It seems self-evident that one should not put a large box on the screen and then change its dominant color frequently (i.e. make it flash) because it's very hard to ignore and will irritate people, but I have not been able to find a definite Web-accessible resource to point at that argues for this statement.  Can anyone suggest anything?  A document arguing that one should not make *anything* on the screen flash for the same reasons would also be fine.

(This is *not* a request to write out an argument *here*, this is a request for an *existing* document that I can link to in something else I'm writing.)