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"Switch Access" Scanning
Not to be confused with a flatbed scanner for input.
Switch access uses one or more switches to select from an electronic (set) of graphic images, symbols, and/or alphanumeric characters. Scanning is an alternative to accessing the keyboard and mouse. This is a slow, but functional alternative for individuals with significant physical limitations. The individual only needs to have consistent control of one or more anatomical sites for accessing a single switch, or multiple switches.
At first glance, switch access might seem the easiest alternative input technique for accessing the computer.
The individual's cognition must be considered. Simply having the ability to activate a switch, does not mean the individual is a likely candidate for scanning as an input method.
There are several "direct scan" methods available for accessing the computer. For example methods include:
- automatic scanning,
- step scanning,
- inverse scanning.
After selecting a method to scan-- a decision as what "selection set" format is best:
- sequential,
- rotary
- row-column,
- group-item.
NOTE: A good practice before recommending switch access for input-- type a paragraph or more using single switch access. You will get a feel of the cognitive demands placed upon an individual. Timing (is the candidate able to activate when desired selection is highlighted), tracking (is the candidate able to follow the scanning selections), cause and effect (does the candidate understand the scanning process).
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