The business of encoding new memories is more like writing a document on a computer than inscribing words onto paper. Until you save the file, there’s a chance that you could lose the information. This vulnerable window can last for a couple of days. Only after that point does the memory become strong and long-lasting. This is called ‘consolidation’.

It’s not a permanent state. Whenever we remember something, the fragile window reopens. Again, it’s more like opening a computer document than getting notes out of a drawer. You could easily add, edit or delete information at a flick of a key.  Every time we bring back an old memory, we run the risk of changing it. Again, it takes a while