Why the details are invisible

Rauno Freiberg opens Invisible Details of Interaction Design by admitting that design can feel like there is no science to it, only feel and intuition, and that even researchers treat interaction design as a black box. Searching the web for depth on the subject yields recycled content about personas and Venn diagrams. The substance, he says, reveals itself only “to those willing to fanatically dig for them,” either in long research papers or by replaying hundreds of slow motion screen recordings. His own method is to make something, fill his head with the problem, and then go for a walk.

The details are invisible on purpose. A gesture that retains its momentum, a menu that appears without animation because you open it a hundred times a day, a loupe that disappears when your finger no longer covers the caret: each is a decision someone made so that you would not have to think. Emil Kowalski, writing about the toast library he built, puts it plainly in Building a Toast Component: “Not all of these details are noticed by the user, but that’s okay. These details add up.” And: “The less details users notice, the better. It means the experience is intuitive.” He borrows Paul Graham’s line about unseen details combining “like a thousand barely audible voices all singing in tune.”

This creates a problem for anyone trying to learn. If the best work is the work you cannot see, you cannot learn it by looking at finished products. You have to take them apart. Freiberg ends his essay with the observation that “understanding and articulating why something feels right does not come as intuitively as designing something to feel right. But they are two sides of the same coin.” Analysing details beyond “it feels nice,” he argues, is what nurtures taste and raises the level of execution. Kowalski’s course and essays rest on the same method: put two versions side by side, decide which feels better, then say why.

That is the method of this book. Each chapter takes the work of people who have done the digging, quotes them where their wording is the point, and puts a figure next to the prose that lets you operate the idea rather than read about it. Where a number appears, it is a number a source states (a 0.05 scale step per stacked toast, a 300 millisecond rule of thumb, a 90 to 10 split between familiar and novel). Where no source states a number, none appears, and the figure says so.

Bartosz Ciechanowski, whose interactive articles are the subject of Explaining with interaction, ends each of his explanations with a note inviting the reader to support the next one. His articles are worth mentioning here because they demonstrate the premise of this whole book: an explanation you can drag teaches something a diagram cannot. Appleton, who lists him in her collection, calls him “a good example of blending design and engineering for educational content.” The figures in these pages are smaller than his, but they aim at the same thing.