I recall telling a friend back in 1984 how music videos would have a much greater impact if they were accompanied by visual images that flew by at a speed people's brains could barely comprehend. It didn't occur to me that that might be a bad thing for a segment of the population - I was just thinking of the earlier efforts toward subliminal advertising.
I don't know about stunting their brains, I do know it corrupts their morals and manners as they imitate their favorite cartoons and characters!
Look up a book entitled "Four Agruments for the Elimination of Television" it is a fascinating read. The author basically says the same things fond in this study and he wrote it in the '70's....