Monday, May 5, 2008

Loftus

False Childhood Memories

It is one thing to change a detail or two in an otherwise intact memory but quite another to plant a false memory of an event that never happened. To study false memory, my students and I first had to find a way to plant a pseudomemory that would not cause our subjects undue emotional stress, either in the process of creating the false memory or when we revealed that they had been intentionally deceived. Yet we wanted to try to plant a memory that would be at least mildly traumatic, had the experience actually happened.

My research associate, Jacqueline E. Pickrell, and I settled on trying to plant a specific memory of being lost in a shopping mall or large department store at about the age of five. Here's how we did it. We asked our subjects, 24 individuals ranging in age from 18 to 53, to try to remember childhood events that had been recounted to us by a parent, an older sibling or another close relative. We prepared a booklet for each participant containing one-paragraph stories about three events that had actually happened to him or her and one that had not. We constructed the false event using information about a plausible shopping trip provided by a relative, who also verified that the participant had not in fact been lost at about the age of five. The lost-in-the-mall scenario included the following elements: lost for an extended period, crying, aid and comfort by an elderly woman and, finally, reunion with the family.

After reading each story in the booklet, the participants wrote what they remembered about the event. If they did not remember it, they were instructed to write, "I do not remember this." In two follow-up interviews, we told the participants that we were interested in examining how much detail they could remember and how their memories compared with those of their relative. The event paragraphs were not read to them verbatim, but rather parts were provided as retrieval cues. The participants recalled something about 49 of the 72 true events (68 percent) immediately after the initial reading of the booklet and also in each of the two follow-up interviews. After reading the booklet, seven of the 24 participants (29 percent) remembered either partially or fully the false event constructed for them, and in the two follow-up interviews six participants (25 percent) continued to claim that they remembered the fictitious event. Statistically, there were some differences between the true memories and the false ones: participants used more words to describe the true memories, and they rated the true memories as being somewhat more clear. But if an onlooker were to observe many of our participants describe an event, it would be difficult indeed to tell whether the account was of a true or a false memory. Of course, being lost, however frightening, is not the same as being abused. But the lost-in-the-mall study is not about real experiences of being lost; it is about planting false memories of being lost. The paradigm shows a way of instilling false memories and takes a step toward allowing us to understand how this might happen in real-world settings. Moreover, the study provides evidence that people can be led to remember their past in different ways, and they can even be coaxed into "remembering" entire events that never happened.

Studies in other laboratories using a similar experimental procedure have produced similar results. For instance, Ira Hyman, Troy H. Husband and F. James Billing of Western Washington University asked college students to recall childhood experiences that had been recounted by their parents. The researchers told the students that the study was about how people remember shared experiences differently. In addition to actual events reported by parents, each participant was given one false event either an overnight hospitalization for a high fever and a possible ear infection, or a birthday party with pizza and a clown that supposedly happened at about the age of five. The parents confirmed that neither of these events actually took place.

Hyman found that students fully or partially recalled 84 percent of the true events in the first interview and 88 percent in the second interview. None of the participants recalled the false event during the first interview, but 20 percent said they remembered something about the false event in the second interview. One participant who had been exposed to the emergency hospitalization story later remembered a male doctor, a female nurse and a friend from church who came to visit at the hospital. In another study, along with true events Hyman presented different false events, such as accidentally spilling a bowl of punch on the parents of the bride at a wedding reception or having to evacuate a grocery store when the overhead sprinkler systems erroneously activated. Again, none of the participants recalled the false event during the first interview, but 18 percent remembered something about it in the second interview. For example, during the first interview, one participant, when asked about the fictitious wedding event, stated, "I have no clue. I have never heard that one before." In the second interview, the participant said, "It was an outdoor wedding, and I think we were running around and knocked something over like the punch bowl or something and made a big mess and of course got yelled at for it. "

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