On the cable side, the VH1 network, owned by Viacom, tested last month a method of keeping viewers tuned in during commercial breaks that it calls Showstoppers. The experiment, during a show named “Hogan Knows Best,” commingled program snippets and spots in a way that was intended to lead the viewers through the commercial pods to the moment the show came back.

The trade publication Mediaweek reported this week the results of the test, including a finding that 47 percent of the viewers surveyed by VH1 said they paid more attention to the commercials in the Showstoppers format than they normally would. The growing interest among all networks in retaining viewers throughout commercial pods is primarily because of the advertisers and agencies are focusing on what are known as commercial ratings.

For decades, the ratings gathered by Nielsen Media Research, which help marketers select the series they support or ignore, have measured viewership of the programs. It was up to Madison Avenue to figure out how many viewers stayed to watch the spots.

Now, Nielsen is moving toward reporting average commercial minute ratings, based on the average of all the spots in a program. Madison Avenue is asking for more, in the form of ratings that would be brand specific — that is, for each individual commercial.

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The subject was a central theme of the conference at which Mr. Shaw spoke, sponsored by the Association of National Advertisers. The conference, called the TV Forum, drew about 400 people to the Marriott Marquis hotel in Midtown Manhattan.

“Without this change, I don’t know how long television can be sustainable as an advertising medium,” said O. Andrew Jung, senior director for advertising and media services at the Kellogg Company. He has been leading the push for brand-specific commercial ratings.

“We need to make our advertising more effective,” Mr. Jung said, but “25 percent of an average hour is not measured properly.” His reference was to the typical amount of commercials during 60 minutes of TV.