Setting up the Selection Technique that is Right for You.
Access Cheat Sheet
Although this article is based on VT/VG Selection technique menu, many of these techniques apply in the Pathfinder also. These are the most basic settings and principles to remember when considering access.
Direct Selectors:
- Makes mis-hits: increase acceptance time
- Makes double hits: increase release time
Headpointers:
- User has large head movements: start with small Vertical/Horizontal adjust #s
- User has limited ROM, i.e. small movements: large Vertical/Horizontal #s
- User makes mis-hits: lower V/H adjust #s and increase acceptance time
- Calibrate Headpointer every few minutes by looking to the edges of the screen (the cursor should be centered when looking at the center)
- Averaging determines how far into the next key the cursor has to move to activate.
Scanning modes quick reference:
- Scan direction: linear or circular for smaller overlay (ex. 8), items below are based mainly on row column/column row used for larger overlays (ex. 45).
- Menu items that most dramatically change scanning are ‘Scan Type’ and ‘Scan Mode’
- Single Switch Scanning
- Scan Type – Auto, Scan Mode 1
- Least amount of driving involved. Need good timing. Scanning is continuous, minimal switch hits.
- Scan Type – Auto, Scan Mode 2
- Mode 2 adds a switch hit. In row/column or column/row will wait for another hit before continuing scan after first hit. Can dramatically help user with minor timing trouble.
- Scan Type – Step, Scan Mode 1
- If switch movement is repeatable and/or timing is poor with automatic scanning
- Scan Type – Step, Scan Mode 2
- Allows for indefinite pause after selecting row.
- Scan Type – Auto, Scan Mode 1
**Increasing scan speed number will allow for more time between switch hits before inadvertent selections are made (relevant for single switch).
- Scan Type – Hold, Scan Mode not relevant
- When holding the switch activated and releasing it at the desired location is the most efficient and accurate method. If too many mistakes make sure to explore 2 switch option.
- 2 Switch Scanning
- Both examples are for Mode 2
- Scan type auto (functions like step in row/column direction)
- 1 switch for scan, 2 switch for selection
- Need two repeatable movements for switch access. Switch 2 will require less hits overall.
- Almost completely eliminates timing requirement
**Increase Scanning Speed number will increase pause time between switch 1 activation and switch 2 activation before timing out.
- Scan type Hold
- When hold/release is most efficient. Second switch allows for continuing to scan if release was incorrect (i.e. second switch acts as manual selection)
Article created by David Kay - PRC Consultant