Real Pictures Can Trigger False Memories

Most of us can be fooled into believing that we remember an event or an experience that never happened, and that false memory can be just as vivid as memories of real events. Now, new research suggests that an old photo of friends and associates can dramatically reinforce that false memory, even if the photo is not directly related to the phony event.

College students who participated in a study were asked if they remembered a prank they supposedly played on their first grade teacher. They recalled the event with surprising clarity, and they did so in "staggering" percentages, if they were shown a class photo depicting their fellow first grade students and their teacher.

But the event never occurred.

Far more of the students "remembered" the prank than students who were not shown a photo.

Giving Memory Something to Grip

Bolstered by the photo, two-thirds of the students recalled the prank, and talked in great detail about putting a gooey substance called "Slime" in their teacher's desk. Stephen Lindsay, a cognitive psychologist at the University of Victoria, in British Columbia, leader of the project, says he was "flabbergasted" by the numbers.

The research is significant because many clinicians who are trying to help their patients deal with traumatic past events sometimes use old family photos to stimulate their memories. But now it turns out that old photos can also stimulate memories of things that never happened.

Lindsay speculates that the photos fire up the imagination by refreshing the memory of real people, like school teachers and classmates who may have been long forgotten, thus facilitating the formation of "fairly vivid fantasy images."

"Seeing the photo gives your imagination something to work with," he says.

Forty-five undergraduates participated in the research. Parents of the students furnished the researchers with two real events that they thought the students might recall, but fell short of family lore or often repeated stories. Both occurred during the 3rd through the 6th grades. The parents concurred that a third event, which was supposed to have happened during the first grade, never occurred.

Enter: Slime

That's the one involving the Slime, a popular gunk marketed by Mattel which feels like, well, slime. Twenty-three of the participants were shown class photos, which had been supplied to the researchers by the parents, for each of the three school years. The others had no photos.

The participants were interviewed in two sessions, one week apart, by researcher Lisa Hagen, co-author of a report in the March issue of Psychological Science. During the first session, Hagen quizzed the students about the real events, those that occurred during the third through the sixth grades. Students who were shown class photos were significantly better at recalling those events than were those who were not shown photos, but most of the students had no memory of either of the events.

A week later Hagen interviewed each student regarding the first grade prank that never occurred, and here the numbers are startling.

Only 27.3 percent of the students without photos "remembered" the Slime story. But a whopping 65.2 percent of those who were shown a class photo recalled even precise details about putting that awful stuff in the teacher's desk, and getting chewed out for it.

The students were also asked how clearly they remembered the prank, and the first grade story was at least equivalent to, and in some times greater, than their memory of the true events.

"This indicates that these subjects false memories were as compelling as memories of the true events," the researchers wrote in their report.

But does that mean we are all just sitting ducks for false memories of things that never happened?

Not really, Lindsay says.

Outside Influence

He points out that there were some "quite potent suggestive influences" that undoubtedly helped shape the students memories.

"We had told the students that their parents said these things happened to them, so the authority of the parent" comes into play, he says. Plus, the first two stories were true, so students who remembered them had no real reason to doubt the third. And Hagen played an aggressive role, cajoling the students and urging them to rev up their memories.

"So it's not like people are developing false memories at the drop of a hat, or in response to one or two suggestive questions," Lindsay says. "There's quite a lot of suggestive influence piled up here."

Of course, some prosecutors digging into possible child abuse cases also have been known to be "suggestive" when interviewing children, but Lindsay says that's a different ball park.

It's one thing to convince someone they remember a relatively harmless childhood prank, and quite another to dredge up memories of traumatic events.

"The likelihood of one kind of false memories doesn't necessarily predict the likelihood of another," he says. Recalling previous research, he adds:"We know that a single passing suggestion can be enough to get two-thirds of a group of undergraduates to report that they saw something in a film that they didn't see. But that's not very rich, and elaborate, and personal or meaningful.

"It takes a lot more to get people to have a false memory of pulling a prank, and it would take far more to get people to believe they had been abducted by aliens, or raped by their parents," Lindsay says.

‘So Weird’

So it takes a much more aggressive approach to implant false memories of a terrible, personal trauma. By the way, at the end of the research project the students were all told that one of the three events was false, and they were asked to guess which one it was. All but three said they thought it was the story about the first grade prank, the "pseudoevent," as the researchers put it.

But they were astonished to realize that an event some of them recalled so clearly had never happened. "You mean that didn't happen to me?" one of them asked.

"If you didn't tell me it was a false event, I would have left here thinking I did this," said another. "No way," said yet another. "I remember it. That is so weird."

Lee Dye’s column appears weekly on A former science writer for the Los Angeles Times, he now lives in Juneau, Alaska.