Let's say you have a dropdown where a user can choose a color. I'm currently comtemplating whether or not to use the following scheme. When a user selects a color, that color disappaers in the sorted list of colors, but of course it is still visible at top (B) This is different from how dropdown menu's usually work (A):
The advantage could be that users cannot reselect something that is already selected. In the color dropdown example this advantage is very small, but consider these cases:
A dropdown with only 6 options. Reducing this dropdown by 1 item makes it faster to mentally process all the options, considering the selected item is already processed in the user's mind and he doesn't have to reprocess/look at it again.
It saves space on the screen (again, the example with the color dropdown might not be relevant for this point).
A navigation bar where selecting an item would cause the page to reload (or go to another page). You do not want the user to be able to select the page they're currently viewing again, because that would cause an annoying and unnecessary reload.
A possible disadvantage could be that the list would change everytime, which actually increases mental load. For example: consider the options:
A B C D E.
When A is selected, then "B" would be the first visible option to select, C the second and so on:
B C D E
When a user now selects D, the order of the unselected items change:
A B C E
Suddenly, users who thought "the first item is always B", might misclick because now A is first and B is second in the list op options.
Any additional thought on this?