Why, when packing for a holiday, does one thing end up left behind? For a simple task, it’s surprisingly easy to forget the suncream, spare socks or, if you’re unlucky, your passport.
The way the brain works makes it much more difficult to remember to do something at a later moment, known as prospective memory. Retrospective memory, remembering something that has already happened, is much easier. This is because the neural encoding of retrospective memories is activated by context - sounds, thoughts and conversations. So, it’s easy to tell someone what you’ve packed if they ask, but nearly impossible to be sure in advance that you will remember to pack the right things, as you can’t predict the exact context of when you’ll be packing. A slight change to the circumstances, such as an interruption, can thwart the prospective memory of even the most conscientious person.
Perhaps one day we will understand how not to forget things but, for now, the best solution is detailed checklists, or phone alarms – as long as you remember to consult them, or recall what that alarm was supposed to remind you of.
Dr Daniel Glaser is director of Science Gallery at King’s College London
