Trackpads use palm rejection to avoid accidental movement while typing

What it is

Trackpad palm rejection identifies palm, heel-of-hand, or unintended contact during typing and does not interpret it as pointer motion, click, or gesture. It lets keyboard and trackpad coexist in adjacent physical space without ordinary hand posture continually changing cursor or focus.

Why it happens

The system combines contact area, location, shape, pressure, duration, typing cadence, and multipoint relations to infer intent. It may raise suppression after a keypress or filter large edge contact. Loose thresholds permit accidental motion; strict ones swallow genuine rapid trackpad actions, so the algorithm balances two error types.

Studying it

During continuous typing, post-pause movement, varied hand size, posture, and external-device conditions, record false touches, missed intended input, recovery time, and frustration. Separate typing-induced cursor moves from real trackpad actions ignored by the system; total error alone conceals the tradeoff.

Where it stops holding

Palm rejection is not only about large palms: sleeves, moisture, braces, and multi-finger gestures alter contact features. For people who type then immediately move the pointer, a long post-typing lockout slows work. External and built-in trackpads also differ in sensing and spatial relation.

Applying it

• Provide a stable default and adjustable sensitivity or temporary input restoration, avoiding permanent lockout.
• Do not create unexplained long unresponsiveness while suppression is active; show state where necessary.
• Test real text entry followed by immediate movement and multi-finger gestures, balancing false touch against missed input.

Related

• Same group: C1.16.2 Zoned virtual buttons depend on contact position rather than separate buttons · C1.16.3 Trackpad size limits single-stroke screen travel, making clutching unavoidable · C1.16.4 A trackpad is both a pointing surface and a multi-finger gesture surface, so inputs need disambiguation · C1.16.5 Trackpad material and friction directly affect fine-pointing feel
• Nearby: C1.02 Absolute and relative positioning · C1.06 Hover states and their absence on touchscreens
• Search terms: palm rejection · trackpad · accidental touch