All psychotherapists -- and most criminal attorneys -- know that memories are fragile things. Once a seemingly well-entrenched memory for a given event -- what psychologists call a declarative memory -- is taken out for inspection, it is subject to being frayed, recolored, reinterpreted and altered. The result is that when that when a memory is returned to long-term storage, it can bear little resemblance to the memory that was laid down initially, or which has been brought out before and subject to change.
A new study finds there is one more thing a bystander can do when someone pulls out a declarative memory: With a bit of sleight-of-mouth and little more, the witness to remembrance can erase it. Or, at least, he or she can make some salient detail of the memory disappear by quietly replacing it with a new and conflicting detail.
The study was published Monday in the journal Proceedings of the National Academies of Science.
Twenty minutes after their viewing ended, some of the subjects had their memories of the episode "reactivated" when they were prompted by researchers to give a full account of the program's details. Others were kept busy for a brief spell with an unrelated task and didn't have that reactivation.
Then, the researchers tried to pull off their memory heist. They read for all subjects a plot-review narrative but replaced the hypodermic needle with a stun gun to see how the subjects' memory of the episode was altered. The subjects whose memory of the
Even when a new crop of subjects watched "24" and were immediately sent home for 48 hours before coming back, the pattern of forgetting was the same. When subjects returned, those whose memories of the episode were reactivated and soon thereafter manipulated with false information were highly likely to have forgotten they had watched a flight attendant subdued with a hypodermic needle. Subjects who came back and first got the narrative with the false detail in it (without first reactivating their own memories of the episode) tended to hold fast to the original memory they had laid down: that it was a hypodermic needle, not a stun gun, that was used to subdue the flight attendant.
In other words, a memory gets laid down one way when it's first experienced. And if you're a psychotherapist (or an unethical criminal attorney) looking to alter that memory by deleting some vital detail, it won't work to simply rewrite the script for the