Square Register turns the trolley into a till that scans, weighs, verifies and charges. The whole shop happens on the tablet, with no checkout lane.
The first goal in the brief read like this:
How might we create a new shopping experience where the user has total autonomy?
The interviews contradicted that goal.
Autonomy was not being left alone
Three in-person interviews, around twenty minutes each. The strongest pain was not the queue. It was being stuck with no way out:
"Always having people nearby helps you feel more confident and call for help quickly if you need it."
For someone shopping, autonomy is solving on your own the part that works, and having someone within reach when it breaks.
Asking for help shows how long it will take to arrive.Waiting with no end in sight is what makes people give up.
Two other quotes decided the form factor. I had come in with three competing bets: an app on your phone, a kiosk to finish the purchase, or a tablet with everything inside it. Both quotes asked to weigh the product without walking anywhere. An app cannot weigh, and a kiosk means crossing the store.
The scale decided the form factor.The trolley-mounted tablet won because of it, not because it was the most modern of the three.
Three decisions that came out of the interviews and the test
Asking for help comes with a deadline. The button does not open a chat or a call centre: it calls a staff member and counts down until they arrive. And you can cancel, because someone who sorts it out mid-wait should not be stuck waiting anyway.
The system is what finds the product. Search returns the aisle, marks the spot on the store plan, and, if you ask, tells you when you walk past it. It was the test that put search at the centre of the screen.
Where the item is, and where you are."Notify me" covers people who would rather pick it up on the way back.
Age is proven once, at the end. In the tested version, every restricted item asked for verification the moment it went into the trolley. That interrupted the shop over and over. It moved to payment, as a single check.
Pick a payment method and prove your age once, at the end.
What the test changed, and what I would do differently
Mid-fidelity usability testing changed two things in the product: age verification left the trolley, and search started returning the aisle. I kept no visual record of the test, so the case describes these changes but cannot show them side by side.
Three interviews and one in-person test do not prove a market, and this case has no adoption numbers to show. But they were enough to redefine the goal: the brief asked for total autonomy, and what the product delivers is autonomy with people nearby. The screens followed that change, and the brief did not. Today I would rewrite the brief along with the screens.