Steve Lee :: Blog :: Analysis of Alt Input methods used in ATs

This is an attempt to present an analysis of alt input methods in preparation for a GNOME discussion on GDM accessibility.

Input Gesture Types

• Discrete - individual events. E.g key press
• Continuous - changing input, may generate discrete after gesture matching . Eg mouse movement
• Timed - select object/action after a predefined time. E.g dwell click, auto scan

Input methods

• Random - select any object/action using a few gestures. Vision required. E.g pointer with mouse or gaze tracker
• Assigned - select one of a limited set of objects/actions with predefined gestures. Vision not required, memory required. E.g key shortcuts
• Sequential - select next or previous object/action or groups with few gestures. Vision optional, little memory. E.g switch input
• Dynamic - select from a varying choice of objects/actions with a couple of gestures. Vision required, cognition required.E.g Dasher
• Analytic - tracking and analysing continuous input: e.g handwriting or voice recognition

• Keyboard only - a mixture of assigned (keys) and sequential (e.g. Tab) selection.
• Pointer only - uses random and timed access.
• OSK - random access selection and activation of cells. Usually for devices with no keyboard.
• Overlay - superset of OSK but focussed on sequential access usually with various scan modes and group slection strategies. Usually for switch users. An intermediate UI that can simplify interaction by offering a subset and alternative presentation. Often used with symbols for communication or to create simple games or training activities.
• Steering - uses dynamic selection to steer through a changing field of objects.
• In Application Selection - sequential navigation and activation through UI without an overlay.
• Recognition - analytic for dictation and control
• Combination

Example Linux ATs

• Orca - keyboard only input (and relies on Keyboard only input of other applications)
• OnBoard - OSK with some Overlay features. Text input and some control.
• GOK - Overlay with OSK features and dynamic generation of selection sets. Control and text input.
• Dasher - Steering input of text plus limited  symbols and control.
• Jambu - In application, Overlay and OSK, immature.