It’s common practice to use a solid icon to highlight the active button in a tab bar, while the other buttons remain in outline form. But this design practice is backward and should be the other way around.
Users need more recognition speed on options they haven’t discovered yet, not on the one they have already selected it. A solid icon for the active button isn’t necessary. It’s more important for the inactive buttons to get solid icons.
I thought that was interesting.
Indeed that's an interesting way to think about this. Makes sense when you read it though.
Solid icons were generally faster to recognize than outline icons, but with a few exceptions.
I wonder why Google is all of a sudden switching to outline icons in some of their products. Specifically, google drive as of late.