Haptic feedback

A touchscreen took away the one thing a physical control always had, which is the small mechanical answer of a key going down or a switch clicking over. Haptics put a version of it back. A linear actuator produces a tap short enough to read as a single event rather than as a buzz, and the interface spends it at the moments a hand expects an answer: a value stepping to the next notch, a switch committing, a long press reaching its threshold, a refresh being armed. It is the cheapest feedback channel an interface has, because it costs no screen space, no reading time, and no sound in a quiet room.

Both mobile platforms publish a vocabulary of events rather than a waveform editor, and learning the vocabulary is most of the work. Apple’s set divides into selection, for a value that has moved past a detent, impact, for something that has landed or hit a limit, in several weights, and notification, which reports the outcome of a task as success, warning, or error. Android’s is shaped the same way, from the older feedback constants up to the composition primitives (a tick, a click, a thud) that newer versions can assemble. Both exist so that a tap means the same thing in every app on the device, which is exactly what a haptic that was designed per screen would destroy: authored buzzes are how a phone starts feeling like a pager.

The web has almost none of this. navigator.vibrate() takes a duration or a pattern of milliseconds, which is a motor turning on rather than a tap, it needs a user gesture to fire, it is absent on iOS Safari, and it is disabled outright in enough contexts that nothing may depend on it. A web interface that wants the feel of a native control is therefore designing for a channel that may simply not be there, which is the practical reason haptics are never allowed to carry a message by themselves.

That is the rule the specimen on this page is built around. Feedback nobody can see needs a partner they can: the tick confirms what the screen already said, and never says anything on its own. Two more worth stating. The system setting is a real preference, so haptics that are routed through the platform’s own generators are silenced when a reader has turned them off, while a hand-rolled vibration pattern quietly is not. And the budget is small: a tick per committed action reads as craft, a tick per scroll notch reads as a fault in the phone.