I’ve noticed a worrying number of professional designers mixing up basic form elements lately. Checkboxes and radio buttons, particularly. This is the Jobs page on Designer News:
See that “Remote Friendly” control? It’s a trick control. It looks like a radio button, but it behaves like a checkbox. It’s deceptive. It leads us to expect one kind of behavior, a standard since 1984, then does something else.
Here’s another example from Aeon Magazine:
The “Daily” and “Weekly” controls look like radio buttons, but they behave like checkboxes. Because the controls are dressed up like a control they aren’t, a user could easily make mistakes. He might accidentally select both options, expecting one selection to clear the other. He could even select neither option and still click “Subscribe”. I have no idea what that does.
Interactive things have perceived affordances; the way they look tells us what they do and how to use them. That’s why checkboxes are square and radio buttons are round. Their appearance isn’t just for show—it signals what to expect from them. Making a checkbox round is like labeling the Push side of a door Pull.
Checkboxes are never round.