Week 43 · Future Architectures

The Button
With Nothing Under It

Drag across these twelve stops. Every one fires an identical, silent flash on the strip. On a phone that supports it, one of them will also buzz your thumb. The pixels never change either way.

Predict

You just crossed the same twelve stops. Does a felt click on the ones that buzzed make the reach itself more precise, or only make it feel more precise?

This page calls navigator.vibrate() at every stop above. iOS Safari carries no Vibration API at all — by design, not by bug, the buzz above will be silent and unfelt there. The visual flash is the one confirmation every device gets; the vibration is a bonus some devices add on top of it.

Part I

The Texture Bench

Four textures, one strip of glass, no moving parts anywhere underneath it.

Smooth has no stops at all. Ridged spaces them evenly, at whatever interval you set. Gravel scatters them, unevenly, at roughly that interval. Notch places only two or three of them, wide apart and stronger, the way a real mechanical detent — a camera’s aperture ring, a volume knob with real clicks — announces a rare, deliberate stop rather than a frequent one. Drag across each, then turn the strength dial to almost nothing and see what actually falls.

The Texture Bench

Drag the glass

Detents on strip: 5; computed
Crossings this drag: 0; measured
Haptic events / sec: 0.0; capped ≈8.3/s
Perceived friction: 27; modelled, not measured

Texture

Detent spacing14%

TightWide

Pulse strength60%

FaintStrong

Perceived friction is modelled, not measured — it is this build’s own formula (see haptic-math.ts), weighted hard toward how often a pulse arrives and only lightly toward how strong it is, to dramatize the manual’s own point that touch reads the attack of a vibration far more than its raw amplitude (Part 2.2). Detents on strip, crossings and events/sec are real: computed from your actual drag, and capped by the manual’s own 120–150ms minimum-interval rule (Part 3, Rule 4) — drag fast across Gravel and watch the events/sec stall well below the raw crossing count.

Part II

A Motor That Fits Inside a Click

Older phones buzzed with an eccentric rotating mass — an off-centre weight spun by a motor shaft, the same mushy attack and decay no matter what triggered it.

It cannot start or stop instantly. The Taptic Engine and its contemporaries use a linear resonant actuator instead: a mass driven back and forth along one axis by a voice-coil magnet, the same principle as a tiny loudspeaker, reaching peak output in a single cycle and producing pulses as short as roughly 10ms. That speed is the entire trick — only an actuator that fast can render a crisp, percussive tick as something categorically different from a longer, rolling buzz.

Human skin backs this up with its own hardware. Pacinian corpuscles, the fast-adapting receptors an LRA is usually tuned toward, peak near 250Hz and respond across roughly 200–300Hz; Meissner’s corpuscles specialise in light touch and slip at a much lower 50Hz. A sharp click and a soft buzz are not the same sensation turned up or down — they are addressed to different receptor populations entirely.

The landmark proof shipped inside the iPhone 7’s Home button in September 2016: a capacitive sensor requiring bare skin, backed by a pressure sensor, with the Taptic Engine firing a tuned pulse the instant a press was detected. There was no button there. Millions of people pressed one anyway, every day, and the overwhelming reaction was not “this feels fake” — it was “this feels like a click.”

That gap between physical reality and felt reality is the entire subject of this manual.

Tactile Haptics manual, Part 1

Apple’s own Core Haptics names the two building blocks a richer pattern is made from: a transient event — short, discrete, a single struck note — and a continuous one — sustained, a held note — each parameterised by intensity and sharpness. Every pattern in the Deconstruction below is built from transients alone; a continuous event is the one this manual reserves for a genuinely different problem — resistance that varies smoothly, like a bowstring drawing tighter, not a discrete click at all (Part 4, DualSense case).

Part III

Seven Words, Not One Buzz

Apple’s own vocabulary formalises this into named categories: selection, three weights of impact, and three notification outcomes.

Scrub through all seven below. Each is built from the same short pulse shape, arranged differently — one tick, two rising, two soft with a pause, three sharp and close together. The waveform is the whole argument: nothing about these patterns is decorative, every difference in shape carries a different meaning.

Pattern

SelectionNotify — error

Selection

A discrete value passed — picker or list scrubbing.

Pulses: 1
Duration: 46ms
Sharpness: 0.3–0.5

Durations and amplitudes above render this build’s own reading of the manual’s Part 7 token set — it gives ranges and qualitative shapes (“double-pulse, rising intensity”), not literal waveforms, and calls itself “a starting token set, not a universal standard.” Graded secondary below.

Part IV

Where the Trick Actually Shipped

Same slider, same pixels, one difference: whether crossing a stop is announced.

Three shipped cases carry the same trick into hardware people touch every day:

2016

iPhone 7 — the button with nothing under it

A capacitive sensor and a pressure sensor replaced a hinge; the Taptic Engine fired the felt click the instant a press registered. It also required bare skin — ordinary gloves stopped working — and no moving switch meant no mechanical wear, which is part of why Apple could gate third-party repairs behind a pairing check. The illusion succeeded completely on feel; the accessibility and repair costs were a separate, unrelated trade.

2015 onward

MacBook trackpad — Force Touch

A hinged trackpad clicks weakly near its own top edge; a rigid glass surface with a Taptic Engine underneath clicks the same everywhere, because the click was never mechanical to begin with. That uniformity is what let a firmer press become a second, distinct gesture — a force click for a dictionary lookup or a Maps preview — on hardware that used to give only one kind of click at all.

2014 / 2015

Apple Watch — the private channel

The first Taptic Engine shipped here, paired with Force Touch, for a device worn against skin in rooms where a chime is the wrong choice and a felt tap is exactly right. Series 4 carried the same idea into the Digital Crown itself — the notification channel spreading to a second physical point.

All three cases are the dossier’s own (Part 4); the iPhone 7 repair-lockout detail is flagged there as a business decision riding alongside the haptic one, not a consequence of it.

Part V

Two Products, Wired Backwards

Both of these are shipping today, exactly as described. Each fires a real pattern from the vocabulary above — just the wrong one. Fix the wiring.

Currently wired

Delete this project — permanently, no undo.

Notify — success

Which pattern should actually fire?

Not yet — that pattern's own meaning still does not fit the stakes of this action. Try another.

Currently wired

Your payment went through.

Notify — error

Which pattern should actually fire?

Not yet — that pattern's own meaning still does not fit the stakes of this action. Try another.

Challenge · Match the Stakes

Open

Assign one pattern from the seven-word vocabulary to each of these five interactions, so that every pulse's category matches the weight of what it confirms.

Scrubbing through a date-picker wheel

Picking a row up to reorder it

Dropping that row into its new place

Confirming a permanent account deletion

A payment finishes processing successfully

Two of these five are worked examples straight out of the manual's own drag-to-reorder case (Part 10) — pick-up, pass, and drop are three different weights, not one repeated tick.

Insight

A click you cannot see is still an interface.

Every pulse on this page was real where your device could feel it, and exactly as silent as the manual predicts everywhere else — iOS Safari has no Vibration API at all, so the version of this page you are reading may never have buzzed once. That silence was never a bug to route around; it is the ordinary state of most of the web, and the reason every pulse above shipped with a visual sibling that needed neither sound nor skin contact to land. A felt click that only some readers ever felt was still, for every one of them, the interface telling them the truth about what just happened.

Mental model

Whenever a flat, moving-part-free surface asks a thumb to trust that something happened,

look for a pulse whose category — selection, impact, or notification — matches the stakes of the action, paired with a visual sibling that carries the same message where there is no motor to feel,

because an unpaired or mismatched click is worse than none at all: it goes unfelt on a third of the web by default, and it trains whoever does feel it to stop trusting the channel.

TomorrowFind one drag, toggle, or swipe in your own product that fires a haptic today. Name its category out loud. If you cannot, it is not a vocabulary yet — it is a buzz with a location.

End of experience

← Back to the constellation

The ButtonWith Nothing Under It

The Texture Bench

A Motor That Fits Inside a Click

Seven Words, Not One Buzz

Where the Trick Actually Shipped

Two Products, Wired Backwards

Where this idea goes next

The ButtonWith Nothing Under It

The Texture Bench

A Motor That Fits Inside a Click

Seven Words, Not One Buzz

Where the Trick Actually Shipped

Two Products, Wired Backwards

The Button
With Nothing Under It

The Button
With Nothing Under It