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CSD 2230

Selection Techniques

Direct Selection

1. Direct selection refers to techniques in which the individual points directly to desired items in some manner. Because it is rapid and simple, it is the most conducive approach to communication.
2. Selection Options
   1. Physical Contact
      1. Physical Pressure or Depression
         1. Hand or arm Movement
         2. Head Movement
         3. Mouth Movement
         4. Foot Movement
         5. Headstick
         6. Chinstick
         7. Targets requiring pressure to be activated.
         8. A guard
   2. Point (no contact)
      1. Eye pointing
         1. Eye Gaze
      2. Use of optical or light generating device
         1. Use of sonar or infrared technology.
         2. Light Beam
         3. Ocular motion
      3. Voice Recognition
3. Comparing nonelectronic and electronic direct selection
   1. More control for electronic aid.
   2. Position sensitive

Scanning

1. Scanning involves presenting items until the individual indicates that the desired item has been reached. A familiar example is Twenty Question. The items in the selection set are displayed wither by a facilitator or by an electronic device in a predetermined configuration. The user must wait while the facilitator or electronic device scans through undesired items before reaching the item of choice. At this point the user indicates in some way that the desired items has been presented. Often thought of as the last-resort selection technique because it is slower than direct selection.
2. Scanning Patterns
   1. Circular Scanning Techniques
   2. Linear Scanning Techniques
      1. Visual Linear Scanning
      2. Auditory Linear Scanning
   3. Group Item Scanning
      1. Auditory Group Item Scanning
         1. Do you want food items?
         2. Drink items?
      2. Row-column scanning
      3. Horizontal group-item scanning (Ke:nx)
   4. Directed scanning
   5. Selection Control Techniques
      1. Directed (Inverse) Scanning
      2. Automatic (Regular or Interrupted) Scanning.
      3. Single-step scan
3. Types of switches
   1. Tread Switch
   2. Lever switch
   3. Puff and sip switch
   4. Cushion switch
   5. P-switch (piezoelectric sensor)
   6. Joystick
   7. Multiple switches-
4. Morse code
   1. Two single switches
   2. Single switch
5. Feedback
6. Comparing nonelectronic with electronic scanning
   1. Greater physical ability is required to use an electronic scanning technique than a nonelectronic one.
   2. Greater cognitive abilities may also be required because the user must select the items independently from the aid's display without assistance from the partner.
7. Advantages of scanning
   1. Used by individual who cannot directly select items
   2. Because scanning requires only minimal movement.
   3. Scanning rate can be modified to accommodate the individual's response time. Less fatiguing over a period of time
   4. Used by visually impaired
8. Disadvantages of scanning
   1. Slow
   2. Requires greater cognitive abilities
      1. Individual must be able to attend to the targets on aid's display while waiting to indicate the desired item. It requires:
      2. Focus on several items at once
      3. Locating desired item
      4. Rejecting unwanted items
      5. Focusing on partner or cursor to indicate
      6. Greater memory ability
      7. Length of message (nonelectronic) - This can be difficult if the message is of any length, unless partner writes down each item as user indicates it.