Yet creating relatively innocuous memories in normal, healthy people may not relate to the experience of trauma victims. Pezdek found that people who are asked to imagine a plausible event may come to think it actually happened to them, but those asked to picture something implausible are not likely to make that mistake. In one of her studies, volunteers read descriptions of one real event and two false events—one plausible and one not—to a younger sibling or other close relative. The plausible false event described the relative’s being lost in a mall while shopping, and the less plausible description was of receiving an enema. In the study, subjects were much more likely to wrongly remember being lost than to wrongly remember an enema. The findings seem to undermine the idea that an unusual, traumatic event could be the product of a suggestion. “It’s easy to plant the memory of walking around a parking lot, being unable ?to find your car, because that happens to many people,” Pezdek says. “But planting a memory of something like sexual abuse is much harder.”
To probe this question, Clancy, McNally, and a Harvard colleague, psychologist Daniel Schacter, initiated a study of women who claimed to have recovered memories of sexual abuse. These women were at the white-hot center of the memory wars, and yet, Clancy says, “nobody was doing laboratory research on memory formation in this population. We wanted to know whether they were prone to creating false memories.” One of the team’s studies tested four groups of women: those who had been sexually abused and always remembered, those who believed they had been sexually abused but had no memory of it, those who had recovered memories of sexual abuse, and a control group who were certain they had never been abused. Each subject was given a standard word-retrieval test, in which she was presented with a list of semantically related words (such as rest, dream, nap, tired). Each was then presented with the list again, but this time it included a new word (such as sleep) that was similar in meaning to those on the original list.
Those with recovered memories of abuse recalled seeing the missing word on the first list 68 percent of the time, compared with only 38 percent for controls. The recovered-memory group scored significantly higher than any of the other three on false remembering. “There’s a heightened tendency for false-memory formation in those who can recall and visualize recovered memories,” McNally says.
Trauma therapists were outraged by the study. One of their objections: Perhaps the trauma had been so horrific it not only was banished from memory for years but also created memory defects that were now showing up in lab tests. So McNally and Clancy recruited individuals with recovered memories of alien abduction for the next study. Seven out of 11 of the abductees in their experiment had reported (under hypnosis) that aliens had extracted their sperm or eggs for breeding purposes. McNally and Clancy figured that nobody could argue that this group of subjects had post-traumatic stress disorder stemming from actual experiences that impaired their ability to remember events accurately in the lab. “We thought we’d found the perfect study group—people who clearly had created vivid, traumatic, false memories,” Clancy says.
The group produced significantly more false memories on the same word-retrieval test, just as the women with recovered memories of sexual abuse had. But that study also drew ire—from both abductees and the general population. “That totally shocked me,” Clancy says. “I got more hate mail, even from very educated people. I’d get letters asking me who I was to say these people hadn’t been abducted.” (Clancy’s 2005 book, Abducted: How People Come to Believe They Were Kidnapped by Aliens, discusses the studies of abductees in more detail.)
The results of another study with abductees were even more intriguing. McNally, Clancy, and others at Harvard studied physiological stress in 10 abductees and 12 controls. Individuals were interviewed about traumatic, neutral, and pleasant experiences. Thirty-second scripts were distilled from the interviews and then recorded by Scott Orr, who runs a psychophysiology lab at the Manchester VA Medical Center in New Hampshire. Abductees listened to the recordings while hooked up to electrodes that monitor perspiration, heart rate, and muscle tension. This approach has been used many times to measure post-traumatic stress disorder in war veterans. In the study, the abductees had a significantly heightened stress response. Even McNally was surprised. “Their reactivity was as great as real post-traumatic stress patients. These people genuinely believe these events happened, and it’s reflected in their physiology.”
McNally thinks that one reason abductees, who by all other measures are sane and healthy individuals, are more vulnerable to false memories is that “they score higher on measures of fantasy and absorption, which is the ability, for instance, to get lost in daydreams or be utterly entranced by a sunset. Their response to script-driven imagery about pleasurable moments in their lives is also higher than normal. So the upshot is, I think this stress response is a marker for intense emotional memories in people with vivid imaging capacities.”
Could our cherished capacity to imagine, which gives life and art richness, be a key to false memory?
People tend to view imagination as a purely mental activity, but it is strongly linked to vision. The work of Stephen Kosslyn, a Harvard psychologist, explains why.
Kosslyn began conducting neuroimaging studies of the brain (PET and fMRI) in 1990 and made a surprising discovery: Every area of the brain that is activated when we see is also activated when we create an image in our mind. “It was absolutely amazing,” he says. “Even the primary visual cortex, the first visual area of the brain that registers input from the eyes, is activated by imagery with the eyes closed. That suggests the opportunity for distortion is huge. The upside is, if imagery simulates what you actually see in the brain, you can use it for memory or reasoning or predicting. The downside is that you can become confused about the source of images. That’s kind of scary.”
One study of eight easily hypnotized individuals found that when they were simply asked to perceive a color, the color areas in the brain were activated—even if they were looking at a gray scale. The control group did not show this effect. (See “Hypnosis Works,” page 64.) Another study found that vivid visualization accompanied by emotion triggered more activation in visual processing systems than did images alone.