Comedian Carol Burnett's familiar face appears on the screen. But her message is no joke. "Shoplifting is dumb," she intones. And during the next 25 seconds another actress -- well dressed, blond, with a 5- or 6-year-old child in tow -- is busted for shoplifting.

The public service ad is the latest in the Greater Washington Board of Trade's 13th annual antishoplifting campaign, a campaign that board officials say is working to reduce the rate of shoplifting thefts that total nearly a half billion dollars a year in the metropolitan area. That, representatives of the board's retail bureau say, works out to about $290 that each adult customer must pay each year in higher prices.

After 10 years of steadily increasing losses to shoplifters, such thefts decreased 2 percent last year and 1 1/2 percent more so far this year, a trend that retail bureau chairman Robert J. Mulligan says is due in part to the bureau's $100,000 warning and education campaign and also to technological advances in security systems.

Some of the new technology, ranging from the now-familiar closed-circuit camera systems to new sensor devices triggered by thin strips of tape on the smallest items, were on display yesterday at a bureau news conference at which officials noted that half of all shoplifting losses occur between Labor Day and Christmas.

According to bureau statistics, housewives in their early 30s make up more than a quarter of those arrested in this area for shoplifting. The majority of the culprits are amateurs, Mulligan said, and few who are caught repeat the offense.

The majority can afford the items they are stealing, according to Fairfax County Police Capt. Andrew Page, one of more than a half-dozen area law enforcement officials at the conference. Most stores are not letting those arrested escape a charge by paying for such items, he said.

Several law enforcement officials, including Alexandria Commonwealth's Attorney John Kloch and Prince George's County State's Attorney Arthur A. (Bud) Marshall Jr., said that most shoplifters are actually caught. Marshall said that in the last month in Prince George's, there were 209 complaints of shoplifting and 131 arrests.