That selective attention — and being selective about what gets filtered into long-term storage — helps you conserve your mental resources and really just kind of makes sense. After all, there's no need to remember what you had for breakfast three weeks ago unless it was a particularly life-changing plate of avocado toast, for instance. On the other hand, this is why our memory can at times be fragile — or at least not quite as reliable as we might hope: Maybe that avocado toast was freakin' mind-blowing, but you only remember the view from the patio of the restaurant, not the restaurant's name. Or maybe you never even ate the avocado toast — you just remember your friend telling you about her avocado toast but your mind has co-opted that story as your own (a.k.a. you've created a false memory ).