Snapping shortens effective distance and reduces pointing difficulty
Aliases: snapping · sticky target · target attraction
What it is
Target snapping automatically pulls a pointer or dragged object toward a candidate object, alignment line, or grid when it is nearby. It shortens the effective distance people must move manually and expands positions from which they can stop successfully, reducing motor-control demand for small targets and precise alignment.
Why it happens
The system defines candidates, snap radius, and post-snap offset, mapping raw input coordinates to a nearby constrained location. Within a threshold, small motion reaches the target; outside it, direct control returns. Snapping discretises continuous space and uses geometric constraints to reduce endpoint noise, while changing the actual location people expect to control.
Studying it
Vary radius, target size, distance, alignment type, and device; measure time, endpoint error, reverse correction, escape attempts, and perceived control. Test single-target selection, precision alignment, and dragging separately because one snap parameter does not benefit every task alike.
Where it stops holding
Snapping helps most with sparse, semantically clear candidates. Dense candidates, free drawing, and continuous path editing can make it obstruct intention. Without visible snap cues, people feel the pointer moved itself. Automatic correction also cannot replace better hit regions or target layout.
Applying it
- Snap only to clear, low-ambiguity candidates and show the current snapped object or alignment line.
- Keep entry, retention, and release rules stable, avoiding large jumps from tiny motion.
- Track immediate post-snap reversal and repeated release attempts as evidence of whether snapping helps.