Advertising executives see blogs, podcasts and web-enabled cellular phones as newcomers in the market that are worth watching, but have yet to prove they're worth major investments, a survey released Tuesday showed.

On a scale of 1 to 5, respondents to the American Advertising Federation survey rated the three new Internet-based channels about in the middle, considerably less than traditional media and other forms of online advertising.

"Because they're so new, there's a bit of caution in approaching these media," Mary Hilton, spokeswoman for the AAF, said. "They haven't been tested enough for people to confidently rate them highly. It's a wait-and-see approach."

That approach, however, is not uncommon in the industry, Hilton said. Other forms of online advertising three years ago was seen as experimental, but has since become part of the traditional mix.

The "cornerstone" of advertising remains the 30-second spot on television, Hilton said, but major advertisers are also looking to stand out by buying time or space on new media.

"You're always looking to break through the clutter, and that's when you look for new ways to reach out through the media," Hilton said.

Consumer adoption of new technology is also forcing ad execs to look beyond newspapers, magazines, TV and radio, and question their return on investment. For example, digital video recorders, which allow people to skip TV ads, have tainted the effectiveness of the 30-second spot.

Fully 58 percent of the survey respondents said they have already changed, or expect to change, their ad buys in response to DVRs, and many said such technology would have a significant impact on TV advertising.

The survey, prepared for the AAF by Atlantic Media Co., was based on responses from 75 ad industry leaders. It was released in conjunction with the Advertising Hall of Achievement in New York City.