Just when you thought 1984 was about to slip harmlessly away, along comes the "RD-100 People Meter and Data Scan Wand" -- a major breakthrough in computerized surveillance of your living room and kitchen.

At a recent press conference here, officials of Arbitron, the TV rating firm, and Burke Marketing Services, a market research company, proudly announced plans to test a new breed of high-tech monitoring equipment designed to provide the most accurate reporting ever on which TV shows Americans watch at home and what products they buy after viewing.

Arbitron's Allison Conte noted that placing the new monitoring devices in people's homes "does have a Big Brother aspect to it." But officials expressed confidence that many Americans would willingly accept the devices.

"We know people will volunteer for this," said Burke vice president Robert L. McCann Jr. "Pavlov knew what the dog would do when the bell rang, and we know what people will do."

The system, to be tested here in 200 volunteer households before going into national use, has two parts.

The "People Meter" flashes a green window on the TV screen every 30 minutes that asks "Who's Watching?" Viewers must punch in codes on the attached keypad reporting the age and sex of everyone in the room before the window will go away.

In a small nook on the meter rests a black electronic wand about the size of a fat fountain pen. Volunteer families are expected to run this wand over the universal product code on all purchases whenever they come home from a store. The codes are stored in the wand's memory.

Then, each morning before dawn, Arbitron's central computer in New York automatically queries the People Meter and the Data Scan Wand to find out what the family watched and bought that day.

"It gives you a combination of data that has not been available before," said Arbitron's Conte. "Now the advertiser knows not only whether you saw his spot, but also whether you went out and bought the product afterwards."

Other consumer research firms, including Arbitron's arch-rival A.C. Nielsen and a smaller outfit called Behavior Scan, are experimenting with such combined testing, which the rating industry refers to as "single-source measurement."

But Arbitron's Ken Wollenberg said here that "the People Meter with the Wand is the only single-source tool that's right in the house. It gives you a degree of measurement that we only dreamed of before."

Households around the country voluntarily take part in purchasing and TV-rating surveys every week. Both Arbitron and Nielsen send out thousands of "diaries" in which volunteer families are supposed to write down the TV shows they watch. About 50,000 families each week keep diaries of their grocery purchases for Burke's surveys, McCann said.

Although these written diaries are the mainstays of the TV ratings today, Wollenberg said they can be inaccurate. He said diaries kept in areas where there are many TV stations, including cable, can be wrong as much as one-third of the time.

"But the People Meter has to be accurate, because you can't ignore the prompt," he said. "You don't see the show until you answer the questions."

Families keeping the written diaries receive a small payment -- about one dollar per week. "They do it because they want to get their two cents in, to have a voice in what's on TV," explains William Behanna of Nielsen.

In contrast, families that volunteer for the People Meter and Data Scan Wand will get "a few hundred dollars per year," Wollenberg said, "if they provide all the data we're asking for."

In addition, the household can earn extra money -- say, $50 at a time -- by answering opinion survey questionnaires that will appear on their TV screen now and then.

For all the pride and bravado at the press conference here, there are those in the TV industry who have their doubts about the new People Meters. "This is the most Orwellian of the single-source measures," said David Poltrack, a leading research executive at CBS. "I don't know that they can really find a representative sample of the American people who will let them put this stuff in the house.

"I mean, somebody's going to come home with five bags of groceries and run this wand over everything? I don't know that I would do it," he said.