We have thought of memory problems principally in terms of forgetting, but using a new experimental method with amnesic animals has revealed that confusion between memories, rather than loss of memory, may be more important.
While previous research has found that amnesic animals couldn't distinguish between a new and an old object, the new method allows responses to new and old objects to be measured separately. Control animals, shown an object and then shown either the same or another object an hour later, spent more time (as expected) with the new object. However, amnesic animals spent less time with the new object, indicating they had some (false) memory of it.
The researchers concluded that the memory problems were the result of the brain's inability to register complete memories of the objects, and that the remaining, less detailed memories were more easily confused. In other words, it’s about poor encoding, not poor retrieval.
Excitingly, when the amnesic animals were put in a dark, quiet space before the memory test, they performed perfectly on the test.
The finding not only points to a new approach for helping those with memory problems (for example, emphasizing differentiating details), but also demonstrates how detrimental interference from other things can be when we are trying to remember something — an issue of particular relevance in modern information-rich environments. The extent to which these findings apply to other memory problems, such as dementia, remains to be seen.
(2010). Paradoxical False Memory for Objects After Brain Damage.
Science. 330(6009), 1408 - 1410.