Prime Time

Three years ago, Tiffany Hogan ditched her VCR for TiVo, and watching TV has never been the same.

''I call it my boyfriend because it's always got something waiting for me when I come home," said Hogan, 31, of Dorchester, who bought a second TiVo system for her bedroom last year.

She now watches NBC drama ''Law & Order," which airs Wednesdays at 10 p.m., on Thursday mornings when she's not as tired. Even when she's awake to watch a show in its scheduled time slot, she waits until about 20 minutes after the show starts so she can fast forward through commercials.

Ad-skipping and the so-called time-shifting of TV -- viewing on your own time instead of the network schedule -- are ushering in an upheaval in television and advertising. Both industries are grappling with how to get people to watch commercials when they don't have to, how to measure audiences when they're watching at different times, and how to capitalize on monitoring viewer habits.

Digital video recorders like TiVo allow you to record TV shows to a hard drive without the hassle of dealing with videotape and setting the VCR. By 2010, about 50 percent of US households will have a digital video recorder, up from 12 percent today, according to Newton research firm Strategy Analytics.

It's a terrifying statistic for advertisers and networks because, ''The thing that scares us most is that they say, 'When we get TiVo, we're going to skip commercials,' " said Kristi Argyilan, executive vice president of channel insight at Arnold, a Boston ad agency.

The new TV-watching behavior spells as much trouble for advertising rates. Networks still slate top shows for weekday evenings, but prime time could become passé because networks may no longer be able to measure viewership by tracking how many people are watching a show at a given time.

''They're disrupting the appointment viewing model," Jim Penhune, director of broadband media and communication research with Strategy Analytics Inc., said of DVRs. ''That's how the advertising is sold, and that's how television is supported."

TiVo Inc. created the digital video recorder in 1997, and the device has become so prevalent that TiVo is less a brand than a verb for recording TV shows. But the technology is taking off, thanks to cable and satellite competitors such as Comcast Corp., which offers a DVR option for a $9.95 a month. By comparison, TiVo charges a one-time box fee of up to $80, plus a monthly service fee of $16.95 to $19.95.

DVRs are forcing advertisers to be more creative. Chicken chain KFC ran a commercial in March that required viewers to record it, watch it in slow motion, find a hidden message (the word ''buffalo"), and enter it on the KFC website to get a free Buffalo Snacker sandwich.

ABC refused to air the ad because the network thought the tactic constituted a subliminal message, but KFC spokeswoman Laurie Schalow deemed it successful nonetheless: KFC.com had a 40 percent increase in traffic during the commercial's run, and more than 300 million of the sandwiches have been sold to date.

Arnold, the Boston ad agency, shot 10 30-second commercials for the Truth antismoking nonprofit that became a five-minute sitcom called ''Fair Enough" when recorded and watched together.

''Creative itself has to be far more entertaining first and advertising second," said Edward Boches, chief creative officer Boston ad firm Mullen.

Some marketers, though, are increasing the number of product placements -- paid mentions or on-screen shots of a product during a show.

Fox's ''American Idol" talent show, for instance, features shots of Coca-Cola cups, and fans are encouraged by host Ryan Seacrest to vote using Cingular Wireless phones. During its two weekly broadcasts the week of May 1 through May 7, ''American Idol" had 129 occurrences of product placement, according to data from Nielsen Media Research, which began tracking product placement in 2003.

The method is popular for good reason: Even if viewers skip commercials, they won't skip important parts of a show. But while Boches said product placements shouldn't be over-the-top, the messages are getting increasingly aggressive: In some cases, product names are even worked into the script.

DVR technology allows consumers to record TV shows to a hard drive. But the box is also connected back to TiVo or your cable company through a phone or cable line, which allows them to monitor what you're watching and when.

TiVo can track every click of a user's remote control and collects second-by-second data on what's being watched, said Davina Kent, the company's vice president of national advertising sales. But she said TiVo monitors subscribers' viewing patterns as a group, not individually.

Still, the data could lead to a whole new way of measuring the audience for commercials, helping advertisers learn if their ads are being watched.

Currently, TiVo uses the data to help advertisers create campaigns that compel consumers to spend more time on commercials they would normally skip.

For example, TiVo helped General Motors Corp. create commercials during this year's Winter Olympics that relied on embedded ''tags" -- icons viewers can click with their remotes for more information. In GM's case, the viewer could pause the live broadcast, click on the tag, and watch a longer-form commercial with information about General Motors cars.

About 10 percent of the 4.4 million TiVo subscribers watch what's behind the advertising tags, Kent said, and 6 percent of those viewers spend at least two minutes with the longer commercials -- four times as long as a typical TV ad.

But perhaps the biggest changes have yet to come. Most homes still don't have a DVR, and networks and advertisers are turning to even newer methods of distribution for their programs. ABC, for example, is planning to put some of its most popular shows online at no charge to viewers, with the caveat that they cannot skip the commercials.

''What you'll see is them take their programming and distribute it in multiple channels, which you can watch on your cellphone, the programming you can watch online," said Arnold's Argyilan, ''and that will get their audience back up again."

Keith Reed can be reached at reed@globe.com.