Using dwell as an onset or offset signal taxes every command with waiting

What it is

Dwell as an onset or offset means: the hand must hold a pose or position long enough before the system accepts the edge. No extra delimiter move is required, so it is cheap to implement. The cost is a mandatory wait on every command, often with the arm still raised. This is not gaze dwell-to-select; the effector here is the hand. It is also not a session timeout. Timeout asks whether listening is still on. Dwell asks when this one hit starts or finishes.

Why it happens

After the pose stabilizes, the recognizer starts a timer and commits when it fills. To reject brief look-alike poses in passing, the window is usually hundreds of milliseconds or more. A short window lets a walking-swing graze through. A long window forces a deliberate stop and hold at the end of the stroke, raising co-contraction; subjectively, “it only counts if I pause.” Dwell also throws speed away: a crisp wave is rejected for not parking at the end, while a hesitant pause gets through. Gravity pulls the arm down, so “still” is really fighting droop. The longer the timer, the more the endpoint slides out of tolerance, the timer resets, and the wait grows.

Studying it

Sweep the dwell window from about 200 ms to over a second. Measure idle false fires, extra wait on intentional commands, and muscle load or reported fatigue during the hold. Use a sequence of ten commands, not a single demo; waits add. A control condition uses a speed valley or an explicit delimiter on the same vocabulary and compares total time. Gaze-dwell thresholds from the eye-input literature are not transferable: fixation stability and raised-arm stability are different physiology.

Where it stops holding

An occasional confirm (pause before delete) can bear the wait. As the default edge on every command, waiting dominates the experience. A supported forearm (elbow on a desk, wrist on the belly) can produce a credible still; unsupported and above the shoulder fails quickly. Continuous control cannot use dwell as its edges, or dragging a slider becomes a string of chopped points. If the dwell window and the session timeout are the same number, pausing to think the next step ejects the whole session. The two clocks must be separate.

Applying it

• Do not make dwell the default edge for every vocabulary item. Prefer a contact delimiter (pinch) or a kinematic edge (speed valley). Reserve dwell for high-consequence confirms.
• If dwell is required, publish the window length and show visible progress while it runs so people know how much longer to hold.
• Accept on total time and mid-sequence arm drops across ten commands. If a longer window cuts false fires but total time and arm drops rise, do not adopt that window as the general scheme.

Related

• Same group: C4.03.1 Every gesture needs a decidable start and end · C4.03.2 Return motion is part of the gesture definition · C4.03.4 Onset/offset failure appears as swallowed or repeated actions
• Adjacent: C8.02 Dwell selection · C4.16 Disengagement and timeout
• Search: dwell delimiter · hold to commit · mid-air dwell