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New Study Suggests Human Memory Easy to Manipulate - 2003-03-08

Do you believe everything you saw yesterday was real? Don't be so sure. The results of some new studies suggest it is easy to manipulate human memory.

In one experiment, researchers worked with people who had witnessed the actual bombing of several apartment buildings in Moscow in September 1999.

Lead researcher Elizabeth Loftus of the University of California at Irvine says investigators used the power of suggestion to plant some false information about the bombing. "And we made people believe that they had seen a wounded animal in conjunction with that particular bombing when in fact they didn't see that," she says. "So in fact about 12 to 13 percent of our subjects bought into the suggestion, and even went on the describe what this made up animal looked like."

Next, researchers wanted to see whether they could plant entirely false information in the memories of their subjects.

In one experiment, investigators convinced participants that they'd met the cartoon character Bugs Bunny. Using a variety of techniques, including telling participants that researchers had spoken to their relatives - Ms. Loftus says over 30 percent of the subjects said they touched and shook hands with Bugs Bunny at Disneyland. But Ms. Loftus says that would have been impossible since Bugs is not a Disney character, but a creation of the entertainment company Warner Brothers.

And in a third study, a significant number of subjects, 15 percent, were convinced they'd kissed a frog even though they hadn't. Ms. Loftus says the study participants reached the conclusion after they were blindfolded and touched a variety of objects that felt like a frog, at the same time imagining that they had kissed it.

Psychologist Elizabeth Loftus says her studies are harmless experiments. But she says there are times false memories are unintentionally planted, and can be dangerous. She points to the recent incident involving the Washington, DC area sniper case, which made international headlines.

Two alleged shooters killed 10 people going about their daily routines. Police eventually caught the suspects, but not before the public called in a lot of false leads. "This presented a kind of natural experiment where we were all some unwitting subjects in some mass memory contamination situation because, as we know now, the bad guys, the perpetrators, had a dark-colored Chevy Caprice, not a white van [as first had been reported]. But it was the communication of that information and the dissemination of it that contaminated others and caused other people, apparently, to see white vans that may not have been there or certainly may not have been relevant," she says.

Investigators say they manipulate human memory in the laboratory to understand how memories get distorted in the real world.

Researchers presented the results of their studies on memory manipulation at the recent annual meeting of the American Association for the Advancement of Science in Denver, Colorado.