Selection and Access Methods Flashcards
control enhancers
aid that enhance or extend the physical control (range and/or resolution), may make direct selection possible, or decrease fatigue
types of control enhancers
- mousticks
- headsticks
- handpointers
- arm supports
- changing angles/positions may be critical
keyboards for direct selection
- standard keyboards
- expanded keyboards: larger size for improved resolution
- contracted keyboards: smaller size for decreased needed ROM
- isolated switch-array keyboards/keypads: separate switches (note that switch joystick is a switch array)
- touch screens/touch tablets
- tongue-touch keyboard (palatal prosthesis?)
- special purpose keyboards: non letter or QWERTY
- chord keyboards
direct selection keyboards
- construction: mechanical keys, membrane
- actuation method: fingers/body parts
- feedback: auditory (click), tactile (push)
- activation force: membrane is lower (minimal movement and pressure), membrane is higher (increased movement and pressure)
standard and alternative pointing devices: questions to ask
- can the patient use pointing device to reach all targets on screen?
- is size/spacing of targets appropriate?
- can patient complete action needed to select and perform other functions (e.g. mouse click)
- does control interface provide sensory feedback?
- does patient use keyboard layout effectively?
mouse
- standard
- trackball
- head-controlled mouse: sensor detects head movement and sip/puff or other switches
joysticks
- continuous (proportional)-input (analog) joystick
- discrete (switch array)
eye gaze systems: non-assisted ETRANS
- clear board that listener looks through to see patient and watches where eyes are
- alternatives is frame/ring with symbols on periphery: center is open and listener watches through opening in frame
eye gaze systems: problems
- confusion of patient scanning (to see what symbols are on board and in which location) with selection: linger time may be a solution, but not optimal
- electronic tracker does not work well with glasses and tracking is suboptimal anyways: needs more work
voice recognition
- speaker dependent vs. speaker independent
- context: isolated words, running conversation
voice recognition: problems with handicapped
performance with dysarthria is not well established, but some articles suggest possibly better performance than humans because humans are tied to pre-expectations of normal speech (as long as dysarthria is consistent, then machine may work)
modifications to keyboards and pointing devices
- keyboard layouts: traditional (sholes), dvorak
- keyguards, shields, and templates
- hardware key latches
- software key latches and filters
single switch and switch arrays for indirect selection: questions to ask
- can patient activate switch
- can patient wait for appropriate selection
- can patient activate switch at the right time
- can patient maintain switch activation (hold)
- can patient release on demand
- can patient repeatedly carry out steps for selection
single switch selection techniques for scanning
- non-hierarchical
- hierarchical
non-hierarchical
- linear (row 1 then row 2, then 3 in order L to R)
- circular (clock communication)
