Designing for a Wearer Who Cannot Read the Interface
When your user may not share a language with your product, the correct amount of interface is none. What that constraint forces you to get right instead.
· 7 min read
The constraint
Our wearer might read Bahasa Indonesia, Bengali, Hausa, Urdu, Turkish, Malayalam or none of the above. They might be eighty-two years old and have never operated a touchscreen. They might be in early heat exhaustion, which degrades reading comprehension before it degrades walking. Any interface built from words fails somebody in that set, and the people it fails are exactly the people the product exists for.
So: no screen, no text, one button
Removing the display was not a cost decision, though it helps the battery enormously. It is that a screen invites you to solve problems by writing words on it, and words are the thing we cannot use. With no screen there is exactly one input (a recessed physical button, pressed and held for three seconds), and the design problem becomes making that one input unambiguous.
Haptics carry the whole conversation
Everything the band says back to the wearer is vibration, and the patterns are deliberately few and deliberately distinct. Two short pulses: your alert went out. A long slow pulse repeating: someone has acknowledged and is coming to you. A distinct triple pattern: stay where you are, somebody is walking toward you. A single soft pulse: you are getting too hot, find shade. Four messages, learnable in ninety seconds at fitting, in no language at all.
Why the button is recessed
A flush or raised SOS button on a wrist worn in the densest crowd on earth will be pressed constantly by accident, and a system that cries wolf forty times a day gets ignored by the people who have to respond to it. Recessing it, and requiring a deliberate three-second hold, is what makes the alert meaningful when it arrives. The three seconds are also long enough for the wearer to change their mind, which matters more than it sounds.
The complexity has to live somewhere
None of this makes the system simple; it relocates the complexity to the people who can handle it. The group leader has a console with maps, lists and priorities, and they are trained on it, indoors, before the season. The family has an app, and they are at home and calm. The wearer has a button and four vibrations. Deciding who carries the cognitive load, and putting almost none of it on the person in difficulty, is the actual design work.
What we still have not solved
Confirming that a wearer has understood the four patterns is currently a human process at fitting, and it depends on the quality of the briefing. We do not have a good way to verify comprehension at scale, and pretending otherwise would be dishonest. It is the open problem we would most like the pilot season to teach us about.