A switch is a simple device that has two states - on and off - just like a light switch.
Switches come in a variety of different shapes and sizes and are operated in different ways. Usually this is through a push motion but you can also buy switches that you grasp, pull, suck or even blink into. The most common type of switch is the jelly bean switch (pictured). There is a selection of switches and some video examples of their operation on my switch hardware page.
People who find it difficult to access the keyboard and the mouse can use a single switch or a combination of switches instead. Switches can help people with a variety of different physical disabilites, from mild conditions like RSI to complete paralysis.
They are also suitable for people with severe learning difficulties as they are a simple, understandable method of accessing a computer.
The correct selection and positioning of a switch is extremely important and support should always be sought from an experienced assessor, occupational therapist or other specialist.
Although the switch itself is very simple we are fortunate to have very clever software that can do all sorts of amazing things with this humble access device.
The function of a switch could be broadly defined into two groups:
This involves the use of a switch to operate a computer, communication aid, environmental control or a wheelchair. In Primary Access Switching, the user relies entirely on a switch or a number of switches to control this device.
Use of switches ranges from single-switch 'hit-and-happen' games for early users and those with severe cognitive difficulties, up to multiple-switch 'scanning' for those who want to use a computer for writing emails and documents, and surfing the Internet.
In these cases a switch plays a supplemental role in the access solution. The most common example is when a switch is used to replace the left mouse button because although the user can move the mouse, or mouse alternative such as a headpointer, they find it very difficult to operate the click button.
See an animated demonstration (requires Flash).
Except in a couple of extremely unusual cases, you can't plug a switch directly into a computer without a special switch interface... [more]
For people who function highly switches can be used to access the standard computer environment using on-screen keyboards and other special tools. There are also some switch-accessible arcade games around.
For younger switch users, or for those who have learning difficulties, there are simpler switch-accessible activities available commercially and on the Internet.
Follow this link to read case studies for switch access.
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