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.)