Bounce clicks are rapid extra triggers from contact rebound, not intent

What it is

A bounce click is the same control firing two or more times in a very short interval when the user believes they tapped once. The usual physical source is elastic rebound of the pad leaving glass: contact breaks, then briefly reseats, and the system sees a fresh begin–end. It is not a double-tap. A double-tap is two intended actions with a recognisable gap and a second aim; the bounce’s second contact usually has near-zero displacement and an interval shorter than a person can deliberately lift and press again.

Why it happens

Skin and subcutaneous tissue are springs. After normal force crosses zero on the way up, the pad can reseat for a few to a few tens of milliseconds because of residual elasticity and slight bending of the panel. The capacitive controller reports a new contact; an app that commits on every end will buy, send, or toggle twice. Films and moisture change the rebound: a softer film lengthens the second contact, sticky wet skin may keep the first contact from breaking at all (a long-press instead of a bounce). If the IC’s lift threshold is aggressive, a noise spike after a true lift can mint a fake begin that looks the same as a bounce but is electrical rather than flesh.

Studying it

Have people tap buttons at a natural force while high-speed video watches for a second seating, with event timestamps alongside. Independent variables are press force, lift speed, film on or off, humidity, and whether the button fires a haptic motor on press. Dependent measures are double-fire rate, the interval distribution between ends, and displacement of the second contact relative to the first. Define the operational bounce as “user reports one tap, log shows two,” so intended double-taps stay out. A motor pulse at lift can worsen rebound and must be its own condition, not pooled with a silent device.

Where it stops holding

Game button mashing, a counter’s plus, and camera burst fire are intended rapid repeats and must not be called bounce. Dwell-click assistive touch and key-repeat from an external keyboard are different mechanisms. Resistive panels depend on pressure and rebound on a different curve. Older adults lift more slowly with a larger contact, so second seatings are rarer; youth bounce rates overestimate the problem on an elderly product. Intervals already long enough to look like two independent taps should be analysed as double-tap or repeat, not rebound.

Applying it

• For submit, pay, and toggle controls whose side effects are large, drop later ends on the same target inside a short window after the first successful fire, and tag them bounce in the log rather than a user double-tap.
• Use high-speed video or an interval histogram to separate bounce (displacement ≈ 0, very short gap) from intended double-tap; do not treat both as user error.
• Accept with film and humidity: if bounce rate only passes on bare dry glass, remeasure on the shipping accessories.

Related

• Same group: C2.22.2 Repeat-trigger intervals trade responsiveness against debounce · C2.22.3 Overlong debounce blocks intentional rapid taps · C2.22.4 Mechanical key bounce likewise requires software debounce
• Nearby: C3.01 Tap · C3.02 Double tap
• Search terms: bounce click · contact bounce · unintended double fire