"Frankly what we're seeing strains credulity," said Alan Wurtzel, the president of research for NBC

"You can't explain a 12 percent decline in men 18 to 34 or close to 20 percent in men 18 to 24 by saying they're playing a lot more video games," said David F. Poltrack, the executive vice president for research at CBS. He added, "The fact that it's concentrated in one small age group makes it worse, and even more likely that it's an aberration."

One possible factor is more basic, Mr. Sternberg said -- the quality of the new shows. "I've always noticed that we never hear anybody talking about the programming."

Few Viewers and Network Executives Scratch Their Heads