Case study · Payments · national infrastructure
When the U.S. finally moved off the magnetic stripe, the hard part wasn't the cryptography — that was solved. It was changing the physical act of paying at millions of terminals at once. I ran moderated usability research across 12 major U.S. cities, and benchmarked against markets a decade ahead, to find where the new "dip" quietly broke down — then turned it into recommendations for major card issuers and terminal manufacturers, before the friction scaled to billions of transactions.
For roughly a decade, the United States was the last major market still running on the magnetic stripe while the rest of the world had moved to chip. That stripe carried the same static data on every swipe — copy it once and you could replay it — which is a big part of why the U.S. had become the world's card-fraud target, with retailer fraud losses running into the tens of billions a year by 2014.
The fix was the EMV chip: instead of a static record, it generates a one-time cryptogram for every transaction, so a stolen copy is worthless. But the cryptography was the easy part. Adopting it meant re-tooling millions of terminals, reissuing hundreds of millions of cards, and — the part everyone underestimated — asking a nation to change a fifteen-year-old reflex at the checkout all at once.
I owned the human-layer research: moderated usability sessions watching real cardholders meet the chip for the first time at a live terminal. The brief wasn't "do people like chip cards." It was sharper and more useful — where does the new interaction silently cost a second, a retry, or a mistake, and what would it take to design that cost out before it scaled.
Almost none of the friction was about the chip itself. It lived in the human moment around it: years of swipe muscle memory fighting the new dip, cards yanked out before the terminal was done, prompts that didn't make clear whether to sign or enter a PIN. Each one is trivial seen once in a lab. Multiplied across a nation's worth of checkouts, every avoidable second and retry becomes the most expensive kind of small. Finding those moments in 12 cities was cheap; finding them live, at national scale, would not have been. That is the whole point of pressure-testing first.
The recommendations fed into how issuers and terminal makers shaped the at-the-counter experience for a transition that is now mandatory nationwide. Every chip dip you've done since runs on choreography that teams doing exactly this kind of field work pressure-tested first — which is precisely why you don't think about it.
Most people will never think about the rails under a card payment — which is exactly why getting them right matters. A second of friction is nothing once. Multiplied by a country's worth of checkouts, it is the most expensive kind of small.
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