Good Design Reduces Cognitive Load

The number at the top of Momentum’s stats screen is a percentage. It shows how consistently you’ve followed your workout routine over the last 7, 30, or 90 days, and when you miss a day it drops a little instead of resetting.

A lot of habit and workout trackers lead with a streak, and a streak has a failure mode. One missed Tuesday turns sixty days into zero, and the person holding the phone now has a question to answer that has nothing to do with exercise: is it worth starting again from nothing? A percentage never asks that. The day after a miss, the number is slightly lower and the sensible thing to do is the same as it was the day before. The same goes for days that don’t fit neatly into done or not done. A day you only partly finished shows as partial in the history, and a rest day you planned counts as a success, so nobody has to decide whether half a workout “counts” or explain a Sunday off to an app.

That’s most of what we mean when we talk about cognitive load. Every product puts questions to the people using it, and each one takes a bit of attention away from what they came to do. A good share of product design is finding the questions the product could have answered itself.

What should I be doing right now?

Tango is our habit tracker, and its Today screen shows only what’s scheduled now. Habits are grouped into the routines people actually keep, like a morning routine or an evening wind-down, so a day with a dozen habits reads as two or three intentions with a count beside each. Every habit has one large button, and tapping it is the whole interaction.

The longer view still exists. History, heatmaps, and completion statistics are one tab away for when someone wants them. They stay off Today because Today has a single job, and a screen that also showed last month would leave you to work out which part of it mattered this morning.

Tango also doesn’t ask for things it can find out. A habit can be tied to one of your Apple Reminders, in which case the reminder stays in charge of the schedule and Tango tracks whether you did it, with completion syncing both ways. Nobody has to keep the same schedule up to date in two places.

Is there anything left to remember?

Burn After sends a sensitive file through a link that works once. The sender makes two choices, which file and how long the link should last, and presses one button. The file is encrypted in their browser before it’s uploaded.

What comes back is a screen headed “Copy this link now,” with one button under it. This is the only point in the product where a mistake can’t be undone, because we don’t store the encryption key and can’t show the link a second time. So it’s also the one place where we added words. A line directly above the button says this is the only time the link can be shown. Cutting that sentence would have made the screen tidier and the product worse, which is worth remembering whenever “simpler” starts to mean “less on the screen.”

After that, there’s nothing to keep track of. The recipient doesn’t need an account. If they open the link, it burns and the file is deleted. If they never open it, the link expires and the file is deleted anyway. A file sent the usual way tends to sit in an inbox or a shared folder until somebody remembers to remove it. Here that was settled when the product was designed, and neither person has to think about it again.

Did I just lose what I typed?

The same thinking applies at a much smaller scale on this site. The logo in the header links to the home page, and on the home page that’s where you already are. An ordinary link would reload the page, and anyone who had started writing in the contact form at the bottom would lose their message. So on that page the logo scrolls back to the top instead, and a half-written note is still there when you return to it.

The form asks for three things: your name, your email, and what you’re working on. If sending fails, what you wrote stays in the box, and the error offers another way to reach us. These are decisions nobody notices unless they were made the other way, where the page reloads and the message is gone.

The decisions that stay with you

In each of these, the product took over a decision that had one sensible answer. Nobody wants a say in whether an expired file gets deleted, and nobody wants to be asked whether a planned rest day counts. The choices that depend on the person stayed with the person: which habits belong in which routine, how long a link should live, which days are for rest. Getting that line wrong costs something in either direction. A product that asks about everything is tiring to use, and one that quietly decides things people care about stops being trusted.

Most of this gets worked out before there are any screens to look at. When we take on product design for a client, the flows come first: the paths people take through the product, including the ones where something fails or they come back tomorrow to finish. At each step we’re asking what the person needs to know right now, what they’d have to carry over from the step before, and what the product could settle for them. The visual design comes afterward, with less on every screen to arrange.