How Stephen Hawking Uses a Computer (Switches and Scanning)

You might wonder how Stephen Hawking can operate his computer and tell it what to say. He uses a single switch activated by the movement of a muscle in his cheek along with some specialized software that presents choices that narrow down to what he wants to say or do. This article discusses the range of switches and related software that allow anyone with a single consistent motion they can control to use a computer.


There are hundreds of switches sold for use by a person with a disability.  A big red button is a popular version, first produced by Ablenet. (Ablenet sells over 15 types of switches.) There are tiny switches can be hit with a small finger movement or may be mounted for hitting with the chin, back of the hand, or side of the head. Some switches are activated when they are tilted. There are sip or puff switches that look like a straw, foot switches, pillow switches and more. Some switches activate when you let go or after you press for a few seconds.

Matching the person with the right switch is often accomplished by trying out some different types. It's best if the person conducting the trial is knowledgable about the many types of switches and related hardware and software.

Some switches can plug right into the USB port of the computer, but others may plug into a switch interface. The switch interface may plug into the computer or it may be wireless. Some use a switch interface in order to use more than a single switch. If a person with a disability can hit more than one switch, it speeds up typing and communication. A single switch can be used by young children to turn on a mechanical toy. An interface might allow someone to turn on a light, a radio, or the TV by hitting a single switch.


It's easier to show than to describe how scanning software allows one to type or do things on the computer. This You Tube video from Easter Seals of Indiana gives the basic idea. This illustration from the University of Washington shows some of the adjustments you can make to a typing scan. 

Most of us directly select a key on a keyboard. Scanning presents a set of choices that let you hone in on the key or command that you want. It may take multiple hits on your switch to get to the final word.

This You Tube video shows a few brief shots of Stephen Hawkings scanning display. He uses a switch to scan through and select a letter, and then the display offers a large number of words beginning with that letter. 

Scanning is also used on dedicated AAC devices for speech. This Cheap Talk 8 video shows how 8 phrases can be selected via a single switch. A wide variety of scanning communicators are available for people with physical and/or cognitive disabilities. Software for the iPad is also available to allow the use of a single switch or to turn the surface of the iPad into a switch for a speech application. One example is called TapSpeak.

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