One fixed gain cannot satisfy both coarse and fine positioning
Aliases: dynamic gain · segmented gain · precision mode
What it is
Variable C-D gain answers a fixed-gain conflict: rapid workspace traversal needs a higher mapping, while pixel-level endpoints need a lower one. A single value can only compromise; dynamic gain, temporary precision modes, and zoom separate the stages.
Why it happens
Target acquisition commonly combines fast transport and endpoint correction. High fixed gain shortens transport but magnifies endpoint noise; low fixed gain eases endpoints but increases long travel and clutching. Varying gain by velocity, task mode, or an explicit user action can assign different mappings to the stages, at the cost of reduced predictability.
Studying it
Compare fixed, velocity-dependent, and explicit precision modes, recording transport time, endpoint error, overshoot, learning time, and unintended mode changes. Velocity-dependent mappings must cover both slow fine adjustment and rapid movement; testing only average speeds hides behaviour at curve transitions.
Where it stops holding
Dynamic mapping is not always better. Tracing, drawing, expert muscle-memory work, and tasks without visual feedback rely on a stable relation, so changing gain introduces bias. If people cannot predict when a change occurs, correction and distrust can erase saved travel.
Applying it
- For tasks needing both transport and precision, offer comprehensible precision modes, zoom, or snapping and make activation visible.
- Do not impose non-disableable speed acceleration on continuous tracing or professional precision control.
- Validate with mixed distances and target sizes, checking for reverse corrections caused by mode misclassification.
Related
- Same group: C1.03.1 Gain is the ratio of cursor displacement to device displacement · C1.03.2 High gain shortens long travel; low gain improves fine positioning · C1.03.3 Gain couples with display size and pixel density, so it cannot transfer directly across devices
- Nearby: C1.04 Mouse acceleration curves · C1.08 Drag and drop
- Search terms:
variable gain·precision mode·pointer acceleration