system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why are some memories ‘out of reach’ until something reminds us of them?

I don’t have the greatest memory in the world.  Yet if something triggers an old memory, suddenly I can not only remember it, but specific details that were not available a few minutes before.

Why is this?
gpt
I studied brain science in university.

This gets to the core of how memory works. We recall things by *association,* that is, a memory gets activated by things that relate to it. The more related things are activated, the more this memory gets activated too.

This is why when you have difficulty remembering an item, event, person, etc., often you succeed after someone gives you some hints or reminds you about the context.