DENVER--Like the people in audiotape commercials who can't tell a recording from a live singer, researchers can't distinguish the physiological responses to false memories from those to the real thing, according to results presented here at a meeting of the American Association for the Advancement of Science (ScienceNOW's publisher) on 17 February. The results add to evidence that even the most vivid recollections are not always trustworthy.
People who have endured horrible ordeals shudder and shake when they recall the events. People who create memories of trauma are often as steadfast in their belief in the reality of the incident as real-life trauma survivors are. Psychologist Richard McNally of Harvard University wanted to know how deep the conviction goes: Do people who remember false traumatic events show the same physiological reactions to the memories as others who experienced real trauma?
McNally investigated people who had memories that were clearly fake--namely, memories of alien abductions. To test how six female and four male "abductees" responded when remembering, the researchers created short audiotapes based on the volunteers' abduction stories. While volunteers listened to the stories, the researchers measured heart rate, sweating, and facial muscle tension. All measures were elevated as the abductees listened to their kidnapping stories. The stress responses mirrored those of people remembering Vietnam combat events and childhood sexual abuse. (Indeed, more than half of the alien abductees exhibited some symptoms of posttraumatic stress disorder.)
The response to trauma "is driven by emotional beliefs, whether accurate or not," McNally reported. "If you sincerely think you were being abducted by aliens, you were." The study suggests that the physical reactions to false memories are the same as those to true memories, says psychologist Michelle Leichtman of the University of New Hampshire, Durham. The result "is troubling ... it underscores the similarities between true and false memories at an even more profound level" than researchers generally think.