety of input methods rely on switches. Scanning and Morse code are two of the most popular. Upon activation of a switch, scanning will bring up a main menu of options on the screen. Additional switch activations allow the user to narrow the options down to the desired keystroke, mouse, or menu action. Morse code is a more direct method of control than scanning and, with practice, can be a very efficient input method. Most learners quickly adapt to using Morse code and can achieve high entry speeds.
Switch systems should be selected and mounted with the assistance of a knowledgeable professional, such as an occupational therapist. If mounted to a wheelchair, a switch must not interfere with wheelchair controls. Seating and positioning specialists can also help determine optimum placement for switches, reduce the time involved in discovering the best switch system, and maximize positive outcomes.
For more information, consult Working Together: Computers and People with Mobility Impairments and Working Together: People with Disabilities and Computer Technology.