Touch, context, and fidgetability

A finger is opaque. Rauno Freiberg points out in Invisible Details of Interaction Design that on touch interfaces the finger sometimes obscures exactly what you are trying to manipulate, which makes pixel-level precision hard. The common answer is what he calls touch content visibility: the interface renders a temporary representation of what is underneath. On iOS, pressing and dragging to move the text caret brings up a magnifying loupe above the touch point. The detail he wants you to see is that when the finger moves down and no longer covers the caret, the loupe disappears. It exists only while it is needed. The keyboard does the same thing in miniature: pressing a key shows an enlarged copy, which gives you confidence that the interface understood what you meant.

Mirroring is not always the right answer. Sliders can be tiny and vanish under a thumb, and for those the useful detail is that the drag gesture does not cancel when the thumb drifts off the slider while still pressing down. Video scrubbing is the case where no technique fully rescues you: seeking is mostly visual, and Rauno describes “an unintelligible level of discomfort” in interacting with an element you cannot see.

The next idea widens the definition of input. The keyboard, mouse, touch, and voice are all explicit inputs, and when dialled in they feel like a natural extension of ourselves. But, he asks, is the mother of all inputs not no input at all? Implicit input is when an interface uses context as input and infers what you want without asking. His examples: Apple Maps shows the active route when you look at the screen, without unlocking. Apple Wallet increases the brightness when you present a pass for scanning. Spotify adjusts its interface to be more accessible while you are driving. And some iOS apps blur their contents when you open the App Switcher, which he first took for a performance optimisation and turned out to be a deliberate attempt to conceal possibly sensitive data, like medical records or a bank statement. Context can hide as well as reveal.

Then there is the problem of finding your place. On macOS you can always find the pointer by shaking the mouse, and Rauno likes it because it taps into the frustration and the natural reaction people already have when they lose track of it. He describes a reading problem of his own: halfway down a page he wants to check something above, but scrolling up means losing a precious scroll position. His tiny prototype lets you double tap the scrollbar to place a scroll landmark at the current position; you can then wander the page and double tap the landmark to return. It feels familiar, he argues, because the scrollbar is already interactive on touch: long-pressing it makes it draggable, which is much faster for scrolling a long way. The same instinct produced his older minimap prototype, inspired by games that always give you a bird’s eye view of the surroundings.

The last detail is the one with no practical purpose at all. “Wonderful interactions don’t have to be entirely practical.” Playing with an AirPods case, or twisting the tip of an Apple Pencil, is fidgeting: repetitive movement that apparently helps release situational stress or enhance concentration. Rauno is careful to footnote that there is no scientific research supporting the claim, but he holds that fidgetability still feels like part of intentional interaction design. It could be an afterthought or a happy side-effect, yet the AirPods case is “uncannily satisfying to play with,” and assuming that is a coincidence would, he says, be very generous. The Pencil is the more obvious candidate: the tip is unscrewable so it can be replaced, and twisting it while rotating the body gives a satisfying friction to play with while thinking.

He ends the essay where this chapter should end. Understanding and articulating why something feels right, he admits, does not come as intuitively to him as designing something to feel right. “But they are two sides of the same coin. There must be a reason.” The reason can be as simple as a particular spring curve or as innate as a metaphor. Analysing design details beyond “it feels nice” nurtures taste, raises the level of execution, and grows an appreciation for how hard excellence is. Emil Kowalski, writing about multi-touch handling in Building a drawer component, says why these details get the name invisible: they align with inherent expectations, so when a feature works as you assume it should, you proceed without a second thought.

Take three habits from this section. When a finger or a pointer will cover the thing it manipulates, show a proxy, and remove it the moment it is no longer needed. Ask what your interface already knows about the situation before you ask the user for input, and remember that context can be used to protect as well as to help. And when you find yourself unable to explain why an interaction feels right, treat that as work left to do. That work, the articulation half of the coin, is what the Taste chapter is about.