CHICAGO - The notion of hidden ad messages has fascinated the public since the 1950s, when a bogus tale emerged about a theater that boosted refreshment sales by subtly flashing ''Eat Popcorn, Drink Coca-Cola'' messages on the screen.
The advertising industry has long dismissed such subliminal ads as fiction, a view backed by experts. But is on the defensive after a Republican TV ad targeting the Democratic presidential ticket fleetingly showed the word ''RATS.'' The industry insists such techniques are nowhere to be found in commercial ads.
''The reaction in our industry is 'Oh man, not again - will this charade never die?''' Hal Shoup, executive vice president of the American Association of Advertising Agencies, said Wednesday. ''This is a myth that has been perpetrated for the last 30 or 40 years.''
Bob Garfield, an industry critic for Advertising Age magazine, agrees there's no evidence the practice has ever been done.
''Subliminal advertising does not exist except in the public consciousness, at least not in consumer advertising,'' he said. ''Nobody bothers with it because it's hard enough to impress people by hitting them upside the head with images.''
Experts say the concept first entered the public consciousness in the '50s when New Jersey advertising executive Jim Vicary said he'd motivated people to buy concessions by flashing the secret messages touting popcorn and Coke, a claim he later admitted was false.
Vance Packard's book ''The Hidden Persuaders'' discussed the concept at about the same time. Then, in a book that was required reading for millions of college students, Wilson Bryan Key took the notion to new levels with his book ''Subliminal Seduction'' in the 1970s, alleging that phallic images were imbedded in renderings of ice cubes and that patterns of dots making up magazine illustrations spelled out ''sex.''
Those familiar with the ad industry labeled Key's claims preposterous. But the Federal Communications Commission in 1974 issued an order saying that broadcast outlets that knowingly carry such ads are operating ''contrary to the public interest.''
Advertisers themselves were not barred from such practices.
The FCC is currently reviewing a complaint about the Republican ad, which is already off the air. Experts on the ad industry say it's silly to think such techniques would work.
''I'm not saying it might not have been tried,'' says Stephen Greyser, professor of marketing at Harvard Business School. ''But there is no methodically believable research that supports the notion that subliminal advertising works.
''Advertising wants to impact on people's consciousness, not on their unconsciousness,'' he said.
Garfield says the myth of subliminal ads endures despite decades' worth of non-evidence because people enjoy it and want it to be true.
''They like to believe there's a Sasquatch and a Loch Ness Monster and aliens in an Air Force hangar in Roswell, New Mexico,'' he said. ''But there aren't.''
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