I frequently see surveys with multiple-select questions that tell the user "check all that apply," and have a final checkbox for "none of the above." Is there any evidence or expert opinion as to whether this is a good idea?
I assume its purpose is distinguish people who skipped / ignored the question from ones who decided that none of the answers apply. But it contradicts the literal instructions, and users may not even see the "none" option if they don't think there's any reason to read through the whole list. For example, if the instructions say "check the flavors of ice cream you like" and I hate ice cream, I probably won't read the whole list of flavors and see the "none of the above" box at the end.
It seems like this has the potential to confuse people, and generate a lot of false negatives (people who did read the question, but didn't check "none").