To illustrate the power of false memories, Yale psychology professor Marcia Johnson recently told the Graduate School community about an incident during her first year in college.
While having dinner with friends at her parents' house, the conversation turned to droughts, and Johnson related the following story about something that happened when she was five years old:
"My family was driving through the central valley in California when we had a flat tire. My father took the tire off the car and hitchhiked up the road to get the tire patched. My mother, brother, sister and I waited in the hot car. We got very thirsty, and finally my sister took a couple of empty pop bottles and walked up the road to a farmhouse. The woman explained there was a drought, and she had only a little bottled water left. She set aside a glass of water for her little boy and filled my sister's pop bottles with the rest. My sister returned to the car, we drank the water and I remembered feeling guilty that we didn't save any for my father.
"When I finished the story, my parents laughed," Johnson continued. "They said we had taken a trip during a drought, had a flat, and my father did go get it fixed. The rest of us waited a long time in the hot car. My sister complained a great deal about the heat, but nobody went anywhere for water.
"Evidently, what I had done at the time was imagine a solution to our problem -- simultaneously getting rid of my fussy sister and getting us something to drink. Years later, in remembering the incident, I confused the products of my perceptual experience with the products of my imagination. I had what we call a failure in 'reality monitoring,'" she said.
Johnson's research explores the nature of human memory -- from how memories are formed, to how they can be distorted to how we tell the difference between memories for real and imagined events. Her laboratory conducts cognitive studies and uses neuroimaging techniques to investigate the relation between cognitive processes and brain mechanisms. Johnson shared some of her methods and findings in her Feb. 26 talk "Memory and Reality," which was part of the Graduate School's "In the Company of Scholars" series, hosted by Dean Susan Hockfield.
Sometimes false memories can cause more problems than a little dinner-table embarrassment, Johnson noted, citing examples of unconscious plagiarism and questionable legal testimony about childhood sexual abuse from individuals who have undergone highly suggestive sessions to recover memories from childhood.
Our mental experiences "do not have tags hanging on them that specify their source or veridicality," explained Johnson. People reconstruct memories from "perceptual information, contextual information such as time and place, semantic detail, affective information and information about cognitive operations engaged when the memory was established," she said.
"A memory will be judged to have been perceived rather than imagined if it has lots of perceptual detail, lots of contextual detail and does not include much information about cognitive operations," she explained.
When people evaluate the truth of their own memories, they also consider whether their memeories are consistent or plausible, she said. "For example, you might decide that a vivid memory of a friend's remark at a party is only the residue of your own earlier thoughts about what he might have said because you retrieve other knowledge that places him in the hospital at the time of the party." Therefore, however vivid the memory, you might conclude it must be false,
she added.
People continually monitor memories to judge their veracity, but many circumstances influence how accurate they are, Johnson has learned. In fact, her laboratory studies have shown that it is not difficult to lead people to form false memories.
In one study, participants listened to a tape of two people talking about emotionally charged topics, saying such things as: "I support the death penalty"; "There is too much violence on TV"; and "Interracial relationships do not bother me." During the experiment, some participants were encouraged to concentrate on the speakers' emotions. Others were asked to reflect on their own feelings about what was said.
Later, participants took a test in which they had to indicate whether various statements had been said by person A or by person B, or were new. "Participants had higher recognition for statements when, at encoding, they focused on how they, themselves, felt about a statement than if they focused on how the speaker was feeling," said Johnson. "In contrast, participants were much better able to identify the source of statements if they had focused on the speakers than if they had focused on themselves.
"We think that this pattern -- good recognition but poor source accuracy -- is a clear illustration that you can process information in a deep, meaningful and personally relevant way but not necessarily bind it to perceptual and contextual features that are critical later" for determining the accuracy of memories, she noted.
Researchers in several laboratories have also demonstrated that "false memories can be created for complex and emotionally significant events," said Johnson. For instance, researchers will ask relatives of study participants about an actual event, then question the participants about those events, including among them a "false event" that never happened.
"After being questioned about it and, especially, after being encouraged to think about the false event, some participants claim to remember the event," notes Johnson. "For example, adults have been induced to remember being lost in a shopping mall as a child, or to remember being taken as a child to the hospital."
Furthermore, said Johnson, "these false memories can contain quite specific details." In studies where children have been induced to provide "compellingly vivid accounts of complex events," such as having their finger caught in a mousetrap, experts "can't tell the difference between children's accounts of true and false memories" when viewing videos of the children recounting the events.
Such induced autobiographical memories reflect a number of factors," she noted. "Repeated questioning or thinking about an event increases the details that are remembered or confidence in the memory. Encouraging participants to embed a 'memory' in personally relevant details creates supporting evidence. Also, individuals with high imagery ability seem to be more susceptible to induced false memories, presumably because they embellish more or create representations that are more like perceptions."
In real life, the creation of memories about real events is "influenced by our expectations, imaginations and other ruminations, seeing photographs, hearing other people's accounts, and even seemingly unrelated events, and by our goals and motives at the time of remembering," explained Johnson.
"False memories arise from the same encoding, rehearsal, retrieval, and source monitoring processes that produce true memories; thus one can never be absolutely sure of the truth of any particular memory," she noted. "Remembering is always a judgment call."
Johnson concluded her talk with a brief outline of "a very exciting area of basic memory research -- the attempt to link cognitive processes to brain mechanism." Using technologies such as functional magnetic resonance imaging, researchers can now study healthy individuals to determine which brain regions are involved in which cognitive processes. These brain scan studies are "much like some of those I've been describing -- except now the participants are lying down in the scanner rather than sitting upright in the lab," said Johnson.
Being able to see how the brain is functioning while forming and later having memories, she noted, is "about as seductive as science gets."
-- By Gila Reinstein
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