CX Strategic Knowledge · Quality & Research
Device myopia & viewport negligence
"My iPhone works, so all iPhones work" is a fallacy. If a team can't name its test devices, it isn't testing.
Teams test on the latest, largest, most convenient devices and assume that covers everyone. It does not. Screen sizes, OS versions, accessibility settings, and interaction patterns vary widely, and testing only the convenient slice excludes large portions of the market.
The iPhone fallacy: my iPhone works, so all iPhones work. Reality is messier. There are many screen sizes, many OS versions, many accessibility settings, many interaction patterns. One device tells you about one device.
Testing only on the latest, largest, most convenient hardware systematically excludes large portions of the market — often the portions least like the people building the product. The bias is invisible from inside the team, because everything works on their machines.
If a team can't tell you which devices they test on, they aren't testing.
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Reading about device myopia & viewport negligence is one thing. Seeing where it applies in your journey is the useful part.