RealTechNews reports that the crawl lines, stock sidebars, weather sidebars (etc) that have become prevalent on news channels are overloading viewers:

From Kansas State University: “We discovered that when you have all of this stuff on the screen, people tend to remember about 10 percent fewer facts than when you don’t have it on the screen,” (journalism/mass comm. professor Tom) Grimes said. “Everything you see on the screen — the crawls, the anchor person, sports scores, weather forecast — are conflicting bits of information that don’t hang together semantically. They make it more difficult to attend to what is the central message.”

I don't know though. I find the crawl line useful myself. The rest of it is often distracting, I'll admit. Looks like they did actual research, so my thoughts probably fall into the anecdotal area.