Given a few bogus details and a little prodding, about a quarter of adults can be convinced they remember childhood adventures that never happened.
The experiment is one of a series of exercises psychologists have developed that can plant false memories in the brain. Once they take root, these thoughts often become as real as genuine ones - indeed, perhaps even more so.
“Over time, people may forget things that did happen and remember things that didn’t,” said Henry L. Roediger III of Washington University in St. Louis.
Roediger and other psychologists described their memory experiments Saturday at a meeting of the American Association for the Advancement of Science.
Together, they say the work demonstrates the malleability of memory, the willingness to recall things that make sense or should have happened, even if they didn’t.
“All of us to some extent are susceptible to these kinds of contamination” of memory, said Elizabeth Loftus of the University of Washington in Seattle, who pioneered the field in the 1970s.
In one experiment, Loftus asked parents to list some incidents in their adult children’s pasts. Then she told the children she wanted to compare their memories with the parents’.
She walked them through a series of real incidents and then threw in a fake one: As a young child, they had been lost in a shopping mall and were frightened and cried until an elderly person found them and reunited them with their parents.
With just a little gentle coaxing, Loftus said, about one-quarter of study subjects agree this happened to them. Some even go on to provide new details. The memory can become so fixed that they refuse to believe it is a fake when the experiment is over.
In another experiment, volunteers are asked to look over a list of possible childhood events, such as falling and breaking a window with their hand, and then rate on a scale of 1 to 8 their certainty of whether they happened.
Two weeks later, they are asked to spend one minute creating mental images of some of the events they said they had never experienced. Then they filled out the list again.
After imagining breaking the window, 24 percent became more certain such an event had actually occurred.
Loftus has been a strong critic of psychologists who help people recover memories of supposedly suppressed traumas, such as child abuse. Such memory recovery has been critical in trials of adults accused of sexual assaults on children.
Loftus contends the techniques of some therapists to bring out blocked memories are similar to the ones she used to create fake ones.
Roediger said his work suggests “illusions of memory,” as he calls them, happen often.
In one experiment, he asked students to look at a list of 15 words that included “bed,” “dream,” “blanket,” “doze” and “pillow.” Just over half said afterward that the word “sleep” had been on the list, even though it wasn’t. They even remembered “sleep” more often than some words they actually had heard.
“People are confused between what happened in the outside world and what happened inside their own heads,” Roediger said.
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