“Users should not have to wonder whether different words, situations, or actions mean the same thing. Follow platform and industry conventions.” — Jakob Nielsen
Below are six small, working demos. Each one deliberately breaks consistency — the same action labelled differently, the same icon meaning different things, or the same colour used for opposite purposes. Try each one, then click “Reveal what actually happened” to see what was really going on.
This button does exactly one thing — save your name — no matter what screen you're on. But its label changes every time you “navigate” to a new screen: sometimes Save, sometimes Submit, sometimes OK. You can never be sure it's the same action.
Every time this confirmation opens, Delete and Cancel randomly swap sides. You can never build the muscle memory of “the safe button is always on the right”, which is exactly the convention real dialogs rely on to prevent mistakes.
Editing and deleting are wildly different in consequence — one is safe and reversible, the other isn't — but the icons for them are two nearly identical writing implements. Neither one looks more "delete" than the other, so the only way to learn which is which is to click one and see what happens.
These are drawn as checkboxes — square boxes that every platform convention says allow multiple selections. Try checking more than one: checking any box silently unchecks all the others, which is how radio buttons behave, not checkboxes.
Red usually means “stop” or “destructive”. Here the exact same red button style is used for a harmless, positive “continue” action in one panel, and for permanently deleting something in the other. The colour tells you nothing.
These look like three different settings in three different cards. Type in any one of them — they are, underneath, the exact same stored value, just relabelled each time it appears.