Also last month, Bryan Strange of the Wellcome department of imaging neuroscience at University College London and colleagues showed that people were more likely to remember a word if it was emotionally arousing - "murder" or "scream", say - than if it was neutral.
And the words most likely to be forgotten were neutral ones presented just before emotionally arousing ones. The effect was more pronounced in women than in men, and both the enhanced memory for the emotional word and the forgettability of the preceding neutral one could be reversed by dosing the volunteers in advance with the drug propranolol. Propranolol, a commonly prescribed beta-blocker, interferes with the neurochemical pathway thought to be responsible for making emotionally arousing events more memorable - the beta-adrenergic system - and it has already been used experimentally in the treatment of patients with PTSD.
In one study, published in October, Guillaume Vaiva of the University of Lille and colleagues offered prop- ranolol to victims of assault or motor accidents shortly after their traumatic experience, and then invited them back for psychological testing two months later.
On their return, almost all the patients exhibited some symptoms associated with PTSD, but they were twice as severe among those who had not taken the drug. The finding that propranolol can be effective at blocking memory when given after an event as well as before is important because, as Loftus explains, "In the real world you can't be there to exert your manipulations right at the time an event is happening, but you can get on the scene later.
But could it also be used to erase false memories - for instance, "recovered" memories of alien abduction - that nevertheless elicit all the physiological responses associated with harrowing, real memories? But Ray Dolan of UCL, a co-author with Bryan Strange of the study on memory for emotional words, points out that not all false memories have a common basis.
If they are interpolations into gaps in memory, such as the gap that opened up before the presentation of an emotionally arousing word, or possibly the gap into which Alan Alda inserted a memory of having over-indulged in eggs, then it is conceivable the drug would work.
But, says Dolan, "Other classes of false memory, for example, where the memories are fantasies or out-and-out fabrications, would be immune to propranolol.
The idea of doctors having the power to wipe the memory clean sends shivers down many people's spines. False memories could safely be erased, perhaps, assuming there was a reliable way of differentiating them from true ones.
Although brain-imaging techniques highlight some differences in patterns of brain activation when a person recalls a true as opposed to a false memory, these are statistical differences only. True memories, too, can get out of control and become destructive, leading to PTSD and other anxiety disorders.
But they start out as an important self-defence mechanism - teaching you, for instance, that too many hard-boiled eggs are bad for you.
In their new study, Oeberst and his team of researchers were able to successfully implant false memories in study subjects, before successfully reversing the same memory. With the help of parents, the researchers implanted false memories in 52 subjects with a median age of The parents identified events in their child's life that had and had not happened — they also invented two events that were plausible but had not happened. In several sessions, the psychologist researchers then questioned the test subjects about these events, and asked them to recall details about the memories.
By the third session, most participants believed the false events had actually occurred. More than 50 percent of those participants also developed false memories about those events.
Short-term memory allows us to be present in the moment, while long-term memory helps piece together our identity through the recollection of our past experiences, among other things. Yet, especially the farther back we go, the more our recollection gets murky. For example, when you think back to your childhood, you are reconstructing your past while also being affected by the current circumstances: who is asking, why, and how, Oeberst explained.
But this certainty can be an illusion. Indeed, our minds are able to fabricate memories of entire events just by piecing together bits of stories, photographs, and anecdotes somebody else shares. Then they had researchers ask the participants to recall these made-up events in a detailed manner, including specifics about what happened.
Moreover, and importantly, this did not affect their ability to remember true events. By empowering people to stay closer to their own truth, rather than rely on other sources, we showed we could help them realise what might be false or misremembered - something that could be very beneficial in forensic settings. Rich false memories of autobiographical events can be reversed.
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