According to a study, (which I believe is a room in a home used as an office or library,) kids who watch Spongebob Squarepants have shorter attention spans than kids who watch, I don't know, The Newshour With Jim Lehrer.
You know what else gives kids short attention spans? EVERYTHING!
Kids are like cute little meth heads. Meth heads that smell bad and do disgusting things constantly. If you have a small child, count how many times a day the kid puts it's finger in it's nose, it's butt, and then it's mouth. Then count how many times he or she pays attention to anything at all that you say. Cartoons are not the problem. Kids are insane.