Motion that runs too long blocks the next action
Aliases: overlong duration · held-up input · transition occupying the loop
What it is
The next action is often planned before the display has settled. If a transition is still running, people either idle until it ends or tap a moving target and miss. Overlong motion splits a continuous sequence; the cost is a forced viewing insert in the action loop, not a lack of polish.
Whether the clip can be interrupted is a separate layer. Even when it can, a long default still makes most people wait it out — the default is the everyday tax.
Why it happens
Pointing needs a stable target location. A hit region that is still updating its coordinates forces motor planning to wait for rest or to fire at stale coordinates. Every extra slice of duration therefore stretches the gap between two successful inputs.
Attention is also captured by motion. While the display is still changing, people treat the current event as unfinished and withhold the next tap. In a demo that reads as ceremony; in a repeated task it breaks expert rhythm. Long and short fail asymmetrically: too short never builds a path; too long builds the path and then refuses to hand control back.
Studying it
Use a serial action task: require a tap on the next target immediately after the transition, and log the gap from animation end to the next successful input, plus errors onto the moving target. Independent variables: duration, whether the target is tappable during travel, whether skip is offered. Dependent variables: sequence time, mis-taps, reports of being held up.
An expert–novice split helps. Novices may use a long transition once to learn space; the same people on the tenth trial judge that duration as obstruction. Do not set duration from a one-shot appreciation rating.
Where it stops holding
- Infrequent, high-consequence confirmations (payment done, permission granted) can run longer, because the loop already contains a pause.
- When the user is watching rather than chaining taps, a slightly longer spatial demonstration may not obstruct — the blockage lives in high input-density stretches.
- Interruptible-but-still-long defaults fail for people who will not interrupt; default duration has to be set on the high-frequency path.
Applying it
- Set duration by input density of the flow: short transitions on chained taps, flicks and paging; a duration that can finish telling space on one-shot entry.
- Do not stamp one duration on every distance and every task; that makes short travel feel sluggish.
- Check: time a continuous task on the target flow at short versus long duration. If completion time degrades linearly with duration, the loop is being held.